X-rays from NASA’s Chandra Observatory reveal that a fast-moving pulsar in orbit around a massive star punched a hole in a circumstellar disk of material and launched a fragment of the disk outward at a speed of about 40 million miles per hour.
X-ray evidence from NASA’s Chandra Observatory suggests that a clump of stellar material has been jettisoned away from the binary system B1259 at incredibly high speeds. The bright source in the center of the bottom images is B1259, while the smaller point-like source to the lower right seen in the second two observations is the clump that has been dislodged. Image credit: X-ray – NASA / CXC / PSU / G. Pavlov et al.; illustration – NASA / CXC / M.Weiss.
This binary star system, catalogued as PSR B1259-63/LS 2883 (B1259 for short), is located about 7,500 light-years from Earth.
It is comprised of two objects in orbit around one another. The first is a star about 30 times as massive as the Sun that has a disk of material swirling around it. The other is a pulsar, an ultra-dense neutron star left behind when an even more massive star underwent a supernova explosion.
The pulsar emits regular pulses as it spins 20 times a second, and moves in a highly elliptical orbit around its companion star. The combination of rapid rotation and intense magnetic field of the pulsar has generated a strong wind of high-energy particles moving away from the pulsar at near the speed of light.
A team of astronomers, led by Dr George Pavlov of Penn State University, suggests that B1259’s pulsar knocked out the chunk of debris, which spans over a hundred times the size of the Solar System, when it collided with the disk around the massive star while traveling in its elliptical orbit lasting 41 months.
“These two objects are in an unusual cosmic arrangement and have given us a chance to witness something special. As the pulsar moved through the disk, it appears that it punched a clump of material out and flung it away into space,” said Dr Pavlov, who is the first author of a paper published online in the Astrophysical Journal (arXiv.org preprint).
The scientists came to this conclusion after analyzing three separate Chandra observations taken between December 2011 and February 2014.
The observations also suggest that the clump is not only moving quickly but may, in fact, be picking up speed.
The average of the three observations shows the clump is moving about 7 percent the speed of light, but the data suggest it may have accelerated to 15 percent the speed of light between the second and third observations. This acceleration could be due to intense winds flowing off of the pulsar’s surface.
“This just shows how powerful the wind blasting off a pulsar can be. The pulsar’s wind is so strong that it could ultimately eviscerate the entire disk around its companion star over time,” said study co-author Dr Jeremy Hare from George Washington University in Washington, DC.
The X-ray emission observed by Chandra is likely produced by a shock wave created as the pulsar’s wind rams into the clump of material. The ram pressure generated by this interaction could also accelerate the clump.
The astronomers will continue monitoring B1259 and its moving clump with Chandra observations scheduled for later this year and in 2016.
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George G. Pavlov et al. 2015. An Extended X-Ray Object Ejected from the PSRB1259-63/LS2883 Binary. ApJ 806, 192; doi: 10.1088/0004-637X/806/2/192
