Email a Friend
Printer Friendly
Slashdot It!
Submit to Reddit
Add to Facebook

Caltech astronomer spots second smallest exoplanet

January 14, 2010

Discovery highlights new potential for eventually finding Earth-mass planets

PASADENA, Calif.-Astronomers from the California Institute of Technology (Caltech) and other institutions, using the highly sensitive 10-meter Keck I telescope atop Hawaii's Mauna Kea, have detected an extrasolar planet with a mass just four times that of Earth. The planet, which orbits its parent star HD156668 about once every four days, is the second-smallest world among the more than 400 exoplanets (planets located outside our solar system) that have been found to date. It is located approximately 80 light-years from Earth in the direction of the constellation Hercules.

The find, made possible through NASA's Eta-Earth Survey for Low-Mass Planets was announced last week at the 215th American Astronomical Society meeting held January 4-7, 2010, in Washington, D.C.

Dubbed HD 156668b, the planet-a so-called "super Earth" that would glow with blast-furnace-like temperatures-offers a tantalizing hint of discoveries yet to come. Astronomers hope those discoveries will include Earth-size planets located in the "habitable zone," the area roughly the distance from the earth to the sun, and thus potentially favorable to life.

HD 156668b was discovered with the radial velocity or wobble method, which relies on Keck's High Resolution Echelle Spectrometer (HIRES) to spread light collected from the telescope into its component wavelengths or colors, producing a spectrum. As the planet orbits the star, it causes the star to move back and forth along our line of sight, which causes the starlight to become redder and then bluer in a periodic fashion.

The color shifts give astronomers the mass of the planet and the characteristics of its orbit, such as how much time it takes to orbit the star. The majority of the exoplanets discovered have been found in this way.

The discovery of low-mass planets like HD 156668b has become possible due to the development of techniques to watch stars wobble with increasing clarity, and of software that can pluck the signals of increasingly smaller planets from amid the 'noise' made by their pulsating, wobbling parent stars.

"If the stars themselves have imperfections and are unstable, their wobbling would cause jumps in velocity that could mimic or hide the existence of a planet," says John A. Johnson, assistant professor of astronomy at Caltech and codiscoverer of the new planet along with Andrew Howard and Geoff Marcy of the University of California at Berkeley, Debra Fischer of Yale University, Jason Wright of Penn State University, and the members of the California Planet Survey collaboration.

"We have been doing simulations to understand the astrophysics of these imperfections, and how to distinguish them from the signals from a planet," says Johnson. "We hope to use these simulations to design even better observing strategies and data-analysis techniques."

The discovery of a planet that is comparable in size to Earth and found within the habitable zone, however, "will require a great deal of work," he says. "If we could build the best possible radial-velocity instrument tomorrow, we might have answers in three years, and a solid census of Earthlike planets within a decade. We'll need gigantic leaps in sensitivity to get there, and we're hot on the trail."

Johnson is also currently building a new camera for the 60-inch telescope at Caltech's Palomar Observatory. The camera will allow astronomers to search for the passages-or transits-of low-mass planets like HD156668 across the faces of their stars.

"If we catch the planet in transit, we can measure the planet's radius and density, and therefore address the question of whether the planet has a composition more like Earth, with a solid surface and thin atmosphere, or is a miniature version of Neptune, with a heavy gaseous atmosphere," he says.

California Institute of Technology

Related Exoplanet Current Events and Exoplanet News Articles

Exoplanet Current Events and Exoplanet News RSS

Caltech astronomer finds planets in unusually intimate dance around dying star
Hundreds of extrasolar planets have been found over the past decade and a half, most of them solitary worlds orbiting their parent star in seeming isolation.

More proof that new planet and star are moving together
A planet about eight times the mass of Jupiter has been confirmed to orbit a Sun-like star that's some 300 times farther from its own star than Earth is from its sun.

Exoplanet caught on the move
Only 12 million years old, or less than three-thousandths of the age of the Sun, Beta Pictoris is 75% more massive than our parent star. It is located about 60 light-years away towards the constellation of Pictor (the Painter) and is one of the best-known examples of a star surrounded by a dusty debris disc.

A gassy mystery: Researchers discover surprising exoplanetary atmosphere
A Neptune-sized exoplanet orbiting a small star about 33 light years away could be a key stepping stone on the path to making sense of an Earth twin.

Turning planetary theory upside down
The discovery of nine new transiting exoplanets is announced today at the RAS National Astronomy Meeting. When these new results were combined with earlier observations of transiting exoplanets astronomers were surprised to find that six out of a larger sample of 27 were found to be orbiting in the opposite direction to the rotation of their host star -- the exact reverse of what is seen in our own solar system.

Newly discovered planet could hold water
The Corot satellite strikes again with another fascinating planet discovery. This time, the newly discovered gas giant planet may have an interior that closely resembles those of Jupiter and Saturn in our own Solar System.

How to hunt for exoplanets
A new report launched by the Institute of Physics (IOP) Exoplanets - The search for planets beyond our solar system explains how new technological advances have seen the discovery of more than 400 exoplanets to date, a number expected to rise to thousands in the next few years.

Sun glints seen from space signal oceans and lakes
In two new videos from NASA's Deep Impact spacecraft, bright flashes of light known as sun glints act as beacons signaling large bodies of water on Earth.

Astronomers find super-Earth using amateur, off-the-shelf technology
Astronomers announced today that they have discovered a "super-Earth" orbiting a red dwarf star 40 light-years from Earth.

Astronomers find world with thick, inhospitable atmosphere and an icy heart
In this week's issue of Nature, astronomers announce the discovery of a planet around the nearby, low-mass star GJ1214.

More Exoplanet Current Events and Exoplanet News Articles

	Exoplanets: Detection, Formation, Properties, Habitability by John Mason (Editor) This edited, multi-author volume will be an invaluable introduction and reference to all key aspects in the field of exoplanet research. The reviews cover: Detection methods and properties of known exoplanets, Detection of extrasolar planets by gravitational microlensing. The formation and evolution of terrestrial planets in protoplanetary and debris disks. The brown dwarf-exoplanet connection. Formation, migration mechanisms and properties of hot Jupiters. Dynamics of multiple exoplanet systems. Doppler exoplanet surveys. Searching for exoplanets in the stellar graveyard. Formation and habitability of extra solar planets in multiple star systems. Exoplanet habitats and the possibilities for life. Moons of exoplanets: habitats for life. Contributing authors: Rory Barnes...
	Dynamics of Small Solar System Bodies and Exoplanets (Lecture Notes in Physics) by Jean J. Souchay (Editor), Rudolf Dvorak (Editor) This book offers an up-to-date overview of current research on Dynamics of Small Solar System Bodies and Exoplanets. In course-tested extensive chapters the authors cover topics of theoretical celestial mechanics, physics and dynamics of asteroids, comets, stability of exoplanets and numerical integration codes applied in dynamical astronomy.
	Exoplanet Atmospheres: Physical Processes (Princeton Series in Astrophysics) by Sara Seager (Author) Over the past twenty years, astronomers have identified hundreds of extrasolar planets--planets orbiting stars other than the sun. Recent research in this burgeoning field has made it possible to observe and measure the atmospheres of these exoplanets. This is the first textbook to describe the basic physical processes--including radiative transfer, molecular absorption, and chemical processes--common to all planetary atmospheres, as well as the transit, eclipse, and thermal phase variation observations that are unique to exoplanets. In each chapter, Sara Seager offers a conceptual introduction, examples that combine the relevant physics equations with real data, and exercises. Topics range from foundational knowledge, such as the origin of atmospheric composition and planetary...
	Exoplanets (Space Science Series) by Sara Seager (Editor) For the first time in human history, we know for certain the existence of planets around other stars. Now the fastest-growing field in space science, the time is right for this fundamental source book on the topic which will lay the foundation for its continued growth. Exoplanets serves as both an introduction for the non-specialist and a foundation for the techniques and equations used in exoplanet observation by those dedicated to the field. Funding to make this important volume an affordable addition to anyone's library was provided by the National Aeronautics and Space Administration.
	Formation and Evolution of Exoplanets by Rory Barnes (Editor) This single, coherent review of the theory behind extrasolar planet formation and interaction systematically covers all aspects of the topic, including different formation processes, planet-planet scattering, giant planets and brown dwarfs. With a chapter on observation, careful referencing and an elaborate bibliography at the end of each chapter, this is indispensable reading for researchers, theorists and observers alike.
	Transiting Exoplanets by Carole A. Haswell (Author) The methods used in the detection and characterisation of exoplanets are presented through the study of transiting systems in this unique textbook for advanced undergraduates. From determining the atmospheric properties of transiting exoplanets to measuring the planetary orbit's alignment with the stellar spin, students will discover what these measurements imply for reinvigorated theories of planet formation and evolution. Worked examples and exercises with full solutions help students to assess their understanding of concepts and results. Key points and equations are highlighted to make them easily identifiable, and there are full colour illustrations throughout. Bridging the gap between introductory, non-mathematical texts and more advanced textbooks, this book is ideal for students...
	New Worlds in the Cosmos: The Discovery of Exoplanets by Michel Mayor (Author), Pierre-Yves Frei (Author), Boud Roukema (Translator) With the discovery in 1995 of the first planet orbiting another star, we now realize that planets are not unique to our own Solar System. For centuries, humanity has wondered whether we are alone in the Universe. We are now finally one step closer to knowing the answer. The quest for exoplanets is an exciting one because it holds the possibility that one day we might find life elsewhere in the Universe, born in the light of another sun. Written from the perspective of one of the pioneers of this scientific adventure, this exciting account describes the development of the modern observing technique that has enabled astronomers to find so many planets orbiting around other stars. It reveals the wealth of new planets that have now been discovered outside our Solar System, and the meaning of...
	Astronomical Objects Discovered in 2001: Exoplanets Discovered in 2001, Gliese 876 C, Hd 28185 B, Hd 80606 B, 47 Ursae Majoris C, Pi Mensae B by Books LLC (Creator) Purchase includes free access to book updates online and a free trial membership in the publisher's book club where you can select from more than a million books without charge. Chapters: Exoplanets Discovered in 2001, Gliese 876 C, Hd 28185 B, Hd 80606 B, 47 Ursae Majoris C, Pi Mensae B, Hd 23079 B, Hd 82943 C, Hd 213240 B, Hd 4208 B, Hd 142 B, Hd 68988 B, Hd 114783 B, Hd 4203 B, Hd 8574 B, Hd 74156 C, Hd 12661 B, Hd 74156 B, Hd 178911 Bb, 23306 Adamfields. Excerpt: Gliese 876 c is an extrasolar planet orbiting the red dwarf star Gliese 876, taking 30.258 days to complete an orbit. The planet was discovered in April 2001 and is the second planet in order of increasing distance from its star. At the time of discovery, Gliese 876 was already known to host an extrasolar planet designated...
	Planetary Systems: Detection, Formation and Habitability of Extrasolar Planets by Springer 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...
	Exoplanet by Contortionist