Eta Microscopii

Eta Microscopii
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Microscopium
Right ascension 21h 06m 25.51950s[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 (Rv)+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]
Distance910 ± 30 ly
(280 ± 9 pc)
Absolute magnitude (MV)−1.13[4]
Details
Mass1.2[5] M☉
Radius47.41+0.95
−5.67[1] R☉
Luminosity735±28[1] L☉
Surface gravity (log g)1.1[5] cgs
Temperature4,365+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
SIMBADdata

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]

  1. ^ a b c d e f g h i j k l Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Drilling1973 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference houk1978 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference starhorse was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference wds was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference dr2c was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference dr2b was invoked but never defined (see the help page).