Iota Microscopii

ι Microscopii, Latinized as Iota Microscopii, is a suspected astrometric binary[10] star system in the southern constellation of Microscopium, near the southern constellation border with Indus. It is visible to the naked eye as a dim, yellow-white hued point of light with an apparent visual magnitude of 5.11.[2] This object is 121 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −14 km/s.[1]

ι Microscopii
Location of ι Microscopii (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Microscopium
Right ascension 20h 48m 29.14779s[1]
Declination −43° 59′ 18.6369″[1]
Apparent magnitude (V) 5.11[2]
Characteristics
Spectral type F2V[3]
U−B color index +0.04[4]
B−V color index +0.35[5]
Astrometry
Radial velocity (Rv)−14.35±0.69 km/s
Proper motion (μ) RA: +178.881[1] mas/yr
Dec.: −112.407[1] mas/yr
Parallax (π)26.9052 ± 0.1782 mas[1]
Distance121.2 ± 0.8 ly
(37.2 ± 0.2 pc)
Absolute magnitude (MV)2.05[2]
Details
Mass1.42[6] M☉
Radius2.4[7] R☉
Luminosity12.65[2] L☉
Surface gravity (log g)3.90±0.14[6] cgs
Temperature6,997±238[6] K
Metallicity [Fe/H]−0.03[2] dex
Rotational velocity (v sin i)115[8] km/s
Age1.094[6] Gyr
Other designations
ι Mic, CD−44°14145, FK5 1542, GC 28980, HD 197937, HIP 102693, HR 7943, SAO 230379, CCDM J20485-4359A, WDS J20485-4359A[9]
Database references
SIMBADdata

The visible component is an ordinary F-type main-sequence star with a stellar classification of F2V,[3] which indicates it is generating energy through core hydrogen fusion. It is around a billion years old with 1.4 times the mass of the Sun[6] and 2.4[7] times the Sun's radius. The star is radiating 13[2] times the luminosity of the Sun from its photosphere at an effective temperature of 6,997 K.[6] It has a high rate of spin with a projected rotational velocity of 115 km/s, which is giving the star an equatorial bulge that is 6% larger than the polar radius.[8]

Iota Microscopii has one visual companion, first observed in 1932, with a separation of 4.3" and a visual magnitude of 15.5.[11]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. 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. Vizier catalog entry
  3. Houk, Nancy (1978). Michigan catalogue of two-dimensional spectral types for the HD stars. Vol. 2. Ann Arbor: Department of Astronomy, University of Michigan. Bibcode:1978mcts.book.....H.
  4. Mermilliod, J. C. (2006). "VizieR Online Data Catalog: Homogeneous Means in the UBV System (Mermilliod 1991)". VizieR On-line Data Catalog: II/168. Originally Published in: Institut d'Astronomie. 2168. Bibcode:2006yCat.2168....0M.Vizier catalog entry
  5. Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers. 42 (2): 443. Bibcode:2014JAVSO..42..443M.Vizier catalog entry
  6. David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146. S2CID 33401607. Vizier catalog entry
  7. Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555–562. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A. Vizier catalog entry
  8. van Belle, Gerard T. (March 2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20 (1): 51, arXiv:1204.2572, Bibcode:2012A&ARv..20...51V, doi:10.1007/s00159-012-0051-2, S2CID 119273474
  9. "iot Mic". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-04.
  10. 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.
  11. Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920. Vizier catalog entry
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