Nu Capricorni

Nu Capricorni
Location of ν Capricorni (circled), to the ESE of the naked eye double, α Capricorni
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Capricornus[1]
Right ascension 20h 20m 39.816s[2]
Declination −12° 45′ 32.69″[2]
Apparent magnitude (V) +4.76[3]
Characteristics
Evolutionary stage main sequence[4][2]
Spectral type B9 IV[5] or B9.5 V[6]
U−B color index −0.11[3]
B−V color index −0.04[3]
Astrometry
Radial velocity (Rv)−1.00[7] km/s
Proper motion (μ) RA: +14.130 mas/yr[2]
Dec.: −15.123 mas/yr[2]
Parallax (π)12.1737±0.1597 mas[2]
Distance268 ± 4 ly
(82 ± 1 pc)
Absolute magnitude (MV)+0.32[1]
Details
Mass2.37[8] M☉
Radius3.04±0.08[9] R☉
Luminosity89±4[9] L☉
Surface gravity (log g)3.88±0.08[9] cgs
Temperature10,200±220[9] K
Metallicity [Fe/H]−0.15±0.04[1] dex
Rotational velocity (v sin i)24[10] km/s
Age115[8] Myr
Other designations
Alshat, ν Cap, Nu Cap, 8 Cap, BD−13°5642, HD 193432, HIP 100310, HR 7773, SAO 163468, ADS 13714, WDS J20207-1246A[11]
Database references
SIMBADdata

Nu Capricorni is a star in the southern constellation of Capricornus. It has the proper name Alshat, pronounced /ˈælʃæt/;[12] Nu Capricorni is the Bayer designation. This star is visible to the naked eye with an apparent visual magnitude of +4.76.[3] It is calculated to be a distance of 268 light-years (82 pc) distant from the Sun based on parallax.[2]

Nu Capricorni is 6.6 degrees north of the ecliptic and so is within the margin of occultations of few if any planets but is well within that of the Moon.[13] The celestial latitude of either of the Alpha Capricorni main stars is about 6.93 degrees by comparison.[14]

Characteristics

The star is a blue-white hued B-type main-sequence star.[15] With an estimated age of 115 million years,[8] it is spinning with a projected rotational velocity of 24 km/s.[10] It has 2.4[8] times the mass of the Sun and 3 times the Sun's radius.[9] The star is radiating 89 times the luminosity of the Sun from its photosphere at an effective temperature of 10,200 K.[9] It has a nearly Sun-like composition of elements.[15]

It has an optical companion, named Nu Capricorni B, a magnitude 11.8 star at an angular separation of 54.1 arcseconds from the primary.[6] Gaia Data Release 2 shows the companion to be much further away from Earth, forming a binary system only in the line-of-sight.[16]

Nomenclature

ν Capricorni, Latinised to Nu Capricorni, is the system's Bayer designation, abbreviated Nu Cap or ν Cap.

The star bore the traditional name Alshat, from the Arabic الشاة aš-šā[t], meaning 'the sheep' that was to be slaughtered by the adjacent Beta¹ Capricorni (Dabih).[17] In 2016, the IAU organized a Working Group on Star Names (WGSN)[18] to catalog and standardize proper names for stars. It approved the name Alshat on 30 June 2017 and it is now so included in the List of IAU-approved Star Names.[12]

References

  1. ^ a b c Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015. XHIP record for this object at VizieR.
  2. ^ a b c d e f Vallenari, A.; et al. (Gaia collaboration) (2023), "Gaia Data Release 3. Summary of the content and survey properties", Astronomy and Astrophysics, 674: A1, arXiv:2208.00211, Bibcode:2023A&A...674A...1G, doi:10.1051/0004-6361/202243940, S2CID 244398875. Gaia DR3 record for this source at VizieR.
  3. ^ a b c d Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
  4. ^ Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy and Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691.
  5. ^ Houk, N.; Smith-Moore, M. (1988), Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars, vol. 4, Bibcode:1988mcts.book.....H.
  6. ^ a b Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  7. ^ Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
  8. ^ a b c d David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
  9. ^ a b c d e f Romanovskaya, A. M.; et al. (December 11, 2023), "Non-LTE abundance analysis of A-B stars with low rotational velocities – II. Do A-B stars with normal abundances exist?", Monthly Notices of the Royal Astronomical Society, 526 (3): 3386–3399, arXiv:2309.08384, doi:10.1093/mnras/stad2862, ISSN 0035-8711.
  10. ^ a b Royer, F.; et al. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224, S2CID 18475298.
  11. ^ "nu. Cap", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2017-05-13.
  12. ^ a b "Naming Stars". IAU. Retrieved 16 December 2017.
  13. ^ White, Nathaniel M.; Feierman, Barry H. (September 1987), "A Catalog of Stellar Angular Diameters Measured by Lunar Occultation", Astronomical Journal, 94: 751, Bibcode:1987AJ.....94..751W, doi:10.1086/114513.
  14. ^ Pratt, John (March 11, 2013). "Zodiac Stars". Archived from the original on 2013-11-24. Retrieved 27 June 2014.
  15. ^ a b Monier, Richard; et al. (August 2023), "The Surface Composition of Six Newly Discovered Chemically Peculiar Stars. Comparison to the HgMn Stars mu Lep and beta Scl and the Superficially Normal B Star nu Cap", The Astronomical Journal, 166 (2), id. 54, arXiv:2306.01601, Bibcode:2023AJ....166...54M, doi:10.3847/1538-3881/acdb50.
  16. ^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  17. ^ Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York: Dover Publications Inc. p. 142. ISBN 0-486-21079-0. Retrieved 2010-12-12.{{cite book}}: CS1 maint: ignored ISBN errors (link)
  18. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
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