Astronomy:Pi Andromedae

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Short description: Binary star system in the constellation Andromeda
Pi Andromedae
Location of π Andromedae (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Andromeda
Right ascension  00h 36m 52.85132s[1]
Declination +33° 43′ 09.6363″[1]
Apparent magnitude (V) 4.36[2] (4.9/5.3)[3]
Characteristics
Spectral type B5 V[4] (B5 V + B5 V[3])
U−B color index –0.55[2]
B−V color index –0.16[2]
Astrometry
Radial velocity (Rv)+8.7[5] km/s
Proper motion (μ) RA: 14.669(118)[1] mas/yr
Dec.: −3.385(93)[1] mas/yr
Parallax (π)5.6563 ± 0.1474[1] mas
Distance580 ± 20 ly
(177 ± 5 pc)
Orbit[6]
Period (P)143.53±0.06 d
Semi-major axis (a)6.69±0.05 mas
Eccentricity (e)0.542±0.006
Inclination (i)103.0±0.2°
Longitude of the node (Ω)94.7±0.2°
Periastron epoch (T)7717.7±0.4
Argument of periastron (ω)
(secondary)		170.7±0.7°
Semi-amplitude (K1)
(primary)		47.50±0.53 km/s
Semi-amplitude (K2)
(secondary)		117.4±2.8 km/s
Details[7]
A
Mass5.8[6] M☉
Radius4.7 R☉
Luminosity1,000 L☉
Surface gravity (log g)4.10[4] cgs
Temperature15,000 K
Metallicity [Fe/H]–0.20[4] dex
Rotational velocity (v sin i)25[8] km/s
Age80 Myr
B
Mass4.8[6] M☉
Radius4.7 R☉
Luminosity1,000 L☉
Temperature15,000 K
Other designations
Pi And, π Andromedae, π And, 29 Andromedae, BD+32°101, FK5 18, HD 3369, HIP 2912, HR 154, SAO 54033, PPM 65480, ADS 513
Database references
SIMBADdata

Pi Andromedae is a binary star[3] system in the northern constellation of Andromeda. Its Bayer designation is latinized from π Andromedae, and abbreviated Pi And or π And, respectively. With an apparent visual magnitude of 4.4,[2] it is visible to the naked eye. Based on parallax measurements, it is located at a distance of approximately 580 light-years (180 parsecs) from Earth.[1]

π Andromedae in optical light

The pair is classified as a blue-white B-type main sequence dwarf, with an apparent magnitude of +4.34. It is a spectroscopic binary with an orbital period of 143.5 days and an eccentricity of 0.54.[6]

The spectroscopic binary forms a triple system with BD+32 102, a magnitude 8.6 star located 35.9 arcseconds away.[3] At 55 arcseconds separation is an 11th magnitude companion that is just located on the same line of sight, but at a very different distance from us.

Naming

In Chinese, 奎宿 (Kuí Sù), meaning Legs (asterism), refers to an asterism consisting of π Andromedae, η Andromedae, 65 Piscium, ζ Andromedae, ε Andromedae, δ Andromedae, ν Andromedae, μ Andromedae, β Andromedae, σ Piscium, τ Piscium, 91 Piscium, υ Piscium, φ Piscium, χ Piscium and ψ¹ Piscium. Consequently, the Chinese name for π Andromedae itself is 奎宿六 (Kuí Sù liù, English: the Sixth Star of Legs.)[9]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 Johnson, H. L. et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory 4 (99): 99, Bibcode: 1966CoLPL...4...99J. 
  3. ↑ 3.0 3.1 3.2 3.3 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. doi:10.1111/j.1365-2966.2008.13596.x. Bibcode: 2008MNRAS.389..869E. 
  4. ↑ 4.0 4.1 4.2 Cenarro, A. J. et al. (January 2007), "Medium-resolution Isaac Newton Telescope library of empirical spectra - II. The stellar atmospheric parameters", Monthly Notices of the Royal Astronomical Society 374 (2): 664–690, doi:10.1111/j.1365-2966.2006.11196.x, Bibcode: 2007MNRAS.374..664C. 
  5. ↑ Wilson, Ralph Elmer (1953), "General Catalogue of Stellar Radial Velocities", Carnegie Institute Washington D.C. Publication (Washington: Carnegie Institution of Washington), Bibcode: 1953GCRV..C......0W. 
  6. ↑ 6.0 6.1 6.2 6.3 Hummel, C. A. et al. (July 1995). "Orbits of Small Angular Scale Binaries Resolved with the Mark III Interferometer". Astronomical Journal 110: 376. doi:10.1086/117528. Bibcode: 1995AJ....110..376H. 
  7. ↑ "Pi And". http://stars.astro.illinois.edu/sow/piand.html. 
  8. ↑ Abt, Helmut A.; Levato, Hugo; Grosso, Monica (July 2002), "Rotational Velocities of B Stars", The Astrophysical Journal 573 (1): 359–365, doi:10.1086/340590, Bibcode: 2002ApJ...573..359A. 
  9. ↑ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 19 日



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