Delta Andromedae

Delta Andromedae (δ And, δ Andromedae) is a multiple star system in the northern constellation of Andromeda. Based upon parallax measurements, it is located at a distance of approximately 105.5 light-years (32.3 parsecs) from the Earth.

δ Andromedae
Location of δ Andromedae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Andromeda
Right ascension  00h 39m 19.67518s[1]
Declination +30° 51′ 39.6783″[1]
Apparent magnitude (V) 3.28[2]
Characteristics
Spectral type K3 III[3]
U−B color index +1.48[2]
B−V color index +1.28[2]
R−I color index +0.66[4]
Astrometry
Radial velocity (Rv)−7.3 ± 0.9[5] km/s
Proper motion (μ) RA: +114.45[1] mas/yr
Dec.: −84.02[1] mas/yr
Parallax (π)30.91 ± 0.15[1] mas
Distance105.5 ± 0.5 ly
(32.4 ± 0.2 pc)
Absolute magnitude (MV)+0.8[6]
Orbit[7]
Period (P)15,000 d
Eccentricity (e)0.34 ± 0.14
Periastron epoch (T)2415568 JD
Argument of periastron (ω)
(primary)		356.1 ± 5.2°
Semi-amplitude (K1)
(primary)		4.0 ± 2.7 km/s
Details
δ And A
Mass~1.3[8] M☉
Radius13.6 ± 0.3[9] R☉
Luminosity68 ± 4[9] L☉
Surface gravity (log g)2.0 ± 0.3[3] cgs
Temperature4,315[10] K
Metallicity [Fe/H]0.04[10] dex
Rotational velocity (v sin i)6.5[10] km/s
Age3.2[11] Gyr
Other designations
δ And, Delta Andromedae, Delta And, 31 Andromedae, 31 And, BD+30 91, FK5 20, HD 3627, HIP 3092, HR 165, NSV 15142, SAO 54058, USNO 790, WDS 00393+3052A.[5][12]
Database references
SIMBADdata

In Chinese, 奎宿 (Kuí Sù), meaning Legs (asterism), refers to an asterism consisting of δ Andromedae, η Andromedae, 65 Piscium, ζ Andromedae, ι Piscium, ε Andromedae, π 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 δ Andromedae itself is 奎宿五 (Kuí Sù wǔ, English: the Fifth Star of Legs.)[13] Apart from its Bayer designation, it was also given the title Delta by Elijah H. Burritt in his star atlas.[14]

This is a long-period spectroscopic binary with an orbital period of approximately 15,000 days (41 years) and an overall apparent visual magnitude of approximately 3.28. The primary of the spectroscopic binary has a stellar classification of K3 III, indicating that it is a giant star.[5][7] It most likely evolved from a F-type main sequence star after consuming the hydrogen at its core.[11] The secondary is a relatively faint K-type dwarf, which has been imaged using a stellar coronagraph.[15] The star has two optical companions, the closest of which may be an orbiting red dwarf of class M3 with a separation of at least 900 astronomical units.[16]

An excess of infrared emission from δ Andromedae suggested that it may be surrounded by a shell of dust.[3] In 2003 it was determined that this is more likely a circumstellar debris disk.[11]

References
  1. van Leeuwen, F. (November 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. Johnson, H. L.; et al. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory. 4 (99). Bibcode:1966CoLPL...4...99J.
  3. Judge, P. G.; Jordan, C.; Rowan-Robinson, M. (January 1, 1987), "Delta Andromedae (K3 III) - an IRAS source with an unusual ultraviolet spectrum", Monthly Notices of the Royal Astronomical Society, 224: 93–106, Bibcode:1987MNRAS.224...93J, doi:10.1093/mnras/224.1.93.
  4. Hoffleit, D.; Warren Jr., W. H., "HR 165, database entry", The Bright Star Catalogue (5th (Preliminary Version) ed.), CDS ID V/50. Accessed on line August 28, 2008.
  5. "del And". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved August 28, 2008.
  6. Ryon, Jenna; et al. (August 2009), "Comparing the Ca ii H and K Emission Lines in Red Giant Stars", Publications of the Astronomical Society of the Pacific, 121 (882): 842, arXiv:0907.3346, Bibcode:2009PASP..121..842R, doi:10.1086/605456.
  7. Bakos, Gustav A. (February 1976), "The spectroscopic orbit of δ Andromedae", Journal of the Royal Astronomical Society of Canada, 70: 23–26, Bibcode:1976JRASC..70...23B.
  8. Gontcharov, G.A.; Kiyaeva, O. V. (2002), "Photocentric orbits from a direct combination of ground-based astrometry with Hipparcos I. Comparison with known orbits", Astronomy and Astrophysics, 391, 647-657, Bibcode:2002A&A...391..647G, doi:10.1051/0004-6361:20020896.
  9. Piau, L.; et al. (February 2011), "Surface convection and red-giant radius measurements", Astronomy and Astrophysics, 526: A100, arXiv:1010.3649, Bibcode:2011A&A...526A.100P, doi:10.1051/0004-6361/201014442
  10. Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209
  11. Decin, G.; et al. (November 2003), "Age Dependence of the Vega Phenomenon: Observations", The Astrophysical Journal, 598 (1): 636–644, arXiv:astro-ph/0308294, Bibcode:2003ApJ...598..636D, doi:10.1086/378800
  12. "Entry 00393+3052", The Washington Double Star Catalog, United States Naval Observatory, archived from the original on 2008-04-12, retrieved 2008-08-28
  13. (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 19 日
  14. Richard Hinckley Allen (1899) Star-names and Their Meanings, p. 38.
  15. Bottom, M.; et al. (August 4, 2015), "Resolving the Delta Andromedae Spectroscopic Binary with Direct Imaging", The Astrophysical Journal, 809 (1), arXiv:1506.07517, Bibcode:2015ApJ...809...11B, doi:10.1088/0004-637X/809/1/11.
  16. Kaler, James B., "DELTA AND (Delta Andromedae)", Stars, University of Illinois, retrieved 2012-01-23
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