Hubble finds carbon dioxide on an extrasolar planet

December 10, 2008

The NASA/ESA Hubble Space Telescope has discovered carbon dioxide in the atmosphere of a planet orbiting another star. This is an important step along the trail of finding the chemical biotracers of extraterrestrial life, as we know it.

The Jupiter-sized planet, called HD 189733b, is too hot for life. But new Hubble observations are a proof-of-concept demonstration that the basic chemistry for life can be measured on planets orbiting other stars. Organic compounds can also be a by-product of life processes and their detection on an Earth-like planet may someday provide the first evidence of life beyond Earth.

Previous observations of HD 189733b by Hubble and the Spitzer Space Telescope found water vapour. Earlier this year Hubble found methane in the planet's atmosphere.

"This is exciting because Hubble is allowing us to see molecules that probe the conditions, chemistry, and composition of atmospheres on other planets," says first author Mark Swain of The Jet Propulsion Laboratory in Pasadena, USA. "Thanks to Hubble we're entering an era where we are rapidly going to expand the number of molecules we know about on other planets."

The international team of astronomers used Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) to study infrared light emitted from the planet, which lies 63 light-years away. Gases in the planet's atmosphere absorb certain wavelengths of light from the planet's hot glowing interior. The team identified not only carbon dioxide, but also carbon monoxide. The molecules leave their own unique spectral fingerprint on the radiation from the planet that reaches Earth. This is the first time a near-infrared emission spectrum has been obtained for an extrasolar planet.
"The carbon dioxide is kind of the main focus of the excitement, because that is a molecule that under the right circumstances could have a connection to biological activity as it does on Earth," Swain says. "The very fact that we're able to detect it, and estimate its abundance, is significant for the long-term effort of characterizing planets both to find out what they're made of and to find out if they could be a possible host for life."

This type of observation is best done for planets with orbits tilted edge-on to Earth. They routinely pass in front of and then behind their parent stars, phenomena known as eclipses. The planet HD 189733b passes behind its companion star once every 2.2 days. This allows an opportunity to subtract the light of the star alone (when the planet is blocked) from that of the star and planet together prior to eclipse), thus isolating the emission of the planet alone and making possible a chemical analysis of its "day-side" atmosphere.

In this way, Swain explains that he's using the eclipse of the planet behind the star to probe the planet's day side, which contains the hottest portions of its atmosphere. "We're starting to find the molecules and to figure out how many of them there are to see the changes between the day side and the night side,""Swain says.

This successful demonstration of looking at near-infrared light emitted from a planet is very encouraging for astronomers planning to use the NASA/ESA/CSA James Webb Space Telescope when it is launched in 2013. These biomarkers are best seen at near-infrared wavelengths.

Astronomers look forward to using JWST to spectroscopically look for biomarkers on a terrestrial planet the size of Earth, or a "super-Earth" several times our planet's mass.

Swain and colleagues next plans to search for molecules in the atmospheres of other extrasolar planets, as well as trying to increase the number of molecules detected in extrasolar planet atmospheres. He also plans to use molecules to study changes that may be present in extrasolar planet atmospheres to learn something about the weather on these distant worlds.

Co-author Giovanna Tinetti from University College London adds: "In the terrestrial planets of our solar system, carbon dioxide plays a crucial role for the stability of climate. On Earth, carbon dioxide is one of the ingredients of the photosynthesis and a key element for the carbon cycle. Our observations represent a great opportunity to understand the role of carbon dioxide in the atmospheres of hot Jupiter type planets".

ESA/Hubble Information Centre

---

---

	The Life of Super-Earths: How the Hunt for Alien Worlds and Artificial Cells Will Revolutionize Life on Our Planet by Dimitar Sasselov (Author) In 1543, Nicolaus Copernicus fomented a revolution when he debunked the geocentric view of the universe, proving instead that our planet wasn’t central to the universe. Almost five hundred years later, the revolution he set in motion is nearly complete. Just as earth is not the center of things, the life on it, it appears, is not unique to the planet. Or is it? The Life of Super-Earths is a breathtaking tour of current efforts to answer the age-old question: Are we alone in the universe? Astronomer Dimitar Sasselov, the founding director of Harvard University’s Origins of Life Initiative, takes us on a fast-paced hunt for habitable planets and alien life forms. He shows how the search for “super-Earths”—rocky planets like our own that orbit other stars—may provide the key to...
	Strange New Worlds: The Search for Alien Planets and Life beyond Our Solar System by Ray Jayawardhana (Author) Soon astronomers expect to find alien Earths by the dozens in orbit around distant suns. Before the decade is out, telltale signs that they harbor life may be found. If they are, the ramifications for all areas of human thought and endeavor--from religion and philosophy to art and biology--will be breathtaking. In Strange New Worlds, renowned astronomer Ray Jayawardhana brings news from the front lines of the epic quest to find planets--and alien life--beyond our solar system. Only in the past fifteen years, after millennia of speculation, have astronomers begun to discover planets around other stars--hundreds in fact. But the hunt to find a true Earth-like world goes on. In this book, Jayawardhana vividly recounts the stories of the scientists and the remarkable breakthroughs that have...
	Scientific Frontiers in Research on Extrasolar Planets: Proceedings of a Conference Held in Washington, D.C., USA, 18-21 June 2002 (Astronomical Society of the Pacific Conference Series) by Drake Deming (Other Contributor)
	Extrasolar Planets and Astrobiology by Caleb A. Scharf (Author) Winner of the 2011 Chambliss Prize for Astronomical Writing from The American Astronomical Society! This book offers an advanced introduction to the increasingly robust fields of extrasolar planets and astrobiology. No other text currently available applies this level of mathematics and physics, while also providing an extensive grounding in key issues of chemistry, biology, and geophysics. With extensive references to the literature and chapter-ending exercises, this book can be used as the core text for teaching undergraduate or introductory graduate level courses. The text will also provide astrobiologists with an indispensable "User's Manual" when quick reference to key mathematical and physical techniques is needed. A continually updated online component, fully cross...
	Planetary Systems: Detection, Formation and Habitability of Extrasolar Planets (Astronomy and Astrophysics Library) by Marc Ollivier (Author), Thérèse Encrenaz (Author), Francoise Roques (Author), Franck Selsis (Author), Fabienne Casoli (Author) Over the past ten years, the discovery of extrasolar planets has opened a new field of astronomy, and this area of research is rapidly growing, from both the observational and theoretical point of view. The presence of many giant exoplanets in the close vicinity of their star shows that these newly discovered planetary systems are very different from the solar system. New theoretical models are being developed in order to understand their formation scenarios, and new observational methods are being implemented to increase the sensitivity of exoplanet detections. In the present book, the authors address the question of planetary systems from all aspects. Starting from the facts (the detection of more than 300 extraterrestrial planets), they first describe the various methods used for...
	The New Worlds: Extrasolar Planets (Springer Praxis Books / Popular Astronomy) by Fabienne Casoli (Author), Thérèse Encrenaz (Author) Offering an engaging and complete story of the hunt for new worlds, this volume fully details the detection and exploration of extrasolar planets. It examines the very wide range of extrasolar planets that have been discovered during the past ten years and looks at what can be learned about such planets by studying the bodies in our own solar system. It also discusses the formation of planetary systems, the way in which such systems may evolve and the final systems of planets that result. In addition, the authors demonstrate how life might evolve on an extrasolar planet and how such life might be detected.
	Planets Beyond Our Solar System: An entry from Gale's Science and Its Times by Leslie A. Mertz (Author) This digital document is an article from Science and Its Times, brought to you by Gale®, a part of Cengage Learning, a world leader in e-research and educational publishing for libraries, schools and businesses. The length of the article is 1549 words. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser. The histories of science, technology, and mathematics merge with the study of humanities and social science in this interdisciplinary reference work. Essays on people, theories, discoveries, and concepts are combined with overviews, bibliographies of primary documents, and chronological elements to offer students a fascinating way to understand the impact of science on the course...
	Extrasolar Planets : Today and Tomorrow: Conference Held 30 June-4 July 2003 at Institut D'Astrophysique de Paris, France (Astronomical Society of the Pacific Conference Series) by Jean-Philippe Beaulieu (Editor), Karen J. Meech (Editor)
	Planet Hunter, Geoff Marcy and the Search for Other Earths by Vicki Oransky Wittenstein (Author) He has discovered more planets than anyone in history. In this inspiring true story, Geoff Marcy's love of space helped him overcome struggles in his studies until finally he became an astronomer. But he was not on track to make major discoveries. Eventually, he went back to the questions that thrilled him as a boy: Are we alone? Do Earth-like planets orbit the stars in the night sky? It would not be easy to find a planet outside our solar system. Others had tried and failed. But Marcy never gave up. Since 1995, he and his colleagues have discovered nearly half of the 380 known "extrasolar" planets. Stunning paintings transport the reader to the exotic worlds that he and others have found.
	Extrasolar Planets: Saas Fee Advanced Course 31 (Saas-Fee Advanced Courses) by Patrick Cassen (Author), Tristan Guillot (Author), A. Quirrenbach (Author), Didier Queloz (Editor), Stephane Udry (Editor), Michel Mayor (Editor), Willy Benz (Editor) Research on extrasolar planets is one of the most exciting fields of activity in astrophysics. In a decade only, a huge step forward has been made from the early speculations on the existence of planets orbiting "other stars" to the first discoveries and to the characterization of extrasolar planets. This breakthrough is the result of a growing interest of a large community of researchers as well as the development of a wide range of new observational techniques and facilities. Based on their lectures given at the 31st Saas-Fee Advanced Course, Andreas Quirrenbach, Tristan Guillot and Pat Cassen have written up up-to-date comprehensive lecture notes on the "Detection and Characterization of Extrasolar Planets", "Physics of Substellar Objects Interiors, Atmospheres, Evolution" and...