Iota Aquarii, Latinised from ι Aquarii, is the Bayer designation for a binary star[7] system in the equatorial constellation of Aquarius. It is visible to the naked eye with an apparent magnitude of +4.279.[2] Based upon parallax measurements made during the Hipparcos mission, the distance to this star is around 175 light-years (54 parsecs).[2] The system is drifting closer to the Sun with a radial velocity of −10 km/s.[5]
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | 22h 06m 26.22742s[1] |
| Declination | –13° 52′ 10.8615″[1] |
| Apparent magnitude (V) | 4.279[2] |
| Characteristics | |
| Spectral type | B8 V[3] |
| U−B color index | –0.288[2] |
| B−V color index | –0.062[2] |
| Variable type | constant[4] |
| Astrometry | |
| Radial velocity (Rv) | –10.0[5] km/s |
| Proper motion (μ) | RA: +36.89[1] mas/yr Dec.: –58.99[1] mas/yr |
| Parallax (π) | 18.62 ± 0.22 mas[1] |
| Distance | 175 ± 2 ly (53.7 ± 0.6 pc) |
| Absolute magnitude (MV) | +0.64[6] |
| Details[7] | |
| A | |
| Mass | 3.20+0.20 −0.16 M☉ |
| Radius | 2.7[8] R☉ |
| Luminosity | 74[6] L☉ |
| Surface gravity (log g) | 4.09±0.08[9] cgs |
| Temperature | 11,284±284[8] K |
| Metallicity [Fe/H] | −0.08±0.12[9] dex |
| Rotational velocity (v sin i) | 135[10] km/s |
| Age | 124+37 −62 Myr |
| B | |
| Mass | 1.00±0.03 M☉ |
| Temperature | 5,710±112 K |
| Metallicity [Fe/H] | −0.5 dex |
| Rotational velocity (v sin i) | 20 km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
The binary nature of this system was reported in 2009 following a radial velocity survey using the HARPS instrument.[4] A 2010 infrared search for companions around this star was unsuccessful.[12] The presence of a stellar companion was confirmed through direct spectral detection in 2016. The companion shows a significant velocity variation over a 77-day interval, suggesting a short orbital period.[7]
The spectrum of the primary, component A, fits a stellar classification of B8 V,[3] showing that this is a B-type main-sequence star. It is roughly 124[7] million years old and is spinning rapidly with a projected rotational velocity of 135 km/s.[10] The star has 3.2[7] times the mass of the Sun and 2.7[8] times the Sun's radius. It is radiating 74[6] times the luminosity of the Sun from its photosphere at an effective temperature of ~11,284 km/s.[8] The secondary, component B, has a spectrum of a solar-mass star.[7] The system is a source for X-ray emission.[13]
References
edit- ^ 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, S2CID 18759600.
- ^ a b c d e Kozok, J. R. (September 1985), "Photometric observations of emission B-stars in the southern Milky Way", Astronomy and Astrophysics Supplement Series, 61: 387–405, Bibcode:1985A&AS...61..387K.
- ^ a b Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.
- ^ a b Lagrange, A. -M.; et al. (2009), "Extrasolar planets and brown dwarfs around A-F type stars. VI. High precision RV survey of early type dwarfs with HARPS", Astronomy & Astrophysics, 495 (1): 335–352, arXiv:0809.4636, Bibcode:2009A&A...495..335L, doi:10.1051/0004-6361:200810105, S2CID 62894956.
- ^ a b Wielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veroeffentlichungen des Astronomischen Rechen-Instituts Heidelberg, 35 (35), Astronomisches Rechen-Institut Heidelberg: 1, Bibcode:1999VeARI..35....1W.
- ^ a b c 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 c d e f Gullikson, Kevin; et al. (August 2016), "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars", The Astronomical Journal, 152 (2): 13, arXiv:1604.06456, Bibcode:2016AJ....152...40G, doi:10.3847/0004-6256/152/2/40, S2CID 119179065, 40.
Note: the observations were made on modified Julian dates 6447.91 and 6524.67, which are separated by 76.76 days. - ^ a b c d Underhill, A. B.; et al. (November 1979), "Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars", Monthly Notices of the Royal Astronomical Society, 189 (3): 601–605, Bibcode:1979MNRAS.189..601U, doi:10.1093/mnras/189.3.601.
- ^ a b Wu, Yue; et al. (January 2011), "Coudé-feed stellar spectral library - atmospheric parameters", Astronomy and Astrophysics, 525: A71, arXiv:1009.1491, Bibcode:2011A&A...525A..71W, doi:10.1051/0004-6361/201015014, S2CID 53480665.
- ^ a b Abt, Helmut A.; Levato, Hugo; Grosso, Monica (July 2002), "Rotational Velocities of B Stars", The Astrophysical Journal, 573 (1): 359–365, Bibcode:2002ApJ...573..359A, doi:10.1086/340590.
- ^ "* iot Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-06-30.
- ^ Ehrenreich, D.; et al. (November 2010), "Deep infrared imaging of close companions to austral A- and F-type stars", Astronomy and Astrophysics, 523: A73, arXiv:1007.0002, Bibcode:2010A&A...523A..73E, doi:10.1051/0004-6361/201014763, S2CID 54913363.
- ^ Haakonsen, Christian Bernt; Rutledge, Robert E. (September 2009), "XID II: Statistical Cross-Association of ROSAT Bright Source Catalog X-ray Sources with 2MASS Point Source Catalog Near-Infrared Sources", The Astrophysical Journal Supplement, 184 (1): 138–151, arXiv:0910.3229, Bibcode:2009ApJS..184..138H, doi:10.1088/0067-0049/184/1/138, S2CID 119267456.