CI/CO Mapping of IC348 & Cepheus B. using SMART on KOSMA

Transcription

1 CI/CO Mapping of IC348 & Cepheus B using SMART on KOSMA B.Mookerjea K.Sun, C. Kramer, M.Masur, M.Röllig, J.Stutzki, R.Simon, V.Ossenkopf, H.Jakob, M.Miller KOSMA, Universität zu Köln 27th September 2005 Cologne, AG2005

2 Kölner Observatorium für Submillimeter Astronomie (KOSMA) Submillimeter Array Receiver for two Frequencies (SMART) 3m dish at 3100m altitude ~25 micron surface rms wobbling subreflector (6' throw) Two Nasmyth ports 1.port: 230/345 GHz receiver 2.port: 492/810 GHz array receiver (SMART) since Sep GHz: 492 GHz: 810 GHz: HPBW 90'' 57'' 44'' Beff 78% 70% 50% Acousto Optical Spectrometers: Resolutions: 30kHz to 1MHz Bandwidth: upto 1 GHz Array-Spectrometers of 4x1GHz Graf, Jacobs, Honingh, Schieder, Stutzki, Heyminck, Stanko, et al. [CI] 2-1 [CI] CO 7-6

3 Probing starmotivation forming regions using [CI] fine structure lines 63 K, 1.2 x 103 cm-3 24 K, 4.7 x 102 cm-3 CI line ratio gives Tgas

4 Probing starmotivation forming regions using CO rotational lines CO K, 1.1 x 107 cm K, 1.4 x 106 cm-3 CO K, 2.6 x 105 cm-3

5 W3Main IRS5 CO cooling curves constrain gas densities and temperatures KOSMA/SMART & ISO/LWS observations: 12 CO 4-3, CO 14-13,..., CO 8-7 Important: high-j transitions (See Poster F01 13CO 8-7 Non-LTE radiative transfer: Warm phase: 10% of gas mass K, 3x104-1x105 cm-3 Cold phase: 90% of gas mass 40K, 103 cm-3 Kramer, Jakob, et al. 2004

6 A physical cloud model: KOSMA-τ -Density -UV field -Mass -Metallicity C+ n, G0, M, Z high Z C Radiative Transfer Energy Balance Chemical Network Röllig et al. 2005a, b see also Posters C02, C09, F08 CO

7 Intensities predicted by KOSMA-τ A spherical clump illuminated from all sides [CI] 1-0 strong at cloud edge 13 CO 2-1 strong in cloud center Only weakly dependent on density profile

8 Observed spatial distribution of CO and CI CO and CI appear to be co-existent! Example: IC348 in Perseus 25' x 25' (5 pc2) D=310 pc 1' = 0.09 pc IC348 KOSMA Kefeng Sun, Ph.D. thesis, KOSMA see Poster P34 Contours: CI 1-0 Colors: CO 4-3

9 Observed spatial distribution of CO and CI CO and CI appear to be co-existent! Example: IC348 in Perseus 25' x 25' (5 pc2) D=310 pc 1' = 0.09 pc BD+31 Kefeng Sun, Ph.D. thesis, KOSMA see Poster P34 S106 Schneider et al. 2004, 2003 W3Main Kramer et al DR21 Holger Jakob, Ph.D. thesis, KOSMA see Poster P13 Cepheus B Mookerjea et al. in prep. Contours: CI 1-0 Colors: CO 4-3

10 Observed spatial distribution of CO and CI CO and CI appear to be co-existent! Possible explanations: - Time dependent effects Störzer, Stutzki, Sternberg 1997 Kamegai et al Scattered FUV photons in a clumpy medium Contours: CI 1-0 Colors: CO 4-3

11 GMC Cepheus OB3: CO 3-2 KOSMA map B F A E The first submillimeter map of Cepheus, complementary to FCRAO CO 1-0 survey Area = 60pc x 20 pc (Distance = 730 pc), Michael Masur (Diploma thesis, Oct. 2005, KOSMA) See CHARM 2x9 array: Poster F06

12 Cepheus Molecular Cloud B Contours: CO 3-2 Colors: FUV-Field derived from FIR continuum (HIRES/IRAS 60 & 100 micron fluxes) Stars: OB-Association Michael Masur (Diploma thesis, Oct. 2005, KOSMA)

13 Cepheus B SMART/KOSMA Evidence for sequential star formation Contours: CO 4-3 Colors: [CI] 1-0 Hot-core strong in mid-j CO lines Mookerjea et al. 2005, in prep.

14 Cepheus B SMART/KOSMA - Contours: 13 CO 2-1 (IRAM-30m) - Colors: [CI] 1-0 Good spatial correlation Not consistent with simple PDR geometry

15 Cepheus B: PDR Modelling of the cloud center Best fitting solution using the KOSMA-tau PDR model assuming one clump only: nclump = cm-3 mclump = 0.15 Msun mlte = 15.1 Msun Nclump 100 Improved modelling in preperation: FUV = 100 from FIR HIRES see Poster C02 of Markus Cubick (KOSMA)

16 The NANTEN2 4m Submillimeter Observatory NANTEN + KOSMA/SMART = NANTEN2 consortium: Nagoya/Japan, KOSMA, RAIUB, Osaka, Seoul/Korea Pampa la Bola, near ALMA site at 4800m altitude (Excellent atmospheric conditions for Submillimeter Astronomy) - NANTEN with new 4m-submmdish & new drive - 3mm Receiver (in operation) NANTEN 4m telescope near La Serena - 492/810 single-pixel KOSMA test receiver (2005/6) - SMART receiver & backends (spring 2006) NANTEN2, March 2005 Photo by U.Klein Large-scale surveys of Atomic Carbon and CO lines in the Southern Sky see NANTEN2 Posters: F18, P23

17 The NANTEN2 4m Submillimeter Observatory NANTEN + KOSMA/SMART = NANTEN2 consortium: Nagoya/Japan, KOSMA, RAIUB, Osaka, Seoul/Korea Pampa la Bola, near ALMA site at 4800m altitude - NANTEN with new 4m-submm-dish & new drive - 3mm Receiver (in operation) - 492/810 single-pixel KOSMA test receiver (2005/6) First Light: M17SW 12 CO 1-0 in NANTEN 4m with telescope near La Serena NANTEN2 Sep. 12, SMART receiver & backends (spring 2006) Large-scale surveys of Atomic Carbon fine structure and CO lines in the Southern Sky see NANTEN2 Poster F18

18 Thank you for your attention

19 Cepheus B SMART/KOSMA - Contours: C18O 1-0 (IRAM-30m) - Colors: [CI] 1-0 Even better correlation! [CI] opt. thin tracing N(H2)

20 Cepheus B : Spectra Cut # 1 Cut # 2 Cut # 1 Selected 2 fully sampled cuts and 3 CI bright positions. Nearly Gaussian profiles with no obvious self-absorption or line wings CI & 13CO(2-1) line profiles match well Cut #2 CI Positions

21 Cepheus B: Intensity Profiles Column density C18O(1-0) intensities & Tex from peak TmbCO(1-0)

22 Simple model of many small clumps One small clump : M =10 3 M o,n s =10 5 cm 3, X =3 R= pc 760 au,1.7' ' 1 13 PDR Model reproduces observations :W CI 1 0 =5 Kkms,CI / CO=1.3, AV =1.6 mag F A =1 82clumps F V =0.11 F A =1, F V =0.11constant...fits the CI and 13CO observations

23 Simple model of many small clumps One small clump : M =10 3 M o,n s =10 5 cm 3, X =3 R= pc 760 au,1.7' ' 1 13 PDR Model reproduces observations :W CI 1 0 =5 Kkms,CI / CO=1.3, AV =1.6 mag

24 Cooling radiation of PDRs Dense PDRs exposed to intense FUV fields: - fine-structure lines - molecular lines - strong far-ir thermal dust continuum emission rot H2 vib

25 PDRs: Abundances

26 Cepheus Molecular Cloud

27 KOSMA: instrumentation SMART: concept SMART: array Acousto optical spectrometer SMART: cold optics

28 Motivation Observations at high spectral resolutions are important... HI emission to seperate individual velocity components to estimate the strength and source of the energy input to the turbulent interstellar medium to estimate the importance of stellar winds and outflows to seperate emission of different phases of the ISM, i.e. the WIM from the CNM. (Diffuse clouds are not visible in CO, rather CII or OI has to be used as tracer and HI.) HI absorption CII emission MHD simulation of the line structure of the cold neutral medium by Hennebelle & Perault (2000)

29 Motivation Observations at high spectral resolutions are important... to seperate individual velocity components to estimate the strength and source of the energy input to the turbulent interstellar medium to estimate the importance of stellar winds and outflows to seperate emission of different phases of the ISM, i.e. the WIM from the CNM. to detect spectral fine structure, e.g. to seperate 13 CII from 12CII. CII in M42 by Boreiko & Betz (1996)

30 Motivation. Photon dominated regions (PDRs) FUV photons from young OB stars impinging on cloud/clump surface layers Heating (thermal balance) Photodissociation (chemical network) Clumps photoevaporate (mass flows, shocks) Usual parametrisation of PDRs: FUV field G0, Density, Mass Open questions (Leiden workshop 4/04): Nature of the interclump medium Gorti & Hollenbach (2002) The importance of non-equilibrium chemistry The importance of clumpiness The importance of PAHs

31 Kölner Observatorium für Submillimeter Astronomie (KOSMA) 3m dish at 3100m altitude ~25 µ m surface rms wobbling subreflector (6'throw) Two Nasmyth ports 1.port: 230/345 GHz receiver 2.port: 492/810 GHz receiver HPBW 345 GHz: 90' ' 492 GHz: 57' ' 810 GHz: 44' ' Beff 78% 70% 50% Acousto Optical Spectrometers: Resolutions: 30kHz to 1MHz Bandwidth: upto 1 GHz Array Spectrometers of 4x1GHz

32 Models of the chemical structure of a PDR H 2 self-shielding and dust attenuation vs. grain surface formation. Controlling parameters: FUV ev 1) cloud density/pressure 2) FUV intensity 3) grain scattering properties 4) H2 formation rate coefficient 5) geometry/clumpiness 6) gas phase abundances 7) magnetic field... Sternberg, Zermatt 2003

33 A physical model: KOSMA-τ Massive clumps failcloud to reproduce observations 13 Variation of the CI/ CO ratio using the PDR model of Störzer et al. 1996: 4 3 M =10 M o,n s =10 cm, X =3

34 SMART Specs Image Rotator Two simultaneous frequency bands: Two sub-arrays, 2x4 pixels each, split by polarization Telescope - - Dual Diplexer LO-Unit 795 to 885 GHz (CI 3P2 3P1 and others) IF-frequency: 1-2 GHz simultaneous measurements of CI 3P2 3P1 and CO 7 6 in two sidebands Noise temperatures: Dewar Electronics Rack 455 to 495 GHz (CI 3P1 3P0 and others) K at 810 Ghz K at 490 GHz