HD 171978

Last updated
HD 171978
Observation data
Epoch J2000.0       Equinox J2000.0 (ICRS)
Constellation Serpens
Right ascension 18h 37m 35.9626s [1]
Declination −00° 18 34.100 [1]
Apparent magnitude  (V)6.33±0.10 (A) [2]
6.73±0.10 (B) [2]
5.74 to 5.86 (AB) [3]
Characteristics
Spectral type A0V [4]
U−B color index +0.06 [5]
B−V color index +0.067±0.010 [6]
R−I color index +0.04 [5]
Variable type suspected [3]
Astrometry
Radial velocity (Rv)+11.415±0.031 [2]  km/s
Proper motion (μ)RA: +14.018 [1]   mas/yr
Dec.: −20.710 [1]   mas/yr
Parallax (π)6.0774 ± 0.0833  mas [1]
Distance 537 ± 7  ly
(165 ± 2  pc)
Absolute magnitude  (MV)0.30±0.15 (A) [2]
0.70±0.15 (B) [2]
Orbit [2]
Period (P)14.684636±0.000029 d
Eccentricity (e)0.2495±0.0011
Periastron epoch (T)2,454,405.073±0.011
Argument of periastron (ω)
(secondary)
230.90±0.30°
Semi-amplitude (K1)
(primary)
37.918±0.050 km/s
Semi-amplitude (K2)
(secondary)
38.569±0.076 km/s
Details [2]
A
Mass 2.5  M
Radius 3.4±0.3  R
Luminosity 60.5±8.5  L
Rotational velocity (v sin i)5.6±1.0 km/s
B
Mass 2.35  M
Radius 2.8±0.2  R
Luminosity41.9±5.9  L
Rotational velocity (v sin i)5.9±1.0 km/s
Other designations
e Ser, NSV  11122, BD−00°3521, FK5  3480, GC  25456, HD  171978, HIP  91322, HR  6993, SAO  142444, PPM  180381 [7]
Database references
SIMBAD data

HD 171978 is a binary star system in the Serpens Cauda segment of the equatorial constellation of Serpens. It may be referred to by its Bright Star Catalogue identifier of HR 6993. This system is dimly visible to the naked eye with a combined apparent visual magnitude of 5.76, [6] although is a suspected variable star of unknown type with a magnitude that has been reported to vary between 5.74 and 5.86. [3] HD 171978 is located at a distance of approximately 537  light-years from the Sun based on parallax, [1] and is drifting further away with a barycentric radial velocity of +11.4 km/s. [2] It is a member of the Ursa Major Moving Group. [8]

The binary nature of this system was reported by Canadian astronomer R. M. Petrie in 1948. [9] It is a double-lined spectroscopic binary with an orbital period of 14.7 days and an eccentricity (ovalness) of 0.25. The orbital inclination is estimated to be ~30°. The two stars have a magnitude difference of 0.4±0.1 mag, which gives respective magnitudes of 6.33 and 6.73. They each show a sharp-lined spectra, indicating their rotation rates are not high. Both are similar A-type main-sequence stars [2] with a combined stellar classification of A0V. [4] In 1970, Geary and Abt noted that the secondary appeared to be an Am star. [8]

Related Research Articles

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<span class="mw-page-title-main">ET Andromedae</span> Star in the constellation Andromeda

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<span class="mw-page-title-main">DV Aquarii</span> Binary star in the constellation Aquarius

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<span class="mw-page-title-main">V923 Aquilae</span> Binary star system in the constellation Aquila

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<span class="mw-page-title-main">HR 4072</span> Star in the constellation Ursa Major

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<span class="mw-page-title-main">31 Cygni</span> Triple star system in the constellation Cygnus

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HD 2421 is a multiple star system in the constellation Andromeda. It is faintly visible to the naked eye with a combined apparent visual magnitude of 5.17. Based on parallax measurements, it is located at a distance of approximately 290 light years from the Sun. The system is drifting further away with a radial velocity of ~2 km/s.

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<span class="mw-page-title-main">HD 1</span> First star in the Henry Draper catalogue

HD 1, also known as HIP 422, is the first star catalogued in the Henry Draper Catalogue. It is located in the northern circumpolar constellation Cephus and has an apparent magnitude of 7.42, making it readily visible in binoculars, but not to the naked eye. The object is located relatively far away at a distance of 1,220 light years but is approaching the Solar System with a spectroscopic radial velocity of −27.3 km/s.

References

  1. 1 2 3 4 5 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.
  2. 1 2 3 4 5 6 7 8 9 Fekel, Francis C.; Tomkin, Jocelyn; Williamson, Michael H. (2013). "New Precision Orbits of Bright Double-lined Spectroscopic Binaries. VIII. HR 1528, HR 6993, 2 Sagittae, and 18 Vulpeculae". The Astronomical Journal. 146 (5). 129. Bibcode:2013AJ....146..129F. doi:10.1088/0004-6256/146/5/129. hdl: 2152/34407 . S2CID   121155872.
  3. 1 2 3 "NSV 11122, database entry". New Catalogue of Suspected Variable Stars, the improved version. Moscow, Russia: Sternberg Astronomical Institute. Retrieved October 3, 2008.
  4. 1 2 Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.
  5. 1 2 Hoffleit, D.; Warren, Jr., W. H. HR 6993, database entry . Retrieved October 3, 2008.{{cite book}}: |work= ignored (help) V/50.
  6. 1 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.
  7. "e Ser". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2015-12-07.
  8. 1 2 Geary, J. C.; Abt, H. A. (August 1970). "Rotational velocities in the Ursa Major group". Astronomical Journal. 75: 718–720. Bibcode:1970AJ.....75..718G. doi: 10.1086/111013 .
  9. Petrie, R. M. (July 1948). "The spectrographic orbits and dimensions of H. D. 171978". Publications of the Dominion Astrophysical Observatory Victoria. 7: 415–418. Bibcode:1948PDAO....7..415P.