HD 155448

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.

HD 155448

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
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
CD–32°12461, HD 155448, HIP 84228, SAO 208540, WDS J17130-3215
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.

References

1. Perryman, M. A. C.; Lindegren, L.; Kovalevsky, J.; Hoeg, E.; Bastian, U.; Bernacca, P. L.; Crézé, M.; Donati, F.; Grenon, M.; Grewing, M.; van Leeuwen, F. (1997-07-01). "The HIPPARCOS Catalogue". Astronomy and Astrophysics. 323: L49–L52. Bibcode:1997A&A...323L..49P. ISSN 0004-6361.
2. "HD 155448". sim-basic. Retrieved 21 March 2021.
3. Schütz, O.; Meeus, G.; Carmona, A.; Juhász, A.; Sterzik, M. F. (2011-09-01). "The young B-star quintuple system HD 155448". Astronomy and Astrophysics. 533: A54. arXiv:1108.1557. Bibcode:2011A&A...533A..54S. doi:10.1051/0004-6361/201016396. ISSN 0004-6361.
4. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
5. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
6. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
7. van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy & Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. ISSN 1432-0746.
8. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
9. Vioque, M.; Oudmaijer, R. D.; Baines, D.; Mendigutía, I.; Pérez-Martínez, R. (December 2018). "Gaia DR2 study of Herbig Ae/Be stars". Astronomy & Astrophysics. 620: A128. arXiv:1808.00476. Bibcode:2018A&A...620A.128V. doi:10.1051/0004-6361/201832870. ISSN 1432-0746.
10. Luna, R.; Cox, N. L. J.; Satorre, M. A.; García Hernández, D. A.; Suárez, O.; García Lario, P. (March 2008). "A search for diffuse bands in the circumstellar envelopes of post-AGB stars". Astronomy & Astrophysics. 480 (1): 133–148. arXiv:0711.1843. Bibcode:2008A&A...480..133L. doi:10.1051/0004-6361:20065282. ISSN 1432-0746.
11. Tokovinin, Andrei (2018-03-01). "The Updated Multiple Star Catalog". The Astrophysical Journal Supplement Series. 235 (1): 6. arXiv:1712.04750. Bibcode:2018ApJS..235....6T. doi:10.3847/1538-4365/aaa1a5. ISSN 0067-0049. S2CID 119047709.