Epsilon Ophiuchi

Epsilon Ophiuchi
Location of ε Ophiuchi (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ophiuchus
Right ascension 16h 18m 19.28974s[1]
Declination –04° 41′ 33.0345″[1]
Apparent magnitude (V) 3.220[2]
Characteristics
Spectral type G9.5 IIIb[3]
U−B color index +0.762[2]
B−V color index +0.972[2]
Astrometry
Radial velocity (Rv)–10.3[4] km/s
Proper motion (μ) RA: +83.40[1] mas/yr
Dec.: +40.58[1] mas/yr
Parallax (π)30.5136 ± 0.1878 mas[5]
Distance106.9 ± 0.7 ly
(32.8 ± 0.2 pc)
Absolute magnitude (MV)+0.55[6]
Details
Mass1.85±0.05[7] M☉
Radius10.39±0.07[7] R☉
Luminosity54[8] L☉
Surface gravity (log g)2.59±0.08[3] cgs
Temperature4,918±28[3] K
Metallicity [Fe/H]−0.13±0.06[3] dex
Rotational velocity (v sin i)5.7[9] km/s
Age0.95–1.01[10] Gyr
Other designations
Yed Posterior, ε Oph, Epsilon Oph, 2 Ophiuchi, BD–04 4086, FK5 605, HD 146791, HIP 79882, HR 6075, SAO 141086[11]
Database references
SIMBADdata

Epsilon Ophiuchi or ε Ophiuchi, formally named Yed Posterior (/ˌjɛd pɒˈstɪəriər/),[12][13] is a red giant[7] star in the constellation of Ophiuchus. Located less than five degrees south of the celestial equator in the eastern part of the constellation,[1] it forms a naked eye optical double with Delta Ophiuchi (named Yed Prior[13]). With an apparent visual magnitude of 3.220,[2] the star can be seen with the naked eye from most of the Earth under suitably dark skies. Parallax measurements yield an estimated distance of 106.4 light-years (32.6 parsecs) from the Sun.

  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 mnras172_667 was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference aaa525_A71 was invoked but never defined (see the help page).
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  5. ^ Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  6. ^ Cite error: The named reference pasj60_4_781 was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference aaa503_2_521 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference aj135_1_209 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference aaa515_A43 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference raa10_12_1265 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  12. ^ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.
  13. ^ a b "Naming Stars". IAU.org. Retrieved 16 December 2017.