¡ð‚á¡ð‚á¦ ÐÚðõºðâð÷¾Ü · astrophysics, isro satellite centre, the srishti...

®ðÂÀ 15 çðü 4 ØððÜÃðóÚð ÃððÜðØððøòÃð¨îó çðüçÆððÐðVolume 15 No. 4 Indian Institute of Astrophysics December 2010

¡ð‚á¡ð‚á¦ ÐÚðõºðâð÷¾ÜòÇçðü×ðÜ 2010

An international conference to commemorate the birth centenary of ProfessorS. Chandrasekhar was held during December 7-11, 2010 at the Indian Instituteof Astrophysics, Bangalore. The main focus of the conference was on researchareas in which Chandrasekhar made seminal contributions during his lifetime.The academic program consisted of several invited talks on topics rangingfrom stellar structure and evolution, astrophysical fluids and plasmas, stellardynamics, magnetic hydrodynamic, compact objects, black hole physics,general relativity, stellar and planetary atmospheres. The rich legacy ofChandra’s work and its vast impact on subsequent developments in the fieldof astronomy and astrophysics were highlighted in a series of stimulatingand inspiring lectures delivered by eminent scientists both from India andabroad.

The conference was inaugurated byDr Kasturirangan, who is currentlya member of the PlanningCommission, Government of India.Among the eminent scientists whospoke at the meeting were: JeremyGoodman (Princeton University,USA), Peter Eggleton (University ofCambridge, UK), David Merritt(Rochester Institute of Technology,USA), Christopher Tout (Universityof Cambridge, UK), James Binney(University of Oxford, UK),Ravi Seth(University of Pennsylvania, USA),Axel Brandenburg (Alba NovaUniversity Center, Nordita, Sweden),Roger Blandford (Stanford University,USA), Ethan Vishniac (Johns Hopk-ins University, USA) and KameshwarWali (Syracuse University, USA). Beside technical talks, a large number ofpeople from various institutes, universities, and science organizations cameto attend a couple of public lectures that were meant for general audience.The conference was co-sponsored by the Indian National Science Academy,the Indian Academy of Sciences, the National Academy of Sciences, theInter-University Centre for Astronomy and Astrophysics (Pune), the TataInstitute of Fundamental Research (Mumbai), the Physical ResearchLaboratory (Ahmedabad), the Harish-Chandra Research Institute (Allahabad)and the Institute of Mathematical Sciences (Chennai).

1. Chandrasekhar Centenary Conference

2. Vainu Bappu Memorial Lecture

3. Kalpaneya Yatre

4. Discovery of HdC stars at HCT

5. CEMP stars

6. Radiation in Multi-Dimensions

7. Design and Development of L Interference Filter

8. Vibration Tests on EM of UVIT

9. IIA Research Publications

10. Symposium on Indian Science

11. Scientific Legacy of S. Chandrasekhar

12. òèÐÇó Ñð®ðãððÀÿð ãð òèÐÇó òÇãðçð çðÙððÜð÷è -2010

13. From IIA Archives

14. New Appointments & Farewell

α

Roger Blandford talking on hydrodynamicand hydromagnetic stability of black holes.

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,

The fourth Vainu Bappu Memorial Lecture was deliveredby Professor James Binney, FRS, on the 9th ofDecember, 2010. This event was organised as an eveningpublic lecture during the Chandrasekhar CentenaryConference hosted by IIA. Professor Binney titled hislecture "What makes spiral galaxies tick?", in which hegave a masterly exposition of the birth, growth and deathof spiral galaxies. Terming them as complex machinesthat are almost alive, Professor Binney traced the lifecycle of a spiral galaxy and the insights gained throughan interesting mix of the application of basic physicsand the analysis of observational data. He described ina very detailed way both what we know and how weknow it.

The scientific programme of the conference wasformulated and overseen by a scientific organizingcommittee chaired by T. Padmanabhan (IUCAA). Thelocal organization was handled by a committee with

Kameshwar Wali, Syracuse University, USA speaking on “TheLegacy of S. Chandrasekhar”.

James Binney being felicitated with a bouquet of flowersat the end of his lecture.

(From the left) : Roger Blandford (Stanford), Robert Wald(University of Chicago), S.S. Hasan (Director, IIA) and KasturiRangan conversing during a coffee break

members from IIA, RRI, IISc and ISRO, under thechairmanship of S.S. Hasan, Director of IIA. - R. Banyal

Vainu Bappu Memorial Lecture

James Binney, FRS, is currently heading the TheoreticalAstrophysics group at the Rudolf Peierls Centre forTheoretical Physics, University of Oxford, Oxford, UKand is a Professorial Fellow of Merton College, Oxford.His research concerns the structure, dynamics andformation of galaxies. Professor Binney is well knownfor his fundamental contributions in the the above areasand, as every student of modern astrophysics wouldinstantly recognise, his text book co-authored with S.Tremaine on 'Galactic Dynamics' has propelled severalgenerations of students in this field. He has been aFellow of the Royal Astronomical Society since 1973,obtained his doctorate from Oxford University in 1975,was a Lindemann Fellow at Princeton University during1976, and became University Lecturer in 1981 and AdHominem Reader in Theoretical Physics in March 1990at Oxford University. In July 1996 he became Professorof Physics at Oxford University. In 2000 he bacame a

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A consortium of institutes from Bangalore, viz., theJawaharlal Nehru Planetarium, the Indian Institute ofAstrophysics, ISRO Satellite Centre, the Srishti Schoolof Art, Design and Technology, Vishveswaraya Industrialand Technological Museum and the Raman ResearchInstitute organised a unique astronomyfestival for the public on the grounds of theJ.N.Planetarium during 25 November - 5December, 2010, in which over 40,000members of the public from Bangalore city,Bangalore rural district as well as moredistant locations in the state participated.

Christened 'Kalpaneya Yatre' or 'Journey of Imagination',this festival was unique in several ways. Firstly, it wasthe first time that multiple institutions came together toorganise an astronomy event for the public in Bangalore.Secondly, it was an inter-disciplinary event with artist-designers from the Srishti school involved right from thebeginning in the conception, design and implementationof the festival. Thirdly, the festival provided a space wherethe amateur astronomers and science popularisers ofBangalore joined hands with the astrophysicists and theartist-designers, to create a rich multi-dimensionalexperience for the public. The expanded partnership ofthe festival thus included the Bharat Gyan VigyanSamithi, Bangalore Astronomical Society, Associationof Bangalore Amateur Astronomers, Navnirmiti (Mumbai),Vigyan Prasar (Delhi), Experimenta Film Society,Karnataka Rajya Vijnana Parishat, the JNP Club andDynam Creativity Programmes.

The festival had a bilngual astronomy exhibition (in

English and in Kannada) that covered the themes ofhistory of astronomy ideas and people, the Sun and theSolar system, Stars, Galaxies and the Universe andSpace Exploration. The exhibition had explanatorypanels, 3-D working models as well as some interactive

exhibits. A set of experiments and demostitled 'Science of Starlight' demonstratedthe underlying principles of astrophysics.In addition, a wide range of activities wereconducted, targeted at both youngstersand adults.

The festival was aimed at people aged 10 and above ofall backgrounds. In order to encourage the widest possibleparticipation, only a nominal fee was charged for adultsand children had free entry. A highlight of the festivalwere the astronomy activity workshops that wereconducted for students. These workshops were mostlydesigned by Navnirmiti (Mumbai), Vigyan Prasar andBharat Gyan Vigyan Samithi, and about thirty childrenof middle- and high-school levels participated in eachworkshop learnt about astronomy, sun-viewing, makingsimple devices for astronomy observations,understanding Jantar Mantar, etc. A total of 950 studentsparticipated in these workshops that occurred every dayduring the festival. The workshops were mostly bilingual.Volunteers from different parts of the state who weretrained as resource persons in a pre-festival workshopconducted by Navnirmiti (Mumbai) conducted andassisted these workshops. A resource base was thuscreated wherein these workshops can be replicated inthe home regions of these volunteers. In addition, therewas also a telescope-making workshop designed by

Kalpaneya Yatre

- S. P. Rajaguru

Fellow of the Royal Society of London and a Fellow ofInstitute of Physics. He was awarded the 1986 MaxwellPrize and Medal, and the 2010 Dirac Medal by the Instituteof Physics, London. He received the 2003 Brouwer Awardof the American Astronomical Society.

Vainu Bappu Memorial Lectures were instituted in 2007,and the Lecture by James Binney was the fourth in theseries. Previous awardees of these Lectures are EugeneN. Parker (2007), Douglas O. Gough (2008) and WilliamD. Phillips (2009).

Children at an Astronomy workshop

Navnirmiti (Mumbai) for school teachers, in which atotal of about 80 teachers made a low-cost telescopefrom a kit, which they could then take back for use intheir schools.

The festival had several lectures by eminentastrophysicists, including three from IIA. VishwanathPalahalli spoke in Kannada on ‘Travellers of the Night’(Yaaminiya Yaatrikaru), Firoza Sutaria spoke on'Cauldrons of Creation: How stars live and die', andJayant Murthy spoke on 'Hrithik, 8-legged freaks fromspace, and us: The search for life in the cosmos'. Avery popular feature of the festival was the face-to-faceinteractions between the public and scientists. Over25 astrophysicists from IIA participated in these 'Askan Astronomer' sessions that occurred once or twiceeach day. With the use of the internet and web-cameras, the public was brought into audio-visualcontact with scientists working at the telescopes indifferent observatories of the country, including IIA'sVainu Bappu Observatory,Kavalur and the IndianAstronomical Observatory, Hanle. The public, andespecially students had exciting conversations withthe scientists at the telescopes in these sessions.Amateur astronomers of the Bangalore AstronomicalSociety, IIA's partners in outreach activities throughthe International Year of Astronomy, co-ordinatedseveral sky-watching sessions in the evenings usingtheir telescopes, including a 17" telescope. A multi-media interactive theatre presentation entitled'Unscientific Storytelling' designed by Srishti, whichexplored the role of imagination and individual worldviews in science education and practice, was performedon three of the festival days, and several scientistsfrom IIA participated as the interactive audience.

The students of Government High School, Madivaala,

with whom IIA has had an extension programme since2008, participated in a two-month long project on'Understanding Satellites', leading up to the festival.This project, designed by the Srishti School incollaboration with IIA and ISAC, had about 30 childrenparticipate in several pre-festival workshops includingat IIA, and visit ISAC to see the satellite models.These activities were meant to trigger the imaginationof the children to design satellite models, andculminated in a parade of satellite lanterns that thechildren made during the festival. In addition, about200 children from the school were funded by IIA tospend a day at the festival to view the exhibition,participate in the student workshops, lectures andAsk-an-Astronomer sessions.

A major highlight of the festival was an inter-disciplinary all-day symposium on the final day. Thesymposium had speakers, respondents andparticipants from a wide variety of backgrounds, andincluded astrophysicists, social scientists, artist-designers, amateur astronomers, sciencepopularisers, educators, facilitators, and members ofthe public, and there were very lively debates on thenature of the inspiration that astronomy is, astronomyas a vehicle for scientific literacy, rationality and thesocial responsibility of astrophysicists, and thedisciplinary and cultural barriers to growth of the spiritof discovery. About ten astrophysicists from IIAparticipated in the symposium.

The Kalpaneya Yatre 2010 festival was funded by theDepartment of Science and Technology (Govt. ofKarnataka), the Department of Science andTechnology (Govt. of India), ISRO, IIA and VigyanPrasar (Govt. of India) (http://kalpaneyayatre.org).

- Prajval Shastri, IIA co-ordinator for Kalpaneya Yatre

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Children of the Government High School,Madivaala and the ‘Understanding Satellites’

project.



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Discovery of a Hydrogen-deficientcarbon star from HCT

A comparison between the spectrum of HE 1015-2050 with thespectra of V460 Cyg (a C-N star), U Aqr, ES Aql (cool HdC starsof RCB type),HD182040 (a non-variable HdC star), and HD 209621(a CH star) in the wavelength region 3850-4950 Å. G-band of CHdistinctly seen in the CH star’s spectrum are barely detectable inthe spectra of HE1015-2050 and other HdC stars spectra. Whenthese stars’ spectra are dominated by features due to carbonmolecular bands the weakness of CH band is a clear indication ofhydrogen deficiency. The large enhancement of Sr II at 4077 Å.,in the spectrum of U Aqr is easily seen to appear with almost equalstrength in the spectrum of HE 1015-2050. Y II line at 3950 Å., isdetected in the spectra of both HE1015$-$2050 is the strength ofthe Sr II l 4215 line; this feature is inextricably blended with thenearby strong blue-degraded (0,1) CN 4216 band head in HD182040. The spectrum of HE 1015-2050 compares closest to thespectrum of U Aqr.

The spectrum of HE 1015-2050 bears a remarkablesimilarity with the spectrum of U Aquirii (U Aqr), a coolHdC star of RCB type. The spectral characteristics andits location in the J-H vs H-K plane certainly places HE1015-2050 in the same group to which U Aqr belongs;however, extended photometric observations of this objectwould be useful to learn the nature and extent ofphotometric variations. In particular, it would be interestingto see if there is any sudden decline in brightness, this

The location of HE~1015$-$2050 is shown in the J-H versus H-Kcolour magnitude diagram (open circle). The solid circles representLMC RCB stars and the positions of the comparison stars and theprototype RCB star R CrB are marked with solid squares. The thickbox on the lower left represents the location of CH stars and thethin box on the upper right represents the location of C-N stars(Totten et al. 2000). The location of HE~1015-2050 in the vicinity ofU Aqr (and other HdC stars) in the J-H, H-K plane supports itsidentification with the group same as that of U Aqr.

being a characteristic property of HdC stars of RCBtype.This work has been published in 2010, ApJ, 723,L238.

- A. Goswami, D. Karinkuzhi, N. S. Shantikumar

Polarization is a characteristic property of starsevolving from red-giant stage to planetary nebula; itserves as an important indicator of stellar evolution.We have reported first-ever estimates of V-bandpolarimetry for a group of carbon-enhanced metal-poor(CEMP) stars from Hamburg/ESO survey. Althoughthey have been well studied in terms of photometricas well as low- and high-resolution spectroscopy, notmuch is known about the polarimetric properties ofthe CEMP stars. V-band polarimetry was planned asthe V-band is known toshow maximum polarizationamong BVRI polarimetry for any scattering of light dueto dust. Stars with circumstellar material exhibit acertain amount of polarization that may be caused byscattering of starlight due to circumstellar dustdistribution into non-spherically symmetric envelopes.The degree of polarization increases with asymmetriespresent in the geometry of the circumstellar dustdistribution. Our results reflect upon these properties.While the sample size is relatively small, thepolarimetric separation of the two groups (p % < 0.4and p % > 1) is very distinct; this finding, therefore,opens up new avenue of exploration with regard toCEMP stars. The results are published in 2010, ApJ,722, L90. - A.Goswami, S. S. Kartha, A. K. Sen

Evidence of V-band polarimetric separationof CEMP stars at high Galactic latitude

Hydrogen deficient carbon (HdC) stars are a rare classof objects; only five Galactic HdC stars and about fiftyone HdC stars of RCB type are known in our Galaxy.While HdC stars are spectroscopically similar to the RCBtype stars, they are distinct from RCBs, as they do notshow the deep minima and infrared excesses that arecharacterististics of RCB stars. The small size of thegroup of HdC stars is a major constrain for understandingtheir formation mechanism(s) and evolutionary properties.Using medium resolution spectroscopic data fromHimalayan ChandraTelescope (HCT) we have identifiedHE 1015-2050 to be a hydrogen-deficient carbon star.The present discovery adds a new member to this raregroup of objects.


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Radiative Transfer in Multi-Dimensional Media

The solution of polarized radiative transfer (RT) equationis essential to understand the polarized (Stokes I, Q,U, V) spectra of the Sun. Most of the polarized RTstudies are based on the assumption that the solaratmosphere is homogeneous at all the planesperpendicular to the atmospheric normal. Only thevariat ion of the physical quanti t ies along theatmospheric normal is considered. This is called a one-dimensional (1D) atmospheric model. However, theobservations of the solar atmosphere have confirmedthe presence of small-scale structures which representthe spatial inhomogeneity within the atmosphere. Asthese structures have different physical properties (e.g.,magnetic field and temperature), it is clear that thelateral transport of radiation becomes important. Theradiation field in an inhomogeneous solar atmosphereis not axi-symmetric. Therefore, the solution of thepolarized line RT equation in multi-dimensional mediabecomes a basic necessity to model these observedsolar atmospheric features. An idealization to simplify

Figure 2 .Panel (a) shows the surface plots of the intensity I andthe degree of linear polarization (Q/I, U/I) on the top surface of thecomputational cube. Panel (b) shows the important differencesbetween CRD and PRD Stokes profiles in a semi-infinite 2Datmosphere. The 1D results are shown for comparison.

Figure 1. This figure shows the radiative transfer in 3D and 2Dgeometries

this problem is to represent the inhomogeneities ascomputational boxes characterized by given physicalparameters. Extensive studies on RT in two-dimensional (2D) and three-dimensional (3D)geometries have been made to understand theintensity profiles in spectroscopic observations. Asthe linear polarization (Stokes Q and U) of the radiationfield is more sensitive to the non-axisymmetry thanthe intensity (Stokes I), the solution of the polarizedRT equation in 2D and 3D geometries is needed tounderstand these spectropolarimetric observations.

Polarized RT problems have been addressed in thepast decade, but only for complete frequencyredistribution (CRD). A first investigation with partialfrequency redistribution (PRD), for 3D geometry,isdeveloped in Anusha & Nagendra (2011, hereaftercalled Paper I). The solution of multi-dimensionalpolarized line transfer equation formulated in theStokes vector basis is complicated. The reason forthis is the explicit dependence of the physicalquantities on 3 spatial co-ordinates, 2 angularvariables defining the ray direction, and a frequencyvariable.Therefore, it is advantageous to write thetransfer equation in a basis where it takes a simplerform.

In Paper I, we have formulated the polarized transferequation in 3D geometry using the technique of the‘irreducible spherical tensors’. In 3D geometries, theradiation field is non-axisymmetric (even in theabsence of magnetic fields), because the finite opticaldepths in the X, Y, and Z directions break the azimuthalsymmetry of the radiation field. In a 1D geometry, theradiation field is axisymmetric about the Z-axis. Dueto these reasons, the shapes and magnitudes of the(Q/I, U/I) spectra differ significantly from thecorresponding 1D cases. We have shown that theadvantage of solving the transfer equation in the‘irreducible spherical tensor basis’ is that theirreducible source vector becomes ‘completely


independent of the angle variables’ — making it easierto extend the existing 1D PALI methods to the 3D case.However, the irreducible intensity components remaindependent on the inclination and also on the azimuthalangle of the ray. In future, we will try to apply the solutionmethod presented in Paper I to model the polarimetricobservations of resolved structures like solar filamentsand prominences.

Solving the polarized RT equation with PRD in multi-dimensional geometries is numerically expensive, bothin terms of computing time and computer memory. Toaddress this problem, in Anusha et al. (2011, hereaftercalled Paper II) we develop an efficient method to solvethe polarized RT equation with PRD in a 2D slab. Weassume that the medium is finite in two directions andinfinite in the third direction. In Paper II, we apply the‘Stokes vector decomposition technique’ developed inPaper I to 2D geometry. We show that due to symmetryof the Stokes I parameter with respect to the infinite

axis, the Stokes Q becomes symmetric and the StokesU becomes anti-symmetric about this axis. Thisdecomposition technique is interesting for thedevelopment of iterative methods. Here we describe anumerical method cal led the Pre-BiCG-STAB(Preconditioned Bi-Conjugate Gradient) and we showthat it is much faster than the Jacobi iteration methodused in Paper I. In Paper II, we consider the case ofsemi-infinite atmospheres and compare the behaviorsof the surface averaged emergent Stokes profiles in 2Dgeometry and the corresponding 1D solutions for CRDand PRD. We show that the deviation of the polarizedradiation field in 2D geometry from that in 1D geometryexists both for CRD and PRD, but is more severe inthe line wings of the PRD solutions. These results arepublished in ApJ, 2011,726, 6 (Paper I) and 726, 96(Paper II).

-L. S. Anusha & K. N. Nagendra

Fig.1.Typical profile of Lyman alpha. The dotted portion of Lymanalpha is the telluric hydrogen absorption core. (Source: TheExtreme Ultraviolet Spectrum of the Sun by Richard Tousey).

Design and Development of Lyman Alpha Interference Filter for Astronomical Applications

On the basis of Lyman alpha profi les and itsimportance in the astronomical studies, we aredeveloping Lyman alpha optical filter in whichmultilayer coating design is used. Filters with only onemetal-dielectric pair resulted in poor filtering propertiesso filters with three metal dielectric pairs have beenused.This provides much better transmittance hithertoachieved.These filters have been design as a part ofinstitute interest in the solar research through spacepayload.

Lyman alpha line has certain important applicationsin the study of chromospheric and coronal regions ofthe sun. Lyman alpha line is also important in the studyof cosmological objects as well. For example Lyman-alpha is used to determine red shifts and star-formationrates. Its profile and strength can also provideconstraints on the age of star-forming galaxies, on theirdust content and other ISM properties and on outflows.Furthermore Lyman-alpha luminosity functions (LFs),their red shift evolution and comparison with e.g. UVLFs provide invaluable information on galaxypopulations and their evolution. Lyman-alpha is of greatinterest to identify very distant galaxies; it serves as asignpost for extremely metal-poor/Pop III galaxies, andis established as a crucial tool to measure cosmicreionization. Lyman-alpha galaxy surveys are alsobeing used to map largescale structure, and to probedark matter properties. 1A typical profile of Lyman alphaline is as shown in Fig. 1.

As the small band gap allows electrons to absorbradiation with energies equal to or less than the energyof the band gap; causing the material to be significantlyabsorbing. So very large band gap energy has the

chance of making a material transparent. There existtwo materials with a band gap equal to or greater than10.2 eV, the energy of the Lyman alpha line. Becauseof this characteristic, these two materials are suitablefor the transmissive property at this wavelength. Thesetwo materials are LiF and MgF2..

2But we preferred to

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MATERIAL THICKNESS (Ao) THICKNESS (Ao) THICKNESS (Ao)

@ CWL = 1215.42 @CWL = 1215.67 @CWL = 1215.921

Aluminum 200.8 200.8 200.8

2 MgF2

153.6 153.7 153.8

3 Aluminum 431.5 431.7 431.8

4 MgF2 159.1 159.2 159.3

5 Aluminum 179.4 179.5 179.6

6 MgF2

197.8 197.9 198.1

LAYERS

1

Total Thickness (A0) Al = 811.6

MgF2 = 510.6

Total = 1322.1

Al = 811.9

MgF2 = 510.8

Total = 1322.7

Al = 812.2

MgF2 = 511.2

Total = 1323.4

Fig. 3. Transmittance (%) vs wavelength (Å).

Fig. 2.

•CWL : Central wavelength

use magnesium fluoride in place of lithium fluoride asit is hygroscopic material which can results in poorquality filters unless great care is taken in their use andstorage. Our designed filter is a metal-dielectric filterwhich consist of six alternating layers of aluminum as ametal and MgF2 as a dielectric spacer layer: Al/MgF2/Al/MgF2/Al/MgF2.

3The advantage of metal- dielectric filteris that the out of band is partly reflected and partlyabsorbed while with all the dielectric transmittance filters,

the out of band is mainly reflected. Also metal dielectricfilters are selected because of the good rejection achievedin the near UV and the visible wavelength. The theoreticaldesign has been done using thin film calculator software.The schematic of the optical design of Lyman alpha filteris shown in Fig. 2.

Transmission curve of the Lyman alpha filter as obtainedfrom 3MDM design is shown in Fig. 3.

The optimized parameters of the filter are given in Table 1.

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- - -i-

Fig.1. Control accelerometers (as required) 15x/15y/15z.

Accelerometers locations

In the period from September 2010 to November 2010,the vibration tests on the EM of the UVIT wasconducted at the Vibration Laboratory of theEnvironmental Test Facility (ETF) of the ISRO SatelliteCentre (ISAC), Bangalore.

Vibration Tests on the Engineering Model (EM) of the UVIT Payload on Astrosat

The three axes of the payload viz. the pitch, yaw androll are shown in the figure.The details of the testsconducted are given below.

The payload is subjected to two types of vibrationdepending on the profile of the input viz. sine vibrationand random vibration. The sinusoidal test simulatesthe vibration pattern experienced by the payload dueto the working of the rocket engines transmitted bythe structure and the random vibration pattern is theone experienced by the payload because of windbuffeting and also the acoustic noise created by theworking of the rocket engines.

The different categories of tests and the expectedresults are given below:

Low level sine: This is used to evaluate the“signatures” ie. to estimate the modal frequencies ofthe various sub-systems. This is also used as a checkfor the structural integrity of the payload after eachtest.

Acceptance level sine: This is the test wherein allsub-systems are subjected to the design load level.

Qualification level sine: This is the test wherein allsub-systems are subjected to a load level higher thanthe design load by a factor equal to the factor ofsafety.The factor of safety normally employed is 1.1.

Quasi Static or dwell test: If any sub-system has notexperienced the design load level, a quasi static testis conducted where the sub-system is subject to thedesign load.

Low level random: This is used to evaluate the“signatures” ie. to estimate the modal frequencies of

References :

1. The Extreme Ultraviolet Spectrum of the Sun :Richard Tousey.

2. Windows and Filters : Experimental Methods in thePhysical Sciences , Vol 31

3. Filters for the WSO/UV by Fernendez-Perea-et al.

- A. K. Saxena & M D. Faisal Nawaz

From the table, it can be noticed that 0.1 Å thicknesscontrolling is necessary to achieve the 0.25 Åaccuracy on the central line transmission.

Remarks: The present metal dielectric design for theLyman alpha transmission filter with six alternatinglayers of Aluminum and Magnesium fluoride canprovide the best transmittance value of 36.38 % forthe Lyman Alpha line with a FWHM of 65.64 Å. Thebigger challenge in the task is to control the thicknessparameters practically as the thickness of eachlayers are less than 50 nm which is difficult to handle.Besides this, thickness controlling of 0.1Å is requiredto achieve the 0.25 Å accuracy on the central linetransmission. The fabrication work of one such filteris in progress.

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is converted into a voltage output by a conditioningamplifier.

36 accelerometers were used in the EM of the UVIT.In addition, 17 accelerometers were used on thevibration table as control accelerometers, the outputof which is used as a feedback for controlling the inputsignal to the vibration table.

The UVIT has two channels viz. Far Ultra-Violet (FUV)and Near Ultra-Violet (NUV). In the EM, the FUVchannel is replaced by a stainless steel model whichsimulates the FUV channel in terms of mass andmoment of inertia.

The various subsystems of the UVIT like the cameraproximity unit (CPU) which is the detector, the highvoltage unit (HVU) for the detector, filter wheel motorand drive electronics and the door mechanism werefound to perform optimally.

The hinges of the door mechanism however, failedduring the qualification level sine test in Z axis. Thesame was replaced by a different material of higherthickness.The structural components were found towithstand the tests.

However, the fasteners holding the secondary baffleloosened during the qualification level random in Yaxis. The system was put back in operation aftermaking suitable modification.

The engineering model of UVIT ( UltraViolet ImagingTelescope) has been successfully tested for vibrationloads at ISAC, ISRO. Given the large size of thisinstrument, vibrations during the launch are expectedto lead to quite large stresses on the structure andthe optical/electrical parts. Thus, this was a verycritical test and the instrument team was very eagerlyand anxiously waiting for its successful completion.The tests involved very detailed monitoring of theacceleration levels; Fig. 1 shows locations of theaccelerometers. In Fig. 2 is shown the assembledinstrument mounted on a fixture for transport to ISAC.During the tests some deficiencies were noted, andthese were rectified in short time. Successfulcompletion of this test opens the way for assembly ofthe flight model without any major change of designin the structure.

The results of the tests were reviewed and approvedby a committee consisting of expert members fromISAC and IIA.

− UVIT Team

the various sub-systems. This is also used as acheck for the structural integrity of the payload aftereach test.

Acceptance level random: This is the test whereinall sub-systems are subjected to the design load level.

Qualification level random: This is the test whereinall sub-systems are subjected to a load level higherthan the design load by a factor equal to the factor ofsafety. The factor of safety normally employed is 1.1.

A electrodynamic shaker was used to vibrate thepayload and the power input is computed by the glevel applied at the centre of gravity of the payload.

The input gets modified at the various sub-systemsdepending on the transfer function at the interfacesof the various subsystems.

During the design phase, a certain value is consideredfor the transfer function and this is verified byconducting the low level test.

The expected force levels at various sub-systems arecomputed for the acceptance level tests from theobserved values of the transfer function termed as“beta”.

If the expected level is higher than the design levelfor a sub-system, then a process known as notchingis introduced where the input levels are reduced whenthelevel of force cross the design limit at thesubsystem. This is normally done by the automaticcontrol system of the vibration test facility.

Accelerometers are used to sense the level of forcethat is experienced by a subsystem. These arepiezoelectric devices that sense the vibration andconvert them into a charge form. This charge output

Fig. 2. EM of UVIT at the MGKM lab, CREST, IIA, Hosakote.Viewof main Baffles and telescope tubes of NUV channel.

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The 21st annual meeting of the Third World Academyof Sciences took place in Hyderabad, India, this yearduring 19-22 October. The conference was inauguratedby the Prime Minister, Dr Manmohan Singh, who in hisinaugural address described how science is a key driverthat guides global discourse. Over 300 delegates fromthe developing world gathered to deliberate on a varietyof topics including current science research, education,scientific priorities for development and means toachieve excellence.The first symposium of theconference was on Science in India, which covered abroad range of topics of Indian research, where PrajvalShastri from IIA gave a talk on Munching Black Holesand Growing Galaxies.

- Prajval Shastri

(1) Hiremath, K. M. 2010, Sun and Geosphere 5,17-22, Physics of the Solar Cycle: New Views.

(2) Banerjee, D., Gupta, G. R., *Teriaca, L., 2010,Space Science Review 120. Propagating MHD Wavesin Coronal Holes

(3) *Moradi, H., ... Rajaguru, S. P.,... et al. ( 22Authors), 2010. SoPh 267, 1-62, Modeling theSubsurface Structure of Sunspots

(4)* Acton, C. E., *Priestley, K., *Mitra, S., Gaur, V.K., 2010. Geophysical J., 441. Crustal structure ofthe Darjeeling-Sikkim Himalaya and southern Tibet

(6) Sujatha, N.V., Murthy, J., *Suresh, R., *Henry,R. C., *Bianchi, L., 2010, Ap J 723, 1549-1557.GALEX Observations of Diffuse UltravioletEmission from Draco

(7) *Bielby, R. M ., ... Stalin, C. S., et al. (15 Authors),2010, A&A 523, A66. The WIRCAM Deep InfraredCluster Survey. I. Groups and clusters at z = 1.1.

(8) *Sbordone, L., ... Sivarani, T., et al. (19 Authors),2010, A&A ,522, A26. The metal-poor end of theSpite plateau. I. Stellar parameters, metallicities,and lithium abundances.

(9) *Balachandran, S. C., Mallik, S. V., *Lambert,D. L., 2010, MNRAS,1582. Lithium abundances inthe alpha Per cluster.

(10) *Taricco, C., ... Sinha, N., et al., ( 9 Authors)2010, Meteoritics and Planetary Science, 45, 1743-1750. Cosmogenic radioisotopes in the AlmahataSitta ureilite.

(11) *Chakrabarty, D., *Sekar, R., Sastri, J. H.,*Pathan, B. M., *Reeves, G. D., *Yumoto, K.,*Kikuchi, T., 2010, J. Geophys. Res., (SpacePhysics) 115, 10316. Evidence for OI 630.0 nmdayglow variations over low latitudes during onset ofa substorm.

(12) Sengupta, S., *Marley, M. S., 2010, ApJL 722,L142-L146. Observed Polarization of Brown DwarfsSuggests Low Surface Gravity

(14) Rajaguru, S. P., *Wachter, R.,*Sankarasubramanian, K., *Couvidat, S., 2010, ApJL721, L86-L91. Local Helioseismic and Spectroscopic

IIA Research Publications

September - December 2010�

Analyses of Interactions Between Acoustic Wavesand a Sunspot.

(15) Muneer, S., Jayakumar, K., Rosario, M. J.,Raveendran, A. V., Mekkaden, M. V., 2010, A&A, 521,A36. Orbital period modulation and spot activity inthe RS CVn binary V711 Tauri.

(16) Aruna Goswami, Sreeja S. Kartha, *Asoke K.Sen, 2010, ApJ, 722, L90, Evidence of V-bandpolarimetric separation of carbon stars at highGalactic latitude

(17) Aruna Goswami, Drisya Karinkuzhi, N.S.Shantikumar, 2010, ApJ, 723, L238, HE 1015-2050:Discovery of a hydrogen deficient carbon star at highGalactic latitude

(18) Sampoorna, M., *Trujillo Bueno, J., *LandDegl’Innocenti, E., 2010, ApJ, 722, 1269-1289, On theSensit iv i ty of Part ia l Redistr ibut ion Scatter ingPolarization Profiles to Various Atmospheric Parameters

(19) Anusha, L. S., Nagendra, K. N., 2011, ApJ, 726, 6,Polarized line formation in multi-dimensional media. I.Decomposit ion of Stokes Parameters in arbitrarygeometries

(20) Anusha, L. S., Nagendra, K. N., *Paletou, F., 2011,ApJ, 726, 96, Polar ized l ine formation in mult i -dimensional media. II. A fast method to solve problemswith partial frequency redistribution

From IIA Repository

§ *

§

* Collaborators

Symposium on Indian Science


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Summary of Chandrasekhar's research

Chandra is well known for his discovery in 1930, duringhis voyage from India to England, of a limit on the massof a star that can become, in its terminal stage, a whitedwarf. The limit, known as the Chandrasekhar limit (1.4M sun), is hailed as one of the most importantdiscoveries of the twentieth century, since it paved theway to the discovery of the other two presently knownterminal stages of a star: neutron stars and black holes.Subsequently, Chandra's distinctive pattern of researchencompassed diverse areas, each of which occupied aperiod of five to ten years, resulting in a sequence of alarge number of papers and ending with a monograph.Six such monographs known for their thoroughness,lucidity, and scholarship have had dramatic and lastingeffects on diverse fields of astronomy and astrophysicsby providing not only numerical results for comparisonwith observations, but also mathematical models andmathematical techniques for solving them.

In brief, Chandra's major contributionsto twentieth century astrophysicswere in studies of the structure andstabil i ty problems during stellarevolution, stellar dynamics dealingwith distributions of matter and motionin the aggregation of stars in galaxiesand star clusters, the principles ofradiat ion transfer and radiat ionequilibrium in stellar atmospheres,part icular ly the theory of theillumination and polarization of thesunlit sky, and the theory of thenegative ion of hydrogen whichresolved a long standing controversyof the thirties pertaining to the solarspectrum and the abundance ofhydrogen in the sun. During 1952-61,he worked on several problems inmagnetic fields culminating in book onHydrodynamic and Hydromagneticstability. Beginning in 1960, Chandra'smain interests turned to Einstein’s general theory ofrelativity and to bringing it into its “natural home,”astronomy. He developed the post-Newtonian schemeto systematically take into account the generalrelativistic effects. Chandra's contributions to themathematical theory of black holes and his studies ofthe exact solutions of Einstein’s equations provided newand important physical and mathematical insights intothe richness and beauty of Einstein’s theory. In the lastyears of his life, Chandra devoted his main efforts to astudy of Newton's Principia, reworking Newton's proofsin more modern scientific language. His monograph onthis work was published just prior to his death in 1995.

Chandra is often thought of as a scholar in theclassical tradition of Lord Rayleigh (John WilliamStrutt) and Jules-Henri Poincare. Some two-thirds ofhis research papers are collected together in sevenvolumes. A book titled “Truth and Beauty” by Chandrais a collection of seven lectures that express histhoughts on aesthetics and motivations in science.His outlook to science is captured in the picture, (inlay)‘Ascent of man’ that adorned his office.

Selected results of Chandrasekhar and its impact

Fluids and Plasmas (1949-1957): Chandrasekhar madefundamental contributions to Magnetohydrodynamics(MHD) with particular attention to generation, staticequilibrium and dynamical stability of magnetic fields invarious settings with conceptualized applications toastronomical problems. Inspired by Heisenberg heworked on a formulation of an equation for the energy

spectrum of statistically isotropichomogeneous hydrodynamicturbulence and generalized theVon Karman-Howarth equation toMHD.

The structure of the Galacticmagnetic field is central toacceleration and propagation ofcosmic rays. Along with EnricoFermi, he worked on the structureand dynamics of the magneticfields in the spiral arms and madethe first estimates which are inrough agreement (within a factorof 2) of modern observations.

Chandrasekhar derived andexploited the magnetic virialtheorem to explain magnetic starsand obtained stability criteria formagnetized equilibria in manygeneral situations. He obtainedwith Prendergast the field

equations for the general case of magnetostaticequilibrium with axisymmetry. He worked out the analyticsolution to the axisymmetric force-free Lorentz equationwhich has important applications for the solar plasma.With Kendall, he extended this solutions to non-axisymmetry and resistive decays.

With Kaufman and Watson he developed a perturbationsolution to the collisionless Boltzmann equation in thestrong field limit applying to the stability of themagnetic pinch. With Bachus he provided the formalproof of the anti-dynamo theorem for the idealaxisymmetric case that proscribes the maintenance

Scientific Legacy of S. Chandrasekhar

Ascent of man


of the magnetic fields in this setting.

He studied several effects of the magnetic fields onthe dynamical instability of the Couette flows, theRayliegh-Taylor and Kelvin-Helmholtz instability. Manyof the situations studied by him continue to berediscovered in modern computer simulations and findapplications in stars and astrophysical disks. Onesuch differential rotation instability is believed to playa key role in angular momentum transport in disks, asubject that is very relevant in the modern context.

Theory of Radiative Transfer (1943-1950):Chandrasekhar's most important contributions in thisarea are the discrete ordinatemethod, the invarianceprinciples and polarization. An integro-differentialequation of transfer with two-point boundary conditionspresents a di f f icul t mathematical problem.Chandrasekhar reduced this finite set of ODE byintroduction of quadrature scheme into the integralterm, whose solutions at large order were shown to beexact.

Chandrasekhar developed and formalized the ideas firstintroduced by Ambartsumian in the late 1940s. Theinvariance principles greatly simplifies the transferproblem by showing the forms of the scattering andtransmission functions. The four elegant invarianceprinciples given Chandrasekhar's text on the subjectrepresent the foundations of radiative transfer theory.

One noteworthy numerical calculation for the problemof Thompson scattering using discrete ordinates wasthe maximum of 11 % in the degree of polarization forgrazing emergence, a result that is widely quoted. Inorder to extend the Rayleigh's theory which was baseon a single scattering approximation, Chandrasekharformulated the full scattering problem with polarizationusing Stokes's parameters. Chandrasekhar went onto find the solution for diffuse reflection of a semi-infiniteRayleigh scattering atmosphere. Along with Elbert heproduced complete polarization sky maps based onthis theory which showed precisely the character ofthe observations, in particular the neutral points onthe Sun's meridian and also the complete neutral lines.

Stellar structure and Evolution (1929-1939): As ayoung student Chandrasekhar built on Fowler'sinvocation of Fermi-Dirac statistics in the structure ofstars. Realizing that relativistic forms are required, hederived the celebrated mass-radius relation for WhiteDwarfs. Chandrasekhar included the correct form for adegenerate relativistic gas and solved the equationsof hydrostatic equilibrium. He predicted a upper imitto the mass of White Dwarf of 1.4 M_sun famouslyknown as theChandrasekhar limit. He went on todevelop and build the theory of stellar structure usingintegral theorems, homologous transformations and the

method of stellar envelopes. These analytic resultsare fundamental in the field and formed the basis forconstructing sophisticated numerical stellar modelsof the modern era. With Schonberg he found a criticalmass limit of an isothermal core which is about 10 %of the mass of the star which has profound implicationsfor the evolution of the star with a helium core and aradiative envelope. It is this critical fraction thatpredicts the Hertzsprung gap in the HR diagram, aregion between the main sequence and the red giantswhere there is a paucity of stars.

His early results led inescapably to the conclusionthat sufficiently massive stars will ultimately collapseto black holes, though he returned to the subject in1964 to make a detai led study of relativist icinstabilities and study of black hole properties for thenext thirty years.

Statistical and Dynamical Problems in Astronomy(1939-1943; 1961-1968): The important resultsobtained by Chandrasekhar in stellar dynamics includethose on ellipsoidal hypothesis and stellar relaxationtime with application to dynamical friction.

He produced both steady state and time dependentmodels for the distribution functions that are constanton ellipsoids in velocity space. He found a largerspace of solutions to the steady state problem thanpreviously thought possible (beyond the Stackelpotentials) and gave the integrability conditions. Heinvestigate various time dependent models to discoverinstability in the steady state models and investigatedspiral structure. He also studied axially symmetricsystems and found a correct prescription for thepotential. He used the formalism to find useful resultsfor spheroidal systems.

Chandrasekhar, in a very intricate calculation,estimated the relaxation time including deflection ofstars and time average of the energy fluctuations whichwas previously incorrectly evaluated by Eddington,Schwarzchild and Rosseland.

Chandrasekhar applied powerful statistical methodsto attempt a better theory of stellar fluctuations. Themain goal was to find the relaxation time as a functionof the random variable of the fluctuating force field. Intwo rigorous papers with the famous Von Neumannhe worked out these ideas which involves the principaltask of evaluating the joint probability distribution offorce field in terms of the rate of the fluctuation. Aftera very difficult calculation, Chandrasekhar and VonNeumann show the existence of dynamical frictionalforce that is proportional to the velocity.

Chandra devoted much of the period from 1960 to 1968to the virial method and analysis of the figures ofclassical ellipsoids and their stability. The importance

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of this lies in the fact that the tensor virial theoremcan be exploited to find approximate information aboutfigures seriously distorted from the spherical byrotation or magnetic fields. He found with Lebovitzthat in the context of incompressible figures of theMaclaurin spheroids, the virial equations yielded exactfrequencies. It presented an attractive alternative toarduous expansions in ellipsoidal harmonics whichwas used in analyzing Jacobi ellipsoids by Poincare,Darwin, Lyapunov and Jeans. He with Lebovitz appliedthe machinery to study Maclaurin and Jacobisequences and extended it to the more general familyof Reimann ellipsoids previously discovered byDirichlet, Dedekind and Riemann. He invented newresults and cleaned up many classical results in thisarea.

General Relativity and Mathematical Theory ofBlack holes (1962-1983): Once Chandrasekharstarted on relativity, he never left it. The first problemhe worked on was the study of pulsation of a sphericalstar in GR. It immediately had an impact in astronomyin showing that quasars were likely to be singlesupermassive stars. He went to attack a veryformidable problem of gravitational radiation reaction,namely how does the emission of gravitationalradiation affect the emitting system, in particular whenthe system is self-gravitating. He produced the answerupto the 2.5 post Newtonian Order. Severalapproaches are based on this valuable work.

Chandrasekhar presented a unified picture of blackhole perturbations which was mired in differentapproaches and explained several mysteries. He alsoworked on Dirac equation in Kerr space time whichhe was able to separate correctly. He also workedon the solution of the Einstein-Maxwell equationsknown as the Kerr-Newman metric. He studied Kerr-Newman holes and their perturbations.He worked oncolliding plane waves in general relativity withXanthapolous which is considered fundamental to theunderstanding of singularities. All this has profoundimplications for calculation of templates for detectionof gravitational waves.

Newton's Principia (1995): Armed with theknowledge of Latin, Chandrasekhar analyzed theresults obtained by Newton by trying to re-discoverhis proofs. He was amazed by simplicity of thegeometric methods used by Newton in the face ofpowerful modern algebraic methods. Chandrasekhar'slast book was written for the scientific community torecover the remarkable insight of the intellectual giantof past era that was lost down the centuries.

To conclude, it is fair to say that S. Chandrasekharwas an extraordinary mathematician, a greaterphysicist and the greatest astronomer of thetwentieth century whose results continue to havelasting impact and have permeated nearly all the fieldsof Astronomy.

- Arun Mangalam

14 òçðÃðÙ×ðÜ 2010 ¨îð÷ ØððÜóÃðóÚð ÃððÜðØððøòÃð¨îó çðüçÆððÐð Ùð÷ü ¡ðÚðð÷ò¸ðÃð òèÐÇóòÇãðçð ¨÷î ÇðøÜðÐð ÑðôÜç¨îðÜ òãð¸ð÷Ãðð¡ð÷ü ¨÷î çððÆð ¡ÐÚð ç¾ðùÒî çðÇçÚð| (×ðð¦ü çð÷Çð¦ü) ¦Ùð.ÑðôÝæðð÷ÄðÙð, ÙðóÐðð, ¦Ðð.çðÃÚð ØððÙðð, ÙððòâðÐðó Üð¸ðÐð, Àðù. Ñðó.¨ôîÙðÜ÷çðÐð,Ñßð÷. ¡ðÜ.çðó.¨îÑðõÜ, ¦Ðð.¨÷î. ÑßÙðóâðð, ¦âð.¸ðð÷çðÒîóÐð, ×ðó.ÑßðÂð÷äð Üðãð

òèÐÇó Ñð®ðãððÀÿð ãð òèÐÇó òÇãðçð çðÙððÜð÷è -2010

01 òçðÃðÙ×ðÜ 2010 çð÷ 14 òçðÃðÙ×ðÜ 2010 ¨÷î ÇðøÜðÐð òèÐÇó Ñð®ðãððÀÿð¨îð ¡ðÚðð÷¸ðÐð ò¨îÚðð ±ðÚðð| ‚çð ¡ðÚðð÷¸ðÐð ¨îð÷ çðÒîâð ¦ãðü Üð÷µð¨î×ðÐððÐð÷ ¨÷î òâð¦ çðüçÆððÐð Ùð÷ü òèÐÇó ãððÇ - òãðãððÇ , òèÐÇó ±ððÐð, òèÐÇó¡üÃÚððêðÜó , òèÐÇó òÐð×ðüÏð ÃðÆðð òèÐÇó ¡ÐðôãððÇ ÑßòÃðÚðð÷ò±ðÃðð¡ð÷ü ¨îð¡ðÚðð÷¸ðÐð ò¨îÚðð ±ðÚðð |

14 òçðÃðÙ×ðÜ 2010 ¨îð÷ ØððÜóÃðóÚð ÃððÜðØððøòÃð¨îó çðüçÆððÐð Ùð÷ü òèÐÇóòÇãðçð ØðãÚð ÞÑð çð÷ ÙðÐððÚðð ±ðÚðð| ‚çð çðÙððÜð÷è ¨îó ¡ÏÚðêðÃðð Àðù.Ñðó. ¨ôîÙðÜ÷çðÐð, ÑßäððçðòÐð¨î ¡òÏð¨îðÜó Ðð÷ ¨îó| £Ðèð÷üÐð÷ ¡ÑðÐð÷ çðü×ðð÷ÏðÐðÙð÷ü çðÜ¨îðÜó ¨îðÙð¨îð¸ð Ùð÷ü òèÐÇó ¨îð ÑßÚðð÷±ð çðØðó çðÜ¨îðÜó ¡òÏð¨îðÜó¦ãðü ¨îÙðáµððòÜÚðð÷ü ¨îð ÐðøòÃð¨î ÇðòÚðÃãð èø ¡ðøÜ ¨îèð ò¨î çðÜ¨îðÜó¨îðÙð¨îð¸ð çðÜâð, çðè¸ð ÃðÆðð ¡ðÙð ×ðð÷âð µððâð ¨îó Øððæðð Ùð÷ü òÐðÑð¾ðÚðð¸ððÐðð µððòè¦| Ñßð÷Ò÷îçðÜ ¡ðÜ.çðó. ¨îÑðõÜ, çðâððè¨îðÜ Ðð÷ ±ðöè ÙðüëððâðÚðÎðÜð Ñß÷òæðÃð ±ðöè Ùðüëðó ¨îð çðüÇ÷äð ÑßçÃðôÃð ò¨îÚðð| ÃðÇð÷ÑðÜðüÃð òãðòØðÐÐðÑßòÃðÚðð÷ò±ðÃðð¡ð÷ü ¨÷î 18 òãð¸ð÷Ãðð¡ð÷ü ¨îð÷ ÑðôÜç¨îðÜ òãðÃðòÜÃð ò¨î¦ ±ð¦|åó ¦. ÐðÜòçðüè Üð¸ðõ, ¨îðòÙðá¨î ¡òÏð¨îðÜó Ðð÷ ¡ðØððÜ ÑßÇòäðáÃð ¨îÜÃð÷èô¦ òèÐÇó òÇãðçð ¨îð çðÙððÜð÷è çðô®ðÇ çðÙððÑðÐð ò¨îÚðð|

òÇÐððü¨î 16 òçðÃðÙ×ðÜ 2010 ¨îð÷ ãð÷Âðô ×ððÑðõ ãð÷Ïðäððâðð, ¨îðãðâðõÜ Ùð÷üòèÐÇó òÇãðçð ¨îð ¡ðÚðð÷¸ðÐð ò¨îÚðð ±ðÚðð | òèÐÇó ±ððÐð ÃðÆðð òèÐÇó¡üÃÚððêðÜó ÑßòÃðÚðð÷ò±ðÃðð ¨îð ¡ðÚðð÷¸ðÐð ò¨îÚðð ±ðÚðð | ÃðÇð÷ÑðÜðüÃðÑßòÃðÚðð÷ò±ðÃðð¡ð÷ü ¨÷î 08 òãð¸ð÷Ãðð¡ð÷ü ¨îð÷ ÑðôÜç¨îðÜ òãðÃðòÜÃð ò¨î¦ ±ð¦|

¦Ùð.ÑðôÝæðð÷ÄðÙð¨îÐçðâ¾÷ü¾ (òèÐÇó)

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The Director, IIA invites applications from exceptionally bright candidates with outstanding academic credentials for theaward of ‘Chandrasekhar Post-Doctoral Fellowships’ in all areas of astrophysics. Applications are accepted at anytime of year. The fellowship is for an initial period of two years, extendable to three, with a minimum monthly stipend ofRs.25,000/-, an annual contingency grant of Rs.1,00,000/-, housing and medical benefits, and support for travel toBangalore. More details are at http://www.iiap.res.in/postdoc.htm.

Chandrasekhar Post-Doctoral Fellowship

Editors: S. P. Rajaguru, T. Sivarani and S. RajivaEditorial Assistance : K. Suchitra, P. MasunaPhoto Credits: T. K. Murali Das

Indian Institute of Astrophysics II Block, Koramangala, Bangalore 560 034, INDIA Tel : 91 (80) 2553 0672 Fax : 91 (80) 2553 4043Voicemail : 91 (80) 2553 9250 E-Mail : [email protected]

... K.S. Subramanian joined IIAas a support staff on 7.8.1975at VBO, Kavalur and retired inOctober 2010.

... V. Murugesan worked as asupport staff at VBO, Kavalurand retired in December 2010.

... V. Chinnappan joined IIA onSeptember 5 1974 and waselevated to various positions. Heacquired his Ph.D on A newapproach to Stellar ImageCorrection for AtmosphericallyDegraded Images during theservice in the year 2009 fromBangaloreUniversity. Chinnappanretired in October 2010.

IIA welcomes ...

.

New Appointments

Farewell

IIA wishes all the best to ...

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... Mousumi Das joined IIAon December 6, 2010 andwill be working with the"Stellar and galacticastrophysics group onobservational astronomy".Her PhD was onFormation, Stability andStarburst in MolecularClouds under the JAPprogram of I ISc,Bangalore. She works

broadly in the area of extragalactic astronomy andher present interests lie in understanding theevolution of dark matter dominated late typegalaxies.She has worked as a postdoctoral fellowat Raman research institute and Kerr Fellow at theUniversity of Maryland where she worked with themillimetre astronomy. She wasAssistant Professor,Department of Physics, BITS, Hyderabad beforejoining IIA.

. . . P r a v a b a t iChingangban joined IIAon December 29, 2010.She worked at theAstrophysics ResearchCentre for the Structureand Evolution of Cosmos(ARSEC) SejongUniversity, Korea, as aResearch Professor till midDecember 2010. She willbe working at the Institute

on research topics of interest to her, in closeassociation with the core group on theoreticalastrophysics. Her thesis was on "Connection andCurvature in the Fibre Bundle Formulation ofQuantum Theory" and she obtained her degree in2003 from Jamia Millia Islamia, New Delhi.

¡ð‚á¡ð‚á¦ ÐÚðõºðâð÷¾Ü · astrophysics, isro satellite centre, the srishti...

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