Diamond-studded planet discovered!
Indo-Asian News Service
Washington, December 09, 2010
Astronomers led by Indian American Nikku Madhusudhan have discovered a giant planet with an atmosphere and core dominated by carbon, raising the prospect that diamond-studded stars may exist. Madhusudhan, a Banaras Hindu University (BHU) alumnus now at Princeton University, New Jersey, and his colleagues have observed that an extremely hot planet discovered last year has more carbon than oxygen - a feature never observed on a planet until now.
The planet, called WASP-12b, orbits a star about 1,200 light-years from Earth, and appears to have temperatures of nearly 2300°C - hot enough to melt stainless steel, the scientists said in the journal Nature.
A computational technique developed two years ago by Madhusudhan while he was at the Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts, was used to analyse the atmosphere of the planet.
Like Jupiter, WASP-12b is made largely of gas, only its core contains carbon-based minerals such as diamonds and graphite, said Madhusudhan now a postdoctoral scientist in the department of astrophysical sciences at Princeton.
"A carbon-rich planet has dramatic implications for its interior, its atmosphere, and may compel us to rethink our long-ingrained ideas of planetary formation," he said.
The planet-larger than Jupiter-is windy, blazing hot and so near its star that it circles in a single day compared with the 365 needed for Earth to go round the sun.
While one side of WASP-12b always faces the star and is daylit, and the other is always dark, the planet's strong winds and gaseous nature distribute energy and keep both sides equally warm.
With that much hotness and no solid surface, WASP-12b couldn't support life, Madhusudhan said. That doesn't mean that other carbon planets are devoid of life, he said.
"If life exists on such planets, it has to be able to sustain low oxygen, low water and lots of methane and other hydrocarbons" that would be in the atmosphere, he said.
If there are other planets with more carbon than oxygen, and some have rocky surfaces instead of gaseous ones, such orbs may have rocks made of diamonds and graphite, instead of silicon and oxygen found on Earth, Madhusudhan said, and sand there may be as rare as diamonds are on Earth.
Scientists used US space agency NASA's Spitzer Space Telescope to observe light emitted by the planet WASP12, discovered in 2009 by researchers in the UK-based consortium called Wide Angle Search for Planets (WASP).
Home page of Nikku Madhusudhan at Princeton University, New Jersey, USA
Dept. of Astrophysical Sciences,
Princeton University, Princeton NJ, 08544
Tel: 617-475-5112/609-258-4850 Fax: 609-258-8226
Modeling atmospheric spectra of extrasolar giant planets and super-Earths
Atmospheric retrieval methods for exoplanets (grid-based and Bayesian)
Equilibrium and non-equilibrium chemistry in exoplanetary atmospheres
Planet formation, planetary interiors, carbon-rich planets
Summary of My Research
I work on several aspects of extrasolar planets (or exoplanets), or planets that orbit other stars. I try to understand what the atmospheres of the wide variety of exoplanets could be composed of. Based on the atmospheric properties, I try to answer what we can say about how exoplanets form, what their interiors could be made up of, what consequences they might have for astrobiology, etc. A major fraction of my time is spent on planning new observations, developing new techniques to estimate atmospheric properties from observations, interpreting available observations, developing new atmospheric models, and new calculations of atmospheric chemistry (equilibrium and non-equilibrium). Recently, I have also become interested in models of planet formation, and in understanding exotic planets, like carbon-rich planets.
Education: PhD (MIT, 2009), MS (MIT, 2004), B. Tech (IT-BHU, India, 2002)
PhD: Retrieval of atmospheric properties of extrasolar planets (MIT, Physics)
Employment: Sep 2010 - Present : Postdoctoral researcher (Princeton Univ.)
Aug 2009 - Aug 2010: Postdoctoral researcher (MIT)
For Immediate Release: December 8, 2010
Contact: Jen Hirsch, MIT News Office
Email: email@example.com phone: 617-253-1682
Astronomers detect first carbon-rich exoplanet
Discovery opens door to new class of exoplanets
Artist concept of the extremely hot exoplanet WASP-12b and the host star.
Image: NASA/JPL-Caltech/R. Hurt (SSC)
CAMBRIDGE, Mass. — A team led by a former postdoctoral researcher in MIT’s Department of Earth, Atmospheric and Planetary Sciences and the MIT Kavli Institute for Astrophysics, recently measured the first-ever planetary atmosphere that is substantially enriched in carbon. The researchers found that the carbon-to-oxygen ratio of WASP-12b, an exoplanet about 1.4 times the mass of Jupiter and located about 1,200 light years away, is greater than one. As they report in a paper published on Dec. 8 in the journal Nature, this carbon-rich atmosphere supports the possibility that rocky exoplanets could be composed of pure carbon rocks like diamond or graphite rather than the silica-based rock found in Earth.
"This is new territory with implications in several areas, from planetary formation and interiors to astrobiology,” says lead author Nikku Madhusudhan, who is now a postdoctoral researcher at Princeton University. WASP-12b is a “hot Jupiter,” or a Jupiter-sized, extremely hot exoplanet that is largely made of gas, but it could also potentially have a form of diamond or graphite in its interior. The first-ever finding of a carbon-rich exoplanet is significant because it introduces an entirely new class of exotic exoplanets to explore. It’s also possible that rockier, Earth-sized exoplanets may have formed around the same star as WASP-12b billions of years ago. If detected, these smaller planets could also have carbon-rich atmospheres and interiors, meaning that for life to exist on these planets, it might have to survive with very little water and oxygen, and plenty of methane, says Madhusudhan. That might not be so far-fetched given last week’s announcement by NASA of the discovery on Earth of bacteria that can survive in arsenic, a poison to humans.
Astronomers can figure out a planet’s atmospheric composition by observing its flux, or the light emitted by the planet, at different wavelengths. The team used NASA's Spitzer Space Telescope to observe the flux from WASP-12b, at four wavelengths, right before it passed behind the star, an event known as secondary eclipse. The Spitzer observations were coordinated by Joe Harrington, a planetary scientist at the University of Central Florida, Those observations were then combined with previously published observations, at three other wavelengths, obtained from Earth using the Canada-France-Hawaii Telescope in Hawaii. The planet was discovered in 2009 by researchers at the United Kingdom-based consortium for Wide Angle Search for Planets (WASP), who are also coauthors of the study.
Madhusudhan used all the observations to conduct a detailed atmospheric analysis using a modeling technique he pioneered for exoplanetary atmospheres. The computer program he developed combines certain variables, such as a planet's temperature distribution, with different amounts of the most prominent molecules that exist in such atmospheres, which are methane, carbon dioxide, carbon monoxide, water vapor and ammonia, into one formula that produces a theoretical spectrum, or flux at different wavelengths. The program analyzes millions of combinations of these variables, tracking those that most closely match the flux values measured by the telescopes. Through statistical analysis of these values, Madhusudhan can determine the most likely composition of the atmosphere.
Based on theories about what extremely hot Jupiters such as WASP-12b should look like, assuming carbon-to-oxygen ratios of 0.5, previous models suggested that their atmospheres should have plenty of water vapor, very little methane and an atmospheric layer known as a stratosphere. Instead, Madhusudhan’s team detected an atmosphere with more than 100 times excess methane and less water than had been expected. The observed composition is consistent with a carbon-to-oxygen ratio that is greater than one. The team also discovered the lack of a strong stratosphere, which contradicts existing theories of hot Jupiter atmospheres.
The discovery suggests that chunks of rock called planetesimals that slammed together to form WASP-12b billions of years ago may have been made of carbon-rich compounds like tar — a far cry from the watery, icy planetesimals that are thought to have formed the solar-system planets. This means that if smaller exoplanets are found to have carbon-rich atmospheres, their surfaces could be covered in a tar-like substance. Future research will investigate whether life — perhaps drastically different from life as we know it — could survive in such a carbon-rich environment.
“It’s exciting to even think about the possibility” of what carbon-rich planets could look like, says Adam Showman, a planetary scientist at the University of Arizona, who explains that although researchers knew that other solar systems should have a range of carbon-to-oxygen values, “this paper finally moves the discussion from pure speculation to plausible reality.” He notes that exoplanets with carbon-based interiors could exhibit a range of surface features, atmospheric compositions and potential for oceans or life.
Source: “A high C/O ratio and weak thermal inversion in the atmosphere of exoplanet WASP-12b,” by Nikku Madhusudhan, Joseph Harrington, Kevin B. Stevenson, Sarah Nymeyer, Christopher J. Campo, Peter J. Wheatley, Drake Deming, Jasmina Blecic, Ryan A. Hardy, Nate B. Lust, David R.Anderson, Andrew Collier-Cameron, Christopher B. T. Britt, William C. Bowman, Leslie Hebb, Coel Hellier, Pierre F. L. Maxted, Don Pollacco8 & Richard G. West. Nature, 8 December, 2010.
NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA. For more information about Spitzer, visit http://spitzer.caltech.edu/ and http://www.nasa.gov/spitzer.
Written by: Morgan Bettex, MIT News Office
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Institute of Technology, Banaras Hindu University
Varanasi 221005, UP