RX J1856-3754
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Star RX J1856.5-3754 |
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Observation dates equinox : J2000.0 , epoch : J2000.0 |
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| Constellation | Southern crown |
| Right ascension | 18 h 56 m 35 s |
| declination | -37 ° 54 ′ 36 ″ |
| Apparent brightness | 25.7 mag |
| Typing | |
| Astrometry | |
| parallax | (8.16 ± 0.80) mas |
| distance | (400) ly (120) pc |
| Physical Properties | |
| Dimensions | 1.4 M ☉ |
| Effective temperature | 700,000 K |
| Rotation time | 7 sec |
| Age | <1 million a |
RX J1856-3754 , also RX J1856 or RXJ1856.5-3754 , is the closest known neutron star to us . It stands in the constellation Corona Australis at 18h 56m 35s ( right ascension ) and −37 ° 54 ′ 36 ″ ( declination ) and shines with an apparent brightness of approx. 25 m . It was discovered in 1992. According to recent observations, it is approx. 500 light years away from us and moves at a speed of approx. 100 km / s relative to the solar system.
RX J1856 is the brightest neutron star from the group of so-called Magnificent Seven (engl. Magnificent seven ). With a temperature of around 700,000 ° C, they are so hot that they emit thermally excited gamma rays. Long-wave (non-thermal) radio waves cannot be detected.
It was only in 2007 that the RX J1856 was able to demonstrate a self-rotation of 7 seconds. It has a mass of about 1.4 solar masses . The supposedly small diameter of less than 11 km was interpreted as an indication of a so-called quark star , but later measurements showed that only the polar caps shine on this star . It has a much larger diameter than 11 km and is therefore no longer a candidate for a quark star.
See also
Web links
Individual evidence
- ↑ a b RX J1856.6-3754. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed on October 19, 2019 .
- ↑ N. Tetzlaff, T. Eisenbeiss, R. Neuhäuser, M.. Hollow: The origin of RX J1856.5−3754 and RX J0720.4−3125 - updated using new parallax measurements . In: MNRAS . 417, No. 1, August, pp. 617-626. doi : 10.1111 / j.1365-2966.2011.19302.x .
- ↑ Archived copy ( memento of the original from September 30, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Drake, JJ et al .: Is RX J185635-375 a Quark Star? . The Astrophysical Journal , Volume 572, 996-1001 ( preprint )
- ↑ Braje, TM et al .: RX J1856-3754: Evidence for a Stiff Equation of State . Astrophysical Journal, Volume 580, 1043-1047 ([arxiv.org/abs/astro-ph/0208069])
