Sigma Andromedae

Sigma Andromedae, Latinized from σ Andromedae, is the Bayer designation for a single[10] star in the northern constellation of Andromeda. It has an apparent visual magnitude of +4.5,[2] which is bright enough to be seen with the naked eye from most locations. Parallax measurements made during the Gaia mission place it at a distance of about 140 light-years (43 parsecs).[1] The magnitude of the star is diminished by 0.08 from extinction caused by intervening gas and dust.[11] It is drifting closer to the Sun with a radial velocity of –8 km/s.[2]

Sigma Andromedae
Location of σ Andromedae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Andromeda
Right ascension 00h 18m 19.65737s[1]
Declination +36° 47′ 06.8085″[1]
Apparent magnitude (V) +4.51[2]
Characteristics
Evolutionary stage main sequence[3]
Spectral type A2 V[4]
U−B color index +0.07[5]
B−V color index +0.05[5]
Astrometry
Radial velocity (Rv)–8.0[2] km/s
Proper motion (μ) RA: −65.212(153)[1] mas/yr
Dec.: −42.221(124)[1] mas/yr
Parallax (π)23.2542 ± 0.1809 mas[1]
Distance140 ± 1 ly
(43.0 ± 0.3 pc)
Absolute magnitude (MV)1.33[6]
Details
Mass2.12±0.01[3] M☉
Radius2.13[7] R☉
Luminosity21.23[7] L☉
Surface gravity (log g)4.02[6] cgs
Temperature8,929[6] K
Rotational velocity (v sin i)123[8] km/s
Age450[7] Myr
Other designations
σ And, 25 Andromedae, BD+35°44, FK5 1005, HD 1404, HIP 1473, HR 68, SAO 53798[9]
Database references
SIMBADdata

This star has a stellar classification of A2 V,[4] which matches the spectrum of an A-type main sequence star. It is about 450 million years old[12] and is spinning rapidly with a projected rotational velocity of 123 km/s.[8] The star has 2.12[3] times the mass of the Sun and 2.13[7] times the Sun's girth. It is radiating 21[7] times the luminosity of the Sun from its photosphere at an effective temperature of 8,929 K,[6] giving it the white-hued glow of an A-type star.[13]

In the past, radial velocity variations have been reported,[14] but this remains unconfirmed.[10] The star does not show any significant photometric variations and is used as an ubvy standard star.[15] A debris disk of warm dust around this star has been detected by Spitzer Space Telescope.[16][17] A model fit to the data yields an orbital distance of 20.3 AU from the host star with a mean temperature of 132.9 K.[7]

Sigma Andromedae is a candidate for membership in the stream of stars associated with the Ursa Major Moving Group. This is a set of stars that share a common motion through space, which suggests they originated together.[6]

Naming

In Chinese, 天廄 (Tiān Jiù), meaning Celestial Stable, refers to an asterism consisting of σ Andromedae, θ Andromedae and ρ Andromedae. Consequently, the Chinese name for σ Andromedae itself is 天廄三 (Tiān Jiù sān, English: the Third Star of Celestial Stable.)[18]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  2. Wielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veroeffentlichungen des Astronomischen Rechen-Instituts Heidelberg, Astronomisches Rechen-Institut Heidelberg, 35 (35): 1, Bibcode:1999VeARI..35....1W.
  3. Zorec, J.; Royer, F. (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, S2CID 55586789.
  4. Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819.
  5. 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.
  6. King, Jeremy R.; et al. (April 2003), "Stellar Kinematic Groups. II. A Reexamination of the Membership, Activity, and Age of the Ursa Major Group", The Astronomical Journal, 125 (4): 1980–2017, Bibcode:2003AJ....125.1980K, doi:10.1086/368241.
  7. Gáspár, András; et al. (August 2016), "The Correlation between Metallicity and Debris Disk Mass", The Astrophysical Journal, 826 (2): 14, arXiv:1604.07403, Bibcode:2016ApJ...826..171G, doi:10.3847/0004-637X/826/2/171, S2CID 119241004, 171.
  8. Royer, F.; Zorec, J.; Gómez, A. E. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224, S2CID 18475298.
  9. "sig And". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-06-24.{{cite web}}: CS1 maint: postscript (link)
  10. Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  11. van Belle, G. T.; et al. (May 2008), "The Palomar Testbed Interferometer Calibrator Catalog", The Astrophysical Journal Supplement Series, 176 (1): 276–292, arXiv:0711.4194, Bibcode:2008ApJS..176..276V, doi:10.1086/526548, S2CID 10713221.
  12. Vican, Laura (June 2012), "Age Determination for 346 Nearby Stars in the Herschel DEBRIS Survey", The Astronomical Journal, 143 (6): 135, arXiv:1203.1966, Bibcode:2012AJ....143..135V, doi:10.1088/0004-6256/143/6/135, S2CID 118539505.
  13. "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on 2013-12-03, retrieved 2012-06-24.
  14. Lee, O. J. (November 1910), "Measures on nineteen new spectroscopic binaries", Astrophysical Journal, 32: 300–308, Bibcode:1910ApJ....32..300L, doi:10.1086/141806.
  15. Lehmann, H.; et al. (August 1995), "Variability investigations of possible Maia stars", Astronomy and Astrophysics, 300: 783, Bibcode:1995A&A...300..783L
  16. Morales, F.Y.; et al. (July 2009), "Spitzer Mid-IR Spectra of Dust Debris Around A and Late B Type Stars: Asteroid Belt Analogs and Power-Law Dust Distributions" (PDF), The Astrophysical Journal, 699 (2): 1067–1086, Bibcode:2009ApJ...699.1067M, doi:10.1088/0004-637X/699/2/1067, S2CID 45235873
  17. Patel, Rahul I.; et al. (2014), "A Sensitive Identification of Warm Debris Disks in the Solar Neighborhood Through Precise Calibration of Saturated Wise Photometry", The Astrophysical Journal Supplement Series, 212 (1): 10, arXiv:1403.3435, Bibcode:2014ApJS..212...10P, doi:10.1088/0067-0049/212/1/10, S2CID 119219094.
  18. (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 18 日
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