HD 172044

HD 172044 is a triple star[11] system in the northern constellation of Lyra. It has a blue-white hue and is visible to the naked eye with an apparent visual magnitude of 5.41.[2] The distance to the primary component is approximately 535 light years based on parallax.[1] It is drifting closer with a radial velocity of −32.5 km/s, and is predicted to come as near as 77.3 light-years to the Sun some 4.5 million years from now.[2]

HD 172044
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Lyra
Right ascension 18h 36m 37.34437s[1]
Declination 33° 28′ 08.5352″[1]
Apparent magnitude (V) 5.41[2] + 10.7[3]
Characteristics
Spectral type B8IIpHgMn[4]
U−B color index −0.509[2]
B−V color index −0.101±0.003[2]
Astrometry
A
Radial velocity (Rv)−32.5±0.8[5] km/s
Proper motion (μ) RA: −7.966[1] mas/yr
Dec.: +0.690[1] mas/yr
Parallax (π)6.0990 ± 0.0893[1] mas
Distance535 ± 8 ly
(164 ± 2 pc)
Absolute magnitude (MV)−0.53[2]
B
Proper motion (μ) RA: −7.403[6] mas/yr
Dec.: +0.479[6] mas/yr
Parallax (π)6.2391 ± 0.0221[6] mas
Distance523 ± 2 ly
(160.3 ± 0.6 pc)
Orbit[7]
Period (P)1675 d
Semi-major axis (a)≥71.6×108 km
Eccentricity (e)0.16
Periastron epoch (T)2,420,438.5 JD
Argument of periastron (ω)
(secondary)		120°
Semi-amplitude (K1)
(primary)		3.2 km/s
Details
A
Mass3.65±0.50[8] M☉
Luminosity262.17[2] L☉
Surface gravity (log g)3.90[9] cgs
Temperature14,500[9] K
Metallicity [Fe/H]−0.25[2] dex
Rotational velocity (v sin i)34[9] km/s
Other designations
BD+33°3154, GC 25443, HD 172044, HIP 91235, HR 6997, SAO 67164, CCDM J18366+3328, WDS J18366+3328, GSC 02641-02396[10]
Database references
SIMBADdata

The dual nature of the primary star, component A, was announced in 1973 by H. A. Abt and M. A. Snowden. It is a single-lined spectroscopic binary with a preliminary orbital period of 4.59 years and an eccentricity (ovalness) of 0.16.[7] The visible component is a B-type bright giant with a stellar classification of B8IIpHgMn,[4] where the suffix notation indicates it is a chemically peculiar mercury-manganese star.[9]

Component B is a magnitude 9.40 companion of an unknown spectral type.[12] It was first reported by F. G. W. Struve in 1830. As of 2016, it has an angular separation of 7.2 arcseconds along a position angle of 204° from the brighter component.[3]

References
  1. 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.
  2. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  3. Mason, B. D.; et al. (2014). "The Washington Visual Double Star Catalog". The Astronomical Journal. 122: 3466–3471. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
  4. Osawa, Kiyoteru (1959). "Spectral Classification of 533 B8-A2 Stars and the Mean Absolute Magnitude of A0 V Stars". Astrophysical Journal. 130: 159. Bibcode:1959ApJ...130..159O. doi:10.1086/146706.
  5. Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
  6. 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.
  7. Abt, Helmut A.; Snowden, Michael S. (February 1973). "The Binary Frequency for AP Stars". Astrophysical Journal Supplement. 25: 137. Bibcode:1973ApJS...25..137A. doi:10.1086/190265.
  8. Hohle, M. M.; et al. (April 2010). "Masses and luminosities of O- and B-type stars and red supergiants". Astronomische Nachrichten. 331 (4): 349. arXiv:1003.2335. Bibcode:2010AN....331..349H. doi:10.1002/asna.200911355. S2CID 111387483.
  9. Ghazaryan, S.; et al. (2018). "New catalogue of chemically peculiar stars, and statistical analysis". Monthly Notices of the Royal Astronomical Society. 480 (3): 2953–2962. arXiv:1807.06902. Bibcode:2018MNRAS.480.2953G. doi:10.1093/mnras/sty1912. S2CID 119062018.
  10. "HD 172044". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-01-25.
  11. Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x.
  12. "HD 172044B". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-01-25.
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