Kavan Ratnatunga

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Kavan Ratnatunga
Born
NationalityFlag of Sri Lanka.svg  Sri Lanka
Education Australian National University
University of Pittsburgh
University of Ceylon, Colombo
Royal College Colombo
Employer(s) Institute for Advanced Study 1984/86
Dominion Astrophysical Observatory 1986/87
NASA Goddard Space Flight Center1989/91
Space Telescope Science Institute 1992
Johns Hopkins University 1992/96
Carnegie Mellon University 1996/2004
Websitewww.lakdiva.org

Kavan Ratnatunga is a Sri Lankan scholar, with interests in astronomy, archaeology and numismatics.

Contents

Education

Kavan Ratnatunga went to school at Royal College, Colombo, Ceylon. In 1976 from the University of Ceylon, Colombo, he was awarded a first-class BSc Honours Degree in Physics. In 1979 he obtained a MS from University of Pittsburgh in USA, and in 1983 a PhD from Australian National University, specializing in automated statistical analysis of astronomical data and digital images.

Career

Ratnatunga's career included research at Institute for Advanced Study in Princeton, Dominion Astrophysical Observatory in Victoria Canada, NASA Goddard Space Flight Center in Greenbelt (1989/91), Space Telescope Science Institute and Johns Hopkins University in Baltimore (1992/96), and Carnegie Mellon University in Pittsburgh (1996/2004).[ citation needed ]

He returned to Sri Lanka in 2005. His current interests include increasing the information on Lanka on the Internet; archaeology with a special interest in numismatics; and rare books on Lanka. At the Post Graduate Institute of Archaeology in 2010, he obtained a Diploma in Museology.

Current activities

He is vice president of the Sri Lanka Numismatic Society, and the Archaeological Society of Sri Lanka. [1] He is ex-co member of the Internet Society of Sri Lanka and the Royal Asiatic Society of Sri Lanka. He is a Trustee of the National Trust of Sri Lanka. [2] He is a life member of the Sri Lanka Rationalist Association, the Sri Lanka Philatelic Society, and the Sri Lanka Association for the Advancement of Science of which he was the Chairman, Committee for the Popularization of Science in 2007. He is President of the Sri Lanka Astronomical Association. He is member of the International Astronomical Union (IAU), on behalf of which he was the chairman of the International Year of Astronomy IYA2009 committee for Sri Lanka.

He writes freelance for the Sunday Times of Sri Lanka. [3] He was a visiting Lecturer on Astronomy (DE1412) at the University of Moratuwa at Katubedda. [4]

Publications

His 50 publications in refereed Journals include the first in-situ sample of field halo K giants in the galactic halo (1983), [5] and the first quadruple gravitational lens discovered with the NASA Hubble Space Telescope (1995). [6]

Related Research Articles

<span class="mw-page-title-main">Galaxy</span> Large gravitationally bound system of stars and interstellar matter

A galaxy is a system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. The word is derived from the Greek galaxias (γαλαξίας), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. Galaxies, averaging an estimated 100 million stars, range in size from dwarfs with less than a thousand stars, to the largest galaxies known – supergiants with one hundred trillion stars, each orbiting its galaxy's center of mass. Most of the mass in a typical galaxy is in the form of dark matter, with only a few percent of that mass visible in the form of stars and nebulae. Supermassive black holes are a common feature at the centres of galaxies.

<span class="mw-page-title-main">Globular cluster</span> Spherical collection of stars

A globular cluster is a spheroidal conglomeration of stars that is bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of member stars, all orbiting in a stable, compact formation. Globular clusters are similar in form to dwarf spheroidal galaxies, and the distinction between the two is not always clear. Their name is derived from Latin globulus. Globular clusters are occasionally known simply as "globulars".

<span class="mw-page-title-main">Gravitational lens</span> Light bending by mass between source and observer

A gravitational lens is matter, such as a cluster of galaxies or a point particle, that bends light from a distant source as it travels toward an observer. The amount of gravitational lensing is described by Albert Einstein's general theory of relativity. If light is treated as corpuscles travelling at the speed of light, Newtonian physics also predicts the bending of light, but only half of that predicted by general relativity.

<span class="mw-page-title-main">Galaxy cluster</span> Structure made up of a gravitationally-bound aggregation of hundreds of galaxies

A galaxy cluster, or a cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity, with typical masses ranging from 1014 to 1015 solar masses. They are the second-largest known gravitationally bound structures in the universe after some superclusters (of which only one, the Shapley Supercluster, is known to be bound). They were believed to be the largest known structures in the universe until the 1980s, when superclusters were discovered. One of the key features of clusters is the intracluster medium (ICM). The ICM consists of heated gas between the galaxies and has a peak temperature between 2–15 keV that is dependent on the total mass of the cluster. Galaxy clusters should not be confused with galactic clusters (also known as open clusters), which are star clusters within galaxies, or with globular clusters, which typically orbit galaxies. Small aggregates of galaxies are referred to as galaxy groups rather than clusters of galaxies. The galaxy groups and clusters can themselves cluster together to form superclusters.

<span class="mw-page-title-main">Hoag's Object</span> Unusual galaxy in the constellation Serpens

Hoag's Object is an unusual ring galaxy in the constellation of Serpens Caput. It is named after Arthur Hoag, who discovered it in 1950 and identified it as either a planetary nebula or a peculiar galaxy. The galaxy has approximately eight billion stars, and is roughly 120,000 light years across.

<span class="mw-page-title-main">Spiral galaxy</span> Class of galaxy that has spiral structures extending from their cores.

Hururyry Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae and, as such, form part of the Hubble sequence. Most spiral galaxies consist of a flat, rotating disk containing stars, gas and dust, and a central concentration of stars known as the bulge. These are often surrounded by a much fainter halo of stars, many of which reside in globular clusters.

<span class="mw-page-title-main">Messier 87</span> Elliptical galaxy in the Virgo Galaxy Cluster

Messier 87 is a supergiant elliptical galaxy in the constellation Virgo that contains several trillion stars. One of the largest and most massive galaxies in the local universe, it has a large population of globular clusters—about 15,000 compared with the 150–200 orbiting the Milky Way—and a jet of energetic plasma that originates at the core and extends at least 1,500 parsecs, traveling at a relativistic speed. It is one of the brightest radio sources in the sky and a popular target for both amateur and professional astronomers.

<span class="mw-page-title-main">Einstein ring</span> Feature seen when light is gravitationally lensed by an object

An Einstein ring, also known as an Einstein–Chwolson ring or Chwolson ring, is created when light from a galaxy or star passes by a massive object en route to the Earth. Due to gravitational lensing, the light is diverted, making it seem to come from different places. If source, lens, and observer are all in perfect alignment (syzygy), the light appears as a ring.

<span class="mw-page-title-main">Sculptor Galaxy</span> Intermediate spiral galaxy in the constellation Sculptor

The Sculptor Galaxy is an intermediate spiral galaxy in the constellation Sculptor. The Sculptor Galaxy is a starburst galaxy, which means that it is currently undergoing a period of intense star formation.

<span class="mw-page-title-main">Gravitational microlensing</span> Astronomical phenomenon due to the gravitational lens effect

Gravitational microlensing is an astronomical phenomenon caused by the gravitational lens effect. It can be used to detect objects that range from the mass of a planet to the mass of a star, regardless of the light they emit. Typically, astronomers can only detect bright objects that emit much light (stars) or large objects that block background light. These objects make up only a minor portion of the mass of a galaxy. Microlensing allows the study of objects that emit little or no light.

<span class="mw-page-title-main">Optical Gravitational Lensing Experiment</span> Long-term variability sky survey

The Optical Gravitational Lensing Experiment (OGLE) is a Polish astronomical project based at the University of Warsaw that runs a long-term variability sky survey (1992–present). The main goals are the detection and classification of variable stars, discovery of microlensing events, dwarf novae, and studies of the structure of the Galaxy and the Magellanic Clouds. Since the project began in 1992, it has discovered a multitude of extrasolar planets, together with the first planet discovered using the transit method (OGLE-TR-56b) and gravitational microlensing. The project has been led by professor Andrzej Udalski since its inception.

<span class="mw-page-title-main">APM 08279+5255</span> Quasar

APM 08279+5255 is a very distant, broad absorption line quasar located in the constellation Lynx. It is magnified and split into multiple images by the gravitational lensing effect of a foreground galaxy through which its light passes. It appears to be a giant elliptical galaxy with a supermassive black hole and associated accretion disk. It possesses large regions of hot dust and molecular gas, as well as regions with starburst activity.

<span class="mw-page-title-main">Abell 2744</span> Galaxy cluster in the constellation Sculptor

Abell 2744, nicknamed Pandora's Cluster, is a giant galaxy cluster resulting from the simultaneous pile-up of at least four separate, smaller galaxy clusters that took place over a span of 350 million years, and is located approximately 4 billion light years from Earth. The galaxies in the cluster make up less than five percent of its mass. The gas is so hot that it shines only in X-rays. Dark matter makes up around 75 percent of the cluster's mass.

<span class="mw-page-title-main">MACS0647-JD</span> The farthest known galaxy from the Earth in the constellation Camelopardalis

MACS0647-JD is a galaxy with a redshift of about z = 10.7, equivalent to a light travel distance of 13.26 billion light-years. If the distance estimate is correct, it formed about 427 million years after the Big Bang.

The MAssive Cluster Survey (MACS) compiled and characterized a sample of very X-ray luminous, distant clusters of galaxies. The sample comprises 124 spectroscopically confirmed clusters at 0.3 < z < 0.7. Candidates were selected from the ROSAT All-Sky Survey data.

<span class="mw-page-title-main">Laura Ferrarese</span> Italian astrophysicist

Laura Ferrarese is a researcher in space science at the National Research Council of Canada. Her primary work has been performed using data from the Hubble Space Telescope and the Canada-France-Hawaii Telescope.

<span class="mw-page-title-main">Georges Meylan</span> Swiss astronomer

Georges Meylan is a Swiss astronomer, born on July 31, 1950, in Lausanne, Switzerland. He was the director of the Laboratory of Astrophysics of the Swiss Federal Institute of Technology (EPFL) in Lausanne, Switzerland, and now a professor emeritus of astrophysics and cosmology at EPFL. He is still active in both research and teaching.

<span class="mw-page-title-main">MACS J1149 Lensed Star 1</span> Blue supergiant and second most distant star from earth detected in the constellation Leo

MACS J1149 Lensed Star 1, also known as Icarus, is a blue supergiant star observed through a gravitational lens. It is the seventh most distant individual star to have been detected so far, at approximately 14 billion light-years from Earth. Light from the star was emitted 4.4 billion years after the Big Bang. According to co-discoverer Patrick Kelly, the star is at least a hundred times more distant than the next-farthest non-supernova star observed, SDSS J1229+1122, and is the first magnified individual star seen.

<span class="mw-page-title-main">Jane Rigby (astrophysicist)</span> American astrophysicist

Jane Rebecca Rigby is an American astrophysicist who works at the Goddard Space Flight Center and is Senior Project Scientist of the James Webb Space Telescope. She was selected one of Nature's 10 Ones to Watch in 2021 and Shape 2022. In 2024 she was awarded the Presidental Medal of Freedom by President Joe Biden.

<span class="mw-page-title-main">Ata Sarajedini</span>

Ata Sarajedini is an astrophysicist, professional astronomer, academic, author, and podcaster. He is the Bjorn Lamborn Endowed Chair and Professor in Astrophysics at Florida Atlantic University.

References

  1. "Office bearers". Archaeological Society of Sri Lanka.
  2. "Trustees". National Trust of Sri Lanka.
  3. "In the Sunday Times of Lanka since 2002 by Dr Kavan Ratnatunga".
  4. "DE2410 - Astronomy and Cosmology: Term 6". University of Moratuwa.
  5. Ratnatunga, Kavan U.; Freeman, K. C. (April 1985). "Kinematics of K giants in the outer galactic halo" (PDF). The Astrophysical Journal. 291: 260–269. Bibcode:1985ApJ...291..260R. doi:10.1086/163064.
  6. "Hubble Discovers New Class of Gravitational Lens for Probing the Structure of the Cosmos". HubbleSite. 18 October 1995.