HD 160529

HD 160529 (V905 Scorpii) is a luminous blue variable (LBV) star located in the constellation of Scorpius. With an apparent magnitude of around +6.8 cannot be seen with the naked eye except under very favourable conditions, but it's easy to see with binoculars or amateur telescopes.

HD 160529
Observation data
Epoch J2000      Equinox J2000
Constellation Scorpius
Right ascension  17h 41m 59.025s[1]
Declination −33° 30′ 13.71″[1]
Apparent magnitude (V) 6.66[2] (6.3 - 6.9[3])
Characteristics
Spectral type LBV
U−B color index +0.30[2]
B−V color index +1.21[2]
Variable type LBV[3]
Astrometry
Radial velocity (Rv)-35[4] km/s
Proper motion (μ) RA: −1.75[1] mas/yr
Dec.: −1.49[1] mas/yr
Parallax (π)0.54 ± 0.54[1] mas
Distance2,500[5] pc
Absolute magnitude (MV)-8.9[6]
Details
Mass13[6] M☉
Radius150-330[3] R☉
Luminosity290,000[5] L☉
Surface gravity (log g)0.55[6] cgs
Temperature8,000-12,000[3] K
Rotational velocity (v sin i)45[3] km/s
Other designations
V905 Sco, HD 160529, CD -33°12361, SAO 209151, HIP 86624
Database references
SIMBADdata

Physical characteristics
V905 Sco in comparison to other LBVs and cool hypergiants

V905 Sco has a peculiar variable spectral type with emission lines and P Cygni profiles. At visual maximum it is similar to an A9 star and at minimum close to B8.[3] The distance has been estimated at 2.5 kiloparsecs (8,200 light years) based on the assumption of an absolute magnitude of -8.9.[6] However this distance is uncertain and values between 1.9 kiloparsecs and 3.5 kiloparsecs have been proposed.[3]

Working with a distance of 2.5 kiloparsecs, the radius varies from 150 R☉ when quiescent to 330 R☉ in outburst. The temperature also varies, from 8,000K in outburst to 12,000K when quiescent. With these parameters, the apparent visual magnitude varies by 0.5 and the bolometric luminosity is constant at 180,000 L☉.[3]

Estimates of the surface gravity lead to a mass of 13 M☉ and a probable initial mass of 25 M☉ This suggests that V905 Sco is a former red supergiant star.[6]

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gollark: And whose fault is that?
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gollark: I have accepted ABR PRs before. Possibly. Maybe.
gollark: Gollarious bee #81828 deployed.

References
  1. Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
  2. Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237: 0. Bibcode:2002yCat.2237....0D.
  3. Stahl, O.; Gäng, T.; Sterken, C.; Kaufer, A.; Rivinius, T.; Szeifert, T.; Wolf, B. (March 2003). "Long-term spectroscopic monitoring of the Luminous Blue Variable HD 160529". Astronomy and Astrophysics. 400: 279–291. arXiv:astro-ph/0212473. Bibcode:2003A&A...400..279S. doi:10.1051/0004-6361:20021908.
  4. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065.
  5. Nazé, Y.; Rauw, G.; Hutsemékers, D. (2012). "The first X-ray survey of Galactic luminous blue variables". Astronomy & Astrophysics. 538: A47. arXiv:1111.6375. Bibcode:2012A&A...538A..47N. doi:10.1051/0004-6361/201118040.
  6. Sterken, C.; Gosset, E.; Juttner, A.; Stahl, O.; Wolf, B.; Axer, M. (July 1991). "HD 160529 - a New Galactic Luminous Blue Variable". Astronomy and Astrophysics. 247 (2): 383. Bibcode:1991A&A...247..383S.
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