NASA recently published a new image of an unusual cosmic view (Fig. 1), revealing the discovery of a new pulsar, a tiny, extremely dense stellar object, characterized by a very powerful magnetic field. The pulsar is located in a small nearby galaxy, known as the Small Magellanic Cloud, lying some 200,000 light years away from Earth. The pulsar discovery was made by combining data from NASA’s Chandra X-ray Observatory, a sophisticated satellite exploring the universe in X-rays, and the European Space Agency’s X-ray space observatory, XMM-Newton satellite.
A pulsar is the collapsed core of a supernova, a massive star which ends its evolution in a tremendous explosion. When the giant star explodes, the pulsar is exposed, and the outer gaseous envelope of the star is flung into space, forming a huge expanding cloud around the pulsar, known as the supernova remnant. A pulsar is only about 20 km across, but its mass is significantly greater than the Sun’s. It is composed primarily of neutrons. Most pulsars rotate very rapidly about their axes. Some pulsars are called millisecond pulsars, since they rotate hundreds of times per second, about their axes.
In Fig. 1, the colors are not true, but they represent the different observations, combined to produce the image. X-rays from Chandra and XMM-Newton have been colored blue, while optical data from the ground-based Cerro Tololo Inter-American Observatory in Chile are colored red and green. The pulsar, technically known as SXP 1062, is the bright white source located on the right of the image. There is a cloud surrounding the pulsar and emitting visual light and X-rays. This cloud may be the remains of the pulsar’s progenitor exploding star. The optical image also shows magnificent clouds of gas and cosmic dust, in a star-forming region, on the left side of the image.
Interestingly, Chandra and XMM-Newton observations show SXP 1062 is a peculiar object, because, compared to most pulsars, it is rotating slowly, about once every 18 minutes. This relatively slow rotation of SXP 1062 makes it one of the slowest known pulsars.
Estimates of the age of the supernova remnant around SXP 1062 show that it formed 10,000 to 40,000 years ago. This means that the pulsar is young, by astronomical time scales, since it was presumably created in the same supernova event that blew the glowing remnant. Therefore, assuming that SXP 1062 initially had a fast spin, it is a mystery why SXP 1062 has so rapidly slowed down. Astronomers are developing theoretical models, to explain the evolution of this bizarre object.
The Chandra observatory orbits Earth every 64 hours, in an elongated elliptical orbit, along which Chandra’s distance from Earth varies between about 16,000 km and 133,000 km. Chandra is approximately 5,000 kg in mass, and was launched into space in 1999. It was named in honor of Subrahmanyan Chandrasekhar, the Indian-American astrophysicist, who made valuable contributions to stellar astronomy.
The XMM-Newton observatory, named in honor of Sir Isaac Newton, orbits Earth every 48 hours, in an elongated elliptical orbit. Its distance from Earth ranges between about 7,000 km and 114,000 km. It is approximately 4,000 kg in mass, and launched in 1999.
References
Chandra Press Release
http://chandra.harvard.edu/photo/2011/sxp1062/
Wikipedia