Subscribe free to our newsletters via your
. 24/7 Space News .




EXO WORLDS
Planets can form around different types of stars
by Staff Writers
Copenhagen, Denmark (SPX) Jun 14, 2012


New research shows that planets up to four times the size of the Earth can form around very different stars - including stars that are poorer in heavy elements. Credit: MediaFarm / Niels Bohr Institute.

It had previously been thought that planets were more likely to form around a star if the star had a high content of heavier elements. But new research from the University of Copenhagen, among others, shows that small planets can form around very different types of stars - also stars that are relatively poor in heavy elements.

This significantly increases the likelihood that Earth-like planets are widespread in the universe. The results have been published in the prestigious scientific journal, Nature.

3,000 exoplanets, i.e. planets orbiting a star other than the Sun, have now been discovered. 2,300 of these potential planets are being observed with the Kepler Satellite by measuring the brightness of the host stars. If a planet moves in front of its star, there is a small decrease in the brightness and if this happens repeatedly, it could be a planet orbiting the star and dimming its light.

A multitude of planets have been discovered so far and by measuring their size it is possible to distinguish between gas giants like Saturn and Jupiter, or whether they are smaller, terrestrial planets like Earth and Mars.

Requirements for planet formation?

But it is not only the planets that are interesting. It is also the stars that they are orbiting. Because what are the requirements for planet formation?

"I wanted to investigate whether planets only form around certain types of stars and whether there is a correlation between the size of the planets and the type of host star it is orbiting," explains Lars A. Buchhave, astrophysicist at the Niels Bohr Institute and the interdisciplinary research centre, StarPlan at the University of Copenhagen.

Lars A. Buchhave therefore developed a method to 'wring' more information from the stellar spectra. Up until now, we have seen that most of the gas giants were associated with stars with a high content of heavy elements. For a star to have a high content of heavy elements it has to have gone through a series of rebirths.

Cosmic cycle
A star is a large ball of glowing gas that produces energy by fusing hydrogen and helium into heavier and heavier elements. When the entire core has been converted into iron, no more energy can be extracted and the star dies flinging massive clouds of dust and gas out into space.

These large clouds of gas and dust condense and are recycled into new stars and planets in a gigantic cosmic cycle. The new stars that are formed will have a higher content of heavier elements than the previous and for each generation of star formation there are more and more of the heavy elements and metals.

Remnants from the stars
The planets are formed from the remnants of the clouds of gas and dust that rotate in disc around the newly formed star. In this protoplanetary disc, the elements begin to accumulate and clump together and slowly the planets are formed.

In the later generations of stars with a high content of heavy elements, the rotating disc of dust and gas particles has an elemental composition that is most likely to promote the formation of gas giants like Saturn and Jupiter.

Recent research shows a different picture for the smaller planets.

Fewer requirements for small planets
"We have analysed the spectroscopic elemental composition of the stars for 226 exoplanets. Most of the planets are small, i.e. planets corresponding to the solid planets in our solar system or up to four times the Earth's radius. What we have discovered is that, unlike the gas giants, the occurrence of smaller planets is not strongly dependent on stars with a high content of heavy elements. Planets that are up to four times the size of Earth can form around very different stars - also stars that are poorer in heavy elements," said Lars A. Buchhave.

The conclusion, says Lars A. Buchhave, is that these observations mean that Earth-like planets could be widespread throughout our galaxy, as they have no special requirements for an elevated content of heavy elements in stars in order to be formed. This conclusion resonates well with the picture that is emerging of the distribution of small planets in our galaxy, namely that it seems more the rule than the exception that a star has small planets orbiting them.

Because small Earth-like planets are not dependent upon a high content of heavy elements in their host star, they could be both widespread and could have been formed earlier in our galaxy.

Article in Nature

.


Related Links
University of Copenhagen
Lands Beyond Beyond - extra solar planets - news and science
Life Beyond Earth






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 WORLDS
Small Planets Don't Need 'Heavy Metal' Stars to Form
Pasadena CA (JPL) Jun 14, 2012
The formation of small worlds like Earth previously was thought to occur mostly around stars rich in heavy elements such as iron and silicon. However, new ground-based observations, combined with data collected by NASA's Kepler space telescope, show small planets form around stars with a wide range of heavy element content and suggest they may be widespread in our galaxy. A research team l ... read more


EXO WORLDS
Nanoparticles found in moon glass bubbles explain weird lunar soil behaviour

UA Lunar-Mining Team Wins National Contest

NASA Lunar Spacecraft Complete Prime Mission Ahead of Schedule

NASA Offers Guidelines To Protect Historic Sites On The Moon

EXO WORLDS
Impact atlas catalogs over 635,000 Martian craters

e2v imaging sensors launched into space on NASA mission to Mars

NASA Mars Rover Team Aims for Landing Closer to Prime Science Site

NASA's Mars rover zeroes in on August landing

EXO WORLDS
The pressure is on for aquanauts

Virgin Galactic Opens New Office

US scientists host 'bake sale for NASA'

XCOR Appoints Space Expedition Corp As General Sales Agent For Space Tourism Flights

EXO WORLDS
China's manned spacecraft in final preparations for mid-June launch

Tiangong's Big Tasks

Media Tonedown for Tiangong

Shenzhou-9 full-system drill a success

EXO WORLDS
Varied Views from the ISS

Strange Geometry - Yes, It's All About the Math

Capillarity in Space - Then and Now, 1962-2012

Dragon on board

EXO WORLDS
NASA's NuSTAR Mission Lifts Off

Orbital Launches Company-Built NuSTAR Satellite Aboard Pegasus Rocket for NASA

NuSTAR Arrives at Island Launch Site

Another Ariane 5 begins its initial build-up at the Spaceport

EXO WORLDS
Extremely little telescope discovers pair of odd planets

Alien Earths Could Form Earlier than Expected

Planets can form around different types of stars

Small Planets Don't Need 'Heavy Metal' Stars to Form

EXO WORLDS
Japanese restrict atomic exposure testing

Microsoft reaches into TV market with Xbox Live ads

iPad to drive stronger tablet sales worldwide: study

New national supercomputer to perform astronomical feats




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