Astronomy:Theta Andromedae

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Short description: Binary star in the constellation Andromeda
Theta Andromedae
Andromeda IAU.svg
Red circle.svg
Location of θ Andromedae (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Andromeda
Right ascension  00h 17m 05.50236s[1]
Declination +38° 40′ 53.8886″[1]
Apparent magnitude (V) 4.61[2]
Characteristics
Evolutionary stage main sequence[3]
Spectral type A2 V[4]
U−B color index +0.05[2]
B−V color index +0.06[2]
Variable type Constant[5]
Astrometry
Radial velocity (Rv)0.9[6] km/s
Proper motion (μ) RA: −57.551(307)[1] mas/yr
Dec.: −14.795(155)[1] mas/yr
Parallax (π)18.8747 ± 0.4251[1] mas
Distance173 ± 4 ly
(53 ± 1 pc)
Absolute magnitude (MV)−0.25[7]
Orbit[8]
Period (P)1033+91
−77
 days
Semi-major axis (a)25+32
−13
 mas
Eccentricity (e)0.95+0.04
−0.40
Inclination (i)69+8
−22
°
Longitude of the node (Ω)263+50
−156
°
Periastron epoch (T)238+343
−143
Argument of periastron (ω)
(secondary)
89+175
−29
°
Details
A
Mass2.83±0.08[3] M
Luminosity113[7] L
Surface gravity (log g)3.95[9] cgs
Temperature8,960[9] K
Metallicity [Fe/H]+0.14[9] dex
Rotational velocity (v sin i)102[3] km/s
Other designations
θ And, 24 Andromedae, BD+37°34, HD 1280, HIP 1366, HR 63, SAO 53777, PPM 65154[10]
Database references
SIMBADdata

Theta Andromedae is a binary star[11] system in the northern constellation of Andromeda. Theta Andromedae, Latinized from θ Andromedae, is its Bayer designation. It is located at a distance of approximately 173 light-years (53 parsecs) from the Sun,[1] and has an apparent visual magnitude of 4.6.[2] On the Bortle Dark-Sky Scale, this makes it visible to the naked eye from outside urban regions. Based on its motion through space, this system appears to be a member of the Sirius supercluster.[12]

The brighter component is a white hued A-type main-sequence star with a stellar classification of A2 V.[4] It is one of the least photometrically variable stars known.[5] The star shows a high rate of rotation with a projected rotational velocity of 102 km/s.[3] It has an estimated 2.8[3] times the mass of the Sun and is radiating 113[7] times the Sun's luminosity from its photosphere at an effective temperature of 8,960 K.[9] The relatively high chemical abundances of iron and heavier elements suggests it may be a fast rotating Am star.[5]

A stellar companion was detected in 1986 and reported in 1989.[13] This fainter companion is separated from Theta Andromedae by 0.06 arcseconds.[11] The secondary appears to be a massive, possibly A-type, star orbiting at a distance of around one astronomical unit with a period of 2.83 years and a large orbital eccentricity (ovalness) of 0.95.[8]

Naming

In Chinese, 天廄 (Tiān Jiù), meaning Celestial Stable, refers to an asterism consisting of θ Andromedae, ρ Andromedae and σ Andromedae. Consequently, the Chinese name for θ Andromedae itself is known as 天廄一 (Tiān Jiù yī, English: the First Star of Celestial Stable.)[14]

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 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. Bibcode2021A&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, Bibcode1966CoLPL...4...99J. 
  3. 3.0 3.1 3.2 3.3 3.4 Zorec, J.; Royer, F. (2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics 537: A120, doi:10.1051/0004-6361/201117691, Bibcode2012A&A...537A.120Z. 
  4. 4.0 4.1 Cowley, A. et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal 74: 375–406, doi:10.1086/110819, Bibcode1969AJ.....74..375C. 
  5. 5.0 5.1 5.2 Koçer, D. et al. (2003), "Elemental abundance analyses with DAO spectrograms-XXVII. The superficially normal stars θ And (A2 IV), ϵ Del (B6 III), ϵ Aqr (A1. 5 V), and ι And (B9 V)", Astronomy & Astrophysics 406 (3): 975–980, doi:10.1051/0004-6361:20030620, Bibcode2003A&A...406..975K. 
  6. Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick, Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, 30, University of Toronto: International Astronomical Union, p. 57, Bibcode1967IAUS...30...57E. 
  7. 7.0 7.1 7.2 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode2012AstL...38..331A. 
  8. 8.0 8.1 Goldin, A.; Makarov, V. V. (September 2006), "Unconstrained Astrometric Orbits for Hipparcos Stars with Stochastic Solutions", The Astrophysical Journal Supplement Series 166 (1): 341–350, doi:10.1086/505939, Bibcode2006ApJS..166..341G. 
  9. 9.0 9.1 9.2 9.3 Hill, G. M. (February 1995), "Compositional differences among the A-type stars. 2: Spectrum synthesis up to V sin i = 110 km/s", Astronomy and Astrophysics 294 (2): 536–546, Bibcode1995A&A...294..536H. 
  10. "tet And". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=tet+And. 
  11. 11.0 11.1 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, Bibcode2008MNRAS.389..869E. 
  12. Palous, J.; Hauck, B. (July 1986), "The Sirius supercluster", Astronomy and Astrophysics 162: 54–61, Bibcode1986A&A...162...54P. 
  13. McAlister, Harold A. et al. (February 1989), "ICCD Speckle Observations of Binary Stars. IV. Measurements During 1986-1988 from the Kitt Peak 4-m Telescope", Astronomical Journal 97: 510, doi:10.1086/115001, Bibcode1989AJ.....97..510M. 
  14. (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 18 日

External links