Iota Serpentis

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Iota Serpentis
Observation data
Epoch J2000      Equinox J2000
Constellation Serpens
Right ascension 15h 41m 33.05469s[1]
Declination 19° 40′ 13.4380″[1]
Apparent magnitude (V) 4.51[2]
Spectral type A1V + A1V[2]
B−V color index +0.06[2]
Radial velocity (Rv) -17.20[3] km/s
Proper motion (μ) RA: -60.86[1] mas/yr
Dec.: -43.69[1] mas/yr
Parallax (π) 17.16 ± 0.67[1] mas
Distance 190 ± 7 ly
(58 ± 2 pc)
Absolute magnitude (MV) 0.68[4]
Other designations
21 Serpentis, BD+20° 3138, GC 21102, HIP 76852, HR 5842, HD 140159, SAO 101682, ADS 9744, CCDM J15416+1940[2]
Database references

Iota Serpentis (ι Ser, ι Serpentis) is a triple star[5] system in the constellation Serpens, in its head (Serpens Caput). It is approximately 190 light years from Earth.[1]

At the centre of the system is a spectroscopic binary, Iota Serpentis A and B. These are both white A-type main sequence dwarfs and both have apparent magnitudes of +5.3. This binary has an orbital period variously reported as 11[6] or 22[7] years. Spectroscopic evidence indicates that component A is an astrometric binary.[5]

There are two visual companions, Iota Serpentis C, a 13th magnitude star 143 arcseconds away and Iota Serpentis D, a 12th magnitude star 151 arcseconds distant.


  1. ^ a b c d e f van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.  Vizier catalog entry
  2. ^ a b c d "Iota Serpentis". SIMBAD Astronomical Database. Retrieved 2015-10-17. 
  3. ^ Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick, Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E 
  4. ^ Absolute magnitude calculated as , where is the star's absolute magnitude, is the star's apparent magnitude, and is the star's measured parallax in arcseconds.
  5. ^ a b 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:0806.2878Freely accessible, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x. 
  6. ^ van den Bos, W. H. (1965). "Note on the Double Star Iota Serpentis". Monthly Notes of the Astronomical Society of Southern Africa. 24: 123. Bibcode:1965MNSSA..24..123V. 
  7. ^ Muterspaugh, Matthew W.; et al. (2010). "The Phases Differential Astrometry Data Archive. II. Updated Binary Star Orbits and a Long Period Eclipsing Binary". The Astronomical Journal. 140 (6): 1623–1630. arXiv:1010.4043Freely accessible. Bibcode:2010AJ....140.1623M. doi:10.1088/0004-6256/140/6/1623.