Breaking the Thermonuclear Behavioral Mold

While black holes currently can’t be observed directly, neutron stars come close. A team of researchers have been picking apart data that came from a neutron star burst in the center of our own galaxy over a year ago. In October 2010, the Rossi X-ray Timing Explorer captured one month’s worth of data on the object. Terzan 5, which hosts the T5X2 system (shown above), is a dense globular star cluster located 25,000 light-years away toward the constellation Sagittarius.

“In a single month from this unique system, we have identified behavior not seen in observations of nearly 100 bursting neutron stars during the past 30 years,” said Manuel Linares, a postdoctoral researcher at the Kavli Institute for Astrophysics and Space Research at the Massachusetts Institute of Technology in Cambridge. He led a study of the RXTE data that will be published in the March 20 issue of The Astrophysical Journal.

IGR J17480-2446 is a type of X-ray binary star system of relatively low mass. The neutron star orbits another object that is actually fairly close to our sun. The neutron star itself is referred by the shortened designation of T5X2, and this particular object has been classified as a pulsar. However, the star is behaving a bit interestingly when it reaches a higher rate of acceleration. During those time periods, the emission spikes occur much more often and are generally smaller.

The faster rate of rotation could be causing friction to occur between the star’s surface and the fuel that drives the reaction. This would cause the different types of emission patterns to occur. “We see T5X2 as a ‘model burster,’ the one that’s doing everything expected of it,” said Diego Altamirano, an astrophysicist at the University of Amsterdam in The Netherlands and a co-author on the paper describing the findings.

Image Credit: NASA/Goddard Space Flight Center

Reference:

Linares, M., Altamirano, D., Chakrabarty, D., Cumming, A., & Keek, L. (2012). MILLIHERTZ QUASI-PERIODIC OSCILLATIONS AND THERMONUCLEAR BURSTS FROM TERZAN 5: A SHOWCASE OF BURNING REGIMES The Astrophysical Journal, 748 (2) DOI: 10.1088/0004-637X/748/2/82

Linares, M., Chakrabarty, D., & van der Klis, M. (2011). ON THE COOLING TAILS OF THERMONUCLEAR X-RAY BURSTS: THE IGR J17480–2446 LINK The Astrophysical Journal, 733 (2) DOI: 10.1088/2041-8205/733/2/L17

Chakraborty, M., & Bhattacharyya, S. (2011). X-RAY BURSTS FROM THE TERZAN 5 TRANSIENT IGR J17480-2446: NUCLEAR RATHER THAN GRAVITATIONAL The Astrophysical Journal, 730 (2) DOI: 10.1088/2041-8205/730/2/L23

NASA – National Aeronautics and Space Administration. (2012, March 09). NASA. Retrieved March 14, 2012, from http://www.nasa.gov/topics/universe/features/rxte-thermo.html

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