Astronomy:Nu Capricorni

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Short description: Star in the constellation Capricornus
Nu Capricorni
Location of ν Capricorni (circled), to the ESE of the naked eye double, α Capricorni
Observation data
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
Spectral type B9 IV[4] or B9.5 V[5]
U−B color index −0.11[3]
B−V color index −0.04[3]
Astrometry
Radial velocity (Rv)−1.00[6] km/s
Proper motion (μ) RA: +14.130[2] mas/yr
Dec.: −15.123[2] mas/yr
Parallax (π)12.1737 ± 0.1597[2] mas
Distance268 ± 4 ly
(82 ± 1 pc)
Absolute magnitude (MV)+0.32[1]
Details
Mass2.37[7] M☉
Radius3.04±0.08[8] R☉
Luminosity89±4[8] L☉
Surface gravity (log g)3.88±0.08[8] cgs
Temperature10,200±220[8] K
Metallicity [Fe/H]−0.15±0.04[1] dex
Rotational velocity (v sin i)24[9] km/s
Age115[7] 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[10]
Database references
SIMBADdata

Nu Capricorni is a star in the southern constellation of Capricornus. It has the proper name Alshat, pronounced /ˈælʃæt/;[11] 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.[12] The celestial latitude of either of the Alpha Capricorni main stars is about 6.93 degrees by comparison.[13]

Characteristics

The star is a blue-white hued B-type main-sequence star.[14] With an estimated age of 115 million years,[7] it is spinning with a projected rotational velocity of 24 km/s.[9] It has 2.4[7] times the mass of the Sun and 3 times the Sun's radius.[8] The star is radiating 89 times the luminosity of the Sun from its photosphere at an effective temperature of 10,200 K.[8] It has a nearly Sun-like composition of elements.[14]

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.[5] Gaia Data Release 2 shows the companion to be much further away from Earth, forming a binary system only in the line-of-sight.[15]

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).[16] In 2016, the IAU organized a Working Group on Star Names (WGSN)[17] 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.[11]

References

  1. ↑ 1.0 1.1 1.2 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.  XHIP record for this object at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940.  Gaia DR3 record for this source at VizieR.
  3. ↑ 3.0 3.1 3.2 3.3 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. ↑ Houk, N.; Smith-Moore, M. (1988), Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars, 4, Bibcode: 1988mcts.book.....H. 
  5. ↑ 5.0 5.1 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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E. 
  6. ↑ Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters 32 (11): 759–771, doi:10.1134/S1063773706110065, Bibcode: 2006AstL...32..759G. 
  7. ↑ 7.0 7.1 7.2 7.3 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, doi:10.1088/0004-637X/804/2/146, Bibcode: 2015ApJ...804..146D. 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 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, doi:10.1093/mnras/stad2862, ISSN 0035-8711. 
  9. ↑ 9.0 9.1 Royer, F. et al. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics 463 (2): 671–682, doi:10.1051/0004-6361:20065224, Bibcode: 2007A&A...463..671R. 
  10. ↑ "nu. Cap". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=nu.+Cap. 
  11. ↑ 11.0 11.1 "Naming Stars". IAU. https://www.iau.org/public/themes/naming_stars/. Retrieved 16 December 2017. 
  12. ↑ White, Nathaniel M.; Feierman, Barry H. (September 1987), "A Catalog of Stellar Angular Diameters Measured by Lunar Occultation", Astronomical Journal 94: 751, doi:10.1086/114513, Bibcode: 1987AJ.....94..751W. 
  13. ↑ Pratt, John (March 11, 2013). "Zodiac Stars". https://www.johnpratt.com/items/astronomy/zodiac/zodiac_stars.html. 
  14. ↑ 14.0 14.1 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, doi:10.3847/1538-3881/acdb50, Bibcode: 2023AJ....166...54M. 
  15. ↑ Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  16. ↑ Star Names: Their Lore and Meaning (Reprint ed.). New York: Dover Publications Inc. 1963. p. 142. ISBN ((0-486-21079-0)). https://archive.org/details/starnamestheirlo00alle/page/142. Retrieved 2010-12-12. 
  17. ↑ "IAU Working Group on Star Names (WGSN)". https://www.iau.org/science/scientific_bodies/working_groups/280/. Retrieved 22 May 2016. 



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