WR 102

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Star
WR 102
Infrared image of the nebula around WR 102 (data from WISE and the Spitzer Space Telescope)
Infrared image of the nebula around WR 102 (data from WISE and the Spitzer Space Telescope )
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation Sagittarius
Right ascension 17 h 45 m 47.5 s
declination −26 ° 10 ′ 27 ″
Apparent brightness 14 likes
Typing
Spectral class WO2
Variable star type Wolf-Rayet star 
Astrometry
Physical Properties
Dimensions approx. 19  M ☉
radius approx. 0.4 R ☉
approx. 0.6  R ☉
Effective temperature approx. 200,000  K
Other names
and catalog entries
2MASS catalog 2MASS J17454754-2610267 [1]
Other names Sand 4, V3893 Sagittarii

WR 102 (also: Sand 4 ) is a Wolf-Rayet star in the constellation Sagittarius of the very rare spectral class WO . Its surface has an extremely high temperature of around 200,000 Kelvin and its development is about to end as a supernova .

The star is surrounded by a nebula called G2.4 + 1.4.

properties

WR 102 with the spectral class WO2 is one of the few Wolf-Rayet stars in the oxygen sequence, of which only four are known in the Milky Way and another five in other galaxies. In addition, with a surface temperature of around 200,000 Kelvin, it is one of the hottest known stars. A model of the atmosphere indicates a luminosity of 282,000  L ☉ , while estimates from brightness and distance speak for 500,000 L ☉ , but the distance estimate is subject  to great uncertainty. Despite its roughly 20 solar masses , the star is about half the diameter of the sun. He loses by strong solar winds at a speed of 5000 kilometers per second about 10 -5  M ☉ / year, more than a hundred million times the sun.

Different methods of determining the distance lead to results that differ widely. Photometric analyzes give 4.9 kpc and 5.56 kpc. Studies of the nebula surrounding the star indicate a distance of 3 kpc.

Fog G2.4 + 1.4

Nebula G2.4 + 1.4 was initially mistaken for a supernova remnant or a bubble created by the solar wind from WR 102, before further investigations showed that the bubble was formed by photoionization . The structure can be reproduced by a numerical simulation of the photoionization. Alternatively, a shed star shell can explain the structural and spectral properties of the nebula.

Stage of development

The star WR 102 presumably had a mass of 40–60 M ☉ when it was formed and is now in its final evolutionary stage before exploding as a supernova, which is estimated to be the case in 1,500 years. At this stage the helium burning of the core has already been completed, the proportion of oxygen on the surface is before helium and below that of carbon, and the surface is at an extremely high temperature. If WR 102 rotates rapidly, a gamma-ray flash can occur due to its mass at the supernova .

Web links

  • wr 102. In: SIMBAD. simbad.u-strasbg.fr, accessed on November 29, 2016 .

Individual evidence

  1. ↑ PL Dufton, SJ Smartt, NC Hambly: A UKST survey of blue objects towards the Galactic center - seven additional fields . In: Astronomy and Astrophysics . tape 373 , no. 2 , July 1, 2001, p. 608–624 , doi : 10.1051 / 0004-6361: 20010613 , bibcode : 2001A & A ... 373..608D .
  2. ↑ a b c Karel A. van der Hucht: The VIIth catalog of galactic Wolf-Rayet stars . In: New Astronomy Reviews . 45, No. 3, 2001, ISSN  1387-6473 , pp. 135-232. bibcode : 2001NewAR..45..135V . doi : 10.1016 / S1387-6473 (00) 00112-3 .
  3. ↑ a b c d e A. Sander, W.-R. Hamann, H. Todt: The Galactic WC stars . In: Astronomy and Astrophysics . tape 540 , April 2012, doi : 10.1051 / 0004-6361 / 201117830 , arxiv : 1201.6354 , bibcode : 2012A & A ... 540A.144S (Article: A144).
  4. ↑ a b c d F. Tramper, SM Straal, D. Sanyal, H. Sana, A. de Koter, G. Gräfener, N. Langer, JS Vink, SE de Mink, L. Kaper: Massive stars on the verge of exploding. The properties of oxygen sequence Wolf-Rayet stars . In: Astronomy and Astrophysics . tape 581 , September 2015, doi : 10.1051 / 0004-6361 / 201425390 , arxiv : 1507.00839v1 , bibcode : 2015A & A ... 581A.110T (Article: A110).
  5. ^ Peter S. Conti, William D. Vacca: The distribution of massive stars in the Galaxy. I - The Wolf-Rayet stars . In: The Astronomical Journal . 1990. bibcode : 1990AJ .... 100..431C .
  6. ↑ a b M. A. Dopita, TA Lozinskaia, PJ McGregor, SJ Rawlings: The extraordinary mass-loss bubble G2.4 + 1.4 and its central star . In: Astrophysical Journal . 1990. bibcode : 1990ApJ ... 351..563D .
  7. ^ F. Brighenti, A. D'Ercole: Evolution of WR ring nebulae generated by moving central stars - I. The paradigm of G2.4 + 1.4 . In: Monthly Notices of the Royal Astronomical Society . 1995. bibcode : 1995MNRAS.273..443B .
  8. ^ VF Polcaro, C. Rossi, L. Norci, R. Viotti: The WO stars. II. Long slit spectroscopy of the G2.4 + 1.4 nebula around Sand 4 . In: Astronomy & Astrophysics . 1995. bibcode : 1995A & A ... 303..211P .