Eta Arae

Eta Arae
Diagram showing star positions and boundaries of the Ara constellation and its surroundings
The location of η Arae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ara
Right ascension 16h 49m 47.15653s[1]
Declination –59° 02′ 28.9575″[1]
Apparent magnitude (V) 3.76[2]
Characteristics
Spectral type K5 III[3]
U−B color index +1.93[2]
B−V color index +1.57[2]
Astrometry
Radial velocity (Rv)+9.0[4] km/s
Proper motion (μ) RA: +39.73[1] mas/yr
Dec.: –24.91[1] mas/yr
Parallax (π)10.90 ± 0.20 mas[1]
Distance299 ± 5 ly
(92 ± 2 pc)
Absolute magnitude (MV)−1.14±0.14[5]
Details[6]
Mass1.12±0.16 M☉
Radius40.44±2.62 R☉
Luminosity575 L☉
Surface gravity (log g)1.06±0.06 cgs
Temperature4,147±29 K
Metallicity [Fe/H]−0.47±0.03 dex
Rotational velocity (v sin i)1.55±0.55 km/s
Age4.98±1.86 Gyr
Other designations
η Ara, CPD–58° 6906, FK5 1435, HD 151249, HIP 82363, HR 6229, SAO 244168, WDS J16498-5902A[7]
Database references
SIMBADdata

Eta Arae, Latinized from η Arae, is the Bayer designation for a single [8] star in the southern constellation of Ara. It is approximately 299 light-years (92 parsecs) from Earth and is visible to the naked eye with an apparent visual magnitude of 3.76.[2] The star is moving away from the Sun with a radial velocity of +9 km/s.[4]

The spectrum of this star matches a stellar classification of K5 III,[3] indicating that, at an estimated age of five billion years,[6] it has reached the giant star stage of its evolution. With 1.12 times the mass of the Sun, it has an outer envelope that has expanded to 40 times the Sun's radius.[6] The star is now spinning so slowly that it takes more than eleven years to complete a single rotation.[9] Eta Arae is radiating energy into space from its photosphere with 575 times the Sun's luminosity at an effective temperature of 4,147 K,[6] giving it the orange-hued glow of a K-type star.[10]

It has a magnitude 13.5 optical companion, located 23.4 arcseconds away along a position angle of 118°, as of 2000.[11]

  1. ^ a b c d e Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference clpl4_99 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. ^ a b Cite error: The named reference gcrv1953 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference aaa458_2_609 was invoked but never defined (see the help page).
  6. ^ a b c d Cite error: The named reference jofre2015 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference mnras389_2_869 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference aaa421_241 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference csiro was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference wds2006 was invoked but never defined (see the help page).