Featured Research

from universities, journals, and other organizations

Wide binary stars wreak havoc in planetary systems, astrophysicists find

Date:
January 6, 2013
Source:
University of Toronto
Summary:
Astrophysicists have shown that planetary systems with very distant binary stars are particularly susceptible to violent disruptions, more so than if they had stellar companions with tighter orbits around them. Unlike the sun, many stars are members of binary star systems -- where two stars orbit one another -- and these stars' planetary systems can be altered by the gravity of their companion stars.

Two simulations of planetary system disruption by galactic disturbances to wide binary stars. On the left is a zoomed-out view showing the orbit of a hypothetical 0.1 solar mass binary star around our own solar system with an initial orbital separation of 10,000 AU (1 AU is the distance between the Earth and the Sun). On the right is a zoomed-in view of the orbits of Jupiter, Saturn, Uranus, and Neptune. As the binary orbit becomes eccentric, this eventually excites the planetary orbits and Uranus and Neptune are both ejected.
Credit: Nathan Kaib

An international team of astrophysicists has shown that planetary systems with very distant binary stars are particularly susceptible to violent disruptions, more so than if they had stellar companions with tighter orbits around them.

Unlike the Sun, many stars are members of binary star systems -- where two stars orbit one another -- and these stars' planetary systems can be altered by the gravity of their companion stars. The orbits of very distant or wide stellar companions often become very eccentric -- ie. less circular -- over time, driving the once-distant star into a plunging orbit that passes very close to the planets once per orbital period. The gravity of this close-passing companion can then wreak havoc on planetary systems, triggering planetary scatterings and even ejections.

"The stellar orbits of wide binaries are very sensitive to disturbances from other passing stars as well as the tidal field of the Milky Way," said Nathan Kaib, lead author of a study published January 6 in Nature describing the findings. "This causes their stellar orbits to constantly change their eccentricity -- their degree of circularity. If a wide binary lasts long enough, it will eventually find itself with a very high orbital eccentricity at some point in its life."

When a wide binary orbit becomes very eccentric, the two stars will pass very close together once per orbit on one side of the orbital ellipse, while being very far apart on the other side of the ellipse. This can have dire consequences for planets in these systems since the gravity of a close-passing star can radically change planetary orbits around the other star, causing planets to scatter off of one another and sometimes get ejected to interstellar space.

Kaib, a postdoctoral fellow in the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and the Department of Physics and Astronomy at Northwestern University and a National Fellow in the Canadian Institute for Theoretical Astrophysics at the University of Toronto, conducted computer simulations of the process with Queen's University physics professor Martin Duncan and Sean N. Raymond, a researcher at the University of Bordeaux and the Centre national de la recherche scientifique in France. They added a a hypothetical wide binary companion to Earth's solar system which eventually triggered at least one of four giant planets (Jupiter, Saturn, Uranus and Neptune) to be ejected in almost half of the simulations.

"This process takes hundreds of millions of years if not billions of years to occur in these binaries. Consequently, planets in these systems initially form and evolve as if they orbited an isolated star," said Kaib, who will present the findings this week at the 221st meeting of the American Astronomical Society in Long Beach, California. "It is only much later that they begin to feel the effects of their companion star, which often times leads to disruption of the planetary system."

"We also found that there is substantial evidence that this process occurs regularly in known extrasolar planetary systems," said Duncan. "Planets are believed to form on circular orbits, and they are only thought to attain highly eccentric orbits through powerful and/or violent perturbations. When we looked at the orbital eccentricities of planets that are known to reside in wide binaries, we found that they are statistically more eccentric than planets around isolated stars like our Sun. "

The researchers believe this is a telltale signature of past planetary scattering events, and that those with eccentric orbits are often interpreted to be the survivors of system-wide instabilities.

"The eccentric planetary orbits seen in these systems are essentially scars from past disruptions caused by the companion star," said Raymond.

The researchers note that this observational signature could only be reproduced well when they assumed that the typical planetary system extends from its host star as much as 10 times the distance between Earth and the Sun. Otherwise, the planetary system is too compact to be affected by even a stellar companion on a very eccentric orbit.

"Recently, planets orbiting at wide distances around their host stars have been directly imaged. Our work predicts that such planets are common but have so far gone largely undetected," says Duncan.


Story Source:

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


Journal Reference:

  1. Nathan A. Kaib, Sean N. Raymond, Martin Duncan. Planetary system disruption by Galactic perturbations to wide binary stars. Nature, 2013; DOI: 10.1038/nature11780

Cite This Page:

University of Toronto. "Wide binary stars wreak havoc in planetary systems, astrophysicists find." ScienceDaily. ScienceDaily, 6 January 2013. <www.sciencedaily.com/releases/2013/01/130106145751.htm>.
University of Toronto. (2013, January 6). Wide binary stars wreak havoc in planetary systems, astrophysicists find. ScienceDaily. Retrieved April 23, 2014 from www.sciencedaily.com/releases/2013/01/130106145751.htm
University of Toronto. "Wide binary stars wreak havoc in planetary systems, astrophysicists find." ScienceDaily. www.sciencedaily.com/releases/2013/01/130106145751.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:
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