Shrinivas Kulkarni | |
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Born | Kurundwad, Maharashtra, India | 4 October 1956
Alma mater | |
Awards |
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Scientific career | |
Fields | Astronomy
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Institutions | California Institute of Technology |
Doctoral advisor | |
Notable students | Alicia M. Soderberg |
Shrinivas Ramchandra Kulkarni (born 4 October 1956) is a US-based astronomer born and raised in India. [2] He is a professor of astronomy and planetary science at California Institute of Technology, [3] and was director of Caltech Optical Observatory (COO) at California Institute of Technology, overseeing the Palomar and Keck among other telescopes. [3] He is the recipient of a number of awards and honours.
Shrinivas Ramchandra Kulkarni was born on 4 October 1956 in the small town of Kurundwad in Maharashtra, into a Hindu family. His father, Dr. R. H. Kulkarni, was a surgeon based in Hubballi and his mother, Vimala Kulkarni, was a home-maker. He is one of four children and has three sisters, Sunanda Kulkarni, Sudha Murthy (educator, author, philanthropist and wife of one of the co-founders of Infosys) and Jaishree Deshpande (wife of Gururaj Deshpande). [4] [5] [6]
Kulkarni and his sisters grew up in Hubballi, Karnataka, and received their schooling at local schools there. [2] [4] [7] [5] He obtained his MS in applied physics from the Indian Institute of Technology, Delhi in 1978 and his PhD from the University of California, Berkeley in 1983. [3]
In 1987, Kulkarni obtained a position as faculty at the California Institute of Technology. [3] According to his website, he has mentored 64 young scholars by the end of 2016.
Kulkarni is known for making key discoveries that open new sub-fields within astronomy, using wide range of wavelength in observation. ADS shows that his papers cover following fields: (1) HI absorption studies of Milky Way Galaxy, (2) pulsars, millisecond pulsars, and globular cluster pulsars, (3) brown dwarfs and other sub-stellar objects, (4) soft gamma-ray repeaters, (5) gamma-ray bursts, and (6) optical transients. He made significant contributions in these sub-fields of astronomy.
Kulkarni started off his career as a radio astronomer. He studied Milky Way Galaxy using HI absorption under the guidance of his advisor Carl Heiles, and observed its four arms. [8] The review articles he wrote with Carl Heiles have been highly cited in the field of interstellar medium. [9] [10]
He discovered the first millisecond pulsar called PSR B1937+21 [11] with Donald Backer and colleagues, while he was a graduate student. In 1986, he found the first optical counterpart of binary pulsars, [12] while he was a Millikan Fellow at California Institute of Technology. He was instrumental in discovery of the first globular cluster pulsar in 1987 [13] using a supercomputer.
With Dale Frail at NRAO and Toshio Murakami and his colleagues at ISAS (predecessor of JAXA that was led by Yasuo Tanaka at that time) Kulkarni showed that soft gamma-ray repeaters are neutron stars associated with supernova remnants. [14] [15] This discovery eventually led to the understanding that neutron stars with extremely high magnetic field called magnetars are the soft gamma-ray repeaters. [16]
Caltech-NRAO team which he led showed in 1997 that gamma-ray bursts came from extra-galactic sources, [17] and identified optical counterparts. [18] Their research initiated the detailed studies of the sources of gamma-ray bursts along with the European team led by Jan van Paradijs.
He was also a member of the Caltech team that observed the first irrefutable brown dwarf in 1994 that orbited around a star called Gliese 229. [19]
His recent work involved Palomar Transient Factory which has succeeded in identifying the new groups of optical transients such as superluminous supernovae, [20] calcium-rich supernovae, [21] and luminous red novae. [22] [23]
The success of his astronomical research is evident by 63 Nature Letters, 7 Science Letters, and total of 479 refereed scientific articles that bear his name by the end of 2015, according to ADS. Recognizing his contribution to astronomy, he was awarded the Dan David Prize in 2017. [24]
Kulkarni has received many awards and honours, including the NSF's Alan T. Waterman Award in 1992, [25] the Helen B. Warner Prize from the American Astronomical Society in 1991, [26] the Jansky Prize in 2002 [27] and the Dan David Prize in 2017. [28] [29] In 2015, he received an honorary doctorate from Radboud University in the Netherlands. [30] In 2024, he was awarded the Shaw Prize in Astronomy. [31] [32]
Kulkarni has been the Jury Chair for the Infosys Prize for the discipline of Physical Sciences since 2009. [33] The prize is awarded by the Infosys Foundation, whose founder is Kulkarni's brother-in-law, Narayana Murthy.
Kulkarni is a member of as many as four national academies around the globe. He was elected a Fellow of the Royal Society, London, in 2001, [1] [34] a member of the United States National Academy of Sciences in 2003, [35] an honorary fellow of Indian Academy of Sciences in 2012, [36] and a foreign member of the Royal Netherlands Academy of Arts and Sciences on 12 September 2016. [37] [38]
Timeline of neutron stars, pulsars, supernovae, and white dwarfs
A magnetar is a type of neutron star with an extremely powerful magnetic field (~109 to 1011 T, ~1013 to 1015 G). The magnetic-field decay powers the emission of high-energy electromagnetic radiation, particularly X-rays and gamma rays.
Vulpecula is a faint constellation in the northern sky. Its name is Latin for "little fox", although it is commonly known simply as the fox. It was identified in the seventeenth century, and is located in the middle of the Summer Triangle.
A pulsar wind nebula, sometimes called a plerion, is a type of nebula sometimes found inside the shell of a supernova remnant (SNR), powered by winds generated by a central pulsar. These nebulae were proposed as a class in 1976 as enhancements at radio wavelengths inside supernova remnants. They have since been found to be infrared, optical, millimetre, X-ray and gamma ray sources.
A pulsar is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. This radiation can be observed only when a beam of emission is pointing toward Earth, and is responsible for the pulsed appearance of emission. Neutron stars are very dense and have short, regular rotational periods. This produces a very precise interval between pulses that ranges from milliseconds to seconds for an individual pulsar. Pulsars are one of the candidates for the source of ultra-high-energy cosmic rays.
The Crab Pulsar is a relatively young neutron star. The star is the central star in the Crab Nebula, a remnant of the supernova SN 1054, which was widely observed on Earth in the year 1054. Discovered in 1968, the pulsar was the first to be connected with a supernova remnant.
Geminga is a gamma ray and x-ray pulsar source thought to be a neutron star approximately 250 parsecs from the Sun in the constellation Gemini.
Dale A. Frail is a Canadian astronomer working at the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico.
The Vela Pulsar is a radio, optical, X-ray- and gamma-emitting pulsar associated with the Vela Supernova Remnant in the constellation of Vela. Its parent Type II supernova exploded approximately 11,000–12,300 years ago.
LS I +61 303 is a binary system containing a massive star and a compact object. The compact object is a pulsar and the system is around 7,000 light-years away.
Carl Eugene Heiles is an American astrophysicist noted for his contribution to the understanding of diffuse interstellar matter through observational radio astronomy.
PSR B1937+21 is a pulsar located in the constellation Vulpecula a few degrees in the sky away from the first discovered pulsar, PSR B1919+21. The name PSR B1937+21 is derived from the word "pulsar" and the declination and right ascension at which it is located, with the "B" indicating that the coordinates are for the 1950.0 epoch. PSR B1937+21 was discovered in 1982 by Don Backer, Shri Kulkarni, Carl Heiles, Michael Davis, and Miller Goss.
The Black Widow Pulsar is an eclipsing binary millisecond pulsar in the Milky Way. Discovered in 1988, it is located roughly 6,500 light-years away from Earth. It orbits with a brown dwarf or Super-Jupiter companion with a period of 9.2 hours with an eclipse duration of approximately 20 minutes. When it was discovered, it was the first such pulsar known. The prevailing theoretical explanation for the system implied that the companion is being destroyed by the strong powerful outflows, or winds, of high-energy particles caused by the neutron star; thus, the sobriquet black widow was applied to the object. Subsequent to this, other objects with similar features have been discovered, and the name has been applied to the class of millisecond pulsars with an ablating companion, as of February 2023 around 41 black widows are known to exist.
PSR J1614–2230 is a pulsar in a binary system with a white dwarf in the constellation Scorpius. It was discovered in 2006 with the Parkes telescope in a survey of unidentified gamma ray sources in the Energetic Gamma Ray Experiment Telescope catalog. PSR J1614–2230 is a millisecond pulsar, a type of neutron star, that spins on its axis roughly 317 times per second, corresponding to a period of 3.15 milliseconds. Like all pulsars, it emits radiation in a beam, similar to a lighthouse. Emission from PSR J1614–2230 is observed as pulses at the spin period of PSR J1614–2230. The pulsed nature of its emission allows for the arrival of individual pulses to be timed. By measuring the arrival time of pulses, astronomers observed the delay of pulse arrivals from PSR J1614–2230 when it was passing behind its companion from the vantage point of Earth. By measuring this delay, known as the Shapiro delay, astronomers determined the mass of PSR J1614–2230 and its companion. The team performing the observations found that the mass of PSR J1614–2230 is 1.97 ± 0.04 M☉. This mass made PSR J1614–2230 the most massive known neutron star at the time of discovery, and rules out many neutron star equations of state that include exotic matter such as hyperons and kaon condensates.
A neutron star merger is the stellar collision of neutron stars. When two neutron stars fall into mutual orbit, they gradually spiral inward due to gravitational radiation. When they finally meet, their merger leads to the formation of either a more massive neutron star, or—if the mass of the remnant exceeds the Tolman–Oppenheimer–Volkoff limit—a black hole. The merger can create a magnetic field that is trillions of times stronger than that of Earth in a matter of one or two milliseconds. These events are believed to create short gamma-ray bursts.
Time-domain astronomy is the study of how astronomical objects change with time. Though the study may be said to begin with Galileo's Letters on Sunspots, the term now refers especially to variable objects beyond the Solar System. Changes over time may be due to movements or changes in the object itself. Common targets included are supernovae, pulsating stars, novas, flare stars, blazars and active galactic nuclei. Visible light time domain studies include OGLE, HAT-South, PanSTARRS, SkyMapper, ASAS, WASP, CRTS, GOTO and in a near future the LSST at the Vera C. Rubin Observatory.
Hakkı Boran Ögelman was a Turkish physicist and astrophysicist. He was an expert on gamma ray astronomy, the physics of neutron stars, and solar energy and worked on several key topics in modern astrophysics. He made many contributions to high energy astrophysics. In his early professional career he engaged in the SAS-II Small Gamma Ray Astronomy Satellite experiment development, data analysis, and first detection and imaging of our universe in gamma rays with his NASA colleagues, as well as in other fields of physics. His main interests in the field of astrophysics were the study of gamma ray astronomy and compact objects such as neutron stars and pulsars. Ögelman worked at NASA Goddard Space Flight Center, Middle East Technical University (METU) in Ankara, Turkey, Çukurova University in Adana, Turkey, Max Planck Institute (MPI) at Garching, Germany and the University of Wisconsin.
Fiona A. Harrison is the Kent and Joyce Kresa Leadership Chair of the Division of Physics, Mathematics and Astronomy at Caltech, Harold A. Rosen Professor of Physics at Caltech and the Principal Investigator for NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) mission. She won the Hans A. Bethe Prize in 2020 for her work on NuSTAR.
The Galactic Center GeV Excess (GCE) is an unexpected surplus of gamma-ray radiation in the center of the Milky Way galaxy. This spherical source of radiation was first detected in 2009 by the Fermi Gamma-ray Space Telescope and is unexplained by direct observation. Two percent of the gamma ray radiation in a 30° radius circle around the galactic center is attributed to the GCE. As of 2020, this excessive gamma-ray radiation is not well understood by astronomers.
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