Delta Ophiuchi

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δ Ophiuchi
Location of δ Ophiuchi (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ophiuchus
Right ascension 16h 14m 20.73853s[1]
Declination –03° 41′ 39.5612″[1]
Apparent magnitude (V) 2.75[2]
Characteristics
Evolutionary stage AGB[3]
Spectral type M0.5 III[4]
U−B color index +1.96[2]
B−V color index +1.59[2]
Variable type Suspected[5]
Distance
171 ± 1 ly
(52.5 ± 0.4 pc)
Absolute magnitude (MV)–0.90[7]
Details
Rotational velocity (v sin i)
7.0[11] km/s
HR 6056, SAO 141052.[12]
Database references
SIMBADdata

Delta Ophiuchi (δ Ophiuchi, abbreviated Delta Oph, δ Oph), formally named Yed Prior

apparent visual magnitude is 2.75,[2] making this a third-magnitude star and the fourth-brightest in the constellation. Parallax measurements from the Hipparcos spacecraft yield a distance estimate of approximately 171 light-years (52 parsecs) from the Sun (Epsilon Ophiuchi is approximately 108 light-years (33 parsecs)).[1]

Nomenclature

δ Ophiuchi (Latinised to Delta Ophiuchi) is the star's Bayer designation.

It bore the traditional name Yed Prior. Yed derives from the

Serpens Caput). Delta is Yed Prior as it leads Epsilon across the sky. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[15] to catalogue and standardize proper names for stars. The WGSN approved the name Yed Prior for this star on 5 October 2016 and it is now so included in the List of IAU-approved Star Names.[14]

Delta Ophiuchi was a member of the indigenous Arabic asterism al-Nasaq al-Yamānī, the "Southern Line" of al-Nasaqān the "Two Lines",[16] along with Alpha Serpentis, Delta Serpentis, Epsilon Serpentis, Epsilon Ophiuchi, Zeta Ophiuchi and Gamma Ophiuchi.[17]

In

Chinese name for Delta Ophiuchi itself is 天市右垣九 (Tiān Shì Yòu Yuán jiǔ, English: the Ninth Star of Right Wall of Heavenly Market Enclosure), representing the state of Liang (梁) (or Leang).[19][20]

Properties

Delta Ophiuchi has a

radius of the Sun.[9] In spite of its enlarged size, this star has only 1.5 times the mass of the Sun and hence a much lower density.[8] The effective temperature of the outer atmosphere of Delta Ophiuchi is a relatively cool 3,679 K,[10] which is what gives it the orange-red hue of an M-type star.[22]

It is listed as a suspected

projected rotational velocity of 7.0 km s−1, which gives a minimum value for the azimuthal velocity along the star's equator.[11] The abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity, is more than double the abundance in the Sun's photosphere.[10]

The star has a high optical linear polarisation that increases from red to blue wavelengths and displays some variability, this has been ascribed to either an asymmetric distribution of dust grains in an envelope expelled from it, or the presence of photometric hot spots.[23]

References

  1. ^
    S2CID 18759600
  2. ^
    Bibcode:1966CoLPL...4...99J
  3. ^
    doi:10.1086/116239
    .
  4. ^
    doi:10.1146/annurev.aa.11.090173.000333
  5. ^
    Bibcode:1992IBVS.3792....1P
  6. Bibcode:1953GCRV..C......0W
  7. doi:10.1002/asna.2123190606
  8. ^
    S2CID 119362842
  9. ^
    ISBN 3-540-29692-1
    . The radius (R*) is given by:
  10. ^
    Bibcode:1977A&A....61...17O
  11. ^
    doi:10.1088/0004-6256/135/1/209
  12. ^
    Centre de Données astronomiques de Strasbourg
    , retrieved 2010-07-06
  13. ISBN 978-1-931559-44-7
    .
  14. ^ a b c "Naming Stars". IAU.org. Retrieved 16 December 2017.
  15. ^ IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016.
  16. ISBN 1-931559-44-9
  17. ISBN 0-486-21079-0
    , retrieved 2010-12-12
  18. ISBN 978-986-7332-25-7
    .
  19. ^ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived August 19, 2010, at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
  20. ^ (in Chinese) English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name Archived August 10, 2010, at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
  21. doi:10.1051/0004-6361:20042039
  22. Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original
    on 2012-03-18, retrieved 2012-01-16
  23. S2CID 11191040
    .

External links
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