HD 159176

HD 159176, also known as Boss 4444 and V1036 Scorpii, is a variable star about 2,800 light years from the Earth, in the constellation Scorpius.[2] It is a 5th magnitude star, so it should be visible to the naked eye of an observer far from city lights. HD 159176 is the brightest star in the young open cluster NGC 6383.[4] It is a binary star composed of two nearly identical O stars in a circular orbit.[7]

HD 159176

A light curve for V1036 Scorpii, plotted from TESS data.[1] The orbital period is marked in red.
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Scorpius
Right ascension 17h 34m 42.49213s[2]
Declination −32° 34′ 53.9955″[2]
Apparent magnitude (V) 5.71 - 5.79[3]
Characteristics
Spectral type O6.5V + O7V[4]
Variable type Rotating ellipsoidal[3]
Astrometry
Proper motion (μ) RA: 2.621±0.083[2] mas/yr
Dec.: −0.798±0.058[2] mas/yr
Parallax (π)1.1666 ± 0.0707 mas[2]
Distance2,800 ± 200 ly
(860 ± 50 pc)
Orbit[5]
PrimaryPrimary
CompanionSecondary
Period (P)3.366767 d
Eccentricity (e)0.0
Periastron epoch (T)2448885.420±0.003
Semi-amplitude (K1)
(primary)		215.7±1.4 km/s
Semi-amplitude (K2)
(secondary)		218.1±1.5 km/s
Details
Primary
Mass46.4+14.3
−9.5[4] M☉
Luminosity5.50±0.10[4] L☉
Temperature38,000[4] K
Secondary
Mass44.2+13.6
−9.1[4] M☉
Luminosity5.41±0.10[4] L☉
Temperature36,750[4] K
Other designations
V1036 Scorpii, HIP 86011, HR 6535, SAO 208977, Boss 4444[6]
Database references
SIMBADdata

In 1930, Robert Trumpler discovered that HD 159176 is a spectroscopic binary. He noted that the two stars have very nearly the same brightness and spectral type. In addition, he was observing at the Lick Observatory, so the far southern declination of the star meant it could only be observed near transit. Those three things together prevented him from unambiguously measuring the orbital period.[8] The first full set of orbital elements, including the 3.3664±0.0003 day period, was derived by Peter Conti et al. in 1975.[9] Also in 1975, photometric observations by J. C. Thomas showed that HD 159176 is a rotating ellipsoidal variable.[10][11] The star's spectra exhibit the Struve–Sahade effect.[4] HD 159176 was given the variable star designation V1036 Scorpii, in 1997.[12]

Although HD 159176 was long considered to be a non-eclipsing binary,[4][7][13][14] data from the Transiting Exoplanet Survey Satellite does show eclipses.[15]

HD 159176 has an X-ray luminosity far higher than would be expected from two isolated O stars. The excess X-rays may arise from interacting stellar winds.[7]

References
  1. "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 24 January 2023.
  2. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  3. Samus', N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID 125853869.
  4. Penny, Laura R.; Epps, Jacob G.; Snyder, Joseph D. (December 2016). "Tomographic Separation of Composite Spectra. XII. The Physical Properties and Spectral Phase Variability of the Massive Close Binary HD 159176". The Astrophysical Journal. 832 (2): 211. Bibcode:2016ApJ...832..211P. doi:10.3847/0004-637X/832/2/211.
  5. Stickland, D. J.; Koch, R. H.; Pachoulakis, I.; Pfeiffer, R. J. (August 1993). "Spectroscopic binary orbits from ultraviolet radial velocities. Paper 12: HD 159176". The Observatory. 113: 204–209. Bibcode:1993Obs...113..204S.
  6. "HD 159176 -- Spectroscopic Binary". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2023-01-29.
  7. De Becker, M.; Rauw, G.; Pittard, J. M.; Antokhin, I. I.; Stevens, I. R.; Gosset, E.; Owocki, S. P. (March 2004). "An XMM-Newton observation of the massive binary HD 159176". Astronomy and Astrophysics. 416: 221–233. arXiv:astro-ph/0402663. Bibcode:2004A&A...416..221D. doi:10.1051/0004-6361:20031710.
  8. Trumpler, Robert J. (December 1930). "A New Double-Line Spectroscopic Binary". Publications of the Astronomical Society of the Pacific. 42 (250): 342–346. Bibcode:1930PASP...42..342T. doi:10.1086/124068.
  9. Conti, P. S.; Cowley, A. P.; Johnson, G. B. (April 1975). "The double-line spectroscopic binary HD 159176". Publications of the Astronomical Society of the Pacific. 87: 327–332. Bibcode:1975PASP...87..327C. doi:10.1086/129763.
  10. Thomas, J. C. (September 1975). "A Photometric Investigation of the Double-Lined O-Star Binary, HD 159176". Bulletin of the American Astronomical Society. 7: 533. Bibcode:1975BAAS....7..533T.
  11. Thomas, J. C.; Pachoulakis, I. (November 1994). "V and UV Photometry of HD 159176". Information Bulletin on Variable Stars. 4115 (1): 1. Bibcode:1994IBVS.4115....1T.
  12. Kazarovets, E. V.; Samus, N. N. (April 1997). "The 73rd Name-List of Variable Stars" (PDF). Information Bulletin on Variable Stars. 4471: 1. Bibcode:1997IBVS.4471....1K. Retrieved 29 January 2023.
  13. Pfeiffer, R. J.; Pachoulakis, I.; Koch, R. H.; Stickland, D. J. (October 1997). "The winds of hot close binaries. Paper 3: HD 159176". The Observatory. 117: 301–309. Bibcode:1997Obs...117..301P.
  14. "V1036 Sco". The International Variable Star Index. AAVSO. Retrieved 30 January 2023.
  15. Burssens, S.; Simón-Díaz, S.; Bowman, D. M.; Holgado, G.; Michielsen, M.; de Burgos, A.; Castro, N.; Barbá, R. H.; Aerts, C. (July 2020). "Variability of OB stars from TESS southern Sectors 1-13 and high-resolution IACOB and OWN spectroscopy". Astronomy and Astrophysics. 639: A81. arXiv:2005.09658. Bibcode:2020A&A...639A..81B. doi:10.1051/0004-6361/202037700.
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