Republic of Iraq Ministry of Higher Education and Scientific Research University of Baghdad College of Science. (B.Sc. in Astronomy and Space 2006)

Transcription

1 Republic of Iraq Ministry of Higher Education and Scientific Research University of Baghdad College of Science Calculating the Central Meridian Longitude of System Three (CML ІІІ ) of Jupiter A Thesis Submitted to the Department of Astronomy and Space, College of Science, University of Baghdad in Partial Fulfillment of the Requirements for the Degree of Master of Science in Astronomy and Space By Rasha Hashim Ibrahim (B.Sc. in Astronomy and Space ) Supervised by Assis.Prof.Dr. Kamal Mohammed Abood August-- Ramadan--

2 Dedication To My Family To My Close Friends Rasha

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6 Acknowledgment I would like to express my deep gratitude and appreciation to my supervisor Dr. Kamal M. Abood for suggesting the topic of the thesis, continuous advice and his guidance through out this work. I would like to thank and to express my deep gratitude to Mrs. Maha Ahmed for her help in programming. I would like also to thank Mr. Nabeel Jameel at remote sensing unit, Mr. Fouad Mahamood and Mrs. Huda Shakr for their help in programming. I am grateful to the Dean of the College of Science, and the staff of Astronomy Department and all friends for their valuable support and for making all facilities necessary for the research available. Finally, I would like to thank my family for their support and patience. Rasha

7 Abstract A program was designed for calculating the Central Meridian Longitude of system ΙΙΙ of Jupiter (CML ΙΙΙ ), phase of Eye-Oh s (Io) satellite (Ф Io ). In addition calculation was made to predict the type of radio storm that related to position of Io (,B,C,D), and unrelated to the position of it (,B,C,D) that was emitted, as a result of the motion of Jupiter and Io with respect to the observer on Earth. The prediction of these storms was taken for three different Iraqi locations (Mousl, Baghdad and Basra). Two Io-storm ranges were used in this program according to the standard observations by the spacecrafts (Voyager and Voyager). The input parameters for this program were specified by the user (year, month, day and the observer s location). The output program result was in form of tables that provide the user information about the day, the month and the Local Time (LT) of beginning and end of each type of predicted storm. The results according to the observations at year gave the observer more types of radio storms as compared with the results that depending on the observations at year, these results indicated to the type of radio storm are not changed for those locations, but their LT is changed, because it depends on the longitude of the location. The difference between the begin and end of the storm for Baghdad location was calculated to notice the difference in time interval along the year, this difference is due to the motion of Jupiter and Io. In addition to the number of storms, which were received by the observer on Earth along the day. The rotation periods of Jupiter and Io were also tested.

8 The obtained results showed a good agreement as compared with the results of Radio Jove. The calculations and results of this study were carried out by using (Visual Basic.) software.

9 Contents: Chapter One: General Introduction and Review. Jupiter s Brief Description Literature Survey Jupiter s Magnetic Field Jupiter s Radio Radiation Radio Bursts The Classification of S-Bursts The Mechanism of the Radiation Io Flux Tube (IFT) Rotation Period The Coordinates Systems Jupiter s Satellites Io s Satellite Phase and Longitude Europa s Satellite Ganymede s Satellite Callisto s Satellite Aim of the Present Work Thesis Layout Chapter Two: The Central Meridian Longitude (CML) System. Introduction Julian Date (JD) Universal Time (UT) and Local Time (LT)... Orbital Elements

10 . The Storms of Jupiter Chapter Three: Program Testing and Results. Introduction Program Testing The Results Testing of the Rotation Period of Jupiter and Io.. Chapter Four: Discussion, Conclusions and Future Work. Discussion and Conclusions Future Work References Appendix (A)..... Appendix (B)...

11 List of Symbols and Abbreviations Symbol І ІІ ІІІ Φ Io λ Ψ J A E B J d R E R J M E N J U V J J Definition System One of Jupiter System Two of Jupiter System Three of Jupiter Phase of Eye-Oh s Satellite Longitude Distance from Earth to Jupiter Phase angle of Jupiter Equation of center of Earth Equation of center of Jupiter Number of days Radius of Earth Radius of Jupiter Mean anomaly for Earth Mean anomaly for Jupiter The angle of Io s satellite Argument of perihelion for the long period Jupiter s Planet Abbreviation CML DAM DIM HOM IFT Io JD KOM bkom nkom L LT N S SGC U Description Central Meridian Longitude Decametric Radiation Decemetric Radiation Hectometic Radiation Eye-Oh Flux Tube Eye-Oh s satellite Julian Date Kilometric Radiation Broad-Band Kilometric Radiation Narrow-Band Kilometric Radiation Long Burst Local Time Narrow Burst Short Burst Superior Geocentric Conjunction Universal Time

12 Chapter One General Introduction and Review

13 . Jupiter s Brief Description Jupiter is the most massive planet. In fact, it makes up % of all planetary matter in the solar system. It is also the largest planet; its diameter is approximately times as large as the diameter of the Earth s, and / as large as the Sun s. Despite its huge size, and tremendous internal pressure, the density of Jupiter is only kg/m. Although the outer layers of it like other outer giant planets consist of entirely of transparent gases, clouds of liquid, and solid droplets producing a wealth of colored features. Alternating dark belts, and light zones lying parallel to its equator [,], as shown in figure (.) []. Figure.: Jupiter s planet []. The colors of Jupiter s surface range from reddish-pink to blue-gray although it is certainly colorful. Its colors are much more quiet than those of Earth. Its red is not as bright as an apple and its blue is not bright as a sky. Some important properties of Jupiter are given in table (.) []. It has three coordinates systems. System І, applies for regions near the equator, system ІІ, applies for regions near the poles (far from the equator), these two coordinates systems are related to the clouds motion while system ІІІ is related to the internal magnetic

14 field of it, for each of these three systems has a CML and a specific rotation period []. Table.: Properties of Jupiter []. Orbital Distance. AU Orbital Period. years Mass M E Escape Velocity km/s Surface Gravity. g Global Temperature K Main Atmospheric Gases He, H Axial Tilt The decametric radio radiations from Jupiter are so intense, affected by the rotational phase of it and the orbital phase of its innermost Galilean satellite Io. Jupiter, Io s satellite and the co-rotating plasma torus constitute a unique system by this radiation [,]. This kind of radiation results from the acceleration of electrons from Jupiter by cones along Io Flux Tube (IFT) and directed towards Io s satellite, then accelerated another time from Io to Jupiter. During this radiation four types of storms are picked up at frequency. MHz, these storms are A,B,C and D [,].. Literature Survey The first discovery of radio radiation was by Burke and Franklin, in, which was found sporadic in nature, picked up at frequency. MHz []. This immediately confirmed on Sydney records by Shain []. In, Gardner and Shain also observed radiation from Jupiter. That was made near Sydney from June to March and these observations occurred at frequency. MHz, but some observations were also made at MHz and MHz. The reasons behind these observations were explained as: Jupiter radiation

15 appeared to be a random noise varying rapidly in intensity, large changes in intensity took place in time as short as. sec, but no shorter, these appeared to be from three sources on Jupiter. The radiation emitted from the main source (Astorm) was confined at angle of central line []. In, James proposed a method for deriving the location of Jupiter magnetic filed from the DAM radiation of Jupiter. The magnetic axis was tilted with respect to its rotation axis, and directed towards system ІІІ at longitude of []. In the same year, he pointed out that certain spectral sources (landmarks) always occurred at the same longitude to within ± and he attributed this spread to the radiation beaming into a narrow (half-angle) cone. His work was done before the discovery of the Io s effect []. In, Bigg pointed out that Io the inner most of Jupiter s large satellite, affects the Jovian DAM radiation []. In, Olsson and Alex pointed out the DAM radio bursts from Jupiter contain pluses of milliseconds duration. Their studies showed that the distribution in the Jovian longitude of these pluses was different from that of the more common pluses of longer duration. The two classes of pluses also appear to be differently affected by the position of inner most Galilean satellite []. In, Barrow and Baart described the short duration (less than milliseconds) pluses that observed in the DAM radiation. For the period of observations ( November to March ), it seemed that this type of radiation was associated with subsidiary B and C "storms" on Jupiter rather than with the main source A [].

16 In, Goldreich and Lynden-Bell proposed that the satellite was a good electrical conductor, and would set up an unusual current system, as it moves relative to the Jovian magnetosphere []. In, Schatten and Ness suggested the observations of the Io- modulated Jovian DAM radiation, which have been compared with calculations of the angle between Earth, and the magnetic field line near Io, and both the northern, and southern intersections of the field line with the surface of Jupiter were undertaken. Four radiations sources for DAM radiation were located by presuming that the angle of intersection between the Earth and the north (or south) threaded field was. These four storms correspond closely to the three major observed radiation regions and to one region infrequently observed []. In, Lecacheux studied the period of rotation of Jupiter, and the apparent shifts of the positions of the sources of DAM radiation from data obtained between the years (-), the result of the radiation period was (P= h m. s ±. s ) []. In, Alexander pointed out that the DAM radiation, that was recorded up to ~ years displayed a high degree of repeatedly at the same CML to within ±.This was due to variations in the precise field geometry or plasma distribution near the source, which control the radiation pattern, and the escape of radiation from the source region []. In, Jorma pointed out that B-region for S-bursts exhibits a drift in longitude similar to that for L-bursts. The Io s phase profile for S-bursts has a maximum in the vicinity of in B region, and in C region []. In, Desselar and Hill, found the Jovian longitude controlled over the Iomodulated radiation, the orbital phase of Io as seen by the observer from Earth

17 with respect to Jupiter from the SGC are known (Φ = ±, for the main storm, and Φ = ±, for the early storm) []. In, Barrow recorded the DAM radiation from Jupiter by Voyager Planetary Radio Astronomy (VPRA) experiment since. The events have been read from the Voyager spectral records in the frequency range (-) MHz []. In, Aubier and Genova estimated Φ Io, CML ІІІ and plotted them in a diagram. Furthermore the control of Io on the radiations was pointed out []. In the same year, they studied the location of the sources of the Io dependent emission in the northern and southern hemispheres and complementally information was deduced from the analysis of the radiation cone []. In, Boischot et al. pointed out that the structure and the position of the storms of radiation and the localization of Io-(A and B) storms on opposite sides of Jupiter. Furthermore non-io-(a and B) storms were shown, which behave exactly like the Io-storms. They concluded that the non-io emissions come from sources along magnetic field lines, seen at a large distance from the central meridian, on the East for the () storm, and on the West for the () []. In the same year, Genova et al. estimated the probability of observing Io independent Jovian DAM radiation from Nancy to be highly variable. This implies the non-io DAM events originate from the same storms regions at high latitudes in the Jovian magnetosphere []. In, Andrew and Peter pointed out that Alvén wave was modeled in a realistic magnetic field, and torus density distribution. The wave pattern produced downstream from the satellite exhibits periodic structure over a range of scales. In terms of the Jovian longitude of a stationary observer, it was > for large structure, and < for small scale structure [].

18 In, Leblanc et al. pointed out a new probability for the location of the source of radiation and better understanding the Io excitation from observations of complete polarization state of the radiation, and from parallel theoretical studies []. In, Boudjada et al. analyzed storm that was observed at Nancy observatory (France). The morphology of it was studied from the dynamic spectra, which allowed to re-occurrence of fine emission features in the same region of the CML-Io diagram, the storm occurs when Io s phase in the vicinity of, and the CML range between (-) []. In, Lecacheux et al. combined the observations from waves radio waves experiment on board the wind spacecraft at frequency range (-.) MHz with Wind/Waves observations made by Nancy decametric array at frequency range (-) MHz, in order to understand the beam geometry in the frame of available models, and usual assumption on the radiation mechanism []. In, Aubier et al. studied the statistical distribution model of the Jovian DAM radiation that observed from space and from ground in the same period when the meridian transit of Jupiter at Nancy was mainly during the night []. In, Bose et al. studied Io s satellite, location of the storms (Io and non-io) related to emission, and their characteristics (shape of beam). Electric noise, and field aligned current sources at Earth, and Jupiter was also studied [].. Jupiter s Magnetic Field Although little is known about the interior structure of Jupiter, several things are clear. First, the low average density of the planet requires that its interior structure consists of mainly of hydrogen and helium; the lightest elements.

19 Second, the temperature and pressure in the deep interior region of it must be very high. Under such extremes of temperature and pressure, the hydrogen gas takes on other forms, it transits from gas to liquid. The electrons within the hydrogen molecules are squeezed away from the hydrogen protons, and become free to flow out the liquid; this state of hydrogen is called metallic hydrogen[,], as shown in figure (.)[]. The electrons in metallic hydrogen can move freely through the liquid, so metallic hydrogen is a very good electrical conductor. This means that large electrical currents can flow within Jupiter [,]. Figure.: The internal structure of Jupiter []. The rapid rotation and vigorous induction within it drive these currents, generating the planet s large magnetic field. The tilt of the dipole with respect to the spin axis is of the order of [,]. The magnetic field at Jupiter surface is times as strong as the magnetic field at the surface of Earth []. The magnetosphere of Jupiter generally resembles the Earth s. It obstructs the flow of the solar wind, just as the Earth s magnetosphere does and causes it to flow around it. The solar wind

20 compresses the magnetic field on the sunward side and stretches it to great lengths on the night side. The strong magnetosphere is much larger than Earth s [,], as shown in figure (.) []. Jupiter s magnetosphere produces a glowing area covering the area of the full Moon. The magneto-tail of Jupiter extends at least ( ) km behind Jupiter []. Figure.: The magnetosphere of Jupiter [].

21 . Jupiter s Radio Radiation Jupiter emits two types of radio radiations thermal and non-thermal radiation. Thermal radiation from the atmosphere, which is occurred at high frequency range is caused by the interactions between electrons and atoms or molecules in a hot dense medium. The amount of radiation emitted depends on the temperature of the material producing it. Non-thermal radiation results from the radio bursts originating on Jupiter s surface, it is called non-thermal, because it does not originate from the energy that every object with a temperature above absolute zero is radiating at all times [,,]. This kind of radiation is divided into decimetric (DIM) and decametric (DAM) (bursts) radiation both of these two radiations considered as a part of synchrotron radiation, which is produced when charged particles in the speed of light flow through a strong magnetic field [,], as shown in figure (.)[]. Figure.: The synchrotron radiation []. The DAM radiation occurs at wavelength of tens of meters, and frequency range (-) MHz, which is described as a complex and highly organized in the

22 frequency time domain. The observations of Jovian DAM radiation is the only one that can be observed from Earth. The studies of the Jovian radiation show, in particular, its great variability. Many kinds of changes of radiation are observed with time scales from milliseconds to days [,,]. The DIM radiation occurs at wavelength range (-) cm and frequency range (-) MHz, which is more constant than the DAM radiation. It is thought to be caused by electrons orbiting along magnetic field lines and interacting with the motion of Io s satellite. These two kinds of radiation remain the main components. No other planets in the solar system emit these two radiations, at frequency below about MHz the hectometric radiation (HOM) is occurred [,]. In addition to another type of non-thermal radiation is occurred at frequency below about MHz, is called kilometric radiation (KOM), which is divided into broad-band and narrow-band (respectively bkom and nkom). These radiations are probably more directly linked to the Io torus itself, or its close environment []. Figure (.) illustrates the bands of radiation from Jupiter []. Figure.: The bands of radiation emitted from Jupiter [].

23 Electromagnetic radiation is emanating from the high latitudes of the planet (or polar latitudes) are generally referred to "auroral emission". The auroral emission of Jupiter is a natural emitter of radio waves, which is increased as the aurora rotates with the magnetic field of it. It results from the precipitation of energetic charged particles from a Jupiter s magnetosphere. It plays an important role in the energy balance between incoming solar radiation (both photons and solar wind particles), and out coming planetary radiation, a bright spot is formed from this, at both hemisphere of Jupiter [-], as shown in figure (.) []. Figure.: The auroral emission at poles of Jupiter []. It consists of a bright main oval, which encircles the magnetic poles in each hemisphere, footprints of the Galilean satellites and polar emissions laying within this oval [], as shown in figure (.) []. The electromagnetic interaction with Io not only produce a bright spot, but an emission trail, that extends in the longitude from Io s magnetic footprint [].

24 . Radio Bursts Figure.: The aurora in Jupiter s northern hemisphere []. On the surface of Jupiter a huge storms are occurred, which can last from a few to several hours. During these storms three types of bursts can be recevied. Long bursts (L-bursts), short bursts (S-bursts or millisecond bursts), and narrow bursts (N-bursts). These types of bursts are caused by the oscillations in the inosphere of Jupiter [,]. Long bursts, that vary slowly in intensity with time are lasting from few seconds to several tens of seconds, with a bandwidth of several MHz. Short bursts are sporadic spikes. The duration of such pulses varies from (-) millisecond, with a bandwidth of few hundreds KHz. In the dynamic spectra of Jovian DAM radio radiation, the most commonly observed components are the long bursts, while short bursts account for a relatively small fraction of about % [,,]. In general, the occurrence probability of detecting DAM radio radiation is depending on two parameters: the first CML of Jupiter (system ІІІ) facing Earth, which is related to the magnetic field of Jupiter, the second phase of Io s satellite with respect to the observer on the ground [,].

25 .. The Classification of S-bursts Since the discovery of short bursts of Jupiter, three interesting classifications have been found based mainly on the observations. Riihimaa has used alphabetical number to each type to distinguish the shape of one S-burst from another [], as shown in figure (.) []. Figure.: The shapes of S-bursts [].. The Mechanism of the Radiation As Io moves through the co-rotating plasma torus, it disturbs the magnetic field as well as the particles distribution in its vicinity. The nature of this disturbance depends on the conductivity of its intrinsic magnetic field, the parameters of the surrounding plasma, and the boundary conditions imposed by the Jovian ionosphere. The DAM radiation is emitted in a thin hollow cone, whose axis is parallel to the magnetic line, the radiation can only be detected at Earth, if

26 the thin walls of the cone intersect the direction of Earth [,], as shown in figure (.)[]. Figure.: The mechanism of the DAM radiation []. The opening angle of the hollow cone seems to be around (-). The electrons are accelerated from Jupiter in spiral motion and directed towards Io s satellite in form of Alvén waves (low frequency waves). The frequency of the accelerated electron from Jupiter should be above the geofrequency of it, at frequency f to reach at Io at frequency f [,,], as shown in figure (.) [], then the electrons are accelerated from Io ascending the (IFT) after having mirrored near the top of the Jovian ionosphere [].

27 Figure.: The acceleration of electrons from Jupiter to Io []... Io Flux Tube (IFT) The decametric radiation from Jupiter consists of numerous separate features, called decametric arcs, which are observed at all Jovian longitudes. In general these arcs are produced by an interaction of Io s satellite with Jupiter s ionosphere [], as shown in figure (.) []. Figure.: The decametric arcs [].

28 These type of radiations are remarkable, because these arcs consist of narrow-band radiations drifting either upward or downward in frequency, so Alvén wave or sometimes is called (Io Flux Tube) (IFT) will result from Io s satellite, which produces a standing magnetospheric disturbance. It is continuing the currents through Io (or rather its ionosphere), by the unipolar inductor effect due to Io s motion within the plasma [,,], as shown in figure (.) []. The reflected Alvén waves may heat the plasma torus and the Jovian ionosphere as well as produce an increase of diffusion of high-energy particles in the torus. They act like an external conductance to travel from Jupiter to Io and back again to Jupiter [].. Rotation Period Figure.: The Alvén wave containing the currents passing through Io[]. The rotation period of Jupiter can be found by measuring how long it takes the obvious atmospheric features to return to the same spot on the disk of the planet. The surface of Jupiter consists of bands, these bands are sub-divided into

29 zones, which are high, cool, light colored, and belts, which are low, warm dark colored. They are seen to move around Jupiter with different speeds, if these are made for features near the equator of it, it is found that Jupiter rotates eastward with a rotation period of h m s, but for features at higher latitudes (at poles), the rotation period is h m s. The minutes difference in rotation period between the equator and poles means that the clouds near the equator rotate eastward faster than those at poles [,]. Astronomers found that electrons trapped in Jupiter s magnetic field emit radio waves. They also found that the radiation varies with a period of h m. s, the time it takes for Jupiter s field to rotate about its axis, when the radio bursts are emitted. Because Jupiter s magnetic field is produced in the interior of the planet, the period of radiation is assumed to be the rotation period of the parts of it deep beneath the visible clouds layers. The internal rotation rate of it is slower than its equatorial rotation rate. This means that the equatorial regions rotate eastwards faster than the interior of the planet [,].. The Coordinates Systems Latitude and longitude coordinates are usually established relative to some solid surface. The coordinates systems of Jupiter are not complicated or cabalistic, but they are different from the other planets in the solar system. This comes from the whole structure of it are a gaseous elements rather than the solid parts, which exist under the visible clouds. Longitudes of a planet are fixed, but well defined prime (zero longitude meridian).the selection of this meridian, as the prime or zero longitude meridian was initially arbitrary, but the problem is the rotation period changes with latitude not longitude. A spin equator is rather easily made out from observation of the cloud motion [,]. The equatorial regions rotate

30 faster then the temperate, and the polar regions, because the materials distributed near the equator regions are much more, as to be compared with those in the polar regions, so the solution was to chose two separate systems, these system are system І which applies for regions near the equator (rotation period h m s ) and system ІІ which applies to regions at poles (far form the equator) (rotation period h m s ). Both of these systems are related to the clouds motion of Jupiter [,,], as shown in figure (.)[].There is another system related to the internal magnetic field of the planet called system ІІІ (rotation period h m. s ) [,], as shown in figure (.) []. In this figure the longitude is measured clockwise from the prime meridian []. Figure.: System І and ІІ of Jupiter []. This system is divided into two types: one is related to the position of Io s satellite, at frequency extending to MHz, while the other is not related to the position of Io s satellite, at frequency extending to MHz. For each of these types there is a special CML, which is defined as the longitude of the planet facing to Earth at a certain time [-].

31 Figure.: The CML of Jupiter (system ІІІ) [].. Jupiter s Satellites Jupiter s satellites can be divided into two groups: regular satellites containing the small satellites inside the orbits of the Galilean satellites, and irregular satellites outside the orbit of the Galilean satellites. It has satellites. There are four main of them discovered by Galileo in, namely Eye-Oh (Io), Eourpa, Ganymede, and Callisto [], as shown in figure (.) []. Figure.: The size of the Galilean satellites as compared with Jupiter[].

32 Some important properties of the Galilean satellites are given in table (.) []. Table.: Properties of the Galilean satellites []. Name of Satellite Orbital Distance (km) Orbital Period (days) Diameter (km) Density (kg/m ) Io,. Europa,. Ganymede,.. Callisto,,... Io s Satellite It has relatively large size, proximity to Jupiter, numerous volcanic eruption and hot spots show that it is the most geologically active solid body known in the solar system. Volcanic activity on it is so intense, that it rapidly changes its surface features. Regardless of this it does not have a huge volcanic activity mountains, the surface of it contains dark spots, and volcanic calderas with surrounding lava flows[], as shown in figure (.)[]. Also there is a bright feature extending above its edge, this proved to be volcanic plume, like the one rising hundreds of kilometers above its edge. The color of the surface is yellow, orange and black. These colors are referred to sulfur compounds such as sulfur dioxide SO. Molten sulfur is very fluid, so it has been suggested that some of the longer flows may be sulfur rather than silicate rock [-].

33 Figure.: Io s satellite []. Two possible models for its interior have been proposed. In one model, a thin rigid crust covers an entirely molten interior. In the other models a thin rigid crust covers a thin molten, or partially molten layer, solid metal is believed to be beneath this molten layer. In both models, Io has an iron rich core extending out to half of its radius []. It has a strong magnetic field generally produced by the dynamo inside it. It is controlling on the DAM radiations. This results from the motion of Io and high electrical conductance through the Jovian magnetic field leads to the acceleration of the particles from Io to the ionosphere of Jupiter [,], as shown in figure (.)[].

34 Figure.: The interaction of Io s satellite with Jupiter []. The interaction between Io and Jupiter is unique in the solar system. This comes from the fact of the strong magnetic field of Jupiter. Jupiter is the fastest rotating planet, and Io is the most volcanically active satellite. Io s interactions can be divided into two kinds: local interaction and far-field interaction. Local interaction occurs within a few satellite radii, which mean Io s atmosphere. The far field interaction includes the plasma torus of Io, Jupiter ionosphere and the high latitudes [,], as shown in figure (.) []. These two interactions regions are strongly coupled as one. The interaction between Io's satellite and Jupiter s planet has been studied extensively since of Io-controlled DAM radiation. The electrodynamics process is occurred by the effect of the solar wind with the elements that exist at the top of Jupiter form a glowing area, from this area the emission is occurred [,]. Io s atmosphere losses matter into Jovian magnetosphere, where the mass arrives partially ionized and partially neutral. The neutral is ionized by UV radiation from the Sun or due to electron impact. The new ions and electrons accumulate around the orbit of Io, and form the plasma

35 torus. The new plasma forms a thick and relatively cool ring of charged particles, which is swept around Jupiter (Io is embedded into it). The plasma mainly consists of SO gases, with a temperature between (,-,,) K, which is much lower than that of particles in the radiation belts ( ) K. It flow past Io, because the plasma originates from Io. This flows of magnetized plasma past the obstacle of Io, because its thin atmosphere acts as an engine of Io s plasma interaction [,,,].... Phase and Longitude The orbital position of Io s satellite around Jupiter s planet is called "phase of Io". The phase is measured counterclockwise from Superior Geocentric Conjunction (SGC), as shown in figure (.). It is zero degrees when it is directly after Jupiter, and it increases to be degrees when it crosses before Jupiter, as the observer seen from Earth []. Figure.: The orbital phase of Io []. The longitude is measured clockwise around Io s satellite starting from the meridian that point in the direction of Jupiter. This definition of a prime meridian

36 is possible for the Jovian satellites, because the same side of a given satellite always faces Jupiter [], as shown in figure (.)[]. Figure.: The longitude of Io with respect to Jupiter[]... Europa s Satellite It is the smallest of the Galilean satellites, a little smaller than the Moon. Its surface is smooth, and covered with ice. Only a few impact craters have been found indicating that the surface is young[], as shown in figure (.)[]. Figure.: Europa s satellite [].

37 It is renewed by fresh water, trickling from the internal ocean. It has a very weak magnetic field. The field varies periodically, as it passes through Jupiter s magnetic field. This shows that there is a conducting material beneath its surface, most likely a salty ocean that could even be km deep. At the center, there is a solid silicate core []... Ganymede s Satellite It is the largest satellite in the solar system. It is larger than the planet Mercury. The age of craters on the surface varies, indicating that there are areas of different ages. Its surface is partly very old, highly cratered dark regions, and somewhat younger, but still ancient lighter regions marked with an extensive array of grooves and ridges. They have a tectonic origin, but the details of the formation are unknown [], as shown in figure (.) []. Figure.: Ganymede s satellite []. About % of the mass of it is water or ice, the other half being rocks. Contrary to Callisto, Ganymede is differentiated a small iron or iron, and sulfur core surrounded by a rocky silicate mantle with an icy (or liquid water) shell on top. It has a weak magnetic field [,].

38 .. Callisto s Satellite It is the outermost of the Galilean satellites, nearly the same size as Mercury, with slight increase of rock towards the center. About % of it is ice, and % is rock, and iron. No signs of tectonic activity are visible. However, there have been some later processes, because small craters have been obliterated, and ancient craters have collapsed [,], as shown in figure (.) []. Figure.: Callisto s satellite [].. Aim of the Present Work The present work aims to predict the type of radio storms that are related to the position of Io (Io-Storm) and unrelated (Non-Io-Storm) to its position, which are emitted from Jupiter at specific LT for three different Iraqi locations (Mousl, Baghdad and Basra) with respect to the observer on Earth. Visual basic software is used in our calculations by designing a program and using equations to obtained the results. Such prediction results from the CML of Jupiter and the rotation of Io s satellite with respect to Jupiter at specific angles. Calculation of the time interval of storm and their distribution along the year. In addition to testing for the rotation periods of Jupiter and Io.

39 . Thesis Layout. Chapter one gives a general introduction and review about the radio radiation from Jupiter, phase, CML, and literature survey.. Chapter two gives the equations that are used to calculate the CML of Jupiter, phase of Io and the ranges of the radio storms.. Chapter three contains the application windows for the program testing and Results.. Chapter four contains discussion of the results, conclusions as well as the future work.. References used in this work are given at the end of thesis.

40 Chapter Two The Central Meridian Longitude (CML) System

41 . Introduction The present chapter is mainly concerned with equations that are used to calculate LT. In addition to calculation the CML of system ІІІ of Jupiter, and phase of Io from the astronomical elements, the motion of Earth, Jupiter, and Io s satellite is taken into account. The ranges of storms are given according to the standard observations by the spacecrafts and discussed in details.. Julian Date (JD) The CML ІІІ and phase change for each instant so it is necessary to express them in terms of Julian Date (JD) and Universal Time (UT) for each instant. The Julian Date can be defined, as the interval of time in days and fractions of a day since January st B.C.. That is midday, as measured on the Greenwich meridian []. The year is chosen from the calendar and it is converted to JD. Considering that (Y) is the year of the calendar date, then calendar date can be converted to JD as follow []: If the calendar date is equal to or greater than (--), which is the Gregorian calendar, then: ( Y ) A INT.... (.) A B A INT( )... (.) If the calendar date is after than (--), it is necessary to calculate A and B. The required JD for specific year, month and day is given by:. Y INT. M D B. JD INT...(.)

42 Where: M: is the number of month. D: is the number of day. The above equation is applied to convert the calendar date of January to JD. The required equation that used in our program to calculate the CML ІІІ and phase along the year for each second is given by: JD INT(. Y). B. (.) The number of days is given in terms of JD []: d JD.... (.). Universal Time (UT) and Local Time (LT) The UT is an important for civil life, based on the rotation of Earth with respect to the axis. Countries laying on east or west of Greenwich do not use UT as their LT, but for greater accuracy in time UT will add the longitude of the city. If the city lies in the east or will subtract the longitude, if the city lies on the west; therefore the world is divided into time zones each zone usually corresponding to a whole number of hours and small countries or part of large countries laying within a zone [,]. It is often convenient in making astronomical calculations to use UT to deduce the LT in hours by []: Where: λcity LT UT ( )... (.)

43 UT: is the universal time measured in hours, λ City : is the longitude of the city measured in degrees. Table (.) gives the longitudes of the cities (all lie on the east direction) [], which was used in equation (.). It is necessary to add the zone correction, because the LT is cross h, so it is necessary to make it, if the LT is greater than h, subtract h, if the LT is negative then add h. The result of the LT is expressed in hours, but it should convert it to hours, minutes, and seconds. The integer part of LT is the number of hours, the fractional part of hours is taken, and multiply by, the integer is the number of minutes, also the fractional part of minutes is taken and multiplied by this gives the number of seconds []. Table.: The longitude of the cities []. The City Longitude (Degrees) Mousl Baghdad Basra. Orbital Elements The motion of the planets around the Sun and of the satellites around their planets, are controlled by the action of the gravity that is by mutual force of attraction between masses. Orbital elements are the parameters required to uniquely identify a specific orbit, as shown in figure (.). In celestial mechanics these elements are generally considered in classical two body systems [].

44 Figure (.): Explains the orbital elements[]. Argument of perihelion (V J ) for the long-period term in the motion of Jupiter, which can defined as the orientation of the ellipse (in which direction it is flattened compared to a circle) in the orbital plane, as an angle measured from the ascending node to the semimajor axis is given by []: V J..d (.) Mean anomaly for Earth ( M E ) and Jupiter ( N J ), defines the position of the orbiting body along the ellipse at a specific time are given by []: M E..d.. (.) N J..d. sin (V ).. (.) J Difference (J) between the mean heliocentric longitude of Earth and Jupiter is given by []:

45 J..d.sin(V )... (.) J Where: V J, M E, N J, and J are expressed in degrees. Equations of center of Earth (A E ), and Jupiter (B J ), they are also expressed in degrees, are given by []: A E.sin (M ).sin (M )... (.) E E B.sin ( N ).sin ( N ) (.) J J And use another relation, which is (K) to link the difference, equations of center of Earth and Jupiter as []: K J A E B J..... (.) J Radius vector of Earth (R E ) and Jupiter (R J ) are given by []. R R E J..cos (M ).cos (M ).... (.) E..cos (N ).cos( N ).... (.) J J E Distance ( ) from Earth to Jupiter is given by []: R ) (R ) R R cos(k)... (.) ( J E J E Where: R J, R E, and are expressed in Astronomical Units (AU) and the distance from Earth to Jupiter always be positive. Phase angle of Jupiter (Ψ J ), which is the angle in phase from Jupiter with respect to the observer on Earth measured in degrees is given by []: R J sin J ( )sin(k) (.)

46 The equations of CML for the three systems (system Ι, ΙΙ and ΙΙΙ) of Jupiter respectively are given by []: Δ Δ CML Ι, ΙΙ. ( d ). ( d ).. (.) CML ΙΙΙ. Ψ B CML... (.) J J Ι,ΙΙ Where: Δ : is the correction for the light time, expressed in days, and the denominator results from the fact, that the light time for unit distance is / day, which is the time required for light to reach Earth form Jupiter. The CML of Jupiter should be reduced to the interval (-). The angles of the Galilean satellites are measured from the inferior conjunction with Jupiter ( when Io between Jupiter and Earth), so that U= corresponds to satellites inferior conjunction, U= with its greatest western elongation, U= with the superior conjunction, and U= with the greatest western elongation, the angles of Io s satellite are given by []: U U. (.)..(d ) J BJ (.).. (d ) J B J The equation of the Io s phase is given by []:.sin (U U ).. (.) Io Where:

47 U,U and Ф Io are measured in degrees and should be reduced to the interval (- ).. The Storms of Jupiter The emission mechanism that determines the phase and CML ІІІ does not depend only on the detailed emission process, but also on the propagation characteristics within the Jovian ionosphere and magnetosphere. The orbital phase controls in terms of an emission mechanism, that determines the radiation within a small range of angles with respect to the magnetic field direction, and the CML, with respect to Jupiter, from this the storms are determined [], as shown in figure (.) []. Figure.: (a): The phase of A (Φ ), (b): The phase of B (Φ ) []. when the probability of reception, as well as the overall energy of the signals received from Jupiter are higher than the average, there is a probability of existence of these storms []. All the radio signals from Jupiter are divided into two types "storm" and "non-storm" events. Each storm consists of Io-related and

48 Io-unrelated (non-io) component according to Io s position has a strong, weak or non-existence influence respectively [], as shown in figure (.) []. Figure.: Explains how the strong and weak radiations are affected by the position of Io []. These storms are main (), early (), wake () and fourth storm (Io-D) [,]. The Earth based observations showed that the exact location varies slowly depending on frequency, these observations from above Earth were continued by the spacecrafts, but the transition in CML ІІІ and Ф Io are limited by the interference in frequency and the speed of the spacecraft. The probability of observing (non-io) from Nancay was shown to be high variable, and there are the same storm regions in Jovian magnetosphere. Data from the United Radio and Plasma Wave (URAPW) experiment were used to determine the angular size and the direction of the radio storms. The URAPW observations of Jovian radio radiations greatly improved the determination of storm locations []. The ranges of the storms that depend on the program to obtain the results are given in tables

49 (.) and (.), these tables are found according to the standard observations at years and [,]. Table.: Ranges of storms []. Type of Storm CML ІІІ (Degrees) Ф Io (Degrees) Io-D Table.: Ranges of storms []. Type of Storm CML ІІІ (Degrees) Ф Io (Degrees)

50 Chapter Three Program Testing and Results

51 . Introduction In this chapter, the program system is tested by using visual basic software, the input parameters to predict of occurrence probability of radio storms that emitted from Jupiter and their LT. The results of the storms are given in tables for three different Iraqi locations (Mousl, Baghdad and Basra) according to the standard observations. The time interval of storm was calculated for Baghdad location to notice the difference in the intervals of continuity of the storm. In addition to testing for the rotation periods of Jupiter s planet and Io s satellite were made.. Program Testing The program testing is very important to make sure that the program is operating well, visual basic software is used in our program, the flowchart of the program that calculates the predicted storm at specific LT is given in appendix (A). The application window of the main program is shown in figure (.), which shows the occurrence probability of radio storm that emitted from Jupiter at specific LT. Figure.: The application window of the main program.

52 The input parameters are the desired year in text (YYYY) and the desired location of the city (Mousl, Baghdad, and Basra), which is determined by three commands for each one of them, the user will press on any command, as he wants to select the location. In this testing Baghdad location was chosen to predict the type of radio storm, then he will press on command "Prediction of Radio Storm in all Years". The program will save all files in years (in days or days according to the year). The longitude of the selected city will appear after finishing of saving all files, as shown in figure (.). The operation of saving lasts a few minutes, after that the user inputs in the month in text (), and the day in text (DD) then presses on command "Prediction of Radio Storm in Specific Day and Month", the result of occurrence radio storm is given at once, explains "There is no radio storm" according to the day, and month that the user input and ask him to select another day, or month in the year, as shown in figure (.). In some of these days one type of radio storm is occurred, while other days more than one type is occurred, as shown in figures (.) and (.). The result applies the type of the storm, and the local time (,, ) of beginning and end of each type, when the user wants to input another year, and selects another location he should press on command "Clear All" to make sure that all the previous files were deleted, then continue the operation. The user can select any location instead of Baghdad like Mousl or Basra to notice the difference in time during of receiving radio storm from Jupiter. The results that display in program testing according to table (.) ( which are the observations at the year ), the user can change the ranges of storms in the program (can take table (.), which are the observations at the year ) to notice the difference in type and its number. The program that designed gives

53 facility for the user to input any location as he wants, not only for the three Iraqi locations to predict the type of radio storm that emitted from Jupiter at specific time and input any year. In general the storm from Jupiter is occurred, but the time of receiving these storms are different due to the longitude of the location. Figure.: The application window of input parameters.

54 Figure.: The application window explains that the observer can not receive any storm. Figure.: The application window of occurrence probability storm in one day.

55 Figure.: The application window of occurrence probability and storms in one day.. The Results According to the ranges of storms that were given in chapter two, which are the basic ranges that used in our program to predict of occurrence probability of radio storm that emitted from Jupiter at specific LT, these ranges are changeable depending on the standard observations by the spacecrafts. The first month in the year was taken for three different Iraqi locations (Mousl, Baghdad, and Basra) and two different ranges were used in the results, to notice the differences in their number and time of occurrence of radio storm with respect to the observer on Earth, which change due to the longitude of the location. The results were given in tables providing the user information about the location (the longitude), the desired year, the month, the day and the LT of beginning and end of each predicted storm. The results according to table (.) showed the observer can receive radio storm in all days in the month, but there is a probability that in one

56 day the observer can receive at least two types of storms regardless of their type. This is opposite to the results according to table (.), which showed there are days in the month when the observer can not receive any radio storm, but there are days the observer receive at least one type. The program gives the user the facility to display the occurrence probability of the storms at any year and at any location, as explained in program testing, not only for Iraqi locations. The results according to tables (.) were: Zone: Iraq, Mousl, longitude =. Year:.

57 Table.: Prediction of radio storms. Type of Storm Local Time Date End Begin Month Day Io-D Io-D Io-D

58 Table.: Continued. Type of Storm Local Time Date End Begin Month Day Io-D Io-D

59 Table.: Continued. Type of Storm Local Time Date End Begin Month Day Io-D Io-D Io-D

60 Table.: Continued. Type of Storm Local Time Date End Begin Month Day Io-D

61 Table.: Continued. Type of Storm Local Time Date End Begin Month Day Io-D

62 Table.: Continued. Storm of Type Local Time Date End Begin Month Day Io-D Io-D

63 Table.: Continued. Type of Storm Local Time Date End Begin Month Day Io-D Io-D

64 Table.: Continued. Type of Storm Local Time Date End Begin Month Day Io-D Zone: Iraq, Baghdad, longitude =. Year:.

65 Table.: Prediction of radio storms. Type of Storm Local Time Date End Begin Month Day Io-D Io-D Io-D

66 Table.: Continued. Type of Storm Local Time D ate End Begin Month Day Io-D Io-D

67 Table.: Continued. Type of Storm Local Time Date End Begin Month Day Io-D Io-D Io-D

68 Table.: Continued. Type of Storm Local Time Date End Begin Month yda Io-D

69 Table.: Continued. Type of Storm Local Time Date End Begin Month Day Io-D

70 Table.: Continued. Type of Storm Local Time Date End Begin Month Day Io-D Io-D

71 Table.: Continued. Type of Storm Local Time Date End Begin Month Day Io-D n

72 Table.: Continued. Type of Storm Local Time Date End Begin Month Day Io-D Io-D

73 Table.: Continued. Type of Storm Local Time Date End Begin Month Day Zone: Iraq, Basra, longitude =. Year:. Table.: Prediction of radio storms. Type of Storm Local Time Date End Begin Month Day Io-D

74 Table.: Continued. Type of Storm Local Time Date End Begin Month Day Io-D Io-D Io-D

75 Table.: Continued. Type of Storm Local Time Date End Begin Month Day Io-D Io-D Io-D

76 Table.: Continued. Type of Storm Local Time Date End Begin Month Day Io-D

77 Table.: Continued. Type of Storm Local Time Date End Begin Month Day Io-D Io-D