20 Aquarii, abbreviated 20 Aqr, is a star in the constellation Aquarius. 20 Aquarii is the Flamsteed designation. It is a dim star with an apparent visual magnitude of 6.38.[2] Based upon an annual parallax shift of 15.34 mas,[1] it is located 213 light years away but is moving closer to the Earth with a heliocentric radial velocity of −23 km/s.[5] The star is predicted to come to within 110 light-years in around 1.9 million years.[2]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | 21h 24m 51.67515s[1] |
| Declination | −03° 23′ 54.0858″[1] |
| Apparent magnitude (V) | 6.38[2] |
| Characteristics | |
| Spectral type | F0 V[3] or F0 III[4] |
| B−V color index | 0.334±0.002[2] |
| Astrometry | |
| Radial velocity (Rv) | −23.2±2.9[5] km/s |
| Proper motion (μ) | RA: −6.125[1] mas/yr Dec.: −49.515[1] mas/yr |
| Parallax (π) | 15.3426 ± 0.0730 mas[1] |
| Distance | 213 ± 1 ly (65.2 ± 0.3 pc) |
| Absolute magnitude (MV) | 2.37[2] |
| Details | |
| Mass | 1.52[6] M☉ |
| Luminosity | 9.38[2] L☉ |
| Surface gravity (log g) | 4.17[6] cgs |
| Temperature | 7,314±249[6] K |
| Rotational velocity (v sin i) | 92[7] km/s |
| Age | 761[6] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is an F-type main-sequence star with a stellar classification of F0 V.[3] (Cowley and Fraquelli [1974] had given it a class of F0 III.)[4] It is a suspected[9] chemically peculiar Am star showing metallic lines.[10] It is 761[6] million years old with a high projected rotational velocity of 92 km/s.[7] The star has 1.52[6] times the mass of the Sun and is radiating 9[2] times the Sun's luminosity from its photosphere at an effective temperature of about 7,314 K.[6]
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 g Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
- ^ a b Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey, 5, Bibcode:1999MSS...C05....0H.
- ^ a b Cowley, A.; Fraquelli, D. (1974), "MK Spectral Types for Some Bright F Stars", Publications of the Astronomical Society of the Pacific, 86 (509): 70, Bibcode:1974PASP...86...70C, doi:10.1086/129562.
- ^ a b Gontcharov, G. A. (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 e f g David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
- ^ a b 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:1201.2052, Bibcode:2002A&A...393..897R, doi:10.1051/0004-6361:20020943, S2CID 14070763.
- ^ "20 Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved October 23, 2018.
- ^ Renson, P.; Manfroid, J. (2009), "Catalogue of Ap, HgMn and Am stars", Astronomy and Astrophysics, 498 (3): 961, Bibcode:2009A&A...498..961R, doi:10.1051/0004-6361/200810788.
- ^ Paunzen, E.; et al. (February 2013), "A photometric study of chemically peculiar stars with the STEREO satellites - II. Non-magnetic chemically peculiar stars", Monthly Notices of the Royal Astronomical Society, 429 (1): 119–125, arXiv:1211.1535, Bibcode:2013MNRAS.429..119P, doi:10.1093/mnras/sts318.