Location of ι Sagittarii (circled) | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 19 55 15.69691 |
| Declination | −41° 52′ 05.8388″ |
| Apparent magnitude (V) | +4.118 |
| Characteristics | |
| Spectral type | K0 II-III |
| U−B color index | +0.911 |
| B−V color index | +1.084 |
| Astrometry | |
| Radial velocity (Rv) | +35.8 km/s |
| Proper motion (μ) | RA: +22.61 mas/yr Dec.: +51.40 mas/yr |
| Parallax (π) | 17.94 ± 0.21 mas |
| Distance | 182 ± 2 ly (55.7 ± 0.7 pc) |
| Absolute magnitude (MV) | +0.39 |
| Details | |
| Mass | 1.40 M☉ |
| Radius | 14 R☉ |
| Luminosity | 87 L☉ |
| Surface gravity (log g) | 1.89 cgs |
| Temperature | 4,594±41 K |
| Metallicity | −0.26 dex |
| Age | 4.74 Gyr |
| Other designations | |
| ι Sgr, CPD−42° 8944, FK5 1520, HD 188114, HIP 98032, HR 7581, SAO 229927 | |
| Database references | |
| SIMBAD | data |
Iota Sagittarii (Iota Sgr, ι Sagittarii, ι Sgr) is a star in the zodiac constellation of Sagittarius. With an apparent visual magnitude of +4.118, it is bright enough to be viewed with the naked eye. Based upon an annual parallax shift of 17.94 mas as seen from Earth, this star is located 182 light years from the Sun. It is moving away from the Earth with a radial velocity of +35.8 km/s.
This is a probable astrometric binary, based upon proper motion data collected during the Hipparcos mission. The visible component shows the spectrum of an evolved K-type giant or bright giant star with a stellar classification of K0 II-III. The measured angular diameter, after correction for limb darkening, is 2.32±0.02 mas. At an estimated distance of this star, this yields a physical size of about 14 times the radius of the Sun. It has 1.4 times the mass of the Sun and is radiating 87 times the Sun's luminosity from its photosphere at an effective temperature of about 4,594 K.
References
- ^ van Leeuwen, F. (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.
- ^ Cousins, A. W. J. (1973), "Revised zero points and UBV photometry of stars in the Harvard E and F regions", Memoirs of the Royal Astronomical Society, 77: 223–236, Bibcode:1973MmRAS..77..223C.
- ^ Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal, 150 (3): 88, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88, S2CID 118505114.
- 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.
- ^ Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R*) is given by:
- ^ Soubiran, C.; Le Campion, J.-F.; Cayrel de Strobel, G.; Caillo, A. (June 2010), "The PASTEL catalogue of stellar parameters", Astronomy and Astrophysics, 515: A111, arXiv:1004.1069, Bibcode:2010A&A...515A.111S, doi:10.1051/0004-6361/201014247, S2CID 118362423.
- "iot Sgr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-07-07.
- 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.
- Frankowski, A.; et al. (March 2007), "Proper-motion binaries in the Hipparcos catalogue. Comparison with radial velocity data", Astronomy and Astrophysics, 464 (1): 377–392, arXiv:astro-ph/0612449, Bibcode:2007A&A...464..377F, doi:10.1051/0004-6361:20065526, S2CID 14010423.
- Richichi, A.; et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039.
