Featured Research

from universities, journals, and other organizations

Astronomers find first multi-planet system around a binary star

Date:
August 28, 2012
Source:
University of Texas at Austin
Summary:
NASA's Kepler mission has found the first multi-planet solar system orbiting a binary star. The finding shows that whole planetary systems can form in a disk around a binary star.

The Hobby-Eberly Telescope (HET) at The University of Texas at Austin's McDonald Observatory in West Texas. HET is a joint project of a joint project of UT-Austin, The Pennsylvania State University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.
Credit: Marty Harris/McDonald Observatory/UT-Austin

NASA's Kepler mission has found the first multi-planet solar system orbiting a binary star, characterized in large part by University of Texas at Austin astronomers using two telescopes at the university's McDonald Observatory in West Texas. The finding, which proves that whole planetary systems can form in a disk around a binary star, is published in the August 28 issue of the journal Science.

"It's Tatooine, right?" said McDonald Observatory astronomer Michael Endl. "But this was not shown in Star Wars," he said, referring to the periodic changes in the amount of daylight falling on a planet with two suns. Measurements of the star's orbits showed that daylight on the planets would vary by a large margin over the 7.4-Earth-day period as the two stars completed their mutual orbits, each moving closer to, then farther from, the planets (which are themselves moving).

The binary star in question is called Kepler-47. The primary star is about the same mass as the Sun, and its companion is an M-dwarf star one-third its size. The inner planet is three times the size of Earth and orbits the binary star every 49.5 days, while the outer planet is 4.6 times the size of Earth with an orbit of 303.2 days.

The outer planet is the first planet found to orbit a binary star within the "habitable zone," where liquid water could exist and thus create a home for life. However, the planet's size (about the same as Uranus) means that it is an icy giant, and not an abode for life. It's a tantalizing taste of discoveries waiting to be made.

The combination of observations from the NASA mission and McDonald Observatory allowed astronomers to understand the characteristics of Kepler-47's two stars and two planets.

The Kepler mission looks for minute dips in the amount of light coming from a star that might indicate a planet is passing in front of it, an event called a "transit." The space telescope is also adept at identifying eclipsing binary stars, in which two stars pass in front of each other as they orbit each other. In the case of Kepler-47, they found both stellar eclipses and planet transits in one system.

So Kepler astronomers Jerome Orosz (lead author on the study) and William Welsh of San Diego State University flagged the Kepler-47 system as worthy of follow up from the ground. They asked the McDonald Observatory Kepler team to work with them.

Endl studied the binary star with the 9.2-meter Hobby-Eberly Telescope (HET, one of the world's largest telescopes), as well as the 2.7-meter Harlan J. Smith Telescope at McDonald.

"The challenging thing is that this is a very faint star," Endl said, "about 6,000 times dimmer than can be seen with the naked eye."

He was taking spectra of the system -- looking for characteristics in its light to indicate the motions of the primary star. (The secondary star is too faint to measure.) The McDonald observations enabled astronomers to calculate the mass of the primary star.

These values, along with the Kepler eclipse and transit timings, were plugged into a model that calculated the relative sizes of all the bodies involved, Endl said.

The Kepler team at McDonald Observatory also includes Bill Cochran (a co-Investigator of the Kepler mission), research scientist Phillip MacQueen, graduate students Paul Robertson and Eric Brugamyer, and recent graduate Caroline Caldwell.

"This is the type of research where McDonald Observatory really excels," Cochran said. "We have excellent scientific instruments on our telescopes, and the queue-scheduled operation of the HET allows us to obtain spectra at the optimal times when they will give us the best information about the stars."


Story Source:

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


Journal Reference:

  1. Jerome A. Orosz, William F. Welsh, Joshua A. Carter, Daniel C. Fabrycky, William D. Cochran, Michael Endl, Eric B. Ford, Nader Haghighipour, Phillip J. MacQueen, Tsevi Mazeh, Roberto Sanchis-Ojeda, Donald R. Short, Guillermo Torres, Eric Agol, Lars A. Buchhave, Laurance R. Doyle, Howard Isaacson, Jack J. Lissauer, Geoffrey W. Marcy, Avi Shporer, Gur Windmiller, Thomas Barclay, Alan P. Boss, Bruce D. Clarke, Jonathan Fortney, John C. Geary, Matthew J. Holman, Daniel Huber, Jon M. Jenkins, Karen Kinemuchi, Ethan Kruse, Darin Ragozzine, Dimitar Sasselov, Martin Still, Peter Tenenbaum, Kamal Uddin, Joshua N. Winn, David G. Koch, and William J. Borucki. Kepler-47: A Transiting Circumbinary Multiplanet System. Science, 2012; DOI: 10.1126/science.1228380

Cite This Page:

University of Texas at Austin. "Astronomers find first multi-planet system around a binary star." ScienceDaily. ScienceDaily, 28 August 2012. <www.sciencedaily.com/releases/2012/08/120828190925.htm>.
University of Texas at Austin. (2012, August 28). Astronomers find first multi-planet system around a binary star. ScienceDaily. Retrieved April 20, 2014 from www.sciencedaily.com/releases/2012/08/120828190925.htm
University of Texas at Austin. "Astronomers find first multi-planet system around a binary star." ScienceDaily. www.sciencedaily.com/releases/2012/08/120828190925.htm (accessed April 20, 2014).

Share This



More Space & Time News

Sunday, April 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

A Hoax? Cosmetics Company Wants To Brighten The Moon

A Hoax? Cosmetics Company Wants To Brighten The Moon

Newsy (Apr. 19, 2014) — FOREO, a Swedish cosmetics company, says it wants to brighten the moon to lower electricity costs. Video provided by Newsy
Powered by NewsLook.com
Raw: Space X Launches to Space Station

Raw: Space X Launches to Space Station

AP (Apr. 18, 2014) — On it's second attempt this week, The Space X company launched Friday from Cape Canaveral to ferry supplies to the International Space Station. (April 18) Video provided by AP
Powered by NewsLook.com
Unmanned Falcon 9 Rocket Blasts Off from Cape Canaveral Air Force Station in Florida

Unmanned Falcon 9 Rocket Blasts Off from Cape Canaveral Air Force Station in Florida

Reuters - US Online Video (Apr. 18, 2014) — The rocket, built and operated by Space Exploration Technologies, carries a Dragon cargo ship loaded with supplies and equipment destined for the International Space Station. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Earth's Near-Twin Found Orbiting Red Dwarf

Earth's Near-Twin Found Orbiting Red Dwarf

Newsy (Apr. 17, 2014) — The newly-discovered planet is roughly the size of Earth and could have liquid water on its surface. Video provided by Newsy
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


Kepler Discovers Planetary System Orbiting Two Suns

Aug. 28, 2012 — Astronomers have announced the discovery of the first transiting circumbinary multi-planet system: two planets orbiting around a pair of stars. The discovery shows that planetary systems can form and ... 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