Over the past 20 years, the exceptional ability of the Chandra X-ray Observatory to create high spatial resolution X-ray images has enabled key advances in our understanding of the behavior of black holes and neutron stars. For example, a longstanding, important question is why some subset of neutron stars, the millisecond pulsars, rotate so rapidly - hundreds of times per second. These are the most rapidly spinning objects in the known Universe, but why they spin so rapidly is not obvious. Chandra's detection of X-ray emission from a millisecond pulsar called 47 Tuc W has provided important clues to help answer this question. This particular neutron star is in a globular cluster called 47 Tuc, a group of a few million stars bound together by gravity into a spherical ball about 100 lightyears across. The optical view of the stars in the cluster is shown in the left image above, while the image on the right shows the X-ray emitting cluster members seen by Chandra. The source marked by the arrow, 47 Tuc W, is an X-ray emitting neutron star which rotates on its axis more than 400 times per second. The combination of the X-ray images and X-ray variability from the Chandra observations with optical and radio data shows that this particular X-ray emitting pulsar is in a binary system, locked in orbit with a low mass star. This evidence indicates that accretion of matter from the companion star helps spin up millisecond pulsars to their extraordinary rotation rates.
CXC: 47 Tuc W: Long-Sought Link to Origin of Millisecond Pulsars
APOD: X-Ray Stars of 47 Tuc (2005 Jul 21)
An X-Ray Variable Millisecond Pulsar in the Globular Cluster 47 Tucanae:
Closing the Link to Low-Mass X-Ray Binaries ~ Slavko Bogdanov, Jonathan E. Grindlay, Maureen van den Berg
- Astrophysical Journal 630(2):1029 (2005 Sep 10) DOI: 10.1086/432249
arXiv.org > astro-ph > arXiv:astro-ph/0506031 > 01 Jun 2005
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