Eta Gruis

Eta Gruis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Grus
Right ascension 22h 45m 37.88285s[1]
Declination −53° 30′ 00.4405″[1]
Apparent magnitude (V) 4.85[2]
Characteristics
Spectral type K2 III CNIV[3]
U−B color index +1.17[2]
B−V color index +1.18[2]
Astrometry
Radial velocity (Rv)+27.8±2.8[4] km/s
Proper motion (μ) RA: +30.207[1] mas/yr
Dec.: +17.921[1] mas/yr
Parallax (π)7.1001 ± 0.1924 mas[1]
Distance460 ± 10 ly
(141 ± 4 pc)
Absolute magnitude (MV)−0.68[5]
Details
Radius31.38+0.92
−1.04[1] R☉
Luminosity338.5±10.5[1] L☉
Temperature4,420+75
−64[1] K
Other designations
η Gru, CPD−54° 10123, FK5 3821, HD 215369, HIP 112374, HR 8655, SAO 247570, WDS J22456-5330A[6]
Database references
SIMBADdata

Eta Gruis, Latinized from η Gruis, is a solitary[7] star in the southern constellation of Grus. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.85.[2] Based upon an annual parallax shift of 7.1 mas as seen from the Earth,[8] the system is located about 460 light years from the Sun. The star is drifting further away with a radial velocity of +28 km/s.[4]

This object is an evolved K-type giant star with a stellar classification of K2 III CNIV,[3] where the suffix notation indicates this is an intermediate CN star. It is a periodic microvariable with an amplitude of 0.0055 magnitude and a frequency of 0.36118 cycles per day.[9] With the supply of hydrogen exhausted at its core, the star has expanded and cooled, now having 31[1] times the Sun's girth. It is radiating 338.5[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,420 K.[1]

Eta Gruis has a magnitude 11.5 visual companion located at an angular separation of 25.6″ along a position angle of 187°, as of 2012.[10]

  1. ^ a b c d e f g h i j k 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 Johnson1966 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference houk1979 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Anderson2012 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 vanLeeuwen2007 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference koen2002 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference WDSC2014 was invoked but never defined (see the help page).