Astronomy:HR 178

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Short description: Likely binary star in the constellation Andromeda
HD 3883
Observation data
Equinox J2000.0]] (ICRS)
Constellation Andromeda
Right ascension  00h 41m 36.0370s[1]
Declination +24° 37′ 44.43″[1]
Apparent magnitude (V) 6.046[2]
Characteristics
Spectral type kA5hF1mF2[3]
B−V color index 0.287[2]
Variable type suspected[4]
Astrometry
Radial velocity (Rv)−15.60±0.9[5] km/s
Proper motion (μ) RA: 106.272±0.499[1] mas/yr
Dec.: −12.324±0.306[1] mas/yr
Parallax (π)8.0963 ± 0.2630[1] mas
Distance400 ± 10 ly
(124 ± 4 pc)
Orbit[6]
Period (P)21.26 yr
Semi-major axis (a)0.126″
Eccentricity (e)0.5
Details
Mass2.44[7] M☉
Radius3.82[1] R☉
Luminosity45[1] L☉
Surface gravity (log g)3.80±0.14[8] cgs
Temperature7800±200[8] K
Metallicity [Fe/H]0.53±0.13[8] dex
Rotational velocity (v sin i)18[3] km/s
Other designations
HIP 3269, HD 3883, BD+23°94, SAO 74200.
Database references
SIMBADdata

HR 178 is a probable binary star in the constellation Andromeda. Located approximately 124 parsecs (400 ly) distant, it is an evolved Am star[9] with a combined apparent magnitude of 6.06, meaning that it can only be seen with the naked eye on dark, clear nights. The star is suspected of variability, possibly varying between magnitudes 6.04 and 6.06.[4] The variable magnitude period of HD 3883 is about 9.17 min.[10]

The spectrum of HR 178 has been extensively studied for establishing element abundances in the evolved Am stars. It is given a spectral class of kA5hF1mF2, meaning its spectral type is A5, F1, or F2, depending on the particular spectral lines examined. The evolutionary stage of the star, and its mass determined from comparison with theoretical evolutionary tracks, is not precisely determined. However, it is very close to the end of its main sequence evolution and the margin of error in its mass is only about 0.1 M☉.[9]

HR 178 has been suspected of being a binary star since 1938 when its spectrum was interpreted as being composite.[11] The pair were resolved using speckle interferometry in 1983.[12] The companion is modelled to be between 1.5 and 3 magnitudes fainter than the primary star.[13] Although there have since been several failed attempts to resolve the pair, a tentative orbit has been calculated with a period of 21.26 years and an eccentricity of 0.5.[6]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  2. ↑ 2.0 2.1 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (2000), "The Tycho-2 catalogue of the 2.5 million brightest stars", Astronomy & Astrophysics 355: L27–L30, Bibcode: 2000A&A...355L..27H. 
  3. ↑ 3.0 3.1 Abt, Helmut A.; Morrell, Nidia I. (1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". The Astrophysical Journal Supplement Series 99: 135. doi:10.1086/192182. Bibcode: 1995ApJS...99..135A. 
  4. ↑ 4.0 4.1 VSX (18 January 2010). "NSV 258". AAVSO Website. American Association of Variable Star Observers. http://www.aavso.org/vsx/index.php?view=detail.top&oid=38882. 
  5. ↑ Gontcharov, G. A. (2006), "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system", Astronomy Letters 32 (11): 759–771, doi:10.1134/S1063773706110065, Bibcode: 2006AstL...32..759G. 
  6. ↑ 6.0 6.1 Malkov, O. Yu.; Tamazian, V. S.; Docobo, J. A.; Chulkov, D. A. (2012). "Dynamical masses of a selected sample of orbital binaries". Astronomy & Astrophysics 546: 5. doi:10.1051/0004-6361/201219774. Bibcode: 2012A&A...546A..69M. 
  7. ↑ Hui-Bon-Hoa, A. (June 2000). "Metal abundances of field A and Am stars". Astronomy and Astrophysics Supplement Series 144 (2): 203–209. doi:10.1051/aas:2000207. ISSN 0365-0138. Bibcode: 2000A&AS..144..203H. http://aas.aanda.org/10.1051/aas:2000207. 
  8. ↑ 8.0 8.1 8.2 Soubiran, Caroline et al. (2016), "The PASTEL catalogue: 2016 version", Astronomy & Astrophysics 591: A118, doi:10.1051/0004-6361/201628497, Bibcode: 2016A&A...591A.118S. 
  9. ↑ 9.0 9.1 Burkhart, C.; Coupry, M. F.; Faraggiana, R.; Gerbaldi, M. (2005). "The field Am and ρ Puppis-like stars: Lithium and heavier elements". Astronomy and Astrophysics 429 (3): 1043. doi:10.1051/0004-6361:20040467. Bibcode: 2005A&A...429.1043B. 
  10. ↑ Chagnon, François (2009). Searching for northern roap stars: the UBC-OAN photometric survey. University of British Columbia (Thesis). doi:10.14288/1.0099308. S2CID 124888408.
  11. ↑ Hynek, J. A. (1938). "A survey of stars with composite spectra". Contributions of Perkins Observatory 1: 10. Bibcode: 1938CoPer...1...10H. 
  12. ↑ McAlister, H. A.; Hendry, E. M.; Hartkopf, W. I.; Campbell, B. G.; Fekel, F. C. (1983). "Speckle interferometric measurements of binary stars. VIII". The Astrophysical Journal Supplement Series 51: 309. doi:10.1086/190851. Bibcode: 1983ApJS...51..309M. 
  13. ↑ Bonneau, D.; Carquillat, J. M.; Vidal, J. L. (1984). "Observations d'etoiles doubles par interferometrie des tavelures AU T2m du PIC du Midi". Astronomy and Astrophysics Supplement Series 58: 729. Bibcode: 1984A&AS...58..729B. 



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