SPECTROSCOPY OF THE EXTENDED ORION NEBULA. A Thesis. Submitted to the Graduate Faculty. Fisk University. Department of Physics. Jessica Anne Harris

Transcription

1 SPECTROSCOPY OF THE EXTENDED ORION NEBULA A Thesis Submitted to the Graduate Faculty of Fisk University Department of Physics by Jessica Anne Harris In Partial Fulfillment of the Requirements for the Degree of Master of Arts May 2010

2 FISK UNIVERSITY Approval Sheet for Thesis Submitted in Candidacy for the Degree of Master of Arts SPECTROSCOPY OF THE EXTENDED ORION NEBULA by Jessica Anne Harris B.S. Grambling State University, 2008 Grambling, Louisiana Approved by the Department of Physics Dr. C.R. O Dell Thesis Supervisor Date Dr. J. Kelly Holley-Bockelmann Committee Member Date Dr. Warren E. Collins Committee Member Date Dr. Steven H. Morgan Department Chair Date

3 Contents 1 Introduction 1 2 Physics Applications of Nebulae Explanation of Photoionization Equilibrium: Hydrogen Only Nebula Explanation of the Photoionization Equilibrium with other Elements Stromgren s Boundary Ionization Zones of He +, He 0, and Ionization Front Thermal Equilibrium: The Process of Heating Cooling Process Interpretation of Emission Line Spectra Explanation of Interstellar Extinction Data Reduction Analysis Spectroscopic Observation Initial Processing of Raw Data Detailed Explanation of Various IRAF Tasks Results of Temperatures and Densities Derived From TEMDEN Explanation of TEMDEN Electron Temperatures and Densities Calculated from TEMDEN Conclusion 127 Bibliography 128

4 List of Figures 2.1 Absorption coefficient vs. Energy Flux distribution Flux of the star vs. the energy Ion Ratio vs. Stromgren s boundary of Hydrogen Ion Ratio vs. Stromgren s boundary of Helium A cartoon illustration of the line of sight into the nebula Radiation Hardening Heating Curve Excitation Energy Diagram Rate of Cooling Equilibrium Rate of Heating and Cooling Energy Level Diagrams of [O III] and [N II] Energy Level Diagrams of [S II] and [Cl III] Emissivity Ratio vs. Density Quantum Efficiency vs. Wavelength Optical Depth vs. Wavelength Gendler 2arcsec:Slits Flow Chart of Spectrophotometric Calibration Spectrum of Nebula One Dimensional Image of A Star Before Removal One Dimensional Image of A Star After Removal Distance vs. Electron Temperatures of [N II] and [O III] Distance vs. Electron Densities of [S II] and [Cl III] Electron Temperature of [N II] on Gendler Image Electron Densities of [O III] on Gendler Image Electron Densities of [S II] on Gendler Image Electron Densities of [Cl III] Gendler Image

5 List of Tables 2.1 Ionization Potentials of the Ions Ionization Zones Critical Densities of [S II] and [Cl III] Observational Log Data* Positions of Samples Positions of Samples Positions of Samples Samples of Star Removed Data* Observed and Extinction Corrected Line Ratios: 1east Observed and Extinction Corrected Line Ratios: 1west Observed and Extinction Corrected Line Ratios: 2east Observed and Extinction Corrected Line Ratios: 2mid Observed and Extinction Corrected Line Ratios: 2west Observed and Extinction Corrected Line Ratios: 3east Observed and Extinction Corrected Line Ratios: 3mid Observed and Extinction Corrected Line Ratios: 3west Observed and Extinction Corrected Line Ratios: 4east Observed and Extinction Corrected Line Ratios: 4mid Observed and Extinction Corrected Line Ratios: 4west Observed and Extinction Corrected Line Ratios: 5east Observed and Extinction Corrected Line Ratios: 5mid Observed and Extinction Corrected Line Ratios: 5west Observed and Extinction Corrected Line Ratios: 6east Observed and Extinction Corrected Line Ratios: 6mid Observed and Extinction Corrected Line Ratios: 6west Observed and Extinction Corrected Line Ratios: 7east Observed and Extinction Corrected Line Ratios: 7mid Observed and Extinction Corrected Line Ratios: 7west Observed and Extinction Corrected Line Ratios: 8east Observed and Extinction Corrected Line Ratios: 8mid Observed and Extinction Corrected Line Ratios: 8west Observed and Extinction Corrected Line Ratios: 9east Observed and Extinction Corrected Line Ratios: 9mid Observed and Extinction Corrected Line Ratios: 9west Observed and Extinction Corrected Line Ratios: 10east Observed and Extinction Corrected Line Ratios: 10mid Observed and Extinction Corrected Line Ratios: 10west Observed and Extinction Corrected Line Ratios: 11east Observed and Extinction Corrected Line Ratios: 11mid Observed and Extinction Corrected Line Ratios: 11west Observed and Extinction Corrected Line Ratios: 12east

6 LIST OF TABLES vi 3.37 Observed and Extinction Corrected Line Ratios: 12mid Observed and Extinction Corrected Line Ratios: 12west Observed and Extinction Corrected Line Ratios: 13east Observed and Extinction Corrected Line Ratios: 13mid Observed and Extinction Corrected Line Ratios: 13west Observed and Extinction Corrected Line Ratios: 14east Observed and Extinction Corrected Line Ratios: 14mid Observed and Extinction Corrected Line Ratios: 14west Observed and Extinction Corrected Line Ratios: 15east Observed and Extinction Corrected Line Ratios: 15mid Observed and Extinction Corrected Line Ratios: 15west Observed and Extinction Corrected Line Ratios: 16east Observed and Extinction Corrected Line Ratios: 16mid Observed and Extinction Corrected Line Ratios: 16west Observed and Extinction Corrected Line Ratios: Observed and Extinction Corrected Line Ratios: Observed and Extinction Corrected Line Ratios: 19east Observed and Extinction Corrected Line Ratios: 19west Observed and Extinction Corrected Line Ratios: Observed and Extinction Corrected Line Ratios: Observed and Extinction Corrected Line Ratios: Observed and Extinction Corrected Line Ratios: Observed and Extinction Corrected Line Ratios: 24north Observed and Extinction Corrected Line Ratios: 24south Observed and Extinction Corrected Line Ratios: 25north Observed and Extinction Corrected Line Ratios: 25south Observed and Extinction Corrected Line Ratios: 26north Observed and Extinction Corrected Line Ratios: 26south Observed and Extinction Corrected Line Ratios: 27east Observed and Extinction Corrected Line Ratios: 27west Observed and Extinction Corrected Line Ratios: 28east Observed and Extinction Corrected Line Ratios: 28west Flux Ratios of [N II], [O III], [Cl III], [S II] for TEMDEN Flux Ratios of [N II], [O III], [Cl III], [S II] for TEMDEN Flux Ratios of [N II], [O III], [Cl III], [S II] for TEMDEN Corrected Flux Values Corrected Flux Values Corrected Flux Values Electron Temperatures and Densities* Electron Temperatures and Densities* Electron Temperatures and Densities*

7 1. Introduction The Extended Orion Nebula (EON) is an ionized region of the dominant molecular cloud in the constellation Orion (O Dell, 2001). Even though the Orion Nebula is the most studied nebula, our research is the first time the Extended Orion Nebula has been spectroscopically observed. The EON is dominantly ionized by θ 1 Ori C, which is the dominant photo-ionizing star in the Orion Nebula (O Dell and Goss, 2009). Little is known about the structure of the EON. The EON has the form of an ellipse on the plane of the sky. With the study of the EON, we can obtain a more comprehensive understanding of the Orion Nebula. We will give a detailed explanation of the physical processes in a nebula. If this physics can be applied to our closet nebula, Orion, then we hope to apply these concepts to various nebulae in the universe. This is done to create a foundation of theoretical concepts which will explain the data reduction analysis. Spectroscopic observations were taken from Cerro Tololo Inter-American Observatory (CTIO) 1.5m in December Further, we will explain the process of photoionization and recombination to explain the process of photoionization equilibrium which occurs throughout nebulae. We will then explain Stromgren s boundaries and ionization zones to illustrate a line of sight into a nebula. This will help identify the specific ions that contribute in the determination of electron temperature and densities. In addition, the process of heating and cooling is explained to illustrate the effects the distance of an ionizing star has upon determining electron temperatures and densities. Finally, we will explain how we use the emission line spectra of [O III], [N II], [S II], and [Cl III] ions to determine electron temperatures and densities.

8 2. Physics Applications of Nebulae In this section, we will give a detailed explanation of the physical processes that occur in a nebula, with the main goal to highlight certain physical processes in Orion (M 42). This will initially involve the explanation of photoionization equilibrium (for hydrogen only), defining and explaining photoionization and recombination, and an explanation of the balance between photoionization and recombination. This section will also explain the line of sight into a nebula through a detailed explanation of the Stromgren s boundary and ionization zones of He +, He 0, and ionization front. We will include the physical process of the rate of heating and cooling as well as an in depth explanation of how the emissivity ratios [S II], [N II], [O III, and [Cl III] are calculated. The process of interstellar extinction will be introduced to explain its effects upon the observed ratio of intensities. 2.1 Explanation of Photoionization Equilibrium: Hydrogen Only Nebula Photoionization (PI) Equilibrium is a balance of the rate of photoionization and recombination which occurs throughout a nebula. Since hydrogen is the most abundant element in a nebula, we will construct an idealized nebula of hydrogen only. Consider a volume of hydrogen gas illuminated by a distant hot star, such as an O or B star. For a volume of gas in a constant state of photoionization equilibrium, the rate of photoionizations is equal to the rate of recombinations. Photoionization is the process of converting an ion to a higher ionization state, through the absorption of a photon. An energy of 13.6 ev, the ionization potential for hydrogen, is required to move an electron from a ground state to an unbound state. If an incident photon has an energy less than 13.6 ev, then the electron will not be removed from the atom. The electron can be excited to another energy state, but then will come back down to the ground state (hydrogen will remain neutral). Recombination is the process of recreating a hydrogen atom. Hydrogen atoms are formed from free electrons into

9 2. Physics Applications of Nebulae 3 an excited state that can then cascade down by radiative transitions to the ground state. The general behavior of recombination is determined by temperature. The recombination coefficient to a particular atomic level n 2 L can be written as: α n 2 L(H 0 )= + 0 vσ nl (H 0, ν) f(ν) dν (2.1) f(ν) = 4 ( m π 2kT ) 3 2 ν 2 e mv 2 2kT (2.2) is the Maxwellian-Boltzmann distribution function for the electrons, and σ nl (H 0, ν) is the recombination cross section to the term n 2 L in H 0 for electrons with velocity, ν (Osterbrock, 1989). There is a greater chance of an electron and proton recombining when moving at slow velocities than at higher velocities, which means recombinations are also most likely to occur at lower temperatures than high temperatures. If the cross section σ is proportional to v 2, then the recombination coefficient will be proportional to 1/T 1 2. The balance of photoionization and recombination is stated best in the photoionization equilibrium equation: + ν 0 L ν 4πr 2 e τν hν N H 0α ν(h 0 )dν = α B (T )N H +N e (2.3) In the left hand side of the equation, the integral is the photon energy over all frequencies than can cause ionization. L ν is the total luminosity of the star; e τν is the attenuation and τ ν is the optical depth. The number of neutral hydrogen atoms is N H 0 ; α ν is the absorption coefficient and N H 0α ν is the probability of an electron being absorbed over a given area. Hence, the left hand side can be considered the photoionization per unit time and volume. The right hand side of the equation is the

10 2. Physics Applications of Nebulae 4 number of recombinations per unit time and volume. α B is the recombination coefficient; N H + the number of photons; N e is the number of elections (Osterbrock, 1989). In a plot of absorption coefficient verses energy one would notice the absorption coefficient is zero until one reaches the ionization potential and then rapidly decreases with increasing energy. Figure 2.1 Absorption coefficient vs. Energy 2.2 Explanation of the Photoionization Equilibrium with other Elements For completeness in the explanation of the photoionization equilibrium we must include heavier elements than hydrogen. The first element to consider is helium, helium being the second most abundant element in a nebula. The photoionization equilibrium equation for singly ionized helium is: + and for doubly ionized helium: ν 0 L ν 4πr 2 e τν hν N He 0α ν(he 0 )dν = α B (T )N He +N e (2.4) + ν 0 L ν 4πr 2 e τν hν N He +α ν(h 0 )dν = α B (T )N He +2N e (2.5) Note that the above equations are very similar to the previous photoionization

11 2. Physics Applications of Nebulae 5 equilibrium for hydrogen, note however N He 0 is the number density of neutral helium, N He + is the number density of singly ionized helium, and N He +2 is the number density of doubly ionized helium. Helium has an ionization potential of 24.6eV and 54.4 ev, meaning a photon of an energy greater than 24.6 ev can singly ionize helium and a photon of an energy greater than 54.4 ev can doubly ionize helium. A photon of an energy greater than 24.6 ev can either ionize hydrogen or helium. Within Orion, there is no temperature which will produce a photon of an energy 54.4 ev, therefore, doubly ionized helium will be omitted in any further explanation of photoionization equilibrium. 2.3 Stromgren s Boundary To better understand a line of sight into a nebula it will be useful to explain Stromgren boundaries, radiation fields seen in different layers in a nebula, and the ionization zones in the nebula. Stromgrens boundary is the point at which an ion goes from one state of ionization to the next lower state of ionization. The Stromgren boundary of hydrogen, r s (H), is the point at which the completely singly ionized hydrogen rapidly changes to completely neutral hydrogen. Similarly, the Stromgren boundary of helium, r s (He), is the point at which completely singly ionized helium rapidly changes to completely neutral helium. Below is a sketch of the flux of the hot star versus energy:

12 2. Physics Applications of Nebulae 6 Figure 2.2 Flux distribution closest to the star vs. energy An illustration of the flux distribution that would be seen by material closest to the hot star is shown in Figure 2.2, highlighting the ionizations that can occur at either an energy of 13.6 ev or 24.6 ev. At each Stromgrens boundary the radiation field changes. The Stromgren boundary of helium Figure (2.5) will rapidly change from being completely singly ionized to completely neutral and hydrogen will continue to remain completely singly ionized. At this Stromgren boundary, photons at an energy greater than 24.6 ev can be removed through photoionization. In the further most region from the star Figure (2.3) only an energy of 13.6 ev or less will be seen; any energy greater than this will have been absorbed by the intervening medium. Helium will remain completely neutral in this region. Hydrogen will rapidly change from being completely singly ionized to completely neutral. Only photons of an energy greater than 13.6 ev can be removed through photoionization at this Stromgrens boundary. Below are figures of the flux distribution of the star versus energy highlighting the radiation fields at various Stromgrens boundaries.

13 2. Physics Applications of Nebulae 7 Figure 2.3 Figure to the left is the region of the solid horizontal lines is an illustration of the cut of He 0 photoionization and the figure to the right is the outer region from the star, the dashed horizontal lines illustrate the cut off by He 0 and H 0 photoionization. The Stromgrens boundaries are related to the distance to a hot star. Close to the star atoms are almost completely ionized and become progressively neutral at a distance away from the star, eventually becoming completely neutral at the Stromgrens boundary. In a plot of ion ratios versus the distance of the Stromgrens boundaries to the star one will notice a rapid decrease in the ion ratios as it approaches distance of the Stromgrens boundaries of either hydrogen d s (H) or helium d s (He) to the star. The figures are illustrated below: Figure 2.4 Illustration of the ion ratio of the number of ionized hydrogen to the number of neutral hydrogen vs. distance of the Stromgren s boundary of hydrogen from the star.

14 2. Physics Applications of Nebulae 8 Figure 2.5 Illustration of the abundance ratio of the number of singly ionized helium to the number of neutral helium vs. distance of the Stromgren s boundary of helium from the star. This rapid decrease can be best explained when referring back to the photoionization equilibrium equation. In the photoionization equilibrium equation (2.4) and (2.5), if the r in the left hand side of the equation is small (meaning close to the star) the flux of the star (L ν /4πr 2 ) is going to be large, meaning to balance the left hand side of the equation N He 0 must be small. The fraction of neutral hydrogen is small. The optical depth is going to be close to zero so e τν goes to 1. Note that the flux of the star is the dominating factor in the determination of the abundance of neutral hydrogen or helium. However, if r is large (further away from the star) the flux of the star is smaller, to balance the equation the fraction of neutral hydrogen must be large, thus causing the optical depth to become larger, the attenuation now being the dominate factor. 2.4 Ionization Zones of He +, He 0, and Ionization Front It is important to elaborate on the determination of the ionization structure specifically within Orion for ions hydrogen, helium, oxygen, nitrogen, sulfur and chlorine. The photoionization equilibrium equation holds true for all ions as in hydrogen and

15 2. Physics Applications of Nebulae 9 helium. The radiation field however is determined by the most abundant elements hydrogen and helium. A line of sight into the nebula from the star then passes through various ionization zones. The ionization zone closest to the star is the He + zone, where helium is completely singly ionized. The Stromgren boundary of He 0, r s (He 0 ), separates the He + and He 0 zones. The He 0 zone is where helium is completely neutral. The Stromgren boundary of H 0, r s (H 0 ), also known as the ionization front, is the last boundary one will see in the further-most region from the star. A cartoon illustration of the line of sight into the nebula is shown below. Figure 2.6 A cartoon illustration of the line of sight into the nebula

16 2. Physics Applications of Nebulae 10 The ionization potentials of the ions allow one to determine whether or not an ion is in the He +, He 0, H 0 zone. A table of the ionization potentials is below: Table 2.1 Ionization Potentials of the Elements (in volts) Element 0 to + + to to to to +5 2 He N O S Cl The He + zone, is a volume of gas which contains H +, N +2, O +2, S +3, and Cl +3. At the Stromgren boundary of He 0, r s (He 0 ), helium transitions from being completely singly ionized to neutral, N +2 to N +, O +2 to O +, S +3 to S +2, Cl +3 to Cl +2. In the further most region from the star is the H 0 zone. At the ionization front, H + can transition to H 0, N + to N 0, O + to O 0, S +2 to S +, and Cl +2 to Cl +. A table of the ionization zones is illustrated in the table below, highlighting ions in each zone and the transition the ions go through at the ionization front. Table 2.2 Ionization Zones Element He + Zone He 0 Zone Ionization Front (I.F.) Hydrogen H + H + H + to H 0 Nitrogen N +2 N + N + to N 0 Oxygen O +2 O + O + to O 0 Sulfur S +3 S +2 S +2 to S + Chlorine Cl +3 Cl +2 Cl +2 to Cl + Tracer [0 III] [N II], [Cl III] [S II]

17 2. Physics Applications of Nebulae 11 With this knowledge of the ionization zones, can use [O III] in the He + zone to determine temperature. In the He 0 zone one is able to use [N II] and [Cl III] to determine temperature and density, respectively. [S II] in the ionization front can be used to determine temperature and density. To determine how this is done one will need to evaluate thermal equilibrium, the processes of heating and cooling. 2.5 Thermal Equilibrium: The Process of Heating The process of heating occurs by photoionization. One need only consider heating in a pure hydrogen nebula. The energy created through heating occurs after the process of photoionization. The difference between hν (the energy of the electron coming in) and hν 0 (the ionization potential energy of the ion to be ionized) is the total amount of energy given into the gas through photoionization. The rate of heating, G(H), is equal to the energy input through photoionization per unit time and volume. If one solves the photoionization equilibrium equation for the number of neutral hydrogen N H0 and substitutes it into the rate of heating equation, then one would notice N H 0 is eliminated from the equation. This substitution can be done because the nebula is in ionization equilibrium. The resulting equation is the product of the recombination rate N p N e α B (H 0,T) and the recombination coefficient α(h 0,T), where N p is the number of protons and N e is the number of electron. 1 2 mv2 = h(ν ν 0 ) (2.6) G(H) =N H 0 + ν 0 L ν 4πr 2 hν α νh(ν ν 0 )dν (2.7) G(H) =N p N e α B (H 0,T) <h(ν ν 0 ) > (2.8)

18 2. Physics Applications of Nebulae 12 Interestingly, the rate of heating is independent of the distance to the star. The heating rate is constant up until the Stromgren edge, where radiation hardening becomes important. Radiation hardening can be best explained when introducing the absorption coefficient versus energy plot (refer to Figure 2.1). This means that the lowest energy photons are removed closest to the star, leaving only higher energy photons. When these higher energy photons are absorbed, the energy of their photoelectrons is greater. The result of radiation hardening is plotted below: Figure 2.7 Radiation Hardening In the heating rate equation, since the α B increases with decreasing temperature, the heating curve takes the form: Figure 2.8 Heating Curve The heating rate decreases with increasing temperature; this is due to the prob-

19 2. Physics Applications of Nebulae 13 ability of recombination. The excess energy from ionization continues to become greater as more hydrogen atoms are ionized. 2.6 Cooling Process Radiative decays from collisionally excited states produce cooling. In low density regions, every collisional excitation is followed by radiative decay. All heavy ions in low quantum states can be collisionally excited by the electrons produced through photoionization. In the low densities of nebulae, these collisional excitations are followed by radiative decays by photons that escape and cool the gas. The excitation energy, x 12 is the energy required to move an electron from a lower energy state to a higher energy state. If the incoming electron energy is greater than the excitation energy, then the electron will be moved to the next energy level. Figure 2.9 Excitation Energy Diagram The cross-sectional area from state 1 to 2 is defined as σ 12. If the kinetic energy of the free electron is greater than the excitation energy of 1 to 2, then σ 12 = π h2 m 2 v 2 Ω(1, 2) w 1 for 1 2 mv2 >x 12 (2.9) The impact parameter is defined by Ω(1, 2) (Osterbrock, 1989), a quantum mechanic dimensionless factor, which is approximately constant near the threshold. The statistical weight is defined by w 1, m is the mass of the electron, ν is the velocity before collision. The cross-sectional area from state l to 2 is zero however, if the

20 2. Physics Applications of Nebulae 14 kinetic energy of the free electron is less than the excitation energy of 1 to 2, then σ 12 =0for 1 2 mv2 <x 12 (2.10) The collisional excitation rate per unit time and volume is q 12 N 1 N e, where q 12 is q 12 = Ω(1, 2) t 1/2 w 1 e x 12/kT (2.11) where N 1, is the number density target ion and N e is the number of electrons. The constant t is used to defined T/10 4 and the Boltzmann constant (κ) has the value κ = 1 ev 11, 606 K (2.12) Thus the rate at which cooling occurs through collisions is: L 12 = q 12 x 12 N 1 N e (2.13) L 12 = t 1/2 Ω(1, 2) w 1 e x 12/kT x 12 N 1 N e (2.14) The rate of cooling plot is: Figure 2.10 Rate of Cooling

21 2. Physics Applications of Nebulae 15 The equilibrium temperature, T e, is the point at which the rate of heating is equal to the rate of cooling. This is plotted below: Figure 2.11 Equilibrium Rate of Heating and Cooling 2.7 Interpretation of Emission Line Spectra The emission line of an ion with a large difference in the third and second energy level can determine temperature. If the difference in the third and second energy level is small one can use these ions to determine density. Consider a three level ion, where the energy levels between 1 and 2 are known as the nebula lines, the energy levels between 2 and 3 are known as the auroral lines, and the energy levels between 1 to 3 are known as the trans-auroral lines. In the energy level diagrams of [O III] and [N II], there is a large difference between the auroral lines (Osterbrock, 1989).

22 2. Physics Applications of Nebulae 16 Figure 2.12 Energy Level Diagrams of [O III] and [N II] The collisional excitation rate per unit time and volume between state 1 and 2 is q 12 N 1 N e = t 1/2 Ω(1, 2) w 1 e x 12/kT N 1 N e (2.15) and the excitation rate per unit time and volume between state 1 and 3 is q 13 N 1 N e = t 1/2 Ω(1, 3) w 1 e x 13/kT N 1 N e (2.16) Each collisional excitation is followed by a radiative decay. Since the photons can be observed and the collisional excitation rates are dependent on temperature, we can use observations of the radiation to determine the temperatures. F 12 F 32 = q 13N 1 N e q 13 N 1 N e hν 12 hν 32 1 [A 32 /(A 32 + A 31 )] (2.17) The rate of collisions up from state 1 to 2 is: L 12 = t 1/2 Ω(1, 2) ω 1 e x 12/kT N 1 N e (2.18)

23 2. Physics Applications of Nebulae 17 The rate of the collisions up from state 1 to 2 is L 12 = t 1/2 Ω(1, 3) ω 1 e x 13/kT N 1 N e (2.19) The rate of collisions up the nebula lines and the rate of collisions from the transauroral lines is similar to equation (1.14) minus the excitation energy, x 12 and x 13, respectively. The emissivity ratio being emitted by transitions: j 2,1 = Ω 12 e x12/kt hν 12 1 j 3,2 Ω 13 e x 13/kT hν 32 [A 32 /(A 32 + A 31 )] (2.20) where the first two terms are the comparison of collisions from state 1 to 2, and state 1 to 3. The factor of e (x 13 x 12 )/kt highlights that temperature, T, is the only non-constant in the rate of energy equation. Branching is the fraction of all the decays from state 3 that will produce an observable 3,2 photon, [A 32 /(A 32 + A 31 )]. The emissivity ratio for [O III] is j 4959 j 5007 = and the emissivity ratio for [N II] is 7.73e 3.29/t 1 (2.21) (N e /t 1/2 ) j j 6583 j 5755 = 6.91e 2.50/t 2 (2.22) (N e /t 1/2 ) Consider a three level ion, where the energy states between the 2 and 3 level is very small. The energy level diagrams of [Cl III] and [S II] are shown below: 1 Equation (5.4), except t= T/10 4. (Osterbrock, 1989) 2 Equation (5.5), except t= T/10 4.(Osterbrock, 1989)

24 2. Physics Applications of Nebulae 18 Figure 2.13 Energy Level Diagrams of [S II] and [Cl III] The collisional excitation per unit time and volume will not depend on temperature. In a high density case the collisional excitation can be determined by the Boltzmann equations, the ratio of N 2 to N 1 is N 2 N 1 = ω 2 ω 1 e x 12/kT (2.23) and the ratio from N 3 to N 1 is: N 3 N 1 = ω 3 ω 1 e x 13/kT (2.24) The quotient of these two ratios equals the ratio of N 3 to N 2 N 3 N 2 = ω 3 ω 2 e x12/kt e x 13/kT (2.25) The difference in the excitation energies is very small, one will consider it to be zero, so the ratio of N 3 to N 2 becomes N 3 N 2 = ω 3 ω 2 (2.26)

25 2. Physics Applications of Nebulae 19 Thus the emissivity ratio is j 3,1 j 2,1 = ω 3A 31 hν 31 ω 2 A 21 hν 21 (2.27) The emissivity ratio for [S II] is and the emissivity for [Cl III] j 6731 j 6713 = ω 3A 6731 hν 31 ω 3 A 6716 hν 21 (2.28) j 5531 j 5518 = ω 3A 5531 hν 31 ω 3 A 5518 hν 21 (2.29) In a low density case every collisional excitation is followed by radiative decay. Thus the emissivity ratio is j 3,1 j 2,1 = ω 3A 31 hν 31 ω 3 A 31 hν 21 = ω 3 ω 2 hν 31 hν 21 (2.30) The collisional excitation is directly related to the statistical weights. Critical density (N c ) is the density at which the probability of radiative decay equals the collisional de-excitation of an electron in an excited state. Electrons bound in an excited state can quantum mechanically emit a photon, causing radiative decay. Alternatively, an electron can be collisionally de-excited mechanically. An electron in its bound excited state can collide with a free electron, causing it to lose its energy to the free electron and de-excite to a lower energy state. The critical density is N 2 A 21 = q 21 N 2 N e N e = ω 2A 21 t 1/ Ω 12 (2.31) Below is a table of the critical densities of [S II] and [Cl III]

26 2. Physics Applications of Nebulae 20 Table 2.3 Critical Densities of [S II] and [Cl III] Ions N c (cm 3 ) Range [S II] 4, ,000 [Cl III] 10, ,000 If the density is much greater than the critical density, then the equilibrium between the excitation and de-excitation in the upper state is N 2 N 1 q 12 = N e N 2 q 21 + N 2 A 21 (2.32) thus, N 2 N 1 = N eq 12 A [(N e q 21 )/(A 21 )] (2.33) The emissivity ratio versus density is sketeched below Figure 2.14 Emissivity Ratio vs. Density In the plot above the critical density occurs at the midpoint of the high and low density cases. This also accounts for the correction term in the emissivity of [O III] (N e /t 1/2 ) (2.34)

27 2. Physics Applications of Nebulae 21 and [N II] (N e /t 1/2 ) (2.35)

28 2. Physics Applications of Nebulae Explanation of Interstellar Extinction The observed ratio of intensities of emission lines will vary from the intrinsic ratio of intensities from the nebula; thus corrections for interstellar extinction is needed. The extinction is due to intervening dust particles which causes the light to be absorbed and scattered. If this correction is made we can derive accurate values of temperature and density, because the ratios of intensities will not be the intrinsic values being produced by the nebula. The obscurity in the observed ratio of intensities of emission lines can be explained in the following equation: I I 0 = e τ (2.36) I 0 is the intensity we would observe in the absence of interstellar extinction and I is the intensity we actually observe. τ, is the optical depth, which is the product of the column density of particles and their effective cross section. If the diameter of the dust particles is much much greater than the wavelength of light, then what is observed is grey extinction. Grey is seen because no light is able to pass through the particle. However, if the diameter of the particle is much much smaller than the wavelength of light, Rayleigh scattering applies. The quantum efficiency is the ratio of the effective cross-section and geometric cross-section. Figure 2.15 Quantum Efficiency vs. Wavelength

29 2. Physics Applications of Nebulae 23 Figure 2.16 Optical Depth vs. Wavelength The sketch in Figure (1.15) is a plot of the quantum efficiency plotted over a given wavelength. This will help us determine the amount of light being transmitted (a ratio of the output of light to input of light). The second sketch Figure (1.16) is a plot of optical depth vs. wavelength: the optical depth decreases as the wavelength increases. Shorter wavelengths of light have a higher optical depth, while higher wavelengths of the light have a lower optical depth. To calculate interstellar extinction: F obs (Hα) F obs (Hβ) = I(Hα) + function (2.37) I(Hβ) F obs (Hα) is the observed 6563 line and F obs (Hβ) is the observed 4861 line. Take the log of each ratio and solve for function: log I(Hα) I(Hβ) log F obs(hα) F obs (Hβ) = c Hβ f Hα (2.38) log I(Hα) log F obs(hα) I(Hβ) F obs (Hβ) = c Hβ (2.39) f Hα f Hα is a function that is the same for all wavelengths and c Hβ is the interstellar extinction for Hβ. We assumed f Hα to be and ratio of F obs(hα) F obs (Hβ) is 2.89, which is appropriate value for a 9,000 K gas. No reddening correction were made for Hα

30 2. Physics Applications of Nebulae 24 flux ratios less than The nomenclature we adopted was F obs (λ) is the observed line ratio and I(λ) is the reddening corrected line ratio. For all wavelengths: log I(λ) I(Hβ) log F obs(λ) F obs (Hβ) = c Hβ f λ (2.40) log I(λ) I(Hβ) = log F obs(λ) F obs (Hβ) + c Hβ f λ (2.41) We needed to calculate how bright (the intensity) of Hα would be in the absence of extinction. logi(λ) logf obs (Hβ) =c Hβ f(λ) (2.42) logi(λ) =c Hβ f(λ)+logf obs (Hβ) (2.43) Therefore, I(λ) = 10 c Hβ f(λ) F obs (Hβ) (2.44) Equation (2.44) is used to calculate the reddening corrected values in Tables f(λ) is the shape of extinction curve related to Hβ and c Hβ is calculated by The values of c Hβ are in Table (4.2). c Hβ =(logi(hα) log( F obs(hλ)) )/ 0.22 (2.45) F obs (Hβ)

31 3. Data Reduction Analysis A brief explanation of the spectroscopic observations from the observation run in December 2008 at Cerro Tololo Inter-American Observatory (CTIO) with the 1.5 m telescope and Cassegrain Spectrograph are presented in this section. A thorough presentation of the data from the observational run is included. A total of 28 samples were observed and we will discuss the various parameters for each sample. We will identify the slit width, exposure times, positions, distance and location in RA and DEC for each sample. We will briefly explain the data analysis process from telescope to calibrated nebular spectra. After this analysis we will explain through various IRAF task such as IMSTAT, IMEXAM, IMEDIT, and SPLOT how we were able to determine flux ratios for the spectrum of each sample. 3.1 Spectroscopic Observation Spectroscopic observations of the Extended Orion Nebula (EON) were made at Cerro Tololo Inter-American Observatory (CTIO) 1.5m telescope. The instrument used was the Cassegrain Spectrograph telescope. Observations were taken on 2008 November 19, 2008 November 21-23, and 2009 January 16 by C.R. O Dell. The filter used was the GG385 and the CCD used was the Loral 1K. The wavelength range was Å. One pixel is equivalent to the height along the slit. The slit width was 144µ, which is 2.6 arcsec; 1 arcsecond corresponds to about 55 µ. 1 1 From manual Observer s Manual of the R-C Spectrograph for the 1.5m Telescope ( 2010)

32 3. Data Reduction Analysis 26 Figure 3.1 Gendler 2arcsec:Slits

33 3. Data Reduction Analysis 27 The slit width was 2.6 arcsecs for all samples except P1772, P1660, P1605, JW75, and P1353 (renamed 24, 25, 26, 27, 28, respectively) which were 110 µ (2 arcsecs). The slits are specified in Figure (3.1). The slit length for each sample is in Table (3.1). The slits orientation are east to west for samples 1-23 and and north to south for samples 24, 25, 26. Each sample was separated into as many as three regions: east, mid, or west. East is to the left and west is to the right. Multiple exposures for the brightest region samples JW337, P1772, P1660 (sample 9, 24, 25, respectively) were taken. This is because these sample would become saturated at long exposure times. The exposure times for each spectrum were, for sample 9: 30, 120, 300, and 1200 sec; for sample 24: 300, 1800sec; for sample 25, 100, 600, 1800 secs. Exposure times were repeated twice for each sample, i.e. 2*30 secs for sample 9; this is done to eliminate the effects of cosmic rays. The exact length in arcsecs, location in RA and DEC, and distance from θ 1 Ori C are listed in Table (3.2).

34 3. Data Reduction Analysis 28 Table 3.1. Observational Log Data* Original Sample Name New Sample Name Date-Observation Exposure Time (sec) Slit Width N N N N N N N N JW ,120,300, S S S S S S S S S JW S S S S P ,600, P , P JW P Note. *This information was acquired through the IRAF task IMHEADER

35 3. Data Reduction Analysis 29 Table 3.2. Positions of Samples Original Name New Name Length( ) RA DEC Distance( ) from θ 1 Ori C N240low 1east 214 5:35:23.7-5:19: N240high 1west 214 5:35:09.3-5:19: N210low 2east 130 5:35:26.5-5:19: N210mid 2mid 130 5:35:16.5-5:19: N210high 2west 130 5:35:09.3-5:19: N180low 3east 130 5:35:26.5-5:20: N180mid 3mid 130 5:35:16.5-5:20: N180high 3west 130 5:35:09.3-5:20: N150low 4east 130 5:35:26.5-5:20: N150mid 4mid 130 5:35:16.5-5:20: N150high 4west 130 5:35:09.3-5:20: N120low 5east 70 5:35:28.5-5:21: N120mid 5mid 263 5:35:17.3-5:21: N120high 5west 96 5:35:05.3-5:21: N90low 6east 70 5:35:28.5-5:21: N90mid 6mid 263 5:35:17.3-5:21: N90high 6west 96 5:35:05.3-5:21: N60low 7east 178 5:35:24.9-5:22: N60mid 7mid 126 5:35:14.7-5:22: N60high 7west 125 5:35:06.3-5:22: N30low 8east 178 5:35:25.1-5:22: N30mid 8mid 126 5:35:14.7-5:22: N30high 8west 125 5:35:06.3-5:22: JW337low 9east 90 5:35:14.4-5:23: JW337mid 9mid 52 5:35:05.7-5:23: JW337high 9west 198 5:34:55.3-5:23: S30low 10east 143 5:35:26.1-5:23: S30mid 10mid 143 5:35:16.5-5:23: S30high 10west 143 5:35:06.9-5:23: S60low 11east 143 5:35:26.1-5:24: S60mid 11mid 143 5:35:16.5-5:24: S60high 11west 143 5:35:06.9-5:24:23 2.4

36 3. Data Reduction Analysis 30 Table 3.2 (cont d) Original Name New Name Length( ) RA DEC Distance( ) from θ 1 Ori C S90low 12east 111 5:35:27.2-5:24: S90mid 12mid 139 5:35:16.4-5:24: S90high 12west 143 5:35:06.9-5:24: S120low 13east 143 5:35:26.1-5:25: S120mid 13mid 143 5:35:16.5-5:25: S120high 13west 143 5:35:06.9-5:25: S150low 14east 143 5:35:26.1-5:25: S150mid 14mid 143 5:35:16.5-5:25: S150high 14west 143 5:35:06.9-5:25: S180low 15east 143 5:35:26.1-5:26: S180mid 15mid 143 5:35:16.5-5:26: S180high 15west 143 5:35:06.9-5:26: S240low 16east 143 5:35:26.1-5:27: S240mid 16mid 143 5:35:16.5-5:27: S240high 16west 143 5:35:06.9-5:27: S :35:16.5-5:29: S :35:13.6-5:30: JW887east 19east 168 5:35:48.7-5:31: JW887west 19west 261 5:35:34.3-5:31: S :35:13.6-5:31: S :35:13.6-5:33: S :35:13.6-5:35: S :35:13.6-5:37: P1772low 24north 156 5:35:13.0-5:25: P1772high 24south 168 5:35:06.7-5:30: P1660low 25north 120 5:35:01.4-5:28: P1660high 25south 116 5:34:48.6-5:32: P1605low 26north 111 5:34:46.9-5:32: P1605high 26south 77 5:34:46.9-5:36: JW75low 27east 234 5:34:48.0-5:25: JW75high 27west 195 5:34:33.6-5:25: P1353low 28east 195 5:34:14.8-5:26:

37 3. Data Reduction Analysis 31 Table 3.2 (cont d) Original Name New Name Length( ) RA DEC Distance( ) from θ 1 Ori C P1353high 28west 209 5:33:59.6-5:26:

38 3. Data Reduction Analysis Initial Processing of Raw Data There was a significant amount of data reduction calibration prior to my analysis of the data. Dr. C.R. O Dell made this calibrations through a series of steps highlighted in the diagram below.

39 3. Data Reduction Analysis 33 Figure 3.2 Flow Chart of Spectrophotometric Calibration

40 3. Data Reduction Analysis 34 After the data from the telescope to raw image is produced, bias must be taken. Bias also known as zeros are read outs of the background detector. An average of bias images are calculated for accuracy and then subtracted from images made. It is assumed that the sky is homogeneous along the slit. If there is a perfect image, then this image would appear smooth. It is not so we have to divide all corrected bias images by curve. The image produced is a plot of x-axis wavelength and y-axis the slits, which is the position on the sky. The reference star spectrum is already calibrated know flux at various wavelength. This helps in making comparison of spectra. Vertical cut of image along slit is in counts versus y and the horizontal cut of image along slit is counts versus x. Comparison are then done with the HeAr lamp. These are done periodically throughout the night between collecting data at different slit widths. HeAr lamp have known wavelength of lines. This information is feed into an IRAF task which converts x(direction along slit) to x as a function of wavelength. Wavelength is a function of x. With this information we can go back to reference star image and convert counts versus x into counts versus wavelength. We will then take the reference values of flux versus wavelength and divide counts versus wavelength by flux versus wavelength, which produces counts per erg versus wavelength. The ratio of counts versus wavelength and flux versus wavelength is the measurement of sensitivity at each wavelength. This is done every y-value in CCD. With counts versus wavelength we will subtract out the bias, conduct a flat field correction. This is done by dividing the counts versus y by the flat field and dividing image by sensitivity. The result is flux at each pixel versus wavelength.

41 3. Data Reduction Analysis 35 Flux (ergs cm -2 s -1 A -1 pixel -1 ) H$ H# HeI H! [OIII] [NII] HeI H" [SII] Wavelength (Angstroms) Figure 3.3 Spectrum of Nebula

42 3. Data Reduction Analysis Detailed Explanation of Various IRAF Tasks After the calibration of data we were able to go through a series of IRAF task to ultimately calculate the temperatures and densities. IMSTAT is used to compute and print image pixel statistics. This task is located in images.imutil in IRAF. This task produces in columns the npix, mean, stddev, min, and max values. #IMAGE NPIX Mean STDDEV MIN MAX JW fits E E E-13 npix, is the number of pixels used to do the statistics, mean is the mean of the pixel distribution, stddev, is the standard deviation of the pixel distribution, min is the minimum pixel value and max is the maximum pixel values. For previous data analysis flux at each pixel versus wavelength was calculated. With this task we are able to know exactly the statistical information for each image. 2 IMEXAM is used to examine images using image display, graphics, and text. IMEXAM is located in images.tv of IRAF and images are viewed in a ds9 window. (DS9 is a IRAF image display server). Of the various parameters in this task the most significant are the ncstat and nlstat. The ncstat is the number of columns for statistics and nlstat is the number of lines for statistics. This will give a clear indication of the area of which the sample was taken. Various commands produce different outputs. The command a post results of R, Mag, Flux, Sky, Peak, E, PA, Beta, Enclosed, moffat, and Direct All in the command line. The command c plots columns (pixel value) versus line (pixels). The command e plots line versus column. l plots a line of pixel value versus column pixel value; b allows you to select 2 ( 2010)

43 3. Data Reduction Analysis 37 a region; m prints on the command line: section, npix, mean, medium, stddev, min, and max. x prints on the command line the x-coordinates, like wise y the y- coordinates. For the command a, R is the radius for photometry and fitting, PA is in degrees -90 and +90 with zero along the x-axis, Beta is the Moffat beta value if a Moffat profiles fit, and Direct All are three measurements of the full width half-max (FWHM), corrected FWHM for the specified profile type. 3 DISPLAY function is to load images in an image display, e.g. DS9. This task was used in the aid of removing stars in various samples. DISPLAY allows for multiple images to be viewed in different frames between 8-16 frames. We are able to blink frames at various intervals of seconds. DISPLAY is located in images.tv of IRAF. 4 Block average or sum n-dimensional image blkavg is used to convert 2D images to 1D. blkavg is located in images.imgeom. To make this conversion we have to supply the task with specific commands. The form is as followed: blkavg input ouput b1 b2 b3 b4 b5 b6 b7 We must supply an input which is a list of images to be block averaged and an output is a list of output image names. We only used the parameters b1 and b2. b1 is the number of columns to be block averaged and b2 is the number of lines to be blocked averaged. b1 and b2 where determined from the imheader of each fit unless other modifications were identified, i.e. avoiding regions of star emissions. A brief list of samples that had star removal are in Table (3.1). An example of the use of blkavg can be shown in N fits. This image was divided into three regions: 1:100, 101:230, and 231:330. For the first region the input name was N fits with parameters [1:1701,1:100] and the output name was onedn low.fits. The 3 ( 2010) 4 ( 2010)

44 3. Data Reduction Analysis 38 last number at the end of the command it the number of pixels being averaged over. 5 blkavg N fits[1:1701,1:100] onedn low.fits This task was used to allow for the task splot to be used to evaluate the spectra lines of each image. IMEDIT is located in images.tv and the purpose of this task is to examine and edit pixels in images. We used this task to edit out stars from the nebula. The images to be edited must be two dimensional. The format to edit images was imedit input output. input is the list of images to be edited and output is a list of output images. The actual removal of the star pixels was done with a series of cursor commands. When the pixels have been removed they are replaced with the nearest interpolated background column or line. The c cursor and l replace rectangular or line regions with interpolated data from the nearest background columns or line. 6 Figure 3.4 One Dimensional Image of A Star Before Removal 5 (ttp://iraf.noao.edu/scripts/irafhelp?blkavg, 2010) 6 ( 2010)

45 3. Data Reduction Analysis 39 Table 3.3. Samples of Star Removed Data* Old Sample Name New Sample Name y-range 1 y-range 2 N high 1west 166 N150.90mid 4mid N90.30mid 6mid N60.30mid 7mid N30.30mid 8mid JW75low 27east 24 P low 25north 42 P high 25south 42. Note. *Does not include all y-values for each removed star Figure 3.5 One Dimensional Image of A Star After Removal The images displayed above are of N fits and N150.90ed.fits. SPLOT is located through noao.onedspec. The purpose of SPLOT is to plot and analyze one-dimensional spectra. The most significant parameters of this task are the input images and save_fi. images are the name of the input images and save_fi is the name of the file were information from SPLOT is stored. The output in save_fi prints: center, cont, flux, eqw, core, gfwhm,1fwhm. The most used cursor commands are a,b, k, v, d, q, and r. The a zooms in on selected region between cursor commands. b sets the plot base level to zero; c will clear all windowing and reset image to the full spectrum; q will quit function mode. To set a fit to the spectra lines we used k,v and d. In the k,v series of cursor commands, the v represents the viogt

46 3. Data Reduction Analysis 40 fit and d was used for deblending. 7 Deblending allowed for fits to be determined for multiple spectra lines at once. We used the wavelength of lines identified by C. Esteban et al. in 2004 to differentiate which lines to deblend. There was a sequence of steps to the process of deblending: the first step was to zoom into selected region with a, select to the left and right of region with d, mark middle peak of each line with v, q quit selection, a fit positions for all, a fit Lorentzian width for all, n no fit background, and +,- to shift between fits. In the display window only center of line, eqw, gfwhm, and fwhm shows in deblending. These fits were calculated for all 29 lines from 3869[Ne III] [Ar III] of each sample. (Except when some spectra lines were too faint). From the output information we were able to determine the ratio of flux(λ)/flux(hβ) for each ion in each fit file. 7 ( 2010)

47 3. Data Reduction Analysis 41 Table 3.4. Observed and Extinction Corrected Line Ratios: 1east Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 [Ne III] [SII] HI Hgama [O III] He I Hbeta [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] HeI SiII [OI] [S III] SiII [OI] [N II] Halpha [N II] HeI [S II] [S II] He I [Ar III]

48 3. Data Reduction Analysis 42 Table 3.5. Observed and Extinction Corrected Line Ratios: 1west Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

49 3. Data Reduction Analysis 43 Table 3.6. Observed and Extinction Corrected Line Ratios: 2east Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

50 3. Data Reduction Analysis 44 Table 3.7. Observed and Extinction Corrected Line Ratios: 2mid Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

51 3. Data Reduction Analysis 45 Table 3.8. Observed and Extinction Corrected Line Ratios: 2west Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

52 3. Data Reduction Analysis 46 Table 3.9. Observed and Extinction Corrected Line Ratios: 3east Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

53 3. Data Reduction Analysis 47 Table Observed and Extinction Corrected Line Ratios: 3mid Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

54 3. Data Reduction Analysis 48 Table Observed and Extinction Corrected Line Ratios: 3west Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

55 3. Data Reduction Analysis 49 Table Observed and Extinction Corrected Line Ratios: 4east Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

56 3. Data Reduction Analysis 50 Table Observed and Extinction Corrected Line Ratios: 4mid Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

57 3. Data Reduction Analysis 51 Table Observed and Extinction Corrected Line Ratios: 4west Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

58 3. Data Reduction Analysis 52 Table Observed and Extinction Corrected Line Ratios: 5east Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

59 3. Data Reduction Analysis 53 Table Observed and Extinction Corrected Line Ratios: 5mid Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

60 3. Data Reduction Analysis 54 Table Observed and Extinction Corrected Line Ratios: 5west Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

61 3. Data Reduction Analysis 55 Table Observed and Extinction Corrected Line Ratios: 6east Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

62 3. Data Reduction Analysis 56 Table Observed and Extinction Corrected Line Ratios: 6mid Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

63 3. Data Reduction Analysis 57 Table Observed and Extinction Corrected Line Ratios: 6west Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

64 3. Data Reduction Analysis 58 Table Observed and Extinction Corrected Line Ratios: 7east Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

65 3. Data Reduction Analysis 59 Table Observed and Extinction Corrected Line Ratios: 7mid Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

66 3. Data Reduction Analysis 60 Table Observed and Extinction Corrected Line Ratios: 7west Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

67 3. Data Reduction Analysis 61 Table Observed and Extinction Corrected Line Ratios: 8east Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

68 3. Data Reduction Analysis 62 Table Observed and Extinction Corrected Line Ratios: 8mid Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

69 3. Data Reduction Analysis 63 Table Observed and Extinction Corrected Line Ratios: 8west Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

70 3. Data Reduction Analysis 64 Table Observed and Extinction Corrected Line Ratios: 9east Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

71 3. Data Reduction Analysis 65 Table Observed and Extinction Corrected Line Ratios: 9mid Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

72 3. Data Reduction Analysis 66 Table Observed and Extinction Corrected Line Ratios: 9west Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

73 3. Data Reduction Analysis 67 Table Observed and Extinction Corrected Line Ratios: 10east Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

74 3. Data Reduction Analysis 68 Table Observed and Extinction Corrected Line Ratios: 10mid Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

75 3. Data Reduction Analysis 69 Table Observed and Extinction Corrected Line Ratios: 10west Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

76 3. Data Reduction Analysis 70 Table Observed and Extinction Corrected Line Ratios: 11east Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

77 3. Data Reduction Analysis 71 Table Observed and Extinction Corrected Line Ratios: 11mid Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

78 3. Data Reduction Analysis 72 Table Observed and Extinction Corrected Line Ratios: 11west Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

79 3. Data Reduction Analysis 73 Table Observed and Extinction Corrected Line Ratios: 12east Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

80 3. Data Reduction Analysis 74 Table Observed and Extinction Corrected Line Ratios: 12mid Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

81 3. Data Reduction Analysis 75 Table Observed and Extinction Corrected Line Ratios: 12west Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

82 3. Data Reduction Analysis 76 Table Observed and Extinction Corrected Line Ratios: 13east Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

83 3. Data Reduction Analysis 77 Table Observed and Extinction Corrected Line Ratios: 13mid Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

84 3. Data Reduction Analysis 78 Table Observed and Extinction Corrected Line Ratios: 13west Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

85 3. Data Reduction Analysis 79 Table Observed and Extinction Corrected Line Ratios: 14east Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

86 3. Data Reduction Analysis 80 Table Observed and Extinction Corrected Line Ratios: 14mid Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

87 3. Data Reduction Analysis 81 Table Observed and Extinction Corrected Line Ratios: 14west Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

88 3. Data Reduction Analysis 82 Table Observed and Extinction Corrected Line Ratios: 15east Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

89 3. Data Reduction Analysis 83 Table Observed and Extinction Corrected Line Ratios: 15mid Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

90 3. Data Reduction Analysis 84 Table Observed and Extinction Corrected Line Ratios: 15west Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

91 3. Data Reduction Analysis 85 Table Observed and Extinction Corrected Line Ratios: 16east Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

92 3. Data Reduction Analysis 86 Table Observed and Extinction Corrected Line Ratios: 16mid Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

93 3. Data Reduction Analysis 87 Table Observed and Extinction Corrected Line Ratios: 16west Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

94 3. Data Reduction Analysis 88 Table Observed and Extinction Corrected Line Ratios: 17 Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

95 3. Data Reduction Analysis 89 Table Observed and Extinction Corrected Line Ratios: 18 Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

96 3. Data Reduction Analysis 90 Table Observed and Extinction Corrected Line Ratios: 19east Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

97 3. Data Reduction Analysis 91 Table Observed and Extinction Corrected Line Ratios: 19west Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

98 3. Data Reduction Analysis 92 Table Observed and Extinction Corrected Line Ratios: 20 Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

99 3. Data Reduction Analysis 93 Table Observed and Extinction Corrected Line Ratios: 21 Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

100 3. Data Reduction Analysis 94 Table Observed and Extinction Corrected Line Ratios: 22 Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

101 3. Data Reduction Analysis 95 Table Observed and Extinction Corrected Line Ratios: 23 Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

102 3. Data Reduction Analysis 96 Table Observed and Extinction Corrected Line Ratios: 24north Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

103 3. Data Reduction Analysis 97 Table Observed and Extinction Corrected Line Ratios: 24south Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

104 3. Data Reduction Analysis 98 Table Observed and Extinction Corrected Line Ratios: 25north Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

105 3. Data Reduction Analysis 99 Table Observed and Extinction Corrected Line Ratios: 25south Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [S III] Si II [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

106 3. Data Reduction Analysis 100 Table Observed and Extinction Corrected Line Ratios: 26north Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

107 3. Data Reduction Analysis 101 Table Observed and Extinction Corrected Line Ratios: 26south Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

108 3. Data Reduction Analysis 102 Table Observed and Extinction Corrected Line Ratios: 27east Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

109 3. Data Reduction Analysis 103 Table Observed and Extinction Corrected Line Ratios: 27west Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

110 3. Data Reduction Analysis 104 Table Observed and Extinction Corrected Line Ratios: 28east Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

111 3. Data Reduction Analysis 105 Table Observed and Extinction Corrected Line Ratios: 28west Region [λ (Å)] Ion [F(line)/F(Hβ)] f λ I λ 3869 Ne[III] [SII] H I Hgama [O III] He I Hbeta [O III] [O III] [N I] [Fe II] [Cl III] [Cl III] [N II] He I Si II [O I] [S III] Si II [O I] [N II] Halpha [N II] He I [S II] [S II] He I [Ar III]

112 4. Results of Temperatures and Densities Derived From TEMDEN We will explain the iteration process in the IRAF task TEMDEN. This iteration process allows us to calculated the electron temperature and density for each sample. The iteration process calculates the electron temperatures of [N II] and [O III] and the electron densities of [S II] and [Cl III] for each sample. We will adopt the nomenclature of T e as electron temperature and N e as electron density. 4.1 Explanation of TEMDEN Temperature and densities were calculated with the IRAF task TEMDEN. TEMDEN is one of the most important task we used in IRAF. This IRAF package is located in STSDAS.analysis.nebular. TEMDEN calculates electron temperature or density from diagnostic line ratios. We calculated line ratios using the task splot; the results of the calculations are in Tables ( ). This task requires the input of reddeningcorrected line ratios (Equation 1.44), name and spectrum of the atom, and an assumed value for the quantity not being calculated. The input parameters are as such: option is the quantity to be calculated either temperature or density; flux ratio are determined by the ratios specified below for temperature and density (Table 2.1); atom is either nitrogen, oxygen, sulfur, or chlorine; spectrum is the atomic spectrum number of each atom (e.g., [N II]=2, [S II]=2, [Cl III]=3,[O III]=3); result will either be density or temperature. 1 Electron temperatures and electron densities are directly dependent upon one another. We recall from equation (2.20) temperature was the only variable. To calculate (2.21) for [O III] and (2.22) for [N II] the corrections terms must be calculated from equation (2.34) and (2.35). These correction terms are dependent upon 1 ( 2010)

113 4. Results of Temperatures and Densities Derived From TEMDEN 107 electron temperature and density. Figure (2.14) indicates as the emissivity ratio increases the electron temperature will decrease. From the emissivity of ratio [S II] and [Cl III] we are able to determine densities, thus being able to determine the electron temperature of [N II] and [O III]. The emissivity of [S II] and [Cl III] must be calculated to determine the electron temperature of [NII] and from the electron density of [Cl III] the electron temperature of [O III] can be determined. Due to this dependence of temperature and density there are iteration processes that occur. To calculate the temperature of [N II] or [O III] the density of [S II] and [Cl III] must be used. For electron density of [S II] the ratio of I(6716)/I(6731) must be calculated and the ratio of I(5517)/I(5537) for [Cl III]. Electron temperature ratio of [N II] is I[ ]/I(5755) and for [O III] the ratio is I( )/I(4363).

114 4. Results of Temperatures and Densities Derived From TEMDEN 108 Table 4.1. Flux Ratios of [N II], [O III], [Cl III], [S II] for TEMDEN Sample Name [N II] [O III] [Cl III] [S II] I( )/I(5755) I( )/I(4363) I(5517)/I(5537) I(6716)/I(6731) 1east west westED east mid west east mid west east mid west midED east mid west east mid west midED east mid west midED east mid west eastED midED westED east

115 4. Results of Temperatures and Densities Derived From TEMDEN 109 Table 4.1 (cont d) Sample Name [N II] [O III] [Cl III] [S II] I( )/I(5755) I( )/I(4363) I(5517)/I(5537) I(6716)/I(6731) 10mid west midED east mid west east mid west eastED midED east mid west eastED westED east mid west eastED east mid west eastED westED east mid west westED ED

116 4. Results of Temperatures and Densities Derived From TEMDEN 110 Table 4.1 (cont d) Sample Name [N II] [O III] [Cl III] [S II] I( )/I(5755) I( )/I(4363) I(5517)/I(5537) I(6716)/I(6731) 18ED east west northED southED northED southED north south east west eastED east west

117 4. Results of Temperatures and Densities Derived From TEMDEN 111 The first step in this iteration process is to calculate the electron temperature of nitrogen. We must first guess an electron density for nitrogen; the output would be the first electron temperature of nitrogen, T e ([N II]) 1. T e ([N II]) Guess at [N II] T e ([N II]) 1 (4.1) For 2mid we guessed an electron density of 2400/cm 3 the output was an electron temperature of K. Step two is to calculate the electron density of [S II]. Using K as the T e ([N II]) 1 value, our output is /cm 3 for the N e ([S II]) 1. N e ([S II]) T e ([N II]) 1 N e ([S II]) 1 (4.2) Step 3 is to calculate electron density of [Cl III]. Again also using K as the T e ([N II]) 1 value, our output is /cm 3. N e ([Cl III]) T e ([N II]) 1 N e ([Cl III]) 1 (4.3) Next we took an average of N e ([S II]) 1 and N e ([Cl III]) 1. The sum will be used to calculate the second electron temperature of [N II], T e ([N II]) 2. T e ([N II]) Avg. N e ([S II]) 1 and N e ([Cl III]) 1 T e ([N II]) 2 (4.4) Step 4 is to take the average of N e ([S II]) 1 and N e ([Cl III]) 1. The result is /cm 3 and the second electron temperature of [N II], becomes K. Steps 2 and 3 are now repeated using the electron temperature of [N II] 2.

118 4. Results of Temperatures and Densities Derived From TEMDEN 112 Step 5 calculates the second electron density, N e ([S II]) 2 as /cm 3. N e ([S II]) T e ([N II]) 2 N e ([S II]) 2 (4.5) Step 6 calculates the new N e ([Cl III]) 2 as /cm 3 N e ([Cl III]) T e ([N II]) 2 N e ([Cl III]) 2 (4.6) Step 7 averages the values produced in step 5 and 6 to produce the third electron temperature, T e ([N II]) 3. The average of N e ([S II]) 2 and N e ([Cl III]) 2 is /cm 3, and the electron temperature of [N II] 3 is K. T e ([N II]) Avg. N e ([S II]) 2 and N e ([Cl III]) 2 T e ([N II]) 3 (4.7) The electron temperatures of [N II] have converged; T e ([N II]) 3 has now become T e ([N II]) final. This pattern is continued until T e ([N II]) converges with T e ([N II]) final. In this sample of 2mid only one iteration was calculated. To calculate N e ([S II]) final and N e ([Cl III]) final the T e ([N II]) final is used. The final electron density of [S II] is /cm 3. N e ([S II]) T e ([N II]) final N e ([S II]) final (4.8) The final electron density of [Cl III] is /cm 3. N e ([Cl III]) T e ([N II]) final N e ([Cl III]) final (4.9) The final step is to calculate the electron temperature of [O III] using the final electron

119 4. Results of Temperatures and Densities Derived From TEMDEN 113 temperature value of [Cl III]. The end result for T e ([O III]) final is K. T e ([O III]) N e ([Cl III]) final T e ([O III]) final (4.10) If the [Cl III] doublet was too weak to get a flux ratio, then we only used the [S II] values for determining T e [N II] final and T e [O III] final. The [Cl III] doublet was too weak in 2east, 6east, 7east, 8east, 19east, 23, and 28west. Densities also could not be calculated for [Cl III] doublet ratio values more than 1.42, because any value beyond this is past the critical density. This occurred in 12east, 19east, 26north, and 29east. 4.2 Electron Temperatures and Densities Calculated from TEMDEN Before we were able to calculate the electron temperatures and densities using TEM- DEN we had to calculate the interstellar extinction correction, chβ from equation (2.45). Other corrections to the flux ratio values had to be made to correct for the error in the recorded slit. The slit width we expected was different from the observed slit width. A brief explanation of this is given in equation (4.11) after table (4.2).

120 4. Results of Temperatures and Densities Derived From TEMDEN 114 Table 4.2. Corrected Flux Values Sample Name F Hβ Values* Corrected F Hβ Values** Equivalent Width H β chβ 1east 4.192E E west 5.457E E east 3.184E E mid 2.041E E west 2.365E E east 5.629E E mid 3.025E E west 3.034E E east 1.052E E mid 4.12E E west 3.759E E east 4.76E E mid 5.572E E west 3.602E E east 7.108E E mid 6.950E E west 3.586E E east 1.537E E mid 1.318E E west 1.189E E east 1.189E E mid 1.690E E west 5.154E E east E E mid E E west E E east 9.634E E mid 1.796E E west 5.555E E east 9.159E E mid 1.474E E west 4.502E E

121 4. Results of Temperatures and Densities Derived From TEMDEN 115 Table 4.2 (cont d) Sample Name F Hβ Values* Corrected F Hβ Values** Equivalent Width H β chβ 12east 4.34E E mid 1.366E E west 4.212E E east 4.902E E mid 9.045E E west 3.865E E east 3.677E E mid 4.611E E west 3.491E E east 3.324E E mid 2.777E E west 2.557E E east 2.492E E mid 1.71E E west 1.145E E E E E E east 2.943E E west 3.701E E E E E E E E E E north E E south 5.17E E north E E south E E north 1.173E E south 2.963E E east 5.979E E west 4.048E E east 2.816E E

122 4. Results of Temperatures and Densities Derived From TEMDEN 116 Table 4.2 (cont d) Sample Name F Hβ Values* Corrected F Hβ Values** Equivalent Width H β chβ 28west 1.171E E Note. *F Hβ is in units of erg cm 2 s 1 pixel. **The corrected F Hβ is in units of erg cm 2 s 1 arcsec 2.

123 4. Results of Temperatures and Densities Derived From TEMDEN 117 The conversion of F Hβ values to corrected F Hβ values in table (4.2) is = (4.11) One pixel on slit is equivalent to 2.6 arcsec in width and one pixel on detector is equivalent to the height along the slit. The 2.6 arcsecs was the expected slit width and 1.3 acrsecs was the true height of slit. The true slit width was 1.93 arcsecs and 1.35 arcsec is the slit measurement we did not expect.

124 4. Results of Temperatures and Densities Derived From TEMDEN 118 Table 4.3. Electron Temperatures and Densities* Sample Name T e [N II] T e [O III] N e [S II] N e [Cl III] 1east west east mid west east mid west east mid west east mid west east mid west east mid west east mid west east mid west east mid west east mid west

125 4. Results of Temperatures and Densities Derived From TEMDEN 119 Table 4.3 (cont d) Sample Name T e [N II] T e [O III] N e [S II] N e [Cl III] 12east mid west east mid west east mid west east mid west east mid west east west north south north south north south east west east

126 4. Results of Temperatures and Densities Derived From TEMDEN 120 Table 4.3 (cont d) Sample Name T e [N II] T e [O III] N e [S II] N e [Cl III] 28west Note. *The units of electron temperature is K and of electron densities is cm 3

127 4. Results of Temperatures and Densities Derived From TEMDEN 121 Figure 4.1 Distance vs. Electron Temperatures of [N II] and [O III]

128 4. Results of Temperatures and Densities Derived From TEMDEN 122 Figure 4.2 Distance vs. Electron Densities of [S II] and [Cl III]

129 4. Results of Temperatures and Densities Derived From TEMDEN 123 Figure 4.3 Electron Temperature of [N II] on Gendler Image

130 4. Results of Temperatures and Densities Derived From TEMDEN 124 Figure 4.4 Electron Densities of [O III] on Gendler Image