HD 150136

HD 150136 is a multiple star system in the southern constellation of Ara, around 4,300 light years away. It is the brightest member of the faint open cluster NGC 6193, part of the Ara OB1 association.

HD 150136
Location of HD 150136 (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ara
Right ascension 16h 41m 20.42426s[1]
Declination −48° 45′ 46.7490″[1]
Apparent magnitude (V) 5.54[2]
Characteristics
Spectral type O3 V((f*)) - O3.5 V((f+)) + O5.5-6 V((f)) + O6.5-7 V((f))[3]
U−B color index −0.76[2]
B−V color index +0.20[2]
Astrometry
Radial velocity (Rv)−27[4] km/s
Proper motion (μ) RA: +9.73[1] mas/yr
Dec.: −7.31[1] mas/yr
Parallax (π)−3.11 ± 2.94[1] mas
Distance4,310 ± 390 ly (1,320 ± 120 pc)[5] ly
Absolute magnitude (MV)−6.47 (−5.91 + −4.90 + −4.44)[3]
Orbit[5]
PrimaryPrimary
CompanionSecondary
Period (P)2.67454 days
Semi-major axis (a)38.2 R☉[3]
Eccentricity (e)0
Inclination (i)49.6°
Semi-amplitude (K1)
(primary)		208.3 km/s
Semi-amplitude (K2)
(secondary)		334.5 km/s
Orbit[5]
PrimaryPrimary/Secondary
CompanionTertiary
Period (P)3,008 days
Semi-major axis (a)20.9 AU
Eccentricity (e)0.73
Inclination (i)107.9°
Semi-amplitude (K1)
(primary)		25.8 km/s
Semi-amplitude (K2)
(secondary)		79.8 km/s
Details[3]
Primary
Mass63[5] M☉
Radius12.13 R☉
Luminosity724,000 L☉
Surface gravity (log g)4.00 cgs
Temperature46,500 K
Rotational velocity (v sin i)171 km/s
Secondary
Mass40[5] M☉
Radius9.54 R☉
Luminosity209,000 L☉
Surface gravity (log g)4.00 cgs
Temperature40,000 K
Rotational velocity (v sin i)136 km/s
Age0-2 Myr
Tertiary
Mass33[5] M☉
Radius8.24 R☉
Luminosity102,000 L☉
Surface gravity (log g)3.50 cgs
Temperature36,000 K
Rotational velocity (v sin i)72 km/s
Age1-3 Myr
Other designations
HD 150136, CD−48°11070, HIP  81702, HR 6187, SAO 227049, WDS J16413-4846
Database references
SIMBADdata

System

HD 150136 is listed in the Washington Double Star Catalog as having seven visual components within 30 arc seconds. Component A is a close triple system containing three massive class O main sequence stars. The brightest companion is catalogued individually as HD 150135 as well as component C of the multiple system, separated by only 10 arc-seconds. It is another O class spectroscopic binary and also a member of NGC 5193. The other stars are all 10th to 12th magnitude, similar to many other stars known to be members of NGC 6193.[6]

The primary star consists of a double-lined spectroscopic binary[4] with a more distant tertiary companion. The third star is orbiting the other two with a period of 8.2 years, an eccentricity of 0.73, and an inclination of 108°. The close binary stars are separated by hardly more than their own diameters and orbit in less than 3 days, but the third is separated enough to have been resolved visually by VLTI. The measured separation in 2012 was 9 milli arc seconds, corresponding to 11-12 AU.[5]

Properties

All three (four, including HD 150135) of the brightest stars are massive luminous O class main sequence stars, 33-63 times as massive as the sun. They are around 10 times the size of the sun, but 6-8 times hotter and each is over 100,000 times as luminous. The primary star is the closest O3 star to Earth, 46,500 K, visually 18,000 times as bright as the sun, but because of its high temperature it is around three quarters of a million times more luminous including all wavelengths.[3]

References
  1. 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.
  2. Schild, R. E.; et al. (April 1983). "UBV photometry for southern OB stars". Astrophysical Journal Supplement Series. 51: 321–336. Bibcode:1983ApJS...51..321S. doi:10.1086/190852.
  3. Mahy, L.; Gosset, E.; Sana, H.; Damerdji, Y.; De Becker, M.; Rauw, G.; Nitschelm, C. (2012). "Evidence for a physically bound third component in HD 150136". Astronomy & Astrophysics. 540: A97. arXiv:1202.6215. Bibcode:2012A&A...540A..97M. doi:10.1051/0004-6361/201118199. S2CID 53517114.
  4. Pourbaix, D.; et al. (2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy & Astrophysics. 424 (2): 727–732. arXiv:astro-ph/0406573. Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213. S2CID 119387088.
  5. Sana, H.; et al. (May 2013). "Three-dimensional orbits of the triple-O stellar system HD 150136". Astronomy & Astrophysics. 553: 5. arXiv:1304.3457. Bibcode:2013A&A...553A.131S. doi:10.1051/0004-6361/201321189. S2CID 41993530. A131.
  6. Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466–3471. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
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