Iota2 Scorpii

ι2 Scorpii, Latinised as Iota2 Scorpii, is a single[9] star in tail of the zodiac constellation of Scorpius. It has an apparent visual magnitude of +4.82,[2] and is visible to the naked eye. Because of parallax measurement errors, the distance to this star is only approximately known: it lies around 2,500 light years away from the Sun. It has a visual companion, a magnitude 11.0 star at an angular separation of 31.60 arcseconds along a position angle of 36°, as of 2000.[10]

For other stars with this Bayer designation, see ι Scorpii
ι2 Scorpii
Observation data
Epoch J2000      Equinox J2000
Constellation Scorpius
Right ascension 17h 50m 11.11291s[1]
Declination −40° 05′ 25.5629″[1]
Apparent magnitude (V) +4.82[2]
Characteristics
Spectral type A2 Ib[3] or A6 Ib[4]
U−B color index +0.19[2]
B−V color index +0.25[2]
Astrometry
Radial velocity (Rv)−10.2[5] km/s
Proper motion (μ) RA: +3.90[1] mas/yr
Dec.: −2.42[1] mas/yr
Parallax (π)1.28 ± 0.24[1] mas
Distanceapprox. 2,500 ly
(approx. 800 pc)
Absolute magnitude (MV)−4.59[6]
Details
Mass8.8±0.2[4] M☉
Luminosity5,798[7] L☉
Temperature6,372[7] K
Age29.8±4.3[4] Myr
Other designations
ι2 Sco, CD−40° 11886, HD 161912, HIP 87294, HR 6631, SAO 228466 .[8]
Database references
SIMBADdata

In the literature, there are two different stellar classifications for this star: A2 Ib[3] and A6 Ib.[4] In either case it is an A-type supergiant star with an estimated age of 30[4] million years and a mass 8.8 times that of the Sun.[4] It shines with a luminosity 5,798 times the Sun's from an outer atmosphere that has an effective temperature of 6,372 K.[7] As with other stars of its type, ι2 Scorpii varies slightly in brightness, showing an amplitude of 0.05 in magnitude.[11]

References
  1. 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.
  2. Dachs, J.; et al. (November 1982), "UBV-Hβ photometry of luminous stars between l equals 335 deg and l equals 6 deg", Astronomy and Astrophysics Supplement Series, 50: 261–275, Bibcode:1982A&AS...50..261D.
  3. Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 2, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
  4. Tetzlaff, N.; et al. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x.
  5. Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick (eds.), "The Revision of the General Catalogue of Radial Velocities", Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E.
  6. 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.
  7. McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x.
  8. "iot02 Sco". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-09-20.
  9. Eggleton, P. P.; Tokovinin, A. A. (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.
  10. Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122: 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
  11. Adelman, S. J.; Albayrak, B. (December 1997), "On the Variability of Early A-Type Supergiants", Information Bulletin on Variable Stars, 4541: 1, Bibcode:1997IBVS.4541....1A.
  • Kaler, James B., "Iota-2 Scorpii", Stars, University of Illinois, retrieved 2016-09-20.
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