Featured Research

from universities, journals, and other organizations

Discovery of two Earth-size planets raises questions about the evolution of stars

Date:
December 21, 2011
Source:
University of Montreal
Summary:
Researchers have detected two planets of sizes comparable to Earth orbiting around an old star that has just passed the red giant stage. This planetary system is located near Lyra and Cygnus constellations at a distance of 3900 light years. This discovery may shed new light on the destiny of stellar and planetary systems.

University of Toulouse and University of Montreal researchers have detected two planets of sizes comparable to Earth orbiting around an old star that has just passed the red giant stage. This planetary system is located near Lyra and Cygnus constellations at a distance of 3900 light years.

This discovery, published by Nature on December 22 2011, may shed new light on the destiny of stellar and planetary systems.

"The two planets, named KOI 55.01 and KOI 55.02, are on very short orbits around their host star," explained University of Montreal astrophysicist Gilles Fontaine and member of the Center for research in astrophysics of Quιbec (CRAQ). "Having migrated so close, they probably plunged deep into the star's envelope during the red giant phase, but survived. The two observed bodies would then be the dense cores of ancient giant planets whose gaseous envelopes were vaporized during the immersion phase." The host star, KIC 05807616, consists of the exposed core of a red giant that has lost nearly its entire envelope, and in fact the planets may have contributed to the increased loss of mass that is necessary for the formation of this type of star. This has lead the researchers to theorize that planetary systems in general may therefore influence the evolution of their parent stars.

Twinkle twinkle little star

While analyzing the data obtained with the NASA Kepler mission to study the pulsations of the star KIC 05807616 (KPD 1943+4058 or KOI 55), an international team of astrophysicists from eight different countries noticed the intriguing presence of two tiny periodic modulations reaching 0.005% of the star brightness. As these variations could not be attributed to the oscillations of the star or to other causes, the presence of the two bodies orbiting around KIC 05807616 became the only plausible explanation.

The observed variations are the joint effects of the reflection of the star light on the illuminated surface of these bodies and of the difference in thermal emission between the heated day-side and cooler night-side hemispheres, modulated by the position of the bodies on their respective orbits. As a comparison, the situation is similar to the brightness variations of the Moon associated with its different illumination phases depending on its position relative to the Sun and the observers on Earth. For KIC 05807616, calculations show that in order to produce such low amplitude brightness modulations, the sizes of the orbiting bodies are likely comparable to that of Earth.

One Astronomical Unit (AU) is the distance between the Sun and Earth. Since these planets are separated from their very hot (27,000 oC), intensely radiating host star by only 0.0060 and 0.0076 AU, extremely harsh conditions must prevail on their surface, especially in the star-facing hemisphere where temperatures could range between 8000 and 9000 oC. Conditions like these have never been found the planets that have been discovered outside our solar system. The discovery raises many questions about what kinds of life might exist in such hellish conditions.

These planets are referred to as Chthonian planets, could be the remnants of ancient gaseous giant planets -- perhaps like hotter versions of Jupiter -- that orbited the star when it was still burning hydrogen in its core, a long time ago. The envelope of these giant planets would have been dissipated during the immersion phase inside the star when the latter became a red giant. Only the dense cores of the planets, composed of iron and other heavy elements, would have survived this extreme episode.

KIC 05807616, a hot and compact sdB star, is all that remains of the former red giant: an active helium-burning core surrounded by a thin hydrogen layer. Forming this type of star requires the red giant progenitor to eject almost its entire envelope via a mechanism that significantly amplifies the normal mass loss from stellar winds. The two planets discovered around this star may have triggered such a process.


Story Source:

The above story is based on materials provided by University of Montreal. Note: Materials may be edited for content and length.


Journal Reference:

  1. S. Charpinet, G. Fontaine, P. Brassard, E. M. Green, V. Van Grootel, S. K. Randall, R. Silvotti, A. S. Baran, R. H. Ψstensen, S. D. Kawaler, J. H. Telting. A compact system of small planets around a former red-giant star. Nature, 2011; 480 (7378): 496 DOI: 10.1038/nature10631

Cite This Page:

University of Montreal. "Discovery of two Earth-size planets raises questions about the evolution of stars." ScienceDaily. ScienceDaily, 21 December 2011. <www.sciencedaily.com/releases/2011/12/111221140357.htm>.
University of Montreal. (2011, December 21). Discovery of two Earth-size planets raises questions about the evolution of stars. ScienceDaily. Retrieved April 23, 2014 from www.sciencedaily.com/releases/2011/12/111221140357.htm
University of Montreal. "Discovery of two Earth-size planets raises questions about the evolution of stars." ScienceDaily. www.sciencedaily.com/releases/2011/12/111221140357.htm (accessed April 23, 2014).

Share This



More Space & Time News

Wednesday, April 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Nuclear-Level Asteroids Might Be More Common Than We Realize

Nuclear-Level Asteroids Might Be More Common Than We Realize

Newsy (Apr. 23, 2014) — The B612 Foundation says asteroids strike Earth much more often than previously thought, and are hoping to build an early warning system. Video provided by Newsy
Powered by NewsLook.com
NASA Chief Outlines Plan for Human Mission to Mars

NASA Chief Outlines Plan for Human Mission to Mars

AFP (Apr. 22, 2014) — NASA administrator Charles Bolden, speaking at the 'Human to Mars Summit' in Washington, says that learning more about the Red Planet can help answer the 'fundamental question' of 'life beyond Earth'. Duration: 00:48 Video provided by AFP
Powered by NewsLook.com
Nasa Gives You An Excuse to Post a Selfie on Earth Day

Nasa Gives You An Excuse to Post a Selfie on Earth Day

TheStreet (Apr. 22, 2014) — NASA is inviting all social media users to take a selfie of themselves alongside nature and to post it to Twitter, Facebook, Flickr, Instagram, or Google Plus with the hashtag #globalselfie. NASA's goal is to crowd-source a collection of snapshots of the earth, ground-up, that will be used to create one "unique mosaic of the Blue Marble." This image will be available to all in May. Since this is probably one of the few times posting a selfie to Twitter won't be embarrassing, we suggest you give it a go for a good cause. Video provided by TheStreet
Powered by NewsLook.com
SpaceX's Dragon Spacecraft Captured by International Space Station

SpaceX's Dragon Spacecraft Captured by International Space Station

Reuters - US Online Video (Apr. 20, 2014) — SpaceX's unmanned Dragon spacecraft makes a scheduled Easter Sunday rendezvous with the International Space Station. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

More Coverage


Astronomers Discover Planets That Survived Their Star's Expansion

Dec. 21, 2011 — Astronomers have discovered two Earth-sized planets that survived their star's red-giant expansion. Researchers say that this is a snapshot of what our solar system might look like in several ... read more
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

    Environment News

    Technology News



    Save/Print:
    Share:  

    Free Subscriptions


    Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

    Get Social & Mobile


    Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

    Have Feedback?


    Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
    Mobile iPhone Android Web
    Follow Facebook Twitter Google+
    Subscribe RSS Feeds Email Newsletters
    Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins