Dr. G. S. D. Babu
Director

Ph: +91 80 2238 5956
Fax: +91 80 2238 5957
E-mail:
gsdbabu@mpbifr-blr.in

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Research Areas:

• Photometry and spectrophotometry of open clusters
• Spectrophotometry of Ap and Am stars
• Study of comets

• PhD., Physics (Astrophysics), Bangalore University, 1987
• MSc, Astronomy, Osmania University, Hyderabad, 1966
• BSc, Andhra Loyola College, Vijayawada, 1962
• SSLC, S.P.G. High School, Nandyal, 1958

• M. P. Birla Institute of Fundamental Research (Director) (2003-till date)
• Indian Institute of Astrophysics, Bangalore (1976-2003)
• Vainu Bappu Observatory, Kavalur (Scientist-in-Charge) (1998-2003)
• Jawaharlal Nehru Planetarium, Bangalore (Director) (1992-1993)
• U.P.State Observatory, Nainital (1966-1976)

Teaching experience outside India:

Taught the subject of Galactic Structure at the IAU/UNESCO/ICSU sponsored 19th International School for Young Astronomers held in Beijing, China during 19 July to 8 August 1992. I was one of the six internationally selected members of the Faculty, besides being the only one from India.

1. Guided the following students in their respective project works at the Vainu Bappu Observatory, Kavalur (1998-99).
   1. Mr.D.Sivananda Moorthy, 2nd year M.Sc.Physics, Voorhees College, Vellore.
   2. Mr.A.Sardar Khan, 2nd year M.Sc.Physics, Voorhees College, Vellore.
   3. Mr.R.Sakthi Kumar,  2nd year M.Sc.Physics, Voorhees College, Vellore.
   4. Mr.N.Ravi Kumar, 2nd year M.Sc.Physics, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore. 
   5. Mr.Ziaur Rahman, 2nd year M.Sc.Computer Science, Jamal Mohamed College, Tiruchirapalli.
   6. Ms.Mary Margaret Francis, Final year B.E.Architecture, Sathyabama Engineering College, Chennai. 
   7. Bro.Alphonse, Final year B.Sc.Chemistry, Sacred Heart College, Tirupattur.
   8. Mr.V.Amal Raj, Final year B.Sc.Chemistry, Sacred Heart College, Tirupattur.
   9. Ms.Thamizisai, Priyadarshini Engineering College, Vaniyambadi.
   10. Mr.Senthil Kumar, Priyadarshini Engineering College, Vaniyambadi.
   11. Ms.Padmalekha, National College, Bangalore.
2. Delivered series of lectures for the students at the Tangerine Geoscience Institute, Bangalore on the subject of “Spherical Trigonometry and Astronomy” (1995).
3. Initiated a dissertation-oriented Honours programme of 100 hours curriculum in Astronomy and Astrophysics for the Under Graduate students at St.Joseph’s College, Bangalore in 1994. A major portion of the syllabus was prepared by me. I taught several topics and guided the students through their dissertations. This programme is the first of its kind in India. A modified version of this programme is presently being carried out at the M. P. Birla Institute of Fundamental Research, Bangalore.
4. Guided a young pre-university student as his mentor/guide in the H.Dudley Wright International Student Contest of “Together to Mars” organised by the Planetary Society, Washington, U.S.A. (1991). He secured fourth rank in the India sector.
5. Guided college level students in observational astronomy, Vainu Bappu Observatory, Kavalur (1987-89).
6. Taught the subject of Basic Astronomy with the emphasis on the Observational aspects to the students of the Joint Astronomy Programme at the Indian Institute of Science, Bangalore (1981-83).
7. Taught the subject of Spherical Astronomy and Techniques in Observational Astronomy to the M.Sc. (Physics) students of D S B Govt.  College, Nainital (1969-72).

Guidance to long term projects:

Guided the following students in their respective Ph.D. projects at M. P. Birla Institute of Fundamental Research, Bangalore (2003-2008).

1. S. M. Sriraghavan – Synopsis of the thesis is submitted to Bangalore University and awaiting further processing.
2. S. Sujatha – Ph. D. degree has been awarded in 2008 by the Bangalore University.

Research Areas:

Photometry and spectrophotometry of open clusters

Broad band photometry of faint young open clusters in the UBVRI bands is carried out and these observations, obtained with telescopes at Vainu Bappu Observatory (of IIA), Kavalur and at Mount Stromlo & Siding Spring Observatories, Australia, were utilised in determining their distances and ages from their respective colour-magnitude diagrams.
The age of the given cluster, if found to be not more than about 10 million years, then it is considered as young enough to be unaffected by the galactic rotation and its position in the galaxy is taken to represent the original place of its formation.  It would then indicate the location of the erstwhile nebulosity in which the star formation has taken place. And since the nebulosities or the molecular clouds are found almost always in the spiral features of the galaxy, a knowledge of the distance of such a young cluster would serve as a tracer of the spiral feature in the galaxy. Thus the distance parameter of young open clusters is used for tracing the spiral features in the study of Galactic structure. Such young clusters were identified using an innovative photographic spectroscopic technique with a low resolution (150 lines/mm) grating. The instrument for this purpose was designed by G. S. D. Babu at Vainu Bappu Observatory, Kavalur (1980-81).

Twelve such open clusters have so far been observed and four of them are very clearly located along the Orion-Cygnus arm of our Galaxy, while one is found to be a member of the Sagittarius-Carina arm. Four of the remaining clusters are found in the outer Perseus region, substantiating the existence of the outer Perseus spiral feature, which in turn appears to be merging with the Orion-Cygnus arm at a distance of about 6.5 kpc. And three of the observed clusters give an indication of a feature which is branching off from the Orion-Cygnus arm and extending towards the Carina constellation.  This, incidentally, happens to be the first indication of this branching-off feature from optical observations, which is in fact strengthening the radio observations. Since the above mentioned tracing of the spiral features requires the study of a number of young open clusters, the programme is being continued covering the clusters in the galactic longitude region of 160^o to 280^o.

Spectrophotometry of Ap and Am stars

The energy distribution curves in the wavelength region of 3900 A^o to 7800 A^o for about 150 Ap and Am stars have so far been obtained using the spectrophotometric facilities available at U.P.State Observatory, Nainital and at Vainu Bappu Observatory (of IIA), Kavalur. The photoelectric spectrum scanner was designed by G. S. D. Babu in which a Hilger and Watts monochromator was incorporated at the U.P.State Observatory, Nainital, during the years 1967-68. These energy distribution curves were utilised for determining the stellar physical parameters namely, the effective temperatures, radii and bolometric magnitudes.

However, these parameters appear to be not very different from those of the normal stars of similar spectral types. From this, it may be inferred that the only difference between the normal and peculiar stars could be the chemical overabundances which are not otherwise affecting the physical nature of the given star.

An extended analysis of these parameters, with reference to the evolutionary aspects, indicates that these chemically peculiar stars are probably transiting towards the yellow giant region and are presently in the hydrogen shell burning phase.

The same energy distribution curves have further been analysed to study the periodic variations in the broad spectral features around 4200 A^o and 5200 A^o, which are readily noticed in some of the observed stars.  The equivalent widths of these features are found to be varying with the same periodicities as those of the light variations, magnetic field variations, etc. of the given chemically peculiar star. Such variations observed in the above mentioned broad spectral features have been interpreted as due to the surface inhomogeneities of these stars having large sized patches of certain predominant chemical compositions.

Study of the chemically peculiar stars is being continued as one of the on-going programmes.

Study of comets

Photometric and spectrophotometric observations of comet Bennet, comet Kohoutek, comet West and comet Halley in addition to some not very bright comets, were obtained  during their respective apparitions, with the telescopes at U.P.State Observatory, Nainital and at Vainu Bappu Observatory (of IIA), Kavalur. These observations were utilised for studying the spatial and temporal variations of fluxes, column densities, etc. of the constituent molecular species as well as the variations of the energy distribution in the cometary continuum with respect to the heliocentric distances.

The variation of the continuum energy distribution curves of the comets show that the reddening of the scattered light decreased as the phase angle increased. An analysis of this aspect indicated that the size of the scattering particles is of the order of 0.5 microns. Further, the variations in the brightness of the continuum with reference to the emission features of C2, showed that comet West was as dusty as comet Kohoutek while being less dusty than what comet Bennet was.

A comparison of the total number of molecules observed in the column of line of sight for comet Halley with that of comet West, indicated that the density of the constituents in the coma of comet Halley is much less than that in comet West. This can perhaps be related to the loss of matter in the coma of comet Halley due to its several apparitions as against the possible first appearance of comet West.

The analysis of the scale lengths of the CN and C2 molecules and their parents in the observed comets provided evidence to show that the CN molecules are produced by the dissociation of two species of parent molecules having entirely different lifetimes. A similar result was seen for C2 molecules also.

The step scans covering most of the visible spectral region taken at different locations over the comae of comet West and comet Halley, provided evidence that the coarser particles were confined to the centre and the finer ones towards the periphery of the cometary coma.

Other related activities:

I was the Leader of the first six-member team that ventured on an expedition to a place called Hanle, a high altitude desert area at an altitude of 4250 mts, in the Ladakh region of the Trans-Himalayan ranges, close to the Indo-Tibetan border, in search of a site suitable for setting up an Astronomical Observatory as a part of the Himalayan Infrared and Optical Telescope Project of DST, Govt.of India (1990-92).

The Indian Astronomical Observatory, world’s highest observatory with the 2 meter class Himalayan Chandra Telescope for optical and infrared astronomy is now located at this site.

Observational programmes conducted outside India:

1. Antarctica: I have been one of the first three Indian astronomers, who carried out a solar astronomy programme at the permanent Indian station, Maitri in Antarctica during the 1989-90 expedition. The programme of studying the supergranular cells on the surface of the Sun was successfully executed and more than 2500 photographs of the Sun were obtained in Ca K line during an uninterrupted and continuous spell of clear sky conditions which lasted for more than 100 hours at a stretch, at the Indian station. 
2. Mauritius: Participated in the month-long expedition to the island country of Mauritius for the photometric observations of the Supernova 1987A as the leader of the expedition team in 1988.
3. Australia: Photometric observations of several young open clusters were obtained with the telescopes at the Mount Stromlo and Siding Spring Observatories of the Australian National University in 1985. These observations were specifically useful in the completion of my thesis ‘The study of faint galactic open clusters’.

G. S. D. Babu in the Indian Expedition to Antarctica:

On the day after Christmas in 1989,  Dr. G. S. D. Babu, Dr. Jagdev Singh - both from Indian Institute of Astrophysics, Bangalore and Mr.Wahabuddin from U.P. State Observatory, Nainital became  the first ever Indian astronomers to have set foot on the icy continent of Antarctica for carrying out a unique solar astronomy programme from the permanent Indian station called Maitri.  These pioneering astronomers were part of the 81-member (including 19 scientists of various disciplines) IX Indian Scientific Expedition to Antarctica which sailed off from Goa (India) on 30 November 1989.

The aim of this astronomy experiment was to study the evolution, decay and preferred location of formation of “supergranular” cells on the surface of the Sun.  Since the lifetime of these cells, based on some statistical studies, was estimated to be around 20-22 hours, it became imperative to have continuous data covering a time span of at least this much period so that one may arrive at some definite results.  Thus, the 24-hour availability of the Sun from  the locations in the continent of Antarctica during the local summer season turned out to be the most appropriate choice.

A solar telescope, which was exclusively designed for the sake of this experiment and fabricated at the Indian Institute of Astrophysics, was successfully installed at Maitri by the three astronomers, who eventually achieved the unique distinction of obtaining a series of uninterrupted Calcium-K filtergrams of Sun continuously for about 100 hours at intervals of 10 minutes.  This experiment has been termed as being the first of its kind in the history of solar observations.

Dr. G. S. D. Babu had the further distinction of being selected as the Scientist-Member of the Core Group Committee for the duration of expedition.  Besides handling, supervising and participating in various tasks of the expedition, the main responsibility of being in such a position was to act as the co-ordinator for all scientist members of the expedition.

Editorial work:

1. "Proceedings of the XVIII ASI Meeting", held at Physical Research Laboratory,  Ahmedabad, November 28 - December 1, 1997, Guest Editors: G. S. D. Babu and
   A.V. Raveendran,  Bulletin of the Astronomical Society of India, Vol. 27, 1999.
2. Assisted Prof. J.C. Bhattacharyya in editing the text book on Astronomy written by late Prof. J.N. Bhar of Calcutta.  This book consists of 12 chapters dealing with various topics in astronomy and is written for the University level students.
3. "Proceedings of the National Symposium on Comet Halley", held at Indian Institute of Astrophysics, Bangalore, October 27-29, 1987, Eds. K.R.Sivaraman and G. S. D. Babu.

Membership of professional organizations:

1. Astronomical Society of India (Founder Member), General Secretary (1994 - 1997)
2. International Astronomical Union, Regular Member
3. National Committee for the restoration of the Jantar Mantars, Executive Member
4. Working Group for the Worldwide Development of Astronomy, Member
5. Commission 25, 41 and 45 of the International Astronomical Union, Member
6. Standing Advisory Committee of the Positional Astronomy Centre, Govt. of India, Member

Publications list (Selected):

1.  “NGC 1624 (OCl 403, Cr 53)– A very young open cluster”
   Sujatha, S. and Babu G.S.D., Astrophysics and Space Sciences, 305, 399 - 410, 2006.
2. “Mass function of open clusters NGC 1857 and Czernik 25”
   Sujatha, S., Babu, G.S.D. and Sharath Ananthamurthy, Bulletin of Astronomical Society of India, 34,     357 – 373, 2006.
3. “UBVRI CCD photometric studies of open clusters Berkeley 15, Czernik 18 and NGC 2401”
   Sujatha, S., Babu G.S.D. and Sharath Ananthamurthy, Bulletin of Astronomical Society of India, 32, 205- 309, 2004.
4. “Variation of the Si II features in the chemically peculiar star – HD 115735”
   Sriraghavan, S. M., Jayakumar, K., Babu, G. S. D., and Sujatha, S., Bulletin of Astronomical Society of India, 32, 113-119, 2004.
5. “Study of Open Cluster NGC 2509”
   Sujatha, S. and Babu, G.S.D., Bulletin of Astronomical Society of India, 31, 9-18, 2003.
6. “Spectral Line Variations in the Ap Star HD42536”
   Babu, G. S. D., Jayakumar, K. J., Velu, C., and Sujatha, S., Bulletin of Astronomical Society of India, 31, 337-339, 2003.
7. “Study of Old Open Clusters NGC 1605, Czernik 18 and NGC 2509”
   Sujatha, S. and Babu G.S.D., Bulletin of Astronomical Society of India, 31, 379-382, 2003.

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