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Eta Microscopii - Wikipedia

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Eta Microscopii
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Microscopium
Right ascension	21^h 06^m 25.51950^s^[1]
Declination	−41° 23′ 09.4805″^[1]
Apparent magnitude (V)	5.53^[2]
Characteristics
Spectral type	K3 III^[3]
U−B color index	+1.50^[2]
B−V color index	+1.35^[2]
Astrometry

Radial velocity (R_v)	+22.29±0.13^[1] km/s
Proper motion (μ)	RA: +28.760^[1] mas/yr Dec.: −11.548^[1] mas/yr
Parallax (π)	3.5657 ± 0.1149 mas^[1]
Distance	910 ± 30 ly (280 ± 9 pc)
Absolute magnitude (M_V)	−1.13^[4]

Details

Mass	1.2^[5] `M`_☉
Radius	47.41+0.95 −5.67^[1] `R`_☉
Luminosity	735±28^[1] `L`_☉
Surface gravity (log g)	1.1^[5] cgs
Temperature	4,365+287 −43^[1] K
Metallicity [Fe/H]	−0.31^[5] dex

Other designations
η Mic, CD−41°14379, FK5 3684, GC 29461, HD 200702, HIP 104177, HR 8069, SAO 230523^[6]
Database references
SIMBAD	data

Eta Microscopii, Latinised as η Microscopii, is a solitary^[7] star in the constellation Microscopium. It is visible to the naked eye as a dim, orange-hued star with an apparent visual magnitude of 5.53.^[2] The star is located around 910 light-years distant from the Sun based on parallax, and is drifting further away with a radial velocity of +22 km/s.^[1]

This is an aging giant star with a stellar classification of K3 III,^[3] indicating that it has exhausted the supply of hydrogen at its core then cooled and expanded. At present it has around 47^[1] times the girth of the Sun. The star is radiating 735 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,365 K.^[1]

Multiple star catalogues list two optical companions.^[8] Two arc-minutes away, the 8th magnitude HD 200733 is a main sequence star much closer to Earth than η Microscopii.^[9] A 14th-magnitude star one arc-minute from η Microscopii is a background object.^[10]

References

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l 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.
^ ^a ^b ^c ^d Drilling, J. S. (February 1973), "Photoelectric UBV photometry of late-type stars in two regions at high galactic latitude", Astronomical Journal, 78: 44–46, Bibcode:1973AJ.....78...44D, doi:10.1086/111370.
^ ^a ^b Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 2, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
^ 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.
^ ^a ^b ^c Anders, F.; Khalatyan, A.; Chiappini, C.; Queiroz, A. B.; Santiago, B. X.; Jordi, C.; Girardi, L.; Brown, A. G. A.; Matijevič, G.; Monari, G.; Cantat-Gaudin, T.; Weiler, M.; Khan, S.; Miglio, A.; Carrillo, I.; Romero-Gómez, M.; Minchev, I.; De Jong, R. S.; Antoja, T.; Ramos, P.; Steinmetz, M.; Enke, H. (2019), "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18", Astronomy and Astrophysics, 628: A94, arXiv:1904.11302, Bibcode:2019A&A...628A..94A, doi:10.1051/0004-6361/201935765, S2CID 131780028.
^ "eta Mic", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2017-08-12.
^ 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.
^ 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.
^ 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.
^ 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.

Constellation of Microscopium

Stars

Bayer	α β γ δ ε ζ η θ¹ θ² ι ν
Flamsteed	2 PsA 3 PsA
Variable	R S T U AT AU AV AX BO DD
HR	7817 7893 7909 7933 7971 7987 8046 8100 8104 8108 8200 8202
HD	202628
Other	PSR J2124−3358 WASP-7

Exoplanets	WASP-7b

Galaxies

NGC	6925 7012 7057 7060
Other	ESO 286-19