// Workers AI · dad joke modeWhat did Iota Sagittarii say to its friend? "You're a star, I owe you one.
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| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 19h 55m 15.69691s[1] |
| Declination | −41° 52′ 05.8388″[1] |
| Apparent magnitude (V) | +4.118[2] |
| Characteristics | |
| Spectral type | K0 II-III[3] |
| U−B color index | +0.911[2] |
| B−V color index | +1.084[2] |
| Astrometry | |
| Radial velocity (Rv) | +35.8[3] km/s |
| Proper motion (μ) | RA: +22.61[1] mas/yr Dec.: +51.40[1] mas/yr |
| Parallax (π) | 17.94±0.21 mas[1] |
| Distance | 182 ± 2 ly (55.7 ± 0.7 pc) |
| Absolute magnitude (MV) | +0.39[4] |
| Details | |
| Mass | 1.40[3] M☉ |
| Radius | 15[5] R☉ |
| Luminosity | 87[3] L☉ |
| Surface gravity (log g) | 1.89[6] cgs |
| Temperature | 4,594±41[3] K |
| Metallicity [Fe/H] | −0.26[6] dex |
| Age | 4.74[3] Gyr |
| Other designations | |
| ι Sgr, CPD−42°8944, FK5 1520, HD 188114, HIP 98032, HR 7581, SAO 229927[7] | |
| 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.[2] Based upon an annual parallax shift of 17.94 mas as seen from Earth,[1] 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.[3]
This is an astrometric binary,[8] based upon proper motion data collected during the Hipparcos mission.[9] The primary component shows the spectrum of an evolved K-type giant or bright giant star with a stellar classification of K0 II-III.[3] The measured angular diameter, after correction for limb darkening, is 2.32±0.02 mas.[10] At an estimated distance of this star, this yields a physical size of about 15 times the radius of the Sun.[5] It has 1.4[3] times the mass of the Sun and is radiating 87[3] times the Sun's luminosity from its enlarged photosphere at an effective temperature of about 4,594 K.[3]
The companion star was directly observed for the first time in 2014 with the SPHERE instrument on the Very Large Telescope. It is separated from the primary star by 0.24″ and is more than 4,000 times fainter than it.[11] This is an M-type red dwarf star with an estimated mass of 0.36 M☉.[12]
References
[edit]- 1 2 3 4 5 6 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.
- 1 2 3 4 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.
- 1 2 3 4 5 6 7 8 9 10 11 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.
- 1 2 Stassun, Keivan G.; et al. (2019), "The Revised TESS Input Catalog and Candidate Target List", The Astronomical Journal, 158 (4): 138, arXiv:1905.10694, Bibcode:2019AJ....158..138S, doi:10.3847/1538-3881/ab3467.
- 1 2 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.
- ↑ "The very faint companion star to Iota Sagitarii seen with SPHERE". ESO. 4 June 2014. Retrieved 14 July 2026.
- ↑ Claudi, R.; Gratton, R.; et al. (2016). "First science with SPHERE". Memorie della Societa Astronomica Italiana. 87: 132. Bibcode:2016MmSAI..87..132C.
