Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Most earthlike exoplanet started out as a gas giant

07.01.2010
The most earthlike planet yet found around another star may be the rocky remains of a Saturn-sized gas giant, according to research presented today at the American Astronomical Society meeting in Washington.

"The first planets detected outside our solar system 15 years ago turned out to be enormous gas-giants in very tight orbits around their stars. We call them 'hot Jupiters,' and they weren't what astronomers expected to find," said Brian Jackson at NASA's Goddard Space Flight Center in Greenbelt, Md. "Now, we're beginning to see Earth-sized objects in similar orbits. Could there be a connection?"


This artist\'s impression shows sunrise over CoRoT-7b, the smallest-known exoplanet. The world is about 70 percent larger than Earth. Now, a team led by Brian Jackson at NASA\'s Goddard Space Flight Center finds that the planet may be the rocky remains of a gas giant planet whose atmosphere was evaporated by close proximity to the star.

Credit: ESO/L. Calçada

Jackson and his colleagues turned to CoRoT-7b, the smallest planet and the most like Earth that astronomers have found to date. Discovered in February 2009 by the Convection, Rotation and Planetary Transits (CoRoT) satellite, a mission led by the French Space Agency, CoRoT-7b takes just 20.4 hours to circle its sunlike star, located 480 light-years away in the constellation Monoceros. Astronomers believe the star is about 1.5 billion years old, or about one-third the sun's age.

"CoRoT-7b is almost 60 times closer to its star than Earth, so the star appears almost 360 times larger than the sun does in our sky," Jackson said. As a consequence, the planet's surface experiences extreme heating that may reach 3,600 degrees Fahrenheit on the daylight side. CoRoT-7b's size (70 percent larger than Earth) and mass (4.8 times Earth's) indicate that the world is probably made of rocky materials.

"But with such a high dayside temperature, any rocky surface facing the star must be molten, and the planet cannot retain anything more than a tenuous atmosphere, even one of vaporized rock," Jackson said. He estimates that solar heating may have already cooked off several Earth masses of material from CoRoT-7b.

With the help of computer models that track the planet's mass loss and orbital changes, the researchers have turned back the planet's clock.

"There's a complex interplay between the mass the planet loses and its gravitational pull, which raises tides on the star," Jackson explained. Those tides gradually change the planet's orbit, drawing it inward in a process called tidal migration. But closer proximity to the star then increases the mass loss, which in turn slows the rate of orbital change.

After accounting for the give-and-take of mass loss and tidal migration, the team finds that CoRot-7b could have weighed in at 100 Earth masses -- or about the heft of Saturn -- when it first formed. At that time, it orbited 50 percent farther from its star than it does now.

The researchers also show that regardless of whether CoRot-7b started life as a Saturn-like gas giant or as a rocky world, the planet has probably lost many Earth masses of material since its formation.

"You could say that, one way or the other, this planet is disappearing before our eyes," Jackson said.

He suggests that similar processes likely have influenced many other exoplanets that lie close to their stars. In fact, several recent studies suggest that many hot Jupiters have undergone similar mass loss and tidal evolution, perhaps leaving behind remnant cores similar to CoRoT-7b.

"CoRoT-7b may be the first in a new class of planet -- evaporated remnant cores," Jackson said. "Studying the coupled processes of mass loss and migration may be crucial to unraveling the origins of the hundreds of hot, earthlike planets space missions like CoRoT and NASA's Kepler will soon uncover."

The research team also includes Neil Miller and Jonathan Fortney at the University of California, Santa Cruz; Rory Barnes at the University of Washington's Virtual Planet Lab in Seattle; Sean Raymond at the Astrophysical Laboratory of Bordeaux, France; and Richard Greenberg at the University of Arizona, Lunar and Planetary Lab, in Tucson.

For more information and images associated with this story, please visit:
http://www.nasa.gov/centers/goddard/news/topstory/2010/earthlike-exoplanet.html

Francis Reddy | EurekAlert!
Further information:
http://www.nasa.gov

More articles from Physics and Astronomy:

nachricht A 100-year-old physics problem has been solved at EPFL
23.06.2017 | Ecole Polytechnique Fédérale de Lausanne

nachricht Quantum thermometer or optical refrigerator?
23.06.2017 | National Institute of Standards and Technology (NIST)

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>