HD 155448

HD 155448 is a quintuple star system consisting of 5 young B-type stars . With an apparent magnitude of 8.72,^[3] it is too dim to be visible with the naked eye.

HD 155448

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Scorpius[1]
Right ascension	17h 12m 58.7680s[2]
Declination	−32° 14′ 33.5690″[2]
Apparent magnitude (V)	8.72[3]
Characteristics
HD 155448 A
Evolutionary stage	Main sequence
Spectral type	B1 V
B−V color index	−0.27±0.02
HD 155448Ba
Evolutionary stage	main sequence star
Spectral type	B6V
B−V color index	−0.15±0.02[4]
HD 155448 Bb
Evolutionary stage	main sequence star
Spectral type	B9V[4]
B−V color index	−0.08±0.02[4]
HD 155448 C
Evolutionary stage	Main sequence
Spectral type	B4 Ve[4]
B−V color index	−0.19±0.02[4]
HD 155448 D
Evolutionary stage	Main sequence
Spectral type	B8 V[4]
B−V color index	−0.11±0.02[4]
Astrometry
A
Proper motion (μ)	RA: +2.551[5] mas/yr[5] Dec.: –1.666[5] mas/yr[5]
Parallax (π)	0.9566±0.0440 mas
Distance	3,400 ± 200 ly (1,050 ± 50 pc)
B
Proper motion (μ)	RA: +1.758[6] mas/yr[6] Dec.: −1.520[6] mas/yr[6]
Parallax (π)	0.8401±0.0384 mas
Distance	3,900 ± 200 ly (1,190 ± 50 pc)
D
Proper motion (μ)	RA: +2.491[7] mas/yr[7] Dec.: −1.567[7] mas/yr[7]
Parallax (π)	0.7837±0.0263 mas
Distance	4,200 ± 100 ly (1,280 ± 40 pc)
Details[4]
A
Mass	>7 M☉
Surface gravity (log g)	4 cgs
Temperature	25,000 K
Rotational velocity (v sin i)	90±5 km/s
Ba
Mass	5 M☉
Surface gravity (log g)	4 cgs
Temperature	14,000 K
Rotational velocity (v sin i)	150±50 km/s
Bb
Mass	3 M☉
Surface gravity (log g)	4 cgs
Temperature	10,000 K
Rotational velocity (v sin i)	150±50 km/s
C
Mass	6 M☉
Surface gravity (log g)	4 cgs
Temperature	16,000 K
Rotational velocity (v sin i)	50±10 km/s
D
Mass	3.5 M☉
Surface gravity (log g)	4 cgs
Temperature	12,000 K
Rotational velocity (v sin i)	300±15 km/s
Other designations
CD−32°12461, HD 155448, HIP 84228, SAO 208540, WDS J17130-3215
Database references
SIMBAD	data
	B
	C
	D

Parallax measurements from the Hipparcos spacecraft in 1997 give the system a distance of 1,976 light years with a margin of error larger than the parallax itself.^[2] The New Hipparcos Reduction gives a distance of 6,272 light years, but still with a statistical margin of error larger than the parallax value.^[8] Gaia parallaxes are available for the visible components. For component C, the Gaia Data Release 2 and Gaia Early Data Release 3 (EDR3) parallaxes are both negative and somewhat meaningless.^[9][7] For components A, B, and D, the Gaia EDR3 parallaxes are 0.9566±0.0440 mas,^[5] 0.8401±0.0384 mas,^[6] and 0.7837±0.0263 mas^[7] respectively, implying a distance around 4,000 light years.

Before 2011, this star was mistaken as either a Herbig Ae/Be star^[10] or a post-AGB object.^[11] When the system was studied in 2011, it was originally believed to contain only 4 stars (or at least more than 2 stars). In 2011, a study conducted at the European Southern Observatory in Chile concluded that the "B" star is actually a binary star, thus reclassifying it as a quintuple star system.^[4] HD 155448 A, B, C, and D. Periods have been estimated at 27,000 years for Bab, 59,000 years for AB, 111,000 years for Ac, and 327,000 years for AD.^[12] However, analysis in 2011 states that the stars are not gravitationally bound to each other.^[4]

All of the stars are currently on the ZAMS. At present the primary star has a mass greater than 7 solar masses and an effective temperature of 25,000 K, while the companions have masses ranging from 3-6 times the mass of the Sun, and temperatures ranging from 10,000-16,000 K.