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[1]
Right ascension	16h 41m 20.41559s[2]
Declination	−48° 45′ 46.7305″[2]
Apparent magnitude (V)	5.54[3]
Characteristics
Spectral type	O3 V((f*)) - O3.5 V((f+)) + O5.5-6 V((f)) + O6.5-7 V((f))[4]
U−B color index	−0.76[3]
B−V color index	+0.20[3]
Astrometry
Radial velocity (Rv)	−27[5] km/s
Proper motion (μ)	RA: +2.514[2] mas/yr Dec.: −4.309[2] mas/yr
Parallax (π)	0.6934±0.0484 mas[2]
Distance	4,310 ± 390 ly (1,320 ± 120 pc)[6] ly
Absolute magnitude (MV)	−6.47 (−5.91 + −4.90 + −4.44)[4]
Orbit[6]
Primary	Primary
Companion	Secondary
Period (P)	2.67454 days
Semi-major axis (a)	38.2 R☉[4]
Eccentricity (e)	0
Inclination (i)	53[7]°
Semi-amplitude (K1) (primary)	208.3 km/s
Semi-amplitude (K2) (secondary)	334.5 km/s
Orbit[7]
Primary	Primary/Secondary
Companion	Tertiary
Period (P)	3069 d
Semi-major axis (a)	16.918" (20.9 AU[6])
Eccentricity (e)	0.6780
Inclination (i)	106.11°
Semi-amplitude (K1) (primary)	22.1 km/s
Semi-amplitude (K2) (secondary)	70.6 km/s
Details[4]
Primary
Mass	54[7] M☉
Radius	12.13 R☉
Luminosity	724,000 L☉
Surface gravity (log g)	4.00 cgs
Temperature	46,500 K
Rotational velocity (v sin i)	171 km/s
Secondary
Mass	34[7] M☉
Radius	9.54 R☉
Luminosity	209,000 L☉
Surface gravity (log g)	4.00 cgs
Temperature	40,000 K
Rotational velocity (v sin i)	136 km/s
Age	0-2 Myr
Tertiary
Mass	27.1[7] M☉
Radius	8.24 R☉
Luminosity	102,000 L☉
Surface gravity (log g)	3.50 cgs
Temperature	36,000 K
Rotational velocity (v sin i)	72 km/s
Age	1-3 Myr
Other designations
HD 150136, CD−48°11070, HIP  81702, HR 6187, SAO 227049, WDS J16413-4846
Database references
SIMBAD	data

System

Closeup of the NGC 6193 cluster, resolving HD 150136 and HD 150135

HD 150136 is listed in the Washington Double Star Catalog as having seven visual components within 30 arcseconds. 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 arcseconds. It is another O class spectroscopic binary and also a member of NGC 6193. The other catalogued components are all 10th to 12th magnitude, similar to many other stars known to be members of NGC 6193.^[8]

The primary star consists of a double-lined spectroscopic binary^[5] 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-arcseconds, corresponding to 11-12 AU.^[6]

Properties

All three (four, including HD 150135) of the brightest stars are massive luminous O class main sequence stars, 27 to 54 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.^[4]

See also

• List of most massive stars