Summary
Epsilon Arietis (ε Ari, ε Arietis) is the Bayer designation for a visual binary[8] star system in the northern constellation of Aries. It has a combined apparent visual magnitude of 4.63[2] and can be seen with the naked eye, although the two components are too close together to be resolved without a telescope. With an annual parallax shift of 9.81 mas,[1] the distance to this system can be estimated as 330 light-years (100 parsecs), give or take a 30 light-year margin of error. It is located behind the dark cloud MBM12.[6]
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aries |
| Right ascension | 02h 59m 12.72536s[1] |
| Declination | +21° 20′ 25.5575″[1] |
| Apparent magnitude (V) | 4.63[2] (5.2/5.5)[3] |
| Characteristics | |
| Spectral type | A2 Vs + A2 Vs[4] |
| U−B color index | +0.08[2] |
| B−V color index | +0.04[2] |
| R−I color index | 0.02 |
| Astrometry | |
| Radial velocity (Rv) | +0.9 ± 0.9[5] km/s |
| Proper motion (μ) | RA: -13.74[1] mas/yr Dec.: -5.12[1] mas/yr |
| Parallax (π) | 9.81 ± 0.79 mas[1] |
| Distance | 330 ± 30 ly (102 ± 8 pc) |
| Orbit[6] | |
| Period (P) | 704.111±1.778 yr |
| Semi-major axis (a) | 2.174±0.035″ |
| Eccentricity (e) | 0.317±0.006 |
| Inclination (i) | 84.2±0.8° |
| Longitude of the node (Ω) | 25.6±0.7° |
| Periastron epoch (T) | 704.111±1.778 |
| Argument of periastron (ω) (secondary) | 162.1±1.0° |
| Details | |
| ε Ari A | |
| Mass | 2.4[6] M☉ |
| Rotational velocity (v sin i) | 60[4] km/s |
| ε Ari B | |
| Mass | 2.4[6] M☉ |
| Rotational velocity (v sin i) | 60[4] km/s |
| Other designations | |
| ε Ari A: HD 18520, HR 888, SAO 75673 | |
| ε Ari B: HD 18519, HR 887. | |
| Database references | |
| SIMBAD | ε Ari |
| ε Ari A | |
| ε Ari B | |
The brighter member of this pair has an apparent magnitude of 5.2.[3] At an angular separation of 1.426 ± 0.010 arcseconds from the brighter component, along a position angle of 209.2° ± 0.3°,[8] is the magnitude 5.5 companion.[3] Both are A-type main sequence stars with a stellar classification of A2 Vs.[4] (The 's' suffix indicates that the absorption lines in the spectrum are distinctly narrow.) In the 2009 Catalogue of Ap, HgMn and Am stars, the two stars have a classification of A3 Ti,[3] indicating they are Ap stars with an anomalous abundance of titanium. Within the measurement margin of error, their projected rotational velocities are deemed identical at 60 km/s.[4]
Name edit
This star system, along with δ Ari, ζ Ari, π Ari, and ρ3 Ari, were Al Bīrūnī's Al Buṭain (ألبطين), the dual of Al Baṭn, the Belly.[9] According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al Buṭain were the title for five stars :δ Ari as Botein, π Ari as Al Buṭain I, ρ3 Ari as Al Buṭain II, ε Ari as Al Buṭain III and ζ Ari as Al Buṭain IV[10]
In Chinese astronomy, Epsilon Arietis may be or may be part of Tso Kang (from Cantonese 左更 zogang, Mandarin pronunciation zuǒgēng).[11][12]
References edit
- ^ 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, S2CID 18759600.
- ^ a b c d Eggen, Olin J. (November 1963), "Luminosities, colors, and motions of the brightest A-type stars", Astronomical Journal, 68: 697, Bibcode:1963AJ.....68..697E, doi:10.1086/109198.
- ^ a b c d Renson, P.; Manfroid, J. (May 2009), "Catalogue of Ap, HgMn and Am stars", Astronomy and Astrophysics, 498 (3): 961–966, Bibcode:2009A&A...498..961R, doi:10.1051/0004-6361/200810788.
- ^ a b c d e Royer, F.; et al. (October 2002), "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i", Astronomy and Astrophysics, 393: 897–911, arXiv:astro-ph/0205255, Bibcode:2002A&A...393..897R, doi:10.1051/0004-6361:20020943, S2CID 14070763.
- ^ Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
- ^ a b c d Rica, Francisco (April 2012), "Orbital Elements for BU 741 AB, STF 333 AB, BU 920 and R 207", Journal of Double Star Observations, 8 (2): 127–139, Bibcode:2012JDSO....8..127R.
- ^ "eps Ari". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-08-05.
- ^ a b Scardia, M.; Prieur, J.-L.; Pansecchi, L.; Argyle, R. W.; Basso, S.; Sala, M.; Ghigo, M.; Koechlin, L.; Aristidi, E. (January 2007), "Speckle observations with PISCO in Merate - III. Astrometric measurements of visual binaries in 2005 and scale calibration with a grating mask", Monthly Notices of the Royal Astronomical Society, 374 (3): 965–978, Bibcode:2007MNRAS.374..965S, doi:10.1111/j.1365-2966.2006.11206.x.
- ^ Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York, NY: Dover Publications Inc. p. 83. ISBN 0-486-21079-0. Retrieved 2010-12-12.
- ^ Jack W. Rhoads - Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars, Jet Propulsion Laboratory, California Institute of Technology; November 15, 1971
- ^ Chevalier, S., and Tsuchihashi, P., (1911): "Catalogue d'Étoiles fixes, observés a Pekin sous l'Empereur Kien Long (Qianlong (Chien-Lung)), XVIIIe siecle", Annales de l'Observatoire Astronomique de Zô-Sé.
- ^ 伊世同 (Yi Shi Tong) (1981): 『中西対照恒星図表』科学出版社.(in Chinese)
External links edit
- HR 887
- Image Epsilon Arietis