Free Newsletters - Space - Defense - Environment - Energy - Solar - Nuclear
..
. 24/7 Space News .




EXO LIFE
Future Evidence for Extraterrestrial Life Might Come from Dying Stars
by Staff Writers
Boston MA (SPX) Feb 27, 2013


A new study finds that we could detect oxygen in the atmosphere of a habitable planet orbiting a white dwarf (as shown in this artist's illustration) much more easily than for an Earth-like planet orbiting a Sun-like star. Here the ghostly blue ring is a planetary nebula - hydrogen gas the star ejected as it evolved from a red giant to a white dwarf. Credit: David A. Aguilar (CfA).

Even dying stars could host planets with life - and if such life exists, we might be able to detect it within the next decade. This encouraging result comes from a new theoretical study of Earth-like planets orbiting white dwarf stars. Researchers found that we could detect oxygen in the atmosphere of a white dwarf's planet much more easily than for an Earth-like planet orbiting a Sun-like star.

"In the quest for extraterrestrial biological signatures, the first stars we study should be white dwarfs," said Avi Loeb, theorist at the Harvard-Smithsonian Center for Astrophysics (CfA) and director of the Institute for Theory and Computation.

When a star like the Sun dies, it puffs off its outer layers, leaving behind a hot core called a white dwarf. A typical white dwarf is about the size of Earth. It slowly cools and fades over time, but it can retain heat long enough to warm a nearby world for billions of years.

Since a white dwarf is much smaller and fainter than the Sun, a planet would have to be much closer in to be habitable with liquid water on its surface. A habitable planet would circle the white dwarf once every 10 hours at a distance of about a million miles.

Before a star becomes a white dwarf it swells into a red giant, engulfing and destroying any nearby planets. Therefore, a planet would have to arrive in the habitable zone after the star evolved into a white dwarf. A planet could form from leftover dust and gas (making it a second-generation world), or migrate inward from a larger distance.

If planets exist in the habitable zones of white dwarfs, we would need to find them before we could study them. The abundance of heavy elements on the surface of white dwarfs suggests that a significant fraction of them have rocky planets. Loeb and his colleague Dan Maoz (Tel Aviv University) estimate that a survey of the 500 closest white dwarfs could spot one or more habitable Earths.

The best method for finding such planets is a transit search - looking for a star that dims as an orbiting planet crosses in front of it. Since a white dwarf is about the same size as Earth, an Earth-sized planet would block a large fraction of its light and create an obvious signal.

More importantly, we can only study the atmospheres of transiting planets. When the white dwarf's light shines through the ring of air that surrounds the planet's silhouetted disk, the atmosphere absorbs some starlight. This leaves chemical fingerprints showing whether that air contains water vapor, or even signatures of life, such as oxygen.

Astronomers are particularly interested in finding oxygen because the oxygen in the Earth's atmosphere is continuously replenished, through photosynthesis, by plant life. Were all life to cease on Earth, our atmosphere would quickly become devoid of oxygen, which would dissolve in the oceans and oxidize the surface. Thus, the presence of large quantities of oxygen in the atmosphere of a distant planet would signal the likely presence of life there.

NASA's James Webb Space Telescope (JWST), scheduled for launch by the end of this decade, promises to sniff out the gases of these alien worlds. Loeb and Maoz created a synthetic spectrum, replicating what JWST would see if it examined a habitable planet orbiting a white dwarf. They found that both oxygen and water vapor would be detectable with only a few hours of total observation time.

"JWST offers the best hope of finding an inhabited planet in the near future," said Maoz.

Recent research by CfA astronomers Courtney Dressing and David Charbonneau showed that the closest habitable planet is likely to orbit a red dwarf star (a cool, low-mass star undergoing nuclear fusion). Since a red dwarf, although smaller and fainter than the Sun, is much larger and brighter than a white dwarf, its glare would overwhelm the faint signal from an orbiting planet's atmosphere. JWST would have to observe hundreds of hours of transits to have any hope of analyzing the atmosphere's composition.

"Although the closest habitable planet might orbit a red dwarf star, the closest one we can easily prove to be life-bearing might orbit a white dwarf," said Loeb.

Their paper has been accepted for publication in the Monthly Notices of the Royal Astronomical Society and is available online.

.


Related Links
Harvard-Smithsonian Center For Astrophysics
Life Beyond Earth
Lands Beyond Beyond - extra solar planets - news and science






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





EXO LIFE
Scientists turn eyes toward Europa in search for life
Boston, Massachusetts (AFP) Feb 16, 2013
US astronomers looking for life in the solar system believe that Europa, one of the moons of Jupiter, which has an ocean, is much more promising than desert-covered Mars, which is currently the focus of the US government's attention. "Europa is the most likely place in our solar system beyond Earth to possess .... life," said Robert Pappalardo, a planetary scientist at NASA's Jet Propulsion ... read more


EXO LIFE
Water On The Moon: It's Been There All Along

Building a lunar base with 3D printing

US, Europe team up for moon fly-by

Russia to Launch Lunar Mission in 2015

EXO LIFE
Mars rover ingests rock powder for tests

Opportunity Is On A Rock Hunt

Big Nickel Rock Target Ahead

NASA Rover Confirms First Drilled Mars Rock Sample

EXO LIFE
Choreographed to Perfection

ATK Launch Abort Motor For First Orion Test Vehicle

Supersonic skydiver's records confirmed

Kennedy Engineers Designing Plant Habitat For ISS

EXO LIFE
Welcome Aboard Shenzhou 10

Reshuffle for Tiangong

China to launch 20 spacecrafts in 2013

Mr Xi in Space

EXO LIFE
Record Number of Students Control ISS Camera

NASA briefly loses contact with space station

Temporary Comm Loss Interrupts Crew's Day

Low-Gravity Flights Will Aid ISS Fluids and Combustion Experiments

EXO LIFE
SpaceX 2 Launch Set for March 1

NASA Releases Glory Taurus XL Launch Failure Report Summary

India's 102nd space mission lifts off successfully

Countdown begins for Indo-French satellite launch

EXO LIFE
NASA's Kepler Mission Discovers Tiny Planet System

Kepler helps astronomers find tiny exo planet

Searching for a Pale Blue SPHERE in the Universe

Earth-like planets are right next door

EXO LIFE
Tokyo hotel shrinks in new-style urban demolition

Fluids in Space, Shaken Not Stirred

The world's most sensitive plasmon resonance sensor inspired by ancient Roman cup

Sustainable new catalysts fueled by a single proton




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement