HD 3

HD 3 is a single,[8] white-hued star in the northern constellation Andromeda. With an apparent visual magnitude of 6.71,[2] it is below the nominal brightness limit for visibility with the typical naked eye but may still be visible by some observers under ideal viewing conditions. Based upon an annual parallax shift of 5.89±0.35 mas,[1] it is located roughly 550 light years away. The star is moving closer with a heliocentric radial velocity of −18 km/s,[4] and will make perihelion in around 2.9 million years at a separation of around 351 ly (107.71 pc).[5]

HD 3
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension  00h 05m 09.7579s[1]
Declination +45° 13′ 44.509″[1]
Apparent magnitude (V) 6.71[2]
Characteristics
Evolutionary stage Main sequence[3]
Spectral type A1 Vn[3]
B−V color index 0.06[2]
Astrometry
Radial velocity (Rv)−18.0±4.4[4] km/s
Proper motion (μ) RA: −27.549[1] mas/yr
Dec.: −19.980[1] mas/yr
Parallax (π)5.89 ± 0.35[1] mas
Distance550 ± 30 ly
(170 ± 10 pc)
Absolute magnitude (MV)+1.02[5]
Details
Mass2.36±0.08[3] M☉
Radius1.9[6] R☉
Luminosity43.5+7.9
−6.7[3] L☉
Temperature9,057+169
−185[3] K
Rotational velocity (v sin i)228[3] km/s
Other designations
BD+44° 4550, FK5 4009, HD 3, HIP 424, HR 1, SAO 36042, WDS J00052+4514A[7]
Database references
SIMBADdata

The stellar classification of this star is A1 Vn,[3] indicating it is an A-type main-sequence star with "nebulous" lines due to rapid rotation. It is a Lambda Boötis candidate star, being classified as chemically-peculiar by Abt & Morrell (1995).[9] Murphy et al. (2015) list the membership likelihood as uncertain.[2] HD 3 has 2.36[3] times the mass of the Sun and about 1.9[6] times the Sun's radius. It is spinning with a projected rotational velocity of 228 km/s.[3] The star is radiating around 43.5[3] times the Sun's luminosity from its photosphere at an effective temperature of about 9,057 K.[3]

HD 3 has two visual companions. Component B is a magnitude 13.70 star at an angular separation of 16″ along a position angle (PA) of 107°, as of 2016. The third star, component C, is magnitude 10.58 and lies at a separation of 21″ along a PA of 235°, also as of 2016.[10]

References
  1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. Murphy, Simon J.; et al. (October 2015), "An Evaluation of the Membership Probability of 212 λ Boo Stars. I. A Catalogue", Publications of the Astronomical Society of Australia, 32: 43, arXiv:1508.03633, Bibcode:2015PASA...32...36M, doi:10.1017/pasa.2015.34, e036.
  3. Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691.
  4. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  5. 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.
  6. Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (Third ed.), 367 (2): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451.
  7. "HD 3". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-04-30.
  8. Abt, H. A. (March 1981), "Visual multiples. VII - MK classifications", Astrophysical Journal Supplement Series, 45: 437–456, Bibcode:1981ApJS...45..437A, doi:10.1086/190719.
  9. Gerbaldi, M.; et al. (December 2003), "The heterogeneous class of lambda Bootis stars", Astronomy and Astrophysics, 412: 447–464, Bibcode:2003A&A...412..447G, doi:10.1051/0004-6361:20031472.
  10. Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.

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