HD 160529

HD 160529

A visual band light curve for V905 Scorpii. The red points are from Sterken et al. (1997),[1] and the blue points are ASAS data.[2]
Observation data Epoch J2000      Equinox J2000
Constellation	Scorpius
Right ascension	17^h 41^m 59.025^s[3]
Declination	−33° 30′ 13.71″[3]
Apparent magnitude (V)	6.66[4] (6.3–6.9[5])
Characteristics
Spectral type	LBV
U−B color index	+0.30[4]
B−V color index	+1.21[4]
Variable type	LBV[5]
Astrometry
Radial velocity (Rv)	−35[6] km/s
Proper motion (μ)	RA: −1.75[3] mas/yr Dec.: −1.49[3] mas/yr
Parallax (π)	0.54 ± 0.54 mas[3]
Distance	2,500[7] pc
Absolute magnitude (MV)	−8.9[8]
Details
Mass	13[8] M☉
Radius	150–330[5] R☉
Luminosity	290,000[7] L☉
Surface gravity (log g)	0.55[8] cgs
Temperature	8,000–12,000[5] K
Rotational velocity (v sin i)	45[5] km/s
Other designations
V905 Sco, HD 160529, CD −33°12361, SAO 209151, HIP 86624
Database references
SIMBAD	data

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 is easy to see with binoculars or amateur telescopes.

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.^[5] The distance has been estimated at 2.5 kiloparsecs (8,200 light years) based on the assumption of an absolute magnitude of −8.9.^[8] However this distance is uncertain and values between 1.9 kiloparsecs and 3.5 kiloparsecs have been proposed.^[5]

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_☉.^[5]

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.^[8]

References

1. Sterken, C.; van Genderen, A. M.; de Groot, M. (January 1997). "Cyclic Light Variations in LBVs". Astronomical Society of the Pacific Conference Series. 120 (Luminous Blue Variables: Massive Stars in Transition): 35. Bibcode:1997ASPC..120...35S. Retrieved 16 March 2022.
2. "ASAS All Star Catalogue". The All Sky Automated Survey. Retrieved 8 December 2021.
3. Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
4. 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.
5. 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. S2CID 15409946.
6. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
7. 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. S2CID 43688343.
8. 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.