RX J1856.5-3754
 X-ray image of RX J1856.5-3754 |
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| Observation data Epoch 1996.7 Equinox J2000.0[1] |
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|---|---|
| Constellation | Corona Australis |
| Right ascension | 18h 56m 35s [1] |
| Declination | −37° 54′ 36″[1] |
| Apparent magnitude (V) | ~25.6[1] |
| Details | |
| Mass | 0.9 M☉ |
| Radius | 1.9–4.1 km |
| Age | 1 million years |
| Other designations | |
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RX J185635-3754, 1ES 1853-37.9, 1RXS J185635.1-375433
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| Database references | |
| SIMBAD | data |
RX J1856.5-3754 (also called RX J185635-3754, RX J185635-375, and various other designations) is a nearby neutron star in the constellation Corona Australis.
Discovery and location
RX J1856.5-3754 is thought to have formed in a supernova explosion of its companion star about one million years ago and is moving at 108 km/s across the sky. It was discovered in 1992, and observations in 1996 confirmed that it is a neutron star, the closest to Earth discovered.[2]
It was originally thought to be about 150–200 light-years away,[3] but further observations using the Chandra X-ray Observatory in 2002 indicate that its distance is greater—about 400 light-years.[4][5]
RX J1856 is one of the Magnificent Seven, a group of young neutron stars at distances between 200 and 500 parsecs (652 and 1630 light years) of Earth.
Quark star?
By combining Chandra X-ray Observatory and Hubble Space Telescope data, astronomers previously estimated that RX J1856 radiates like a solid body with a temperature of 700,000 °C and has a diameter of about 4–8 km. This estimated size was too small to reconcile with the standard models of neutron stars, therefore it was suggested that it might be a quark star.[4]
However, later refined analysis[5][6] of improved Chandra and Hubble observations revealed that the surface temperature of the star is lower, only 434,000 °C, and respectively the radius is larger, about 14 km (with account of the effects of general relativity, the observed radius appears about 17 km).[5] Thus, RX J1856.5-3754 is now excluded from the list of quark star candidates.[6]
See also
- 3C 58 a possible quark star
References
- RX-J185635-375 at jumk.de
- RX J1856.5-3754 and 3C58: Cosmic X-rays May Reveal New Form of Matter Chandra X-Ray Observatory. July 16, 2009.
- Walter, Frederick M.; Lattimer, James M., The Astrophysical Journal, 2002
- ↑ 1.0 1.1 1.2 1.3 RX J185635-3754 - an Isolated Neutron Star, F. M. Walter, web page at the Department of Physics and Astronomy, State University of New York at Stony Brook. Accessed on line June 29, 2007.
- ↑ Rees, Martin (2012) Universe. Dorling Kindersley. p. 528
- ↑ "The Mystery of the Lonely Neutron Star". European Southern Observatory press release, September 11, 2000. Accessed online at spaceref.com May 20, 2007.
- ↑ 4.0 4.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 5.0 5.1 5.2 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 6.0 6.1 Lua error in package.lua at line 80: module 'strict' not found.
