Omega Andromedae

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search

Omega Andromedae
Diagram showing star positions and boundaries of the Andromeda constellation and its surroundings
Cercle rouge 100%.svg
Location of ω Andromedae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension  01h 27m 39.38177s[1]
Declination +45° 24′ 24.0727″[1]
Apparent magnitude (V) +4.83[2][3]
Spectral type F5 IVe[4] or F3 V + F5 V[5]
U−B color index +0.00[3]
B−V color index +0.42[3]
Radial velocity (Rv)+14.7[2] km/s
Proper motion (μ) RA: +356.99[1] mas/yr
Dec.: –109.40[1] mas/yr
Parallax (π)34.94 ± 0.31[1] mas
Distance93.3 ± 0.8 ly
(28.6 ± 0.3 pc)
Absolute magnitude (MV)+2.57[2]
ω And A
Mass0.963±0.049[5] M
Radius2.2[6] R
Luminosity7.1[7] L
Temperature6,628[7] K
Metallicity [Fe/H]–0.16[2] dex
Rotational velocity (v sin i)57.1[8] km/s
Age2.1[2] Gyr
ω And B
Mass0.860±0.051[5] M
Other designations
48 Andromedae, BD+44°307, FK5 1040, HD 8799, HIP 6813, HR 417, SAO 37228.[4]
Database references

Omega Andromedae (ω And, ω Andromedae) is the Bayer designation for a slowly co-rotating binary star system[9] in the northern constellation of Andromeda. Parallax measurements made during the Hipparcos mission make this system to be approximately 93.3 light-years (28.6 parsecs) from Earth. Its apparent visual magnitude is +4.83,[2] which makes it bright enough to be seen with the naked eye.

The primary component has a stellar classification of F5 IVe.[4] The IV luminosity class indicates that it is probably a subgiant star that is in the process of evolving away from the main sequence as the supply of hydrogen at its core depletes. However, Abt (1985) gives a classification of F3 V, suggesting it is an F-type main sequence star.[5] The measured angular diameter of the primary star is 0.70 ± 0.03 mas.[10] At the system's estimated distance this yields a size of about 2.2 times that of the Sun.[6] It is emitting about seven times solar luminosity from its outer atmosphere at an effective temperature of 6,628 K.[7] This heat gives it the yellow-white hued glow of an F-type star.[11]

In 2008, the companion star was resolved using adaptive optics at the Lick Observatory. Later observations showed the magnitude difference between the two stars is 3.65 ± 0.03 and they are separated by 0.669 arcseconds.[9] Abt (1985) lists the class as F5 V.[5]


  1. ^ a b c d e 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. ^ a b c d e f Nordström, B.; et al. (May 2004), "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14 000 F and G dwarfs", Astronomy and Astrophysics, 418: 989–1019, arXiv:astro-ph/0405198, Bibcode:2004A&A...418..989N, doi:10.1051/0004-6361:20035959.
  3. ^ a b c 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.
  4. ^ a b c "ome And". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-06-26.
  5. ^ a b c d e Farrington, C. D.; et al. (September 2014), "Separated Fringe Packet Observations with the CHARA Array. II. ω Andromeda, HD 178911, and ξ Cephei", The Astronomical Journal, 148 (3): 8, arXiv:1407.0639, Bibcode:2014AJ....148...48F, doi:10.1088/0004-6256/148/3/48, 48.
  6. ^ a b Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R*) is given by:
  7. ^ a b c do Nascimento, J. D. Jr.; et al. (July 2003), "On the link between rotation, chromospheric activity and Li abundance in subgiant stars", Astronomy and Astrophysics, 405: 723–731, arXiv:astro-ph/0307196, Bibcode:2003A&A...405..723D, doi:10.1051/0004-6361:20030633.
  8. ^ Schröder, C.; Reiners, A.; Schmitt, J. H. M. M. (January 2009), "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo" (PDF), Astronomy and Astrophysics, 493 (3): 1099–1107, Bibcode:2009A&A...493.1099S, doi:10.1051/0004-6361:200810377.
  9. ^ a b Gladysz, Szymon; Christou, Julian C. (June 2009), "Reference-Less Detection, Astrometry, and Photometry of Faint Companions with Adaptive Optics", The Astrophysical Journal, 698 (1): 28–42, arXiv:0805.1870, Bibcode:2009ApJ...698...28G, doi:10.1088/0004-637X/698/1/28.
  10. ^ Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431: 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039
  11. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, retrieved 2012-01-16.

External links[edit]