HD 155448 is a quintuple star system consisting of 5 young B-type stars . With an apparent magnitude of 8.72,[2] it is too dim to be visible with the naked eye.
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
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Constellation | Scorpius |
Right ascension | 17h 12m 58.7680s[1] |
Declination | −32° 14′ 33.5690″[1] |
Apparent magnitude (V) | 8.72[2] |
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[3] |
HD 155448 Bb | |
Evolutionary stage | main sequence star |
Spectral type | B9V[3] |
B−V color index | −0.08±0.02[3] |
HD 155448 C | |
Evolutionary stage | Main sequence |
Spectral type | B4 Ve[3] |
B−V color index | −0.19±0.02[3] |
HD 155448 D | |
Evolutionary stage | Main sequence |
Spectral type | B8 V[3] |
B−V color index | −0.11±0.02[3] |
Astrometry | |
A | |
Proper motion (μ) | RA: +2.551[4] mas/yr[4] Dec.: –1.666[4] mas/yr[4] |
Parallax (π) | 0.9566 ± 0.0440 mas |
Distance | 3,400 ± 200 ly (1,050 ± 50 pc) |
B | |
Proper motion (μ) | RA: +1.758[5] mas/yr[5] Dec.: –1.520[5] mas/yr[5] |
Parallax (π) | 0.8401 ± 0.0384 mas |
Distance | 3,900 ± 200 ly (1,190 ± 50 pc) |
D | |
Proper motion (μ) | RA: +2.491[6] mas/yr[6] Dec.: –1.567[6] mas/yr[6] |
Parallax (π) | 0.7837 ± 0.0263 mas |
Distance | 4,200 ± 100 ly (1,280 ± 40 pc) |
Details[3] | |
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 | |
Database references | |
SIMBAD | data |
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.[1] 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.[7] 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.[8][6] For components A, B, and D, the Gaia EDR3 parallaxes are 0.9566±0.0440 mas,[4] 0.8401±0.0384 mas,[5] and 0.7837±0.0263 mas[6] respectively, implying a distance around 4,000 light years.
Before 2011, this star was mistaken as either a Herbig Ae/Be star[9] or a post-AGB object.[10] 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.[3] 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.[11] However, analysis in 2011 states that the stars aren't gravitationally bound to each other.[3]
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.
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