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 Further Improvement of Qubit Lifetime for Quantum Computers
09.12.2016 | Forschungszentrum Jülich

nachricht Electron highway inside crystal
09.12.2016 | Julius-Maximilians-Universität Würzburg

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: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>