New York University Skip to Content Skip to Search Skip to Navigation Skip to Sub Navigation

Pulsating Star Sheds Light on Exoplanet

September 17, 2013

By James Devitt


A team of researchers has devised a way to measure the internal properties of stars—a method that offers more accurate assessments of their orbiting planets.


The method, which appeared in Proceedings of the National Academy of Sciences (PNAS), was conducted by a multinational team of scientists that included NYU-Poly President and University Professor Katepalli Sreenivasan as well as physicists from Princeton University and the Max Planck Institute for Solar System Research.


The researchers examined HD 52265—a star approximately 92 light years away and nearly 20 percent more massive than our sun. More than a decade ago, scientists identified an exoplanet—a planet outside our solar system—in the star’s orbit. HD 52265, then, served as an ideal model for both measuring stars’ properties and how such properties can shed light on planetary systems.
Previously, scientists inferred stars’ properties, such as radius, mass, and age, by considering observations of their brightness and color. Often these stars’ properties were not known to sufficient accuracy to further characterize the nearby planets.


In the PNAS study, the scientists adopted a new approach to characterize star-planet systems: asteroseismology, which identifies the internal properties of stars by measuring their surface oscillations. Some have compared this approach to seismologists’ use of earthquake oscillations to examine the Earth’s interior.


Here, they were able to make several assessments of the star’s traits, including its mass, radius, age, and—for the first time—internal rotation. They used the COROT space telescope, part of a space mission led by the French Space Agency in conjunction with the European Space Agency, to detect tiny fluctuations in the intensity of starlight caused by starquakes. The researchers confirmed the validity of the seismic results by comparing them with independent measurements of related phenomena. These included the motion of dark spots on the star’s surface and the star’s spectroscopic rotational velocity.


Unlike other methods, the technique of asteroseismology returns both the rotation period of the star and the inclination of the rotation axis to the line of sight.


The scientists could then use these findings to make a more definitive determination of an orbiting exoplanet. While it had previously been identified as an exoplanet by other scientists, some raised doubts about this conclusion, positing that it could actually be a brown dwarf—an object too small to be a star and too large to be a planet.


But, armed with the precise calculations yielded by asteroseismology, the researchers on the PNAS study were able to enhance the certainty of the earlier conclusion. Specifically, given the inclination of the rotation axis of HD 52265 and the minimum mass of the nearby exoplanet, the researchers could infer the true mass of the latter—which was calculated to be roughly twice that of our planet Jupiter and therefore too small to be a brown dwarf.

Type: Article

Pulsating Star Sheds Light on Exoplanet

Search News



NYU In the News

NYU Offers Financial Aid to Undocumented Students

The Wall Street Journal reported that NYU will begin offering scholarship aid to undocumented students for the school year beginning next September.

NYU Adopts Lean LaunchPad Program to Teach Entrepreneurship

Startup guru Steve Blank, in a Huffington Post blog, described how NYU adopted the Lean LaunchPad model to teach entrepreneurship to students and faculty at NYU.

Biology Professor Jane Carlton Examines Wastewater for the City’s Microbiome

The New York Times’ Science Times column “Well” profiled Biology Professor Jane Carlton and her research project to sequence microbiome of New York City by examining wastewater samples.

Steinhardt Professors Use a Play as Therapy

The New York Times wrote about a play written by Steinhardt Music Professor Robert Landy about the relationship between Adjunct Professor Cecilia Dintino, a clinical psychologist in the Drama Therapy Program, and a patient, former Broadway actress Jill Powell.

NYU Public Health Experts Urge Strengthening Local Health Systems to Combat Ebola

Dean Cheryl Healton of the Global Institute of Public Health and Public Health Professor Christopher Dickey wrote an op-ed in the Huffington Post saying international health agencies need to strengthen their presence in countries at the local level to prevent future ebola outbreaks.

NYU Footer