18 Andromedae
18 Andromedae, abbreviated 18 And, is a single[7] star in the northern constellation of Andromeda. 18 Andromedae is the Flamsteed designation. It is visible to the naked eye with an apparent visual magnitude of 5.350.[2] The annual parallax shift of 7.9 mas[1] can be used to estimate a distance of 413 light years. It is moving further from the Earth with a heliocentric radial velocity of +10 km/s.[5]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 23h 39m 08.33195s[1] |
| Declination | +50° 28′ 18.2328″[1] |
| Apparent magnitude (V) | 5.350[2] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | B9 Ve[4] |
| B−V color index | −0.110[2] |
| Astrometry | |
| Radial velocity (Rv) | +9.9±2.2[5] km/s |
| Proper motion (μ) | RA: −17.222[1] mas/yr Dec.: −1.739[1] mas/yr |
| Parallax (π) | 7.8893 ± 0.1288 mas[1] |
| Distance | 413 ± 7 ly (127 ± 2 pc) |
| Details | |
| Mass | 3.09±0.06[3] M☉ |
| Luminosity | 146.6+14.1 −12.9[3] L☉ |
| Surface gravity (log g) | 3.632±0.014[2] cgs |
| Temperature | 10,351±50[2] K |
| Rotational velocity (v sin i) | 183[3] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is a B-type main-sequence star with a stellar classification of B9 Ve,[4] where the 'e' notation indicates this is a Be star. The stellar spectrum of 18 And displays an emission line in the hydrogen Brackett series due to a dense gaseous circumstellar envelope.[4] The star is spinning rapidly with a projected rotational velocity of 183[3] km/s and has about three[3] times the mass of the Sun. It is radiating 147[3] times the Sun's luminosity from its photosphere at an effective temperature of 10,351 K.[2]
References edit
- ^ a b c d e f Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051.
- ^ a b c d e f Soubiran, Caroline; et al. (2016), "The PASTEL catalogue: 2016 version", Astronomy & Astrophysics, 591: A118, arXiv:1605.07384, Bibcode:2016A&A...591A.118S, doi:10.1051/0004-6361/201628497, S2CID 119258214.
- ^ a b c d e f g 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.
- ^ a b c Granada, A.; et al. (May 2010), "Simultaneous K- and L-band spectroscopy of Be stars: circumstellar envelope properties from hydrogen emission lines", The Astronomical Journal, 139 (5): 1983–1992, Bibcode:2010AJ....139.1983G, doi:10.1088/0004-6256/139/5/1983, hdl:11336/9567.
- ^ a b 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.
- ^ "18 And". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved September 20, 2018.
- ^ 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, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.