U.S.-India cooperation in astronomy and astrophysics
Think of astronomy and astrophysics and many of us are perplexed. The cosmos, and more specifically research associated with it, seems too complex to appreciate. But in this cosmos and its diverse phenomena lie the unsolved mysteries of matter. Astrophysicists spend years, and at times decades, to stumble upon a small finding that adds to the gamut of existing knowledge about matter and the universe.
Just after independence in 1949, Indian astronomer Manali Kallat Vaini Bappu went to Harvard and discovered the "Bappu-Bok-Newkirk Comet" with colleagues Bart Bok and Gordon Newkirk. Later he went to the Palomar Observatory in California where he and Colin Wilson discovered the "Wilson-Bappu Effect," which is one of the fundamental relations used to determine a star's luminosity. Among the initial collaborations between the United States and India in this field was a cosmic-ray experiment in the early 1950s carried out by Eknath V. Chitnis of the Ahmedabad-based Physical Research Laboratory with George W. Clark of the Massachusetts Institute of Technology (MIT) at Kodaikanal, Tamil Nadu. Another event that received public attention was the Indian cosmic-ray experiment Anuradha flown aboard the Spacehab-3 shuttle in 1985.
Also known is the ongoing collaboration between Jayant V. Narlikar from Inter University Centre for Astronomy and Astrophysics (IUCAA) in Pune and Geoffrey R. Burbidge from the University of California at San Diego on the nature of quasars, which are star-like objects that seem to be moving away from earth at high-speeds. Working with the late British astrophysicist Fred Hoyle, they also introduced in 1993 the Quasi-Steady State Cosmology, an alternative to the Big Bang Theory on the origin of the universe. But there are numerous other examples-both past and ongoing-that are quite significant from the research perspective but are not well known outside the astronomical community. Many such joint works are voluntary one-to-one interactions between researchers from both sides without any formal institutional agreement.
The Aryabhatta Research Institute of Observational Sciences (ARIES) in Nainital, formerly called the Uttar Pradesh State Observatory (UPSO), has a long history of American collaborations. A project on optical tracking of artificial earth satellites was started in 1958 in collaboration with the Smithsonian Astronomical Observatory (SAO) in Cambridge, Massachusetts, that continued for about two decades. SAO loaned a Baker-Nunn camera and ancillary equipment to UPSO. Satellites photographed included India's Aryabhatta and Apollo-11, 12 and 17 of the United States.
ARIES and the Vaini Bappu Observatory at Kavalur, Tamil Nadu, have participated in the Whole Earth Telescope (WET) effort coordinated by the University of Texas (UT) at Austin and Iowa State University in Ames through which variability of astronomical objects are studied by astronomers worldwide. Scientists from the Indian Space Research Organisation Satellite Centre (ISAC) in Bangalore have been working with American colleagues on this project since 1988 and have taken part in seven campaigns to date. In a typical WET campaign, about 15 observatories participate for around two weeks to get continuous data. "The Indian longitude has formed one of the important links in the WET, because there are very few collaborators covering the Asian longitudes. We are still continuing our collaboration," says S. Seetha from ISAC.
Quasars are enormously bright objects at the edge of the universe that emit massive amounts of energy. The first quasars discovered were very powerful sources of radio waves that are low-energy electromagnetic radiation much longer in wavelength than light. These travel at the speed of light, and the telescopes used to detect them are much larger than optical telescopes. But over the past 40 years astronomers have shown that less than 10 percent of all quasars are strong radio wave emitters. Despite the large difference in the intensity of radio waves from "radio-quiet" and "radio-loud" quasars (this phenomenon is called "quasar dichotomy"), the extraordinary amount of energy-often a trillion times that of the sun-coming from both is very similar in many parts of their spectra. Ram Sagar and C.S. Stalin from ARIES, and Gopal Krishna from National Centre for Radio Astrophysics (NCRA) in Pune, along with Paul Wiita from Georgia State University in Atlanta and a German astrophysicist, started a detailed investigation of quasar dichotomy about a decade ago. They found there is no fundamental difference between the central processes of these two quasar types.
In the mid-1990s, Stephen A. Drake from NASA's Goddard Space Flight Center (GSFC) and Kulinder Pal Singh, who was also at GSFC, studied the X-ray emission from the outermost layers (coronae) of "active" stars (stars of similar or lower mass than the sun that are much stronger X-ray and radio-wave emitters). Singh later returned to the Tata Institute of Fundamental Research (TIFR) in Mumbai and continued the work with Drake along with co-researchers from ARIES. "The active stars are particularly interesting because they are often very young compared with the sun-maybe a hundredth of the sun's 4.6 billion years of age. In the last 15 years our work has helped establish that such 'adolescent stars' are present in the solar neighborhood (within, say, 100 light-years) which was previously thought to consist of only middle-aged stars like the sun," Drake explains. About half-a-dozen American institutes are collaborating with ARIES on gamma-ray bursts (GRBs), short-lived bursts of gamma-ray photons that are about a million trillion times as bright as the sun. "India is halfway across the world from the observatories in the USA and hence a very critical site for us," says Anjum Mukadam, an astrophysicist from the University of Washington in Seattle, who is also involved in the WET project.
The U.S.-funded Global Oscillation Network Group (GONG) studies seismic oscillations of the sun to know more about its internal structure and dynamics. GONG selected the Udaipur Solar Observatory (USO) of the Ahmedabad-based Physical Research Laboratory as one of the six observation sites worldwide and began a three-year observation program in 1995. Excellent initial results led to upgradation of instruments at USO, and the collaboration is now planned to continue indefinitely, says GONG director John Leibacher from the National Solar Observatory (NSO).
IUCAA is a partner in the International Virtual Observatory Alliance (IVOA). The U.S. Virtual Observatory (VO) project aims to achieve for astronomical data worldwide what the World Wide Web has achieved for documents, i.e., data from world's telescopes-both ground and space based-will be available anywhere via the Internet. IUCAA has pioneered a VO-India initiative funded by the Indian Ministry of Communications and Information Technology and helped by Johns Hopkins University (JHU) in Baltimore, Maryland, and the California Institute of Technology (Caltech). The Indian Institute of Astrophysics (IIA) in Bangalore is also participating in VO-India.
A replica of the data archive from the Sloan Digital Sky Survey (SDSS)-by far the largest astronomical survey ever undertaken, with an information content greater than the total information in the U.S. Library of Congress-is being hosted at IUCAA so that Indian astronomers can access it more efficiently. JHU has also provided the Web interface and software tools to access the data, and a software program developed at IUCAA has been incorporated into a larger SDSS application to access data. "India's talent in computational fields and IUCAA's involvement can bring a lot to VO's efforts," says G. Jogesh Babu, director of the Center for Astrostatistics at Pennsylvania State University, who is helping VO-India.
Last March a joint team from IUCAA, the University of Delhi, the University of North Carolina and the National Optical Astronomy Observatory in Tucson, Arizona, completed a seven-year task of creating a library of spectra (spectrum is the distribution of wavelengths and frequencies) of 1,273 stars, which is the largest such library to date. A star's spectrum gives information used in automated classification of stellar and galaxy spectra. In yet another effort IUCAA's Sanjeev Dhurandhar, Caltech's A. Lazzarini and Penn State's S. Finn are researching gravitational-wave signal extraction techniques for binary systems-a pair of stars or black holes or one each that go around each other emitting gravitational waves in the process. Gravitational waves are ripples in the fabric of space and time produced by violent events in the distant universe and are emitted by accelerating masses.
Then there is Yogesh Wadadekar, the only Indian in a 10-member team working on the Archival Pure Parallel Program (APPP), that aims to process and combine about 2,000 high-resolution WFPC2 (Wide Field Planetary Camera) images obtained in parallel with the Hubble Space Telescope (HST) instruments. These processed images will be used to discover galaxies and address a wide range of science topics, says Wadadekar.
Astrophysicists from MIT, Cornell University and NCRA got together to discover a pulsar-the first using NCRA's Giant Meterwave Radio Telescope (GMRT). The four-member team, which published its finding in the Astrophysical Journal last May, says it is the first known pulsar in the globular cluster NGC 1851. Globular clusters are huge, spherical concentrations of stars, tens of hundreds of light-years in diameter. Pulsars are fast rotating stars made up primarily of neutrons.
Joanna Rankin from University of Vermont, who has extensively interacted with Indian astronomers, participated in discussions to establish GMRT. She has worked on pulsars with Avinash Despande of the Raman Research Institute (RRI) in Bangalore, who is now with the Arecibo Observatory in Puerto Rico. Rankin was instrumental in an NSF grant in 1992 to promote an Indo-U.S. program on pulsars that continued for eight years. She continues her work with NCRA's Dipankar Mitra.
The late K.R. Anantharamaiah from RRI was well known at the Very Large Array (VLA) and the Very Long Baseline Array (VLBA) at the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico, where he spent five years. These arrays function as the radio equivalent of a zoom lens. On a Jansky Fellow-ship awarded by NRAO, Anantha-ramaiah was active in research on "radio recombination lines"-a narrow field of high-energy astrophysics-at VLA from 1986 through 1989. With NRAO's Tim Cornwell and others, Anantha-ramaiah started work on radio recombination lines from spiral galaxies (these are one of the four major types of galaxies classified by astronomer Edwin Hubble) beyond our own galaxy-the Milky Way. "Anantha was the driving force for this innovative, difficult and exciting research," said one of his American colleagues after he died of cancer in 2001. An additional area of ground-breaking research in the 1980s was the confirmation of carbon recombination lines at low frequencies in a particular direction by Anantharamaiah and V. Radhakrishnan from RRI and a few others using the Green Bank Telescope in West Virginia. Anantharamaiah spent two years at Socorro from 1997 to 1999 and revived a lot of the ongoing research on the central region of galaxies (called "Galactic Center" or GC). He also collaborated on GC studies with NRAO researchers, including Miller Goss, the former director of VLA and VLBA and now head of NRAO's Division of Science and Academic Affairs.
"We had a tremendous amount of success in detecting radio recombination lines from external galaxies. This is important because this is the way to determine the physical properties of the gas that is being ionized by various types of stars in the galaxies," says Goss, with whom RRI's Neeraj Mohan continues to work.
NRAO has also collaborated with IIA on VLA. Goss says Indians provided part of the engineering expertise on VLA decades back. In fact, GMRT's correlator-an instrument used to put together signals from all their radio telescopes-is an exact copy of the one at VLBA, according to Goss. "More recently, our Indian colleagues have provided tremendous stimulus to the types of work that we can do with these instruments. We really benefited from the astrophysical expertise of our colleagues in the three Indian institutes [IIA, GMRT and RRI]," he says. V. Radhakrishnan, a former RRI director, working with other astronomers at Caltech in the 1960s, pioneered new observational techniques for radio astronomy.
Since June 1999, IIA has been collaborating with the McDonnel Center for Space Sciences of Washington University in St. Louis, Missouri, in the area of astronomical transient phenomena, specifically on the installation and utilization of two Cassegraine telescopes. This will form the Antipodal Transient Observatory-the telescopes, one each in India and Arizona will be at approximately opposite ends of the earth (antipodes) 170 degrees apart. Apart from round-the-clock monitoring of transient phenomena in the sky, this can also monitor the afterglow produced by gamma-ray bursts. The Indian telescope is being commissioned at Hanle in Ladakh.
IIA and Steward Observatory at the University of Arizona have agreed to collaborate on a Himalayan Binocular Telescope (HBT) at Hanle. This collaboration, flagged in a meeting of the Indo-U.S. Roundtable during President Bill Clinton's visit to India in 2000, was also discussed at the bilateral conference on space last June in Bangalore. IIA and Steward Observatory are discussing adopting the design of the U.S.-based Large Binocular Telescope (LBT) for HBT, says IIA professor R.C. Kapoor. After completion, LBT will be the world's most advanced optical telescope to photograph planets outside the solar system. IIA researchers also have and have had joint work with many American institutes. A brief picture of some of these follows.
Gajendra Pandey and N. Kameswara Rao are working with UT Austin's David Lambert on the origin and evolution of stars deficient in hydrogen. They are investigating the possibility of an evolutionary connection between such stars and normal stars and also testing the proposed scenarios for the formation of these enigmatic stars by estimating their chemical composition. Jagdev Singh visited the Kitt Peak National Observatory in Arizona in 1984 to work with W.C. Livinston and J. Harvey on solar physics. They analyzed the excellent coronal spectra obtained during the total solar eclipse of 1983 at Tanjung Kodok, Indonesia, to study the flow of plasma in the polar regions of the corona to understand the heating processes in the solar corona. The team also found that it is possible to study the variation of the sun's rotation rate with time. (The sun does not rotate like a rigid body; it rotates faster at the equator and slower at the poles.)
B. Eswar Reddy and Lambert teamed up with UT Austin's Jocelin Tomkin to select and study samples of stars from different parts of our galaxy. "By chemically tagging samples of stars drawn from different locations of the galaxy, we are hoping to understand better the chronological formation and evolution of our galaxy," Reddy says. Reddy and Lambert are working with Bruce J. Hrivnak of Valparaiso University in Indiana to understand a small group of stars with surprisingly large amounts of lithium, and with Iowa State's Guillermo Gonzalez on richness of metals in stars and their relationship with surrounding planets. IIA's M. Parthasarathy worked with the McDonald Observatory of UT Austin to understand the early chemical history of our galaxy. He has also used HST observations to discover a specific planetary nebula (a nebula forms when a star blows off its outer layers) the study of which led to the understanding of the birth and early evolution of planetary nebulae and the advanced stages of evolution of stars with low mass.
In 1982-83 IIA's Siraj Hasan worked with NSO astrophysicists at Sacramento Peak, New Mexico, on tiny grass-like patterns of gases on the sun's boundary called "spicules." From 1991 to 2004 he was associated with Harvard-Smithsonian Center for Astrophysics (CfA) at Cambridge for NASA-funded joint work on the sun's magnetism. In 1995, he spent four months on related work at the High Altitude Observatory of the National Center for Atmospheric Research at Boulder, Colorado.
Sandip Chakrabarti, who heads the astrophysics division at the Bose Institute (BI) in Calcutta, teamed up with W.D. Arneet of the University of Chicago on black hole identification when he was a R.C. Tolman Fellow at Caltech from 1985 to '87. He has also worked with Paul Wiita on quasars and active galaxies and with GSFC on interpretation of satellite observations. GSFC has been regularly allocating observational time to BI researchers on the Rossi X-Ray Timing Explorer (RXTE) satellite for the past eight years for work on observational techniques, according to Chakrabarti. Bose Institute's B. Mukhopadhyay is now at Harvard researching nuclear reactions around black holes and T. Das has recently completed his two-year research at the University of California in Los Angeles on cosmic radio jets and outflows from black holes.
Researchers admit that many of these findings may not have immediate applications but they do immensely contribute to the spirit of scientific exploration. The field of astronomy itself being free of boundaries, investigators on both sides understand that cooperation is the key to future advances. Joint activities galore, and the sky is not the limit for these researchers.