Eta Serpentis

Eta Serpentis
Location of η Serpentis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Serpens
Right ascension 18h 21m 18.60056s[1]
Declination −02° 53′ 55.7766″[1]
Apparent magnitude (V) 3.260[2]
Characteristics
Spectral type K0 III-IV[3]
U−B color index +0.643[2]
B−V color index +0.940[2]
Astrometry
Radial velocity (Rv)+8.4[4] km/s
Proper motion (μ) RA: −547.75[1] mas/yr
Dec.: −701.42[1] mas/yr
Parallax (π)53.93 ± 0.18 mas[1]
Distance60.5 ± 0.2 ly
(18.54 ± 0.06 pc)
Absolute magnitude (MV)+1.87[5]
Details
Mass2.0[6] M☉
Radius5.897 ± 0.028[7] R☉
Luminosity19 ± 1[8] L☉
Surface gravity (log g)3.21[3] cgs
Temperature4,890[3] K
Metallicity [Fe/H]−0.42[3] dex
Rotational velocity (v sin i)2.6[9] km/s
Other designations
η Ser, 58 Serpentis, BD−02° 4599, HD 168723, HIP 89962, HR 6869, SAO 142241[10]
Database references
SIMBADdata

Eta Serpentis, Latinized from η Serpentis, is a star in the constellation Serpens. In particular, it lies in Serpens Cauda, the snake's tail. The star has an apparent visual magnitude of 3.260,[2] making it visible to the naked eye. Parallax measurements give a distance estimate of 60.5 light-years (18.5 parsecs) from the Earth.[1]

This star is larger than the Sun, with twice the mass and almost six times the radius.[6][7] The spectrum matches a stellar classification of K0 III-IV,[3] with the luminosity class of III-IV corresponding to an evolved star that lies between the subgiant and giant stages. The expanded outer envelope star is radiating about 19 times the luminosity of the Sun at an effective temperature of 4,890 K.[3] At this temperature, it has an orange hue typical of a K-type star.[11] Eta Serpentis displays solar-like oscillations with a period of 0.09 of a day.[12]

Eta Serpentis was previously classified as a carbon star, which would have made it the brightest carbon star in the sky, although this classification was since found to be erroneous.[13]

Eta Serpentis is currently 1.6 light-years away from Gliese 710.[citation needed]

  1. ^ a b c d e f 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 saaoc8_59 was invoked but never defined (see the help page).
  3. ^ a b c d e f Cite error: The named reference aaa508_3_1313 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference scfs was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference aj135_3_892 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference aaa190_1_148 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference aaa517_A64 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference aaa526_A100 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference aj135_1_209 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference csiro was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference mnras409_2_777 was invoked but never defined (see the help page).
  13. ^ Antipova, L. I.; Boyarchuk, A. A. (2001). "The chemical composition of the red giant η Ser". Astronomy Reports. 45 (9): 700. Bibcode:2001ARep...45..700A. doi:10.1134/1.1398919. S2CID 62893990.