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 New manifestation of magnetic monopoles discovered
08.12.2017 | Institute of Science and Technology Austria

nachricht NASA's SuperTIGER balloon flies again to study heavy cosmic particles
07.12.2017 | NASA/Goddard Space Flight Center

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: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

Im Focus: Virtual Reality for Bacteria

An interdisciplinary group of researchers interfaced individual bacteria with a computer to build a hybrid bio-digital circuit - Study published in Nature Communications

Scientists at the Institute of Science and Technology Austria (IST Austria) have managed to control the behavior of individual bacteria by connecting them to a...

Im Focus: A space-time sensor for light-matter interactions

Physicists in the Laboratory for Attosecond Physics (run jointly by LMU Munich and the Max Planck Institute for Quantum Optics) have developed an attosecond electron microscope that allows them to visualize the dispersion of light in time and space, and observe the motions of electrons in atoms.

The most basic of all physical interactions in nature is that between light and matter. This interaction takes place in attosecond times (i.e. billionths of a...

Im Focus: A transistor of graphene nanoribbons

Transistors based on carbon nanostructures: what sounds like a futuristic dream could be reality in just a few years' time. An international research team working with Empa has now succeeded in producing nanotransistors from graphene ribbons that are only a few atoms wide, as reported in the current issue of the trade journal "Nature Communications."

Graphene ribbons that are only a few atoms wide, so-called graphene nanoribbons, have special electrical properties that make them promising candidates for the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

Blockchain is becoming more important in the energy market

05.12.2017 | Event News

 
Latest News

Making fuel out of thick air

08.12.2017 | Life Sciences

Rules for superconductivity mirrored in 'excitonic insulator'

08.12.2017 | Information Technology

Smartphone case offers blood glucose monitoring on the go

08.12.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>