| appmag_4_passband = K
| appmag_4 = 10.17[7]
| b-v
}}{{Starbox astrometry
| radial_v =
| prop_mo_ra = {{val|-0.579|0.096}}[8]
| prop_mo_dec = {{val|-2.171|0.075}}[8]
| parallax = 0.3735
| p_error = 0.0658
| parallax_footnote = [8]
| dist_ly =
| dist_pc = {{val|2,300|300|fmt=commas}}[11]
| absmag_v =
| space_v_u =
| space_v_v =
| space_v_w =
}}{{Starbox detail
| source =
| mass = {{val|7.1|2.4|1.8}}[11]
| luminosity = {{val|91,200|60,200|36,200|fmt=commas}}[11]
| luminosity_visual =
| temperature = 160,000[3]
| radius = {{val|0.39|0.11|0.09}}[11]
| gravity =
| metal_fe =
| rotational_velocity =
| age_myr =
}}{{Starbox catalog
| names= 2MASS J17320330-3504323, SSTGLMC G353.2744-00.8460
}}{{Starbox reference
| Simbad = WR+93b
| ARICNS =
}}{{Starbox end}}WR 93b is a Wolf-Rayet star in the constellation Scorpius, an extremely rare star on the WO oxygen sequence.
Discovery
WR 93b was discovered in 2003 during a study of emission line stars from the AAO/UKST Southern Galactic Plane Hα Survey. It was published as the fourth galactic WO class star in 1994.[16] This was too late to be included in the VIIth Wolf Rayet catalogue,[17] but it is listed in an annex published in 2006.[7]
It lies in the direction of the galactic centre and is thought to be part of the Scutum-Crux spiral arm. It is highly reddened and Interstellar extinction causes it to be 6.5 magnitudes fainter at visual wavelengths.[16]
Features
WR 93b, of spectral classification WO3, is one of the very few known oxygen-sequence Wolf-Rayet stars, just four in the Milky Way galaxy and five in external galaxies. Modelling the atmosphere gives a luminosity around {{solar luminosity|200,000|link=y}}. It is a very small dense star, with a radius less than the sun's but with a mass nearly 10 solar masses. Very strong stellar winds, with a terminal velocity of 5,000 kilometers per second are causing WR 93b to lose {{solar mass|10−5}}/year.[3] For comparison, the Sun loses (2-3) x 10−14 solar masses per year due to its solar wind, several hundred million times less than WR 93b.
Evolutionary status
WO Wolf-Rayet stars are the last evolutionary stage of the most massive stars before exploding as supernovae, possibly with a gamma-ray burst.[1] It is very likely that WR 93b is on its last stages of nuclear fusion, near or beyond the end of helium burning.[2] It has been calculated that WR 93b will explode as a supernova within 8,000 years.[3]
See also
- WR 102
- WR 142
- WR 30a
- List of supernova candidates
References
1. ^{{Cite journal|arxiv=1308.4681|last1= Groh|first1= Jose H.|title= Fundamental properties of core-collapse Supernova and GRB progenitors: Predicting the look of massive stars before death|journal= Astronomy & Astrophysics|volume= 558|pages= A131|last2= Meynet|first2= Georges|last3= Georgy|first3= Cyril|last4= Ekstrom|first4= Sylvia|year= 2013|doi= 10.1051/0004-6361/201321906|bibcode= 2013A&A...558A.131G}}
2. ^{{Cite journal|last=Groh |first=Jose |arxiv=1401.7322 |title=The evolution of massive stars and their spectra I. A non-rotating 60 Msun star from the zero-age main sequence to the pre-supernova stage |journal=Astronomy & Astrophysics |volume=564 |pages=A30 |year=2014 |doi=10.1051/0004-6361/201322573 |bibcode=2014A&A...564A..30G }}
3. ^1 2 3 4 {{Cite journal|arxiv=1507.00839v1|last1= Tramper|first1= F.|title= Massive stars on the verge of exploding: The properties of oxygen sequence Wolf-Rayet stars|journal= Astronomy & Astrophysics|volume= 581|issue= 110|pages= A110|last2= Straal|first2= S. M.|last3= Sanyal|first3= D.|last4= Sana|first4= H.|last5= de Koter|first5= A.|last6= Gräfener|first6= G.|last7= Langer|first7= N.|last8= Vink|first8= J. S.|last9= de Mink|first9= S. E.|last10= Kaper|first10= L.|year= 2015|doi= 10.1051/0004-6361/201425390|bibcode= 2015A&A...581A.110T}}
4. ^1 2 {{cite journal|bibcode=2006A&A...458..453V|arxiv=astro-ph/0609008|title=New Galactic Wolf-Rayet stars, and candidates. An annex to the VIIth Catalogue of Galactic Wolf-Rayet Stars|journal=Astronomy and Astrophysics|volume=458|issue=2|pages=453–459|author1=Van Der Hucht|first1=K. A.|year=2006|doi=10.1051/0004-6361:20065819}}
5. ^1 {{cite journal|last1=van der Hucht|first1=Karel A.|title=The VIIth catalogue of galactic Wolf–Rayet stars|journal=New Astronomy Reviews|volume=45|issue=3|year=2001|pages=135–232|issn=1387-6473|doi=10.1016/S1387-6473(00)00112-3|bibcode = 2001NewAR..45..135V }}
6. ^1 2 {{cite journal|bibcode=2004MNRAS.351..206D|arxiv=astro-ph/0403482|title=Discovery of a WO star in the Scutum-Crux arm of the inner Galaxy|journal=Monthly Notices of the Royal Astronomical Society|volume=351|pages=206–214|author1=Drew|first1=Janet E.|last2=Barlow|first2=M. J.|last3=Unruh|first3=Y. C.|last4=Parker|first4=Q. A.|last5=Wesson|first5=R.|last6=Pierce|first6=M. J.|last7=Masheder|first7=M. R. W.|last8=Phillipps|first8=S.|year=2004|doi=10.1111/j.1365-2966.2004.07771.x|url=https://arxiv.org/pdf/astro-ph/0403482|format=Submitted manuscript}}
7. ^1 2 3 4 {{cite journal|doi=10.1093/mnras/sty1827|bibcode=2018MNRAS.tmp.1751S|arxiv=1807.02117|title=Probing the rotational velocity of Galactic WO stars with spectropolarimetry|journal=Monthly Notices of the Royal Astronomical Society|volume=479|issue=4|pages=4535–4543|year=2018|last1=Stevance|first1=H F|last2=Ignace|first2=R|last3=Crowther|first3=P A|last4=Maund|first4=J R|last5=Davies|first5=B|last6=Rate|first6=G}}
8. ^1 2 3 {{cite DR2|5975043607541238016}}