Featured Research

from universities, journals, and other organizations

Sun-like stars reveal their ages

Date:
July 10, 2014
Source:
Harvard-Smithsonian Center for Astrophysics
Summary:
A new technique for measuring the age of a star using its spin -- gyrochronology -- is coming into its own. Today astronomers are presenting the gyrochronological ages of 22 sun-like stars. Before this, only two sun-like stars had measured spins and ages.

Artist's conception of a hypothetical exoplanet orbiting a yellow, Sun-like star. Astronomers have measured the ages of 22 Sun-like stars using their spins, in a method called gyrochronology. Before now, only two Sun-like stars had measured spins and ages.
Credit: David A. Aguilar (CfA)

Defining what makes a star "Sun-like" is as difficult as defining what makes a planet "Earth-like." A solar twin should have a temperature, mass, and spectral type similar to our Sun. We also would expect it to be about 4.5 billion years old. However, it is notoriously difficult to measure a star's age so astronomers usually ignore age when deciding if a star counts as "Sun-like."

A new technique for measuring the age of a star using its spin -- gyrochronology -- is coming into its own. Today astronomers are presenting the gyrochronological ages of 22 Sun-like stars. Before this, only two Sun-like stars had measured spins and ages.

"We have found stars with properties that are close enough to those of the Sun that we can call them 'solar twins,'" says lead author Jose Dias do Nascimento of the Harvard-Smithsonian Center for Astrophysics (CfA). "With solar twins we can study the past, present, and future of stars like our Sun. Consequently, we can predict how planetary systems like our solar system will be affected by the evolution of their central stars."

To measure a star's spin, astronomers look for changes in its brightness caused by dark spots known as starspots crossing the star's surface. By watching how long it takes for a spot to rotate into view, across the star and out of view again, we learn how fast the star is spinning.

The change in a star's brightness due to starspots is very small, typically a few percent or less. NASA's Kepler spacecraft excels at such exacting brightness measurements. Using Kepler, do Nascimento and his colleagues found that the Sun-like stars in their study spin once every 21 days on average, compared to the 25-day rotation period of our Sun at its equator.

Younger stars spin faster than older ones because stars slow down as they age, much like humans. As a result, a star's rotation can be used like a clock to derive its age. Since most of the stars the team studied spin slightly faster than our sun, they tend to be younger too.

This work expands on previous research done by CfA astronomer (and co-author on the new study) Soren Meibom. Meibom and his collaborators measured the rotation rates for stars in a 1-billion-year-old cluster called NGC 6811. Since the stars had a known age, astronomers could use them to calibrate the gyrochronology "clock." The new research led by do Nascimento examines free-floating "field" stars that are not members of a cluster.

Since stars and planets form together at the same time, by learning a star's age we learn the age of its planets. And since it takes time for life to develop and evolve, knowing the ages of planet-hosting stars could help narrow down the best targets to search for signs of alien life. Although none of the 22 stars in the new study are known to have planets, this work represents an important step in the hunt for Sun-like stars that could host Earth-like planets.

The paper was accepted for publication in The Astrophysical Journal Letters.


Story Source:

The above story is based on materials provided by Harvard-Smithsonian Center for Astrophysics. Note: Materials may be edited for content and length.


Journal Reference:

  1. J.-D. do Nascimento Jr, R. A. Garcia, S. Mathur, F. Anthony, S. A. Barnes, S. Meibom, J.S. da Costa, M. Castro, D. Salabert, T. Ceillier. Rotation periods and ages of solar analogs and solar twins revealed by the Kepler Mission. The Astrophysical Journal Letters, 2014 [link]

Cite This Page:

Harvard-Smithsonian Center for Astrophysics. "Sun-like stars reveal their ages." ScienceDaily. ScienceDaily, 10 July 2014. <www.sciencedaily.com/releases/2014/07/140710131024.htm>.
Harvard-Smithsonian Center for Astrophysics. (2014, July 10). Sun-like stars reveal their ages. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2014/07/140710131024.htm
Harvard-Smithsonian Center for Astrophysics. "Sun-like stars reveal their ages." ScienceDaily. www.sciencedaily.com/releases/2014/07/140710131024.htm (accessed July 31, 2014).

Share This




More Space & Time News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Supply Ship Takes Off for International Space Station

Supply Ship Takes Off for International Space Station

AFP (July 30, 2014) The European Space Agency's fifth Automated Transfer Vehicle (ATV-5) is takes off to the International Space Station on an Ariane 5 rocket from French Guiana. Duration: 00:34 Video provided by AFP
Powered by NewsLook.com
Raw: Rocket Launches Into Space With Cargo Ship

Raw: Rocket Launches Into Space With Cargo Ship

AP (July 30, 2014) Arianespace launched a rocket Tuesday from French Guiana carrying a robotic cargo ship to deliver provisions to the International Space Station. (July 30) Video provided by AP
Powered by NewsLook.com
In Virginia, the Rise of a New Space Coast

In Virginia, the Rise of a New Space Coast

AP (July 30, 2014) Every summer, tourists make the pilgrimage to Chincoteague Island, Va. to see wild ponies cross the Assateague Channel. But, it's the rockets sending to supplies to the International Space Station that are making this a year-round destination. (July 30) Video provided by AP
Powered by NewsLook.com
Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Newsy (July 27, 2014) The satellite is back under ground control after a tense few days, but with a gecko sex experiment on board, the media just couldn't help themselves. 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:
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