Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Newly Born Identical Twin Stars Show Surprising Differences

20.06.2008
The analysis of the youngest pair of identical twin stars yet discovered has revealed surprising differences in brightness, surface temperature and possibly even the size of the two.

The study, which is published in the June 19 issue of the journal Nature, suggests that one of the stars formed significantly earlier than its twin. Because astrophysicists have assumed that binary stars form simultaneously, the discovery provides an important new test for successful star formation theories, forcing theorists back to the drawing board to determine if their models can produce binaries with stars that form at different times.

The identical twins were discovered in the Orion Nebula, a well-known stellar nursery, that is 1,500 light years away. The newly formed stars are about 1 million years old. With a full lifespan of about 50 billion years, that makes them equivalent of one-day-old human babies.

“Very young eclipsing binaries like this are the Rosetta stones that tell us about the life history of newly formed stars,” says Keivan Stassun, associate professor of astronomy at Vanderbilt University. He and Robert D. Mathieu from the University of Wisconsin-Madison headed up the project.

Eclipsing binaries are pairs of stars that revolve around an axis at a right angle to the direction to Earth. This orientation allows astronomers to determine the rate that the two stars orbit around each other – even when they cannot resolve the individual stars – by measuring the periodic variations in brightness that result when the stars pass in front of each other. With this information, astronomers can determine the masses of the two stars using Newton’s laws of motion.

In this fashion, the astronomers calculate that the newly discovered twins have nearly identical masses 41 percent that of the sun. According to current theories, mass and composition are the two factors that determine a star’s physical characteristics and dictate its entire life cycle. Because the two stars condensed from the same cloud of gas and dust they should have the same composition. With identical mass and composition, they should be identical in every way. So the astronomers were surprised when they discovered that the twins exhibited significant differences in brightness, surface temperature and possibly size.

The astronomers made the initial measurements of the eclipses of the two stars by sifting through nearly 15 years’ worth of observations of several thousand stars using a telescope at the Kitt Peak National Observatory in Arizona and the SMARTS telescopes at the Cerro Tololo Inter-American Observatory in Chile. In order to gain more information about the two stars, they made additional measurements using the Hobby Eberly Telescope in Texas. By measuring the difference in the amount that the light dipped during the eclipses, the astronomers were able to determine that one of the stars is two times brighter than the other and calculate that the brighter star has a surface temperature about 300 degrees higher than its twin. An additional analysis of the light spectrum coming from the pair also suggests that one of the stars is about 10 percent larger than the other, but additional observations are needed to confirm it.

“The easiest way to explain these differences is if one star was formed about 500,000 years before its twin,” says Stassun. “That is equivalent to a human birth-order difference of about half of a day.”

In addition to causing theorists to re-examine star-formation models, the new discovery may cause astronomers to readjust their estimates of the masses and ages of thousands of young stars less than a few million years old. Current estimates are based on models that were calibrated with measurements of young binary stars that were presumed to have formed simultaneously. The recalibration required could be as much as 20 percent for the mass of a typical young star and as much as 50 percent for very low-mass stars like brown dwarfs, Stassun estimates.

Other participants in the study are doctoral students Phillip Cargile and Alicia Aarnio from Vanderbilt and Aaron Geller from the University of Wisconsin-Madison along with Eric Stempels from the University of St. Andrews in Scotland.

The research is part of the Vanderbilt Initiative in Data-Intensive Astrophysics (http://www.vanderbilt.edu/AnS/physics/vida/) and was supported by grants from the National Science Foundation and the Research Corporation.

Vanderbilt University is a private research university of approximately 6,500 undergraduates and 5,300 graduate and professional students. Founded in 1873, the University comprises 10 schools, a public policy institute, a distinguished medical center and The Freedom Forum First Amendment Center. Vanderbilt, ranked as one of the nation’s top universities, offers undergraduate programs in the liberal arts and sciences, engineering, music, education and human development, and a full range of graduate and professional degrees.

David F. Salisbury | newswise
Further information:
http://www.vanderbilt.edu/AnS/physics/vida/
http://www.vanderbilt.edu

More articles from Physics and Astronomy:

nachricht Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun
18.04.2019 | University of Warwick

nachricht In vivo super-resolution photoacoustic computed tomography by localization of single dyed droplets
18.04.2019 | Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun

A stellar flare 10 times more powerful than anything seen on our sun has burst from an ultracool star almost the same size as Jupiter

  • Coolest and smallest star to produce a superflare found
  • Star is a tenth of the radius of our Sun
  • Researchers led by University of Warwick could only see...

Im Focus: Quantum simulation more stable than expected

A localization phenomenon boosts the accuracy of solving quantum many-body problems with quantum computers which are otherwise challenging for conventional computers. This brings such digital quantum simulation within reach on quantum devices available today.

Quantum computers promise to solve certain computational problems exponentially faster than any classical machine. “A particularly promising application is the...

Im Focus: Largest, fastest array of microscopic 'traffic cops' for optical communications

The technology could revolutionize how information travels through data centers and artificial intelligence networks

Engineers at the University of California, Berkeley have built a new photonic switch that can control the direction of light passing through optical fibers...

Im Focus: A long-distance relationship in femtoseconds

Physicists observe how electron-hole pairs drift apart at ultrafast speed, but still remain strongly bound.

Modern electronics relies on ultrafast charge motion on ever shorter length scales. Physicists from Regensburg and Gothenburg have now succeeded in resolving a...

Im Focus: Researchers 3D print metamaterials with novel optical properties

Engineers create novel optical devices, including a moth eye-inspired omnidirectional microwave antenna

A team of engineers at Tufts University has developed a series of 3D printed metamaterials with unique microwave or optical properties that go beyond what is...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

Fraunhofer FHR at the IEEE Radar Conference 2019 in Boston, USA

09.04.2019 | Event News

 
Latest News

New automated biological-sample analysis systems to accelerate disease detection

18.04.2019 | Life Sciences

Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun

18.04.2019 | Physics and Astronomy

New eDNA technology used to quickly assess coral reefs

18.04.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>