Eta Arietis

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Eta Arietis
Diagram showing star positions and boundaries of the Aries constellation and its surroundings
Cercle rouge 100%.svg
Location of η Arietis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aries
Right ascension 02h 12m 48.08619s[1]
Declination +21° 12′ 39.5839″[1]
Apparent magnitude (V) 5.231[2]
Spectral type F5 V[3]
U−B color index –0.04[4]
B−V color index +0.44[4]
Radial velocity (Rv)+4.5[2] km/s
Proper motion (μ) RA: +163.49[1] mas/yr
Dec.: +5.22[1] mas/yr
Parallax (π)34.64 ± 0.33[1] mas
Distance94.2 ± 0.9 ly
(28.9 ± 0.3 pc)
Absolute magnitude (MV)+2.93[2]
Mass1.3 M
Radius0.98[5] R
Surface gravity (log g)4.01[3] cgs
Temperature6,380[3] K
Metallicity [Fe/H]–0.35[3] dex
Rotational velocity (v sin i)9[6] km/s
Age2.6[2] Gyr
Other designations
17 Arietis, BD+20 348, GJ 1043, HD 13555, HIP 10306, HR 646, SAO 75204.[4]
Database references

Eta Arietis (η Ari, η Arietis) is the Bayer designation for a star in the northern constellation of Aries. It is dimly visible to the naked eye with an apparent visual magnitude of 5.231.[2] With an annual parallax shift of 34.64 mas,[1] the distance to this star is approximately 94.2 light-years (28.9 parsecs).

This is an F-type main sequence star with a stellar classification of F5 V.[3] It is younger than the Sun at an age of about 2.6 billion years.[2] The effective temperature of the outer atmosphere is 6,380 K,[3] giving it the yellow-white-hued glow of an F-type star. Eta Arietis was examined using the HARPS instrument for radial velocity variations that may be caused by an orbiting companion, but no signal was detected.[7] Nor has an infrared excess been detected using the Spitzer Space Telescope, which might otherwise indicate the presence of circumstellar gas or dust.[8]


  1. ^ a b c d e f 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 Holmberg, J.; Nordström, B.; Andersen, J. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, arXiv:0811.3982, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191.
  3. ^ a b c d e f 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, arXiv:astro-ph/0611618, Bibcode:2007MNRAS.374..664C, doi:10.1111/j.1365-2966.2006.11196.x.
  4. ^ a b c "eta Ari". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-08-04.
  5. ^ Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics", Astronomy and Astrophysics, 367: 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451.
  6. ^ Takeda, Yoichi; et al. (February 2005), "High-Dispersion Spectra Collection of Nearby F--K Stars at Okayama Astrophysical Observatory: A Basis for Spectroscopic Abundance Standards", Publications of the Astronomical Society of Japan, 57 (1): 13–25, Bibcode:2005PASJ...57...13T, doi:10.1093/pasj/57.1.13.
  7. ^ Lagrange, A.-M.; et al. (February 2009), "Extrasolar planets and brown dwarfs around A-F type stars. VI. High precision RV survey of early type dwarfs with HARPS", Astronomy and Astrophysics, 495 (1): 335–352, arXiv:0809.4636, Bibcode:2009A&A...495..335L, doi:10.1051/0004-6361:200810105.
  8. ^ Trilling, D. E.; et al. (February 2008), "Debris Disks around Sun-like Stars", The Astrophysical Journal, 674 (2): 1086–1105, arXiv:0710.5498, Bibcode:2008ApJ...674.1086T, doi:10.1086/525514.

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