Nu 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 | |
| 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 mas/yr[2] Dec.: −15.123 mas/yr[2] |
| Parallax (π) | 12.1737±0.1597 mas[2] |
| Distance | 268 ± 4 ly (82 ± 1 pc) |
| Absolute magnitude (MV) | +0.32[1] |
| Details | |
| Mass | 2.37[7] M☉ |
| Radius | 3.04±0.08[8] R☉ |
| Luminosity | 89±4[8] L☉ |
| Surface gravity (log g) | 3.88±0.08[8] cgs |
| Temperature | 10,200±220[8] K |
| Metallicity [Fe/H] | −0.15±0.04[1] dex |
| Rotational velocity (v sin i) | 24[9] km/s |
| Age | 115[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 | |
| SIMBAD | data |
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
[edit]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
[edit]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
[edit]- ^ 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.
- ^ a b c d e 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.
- ^ 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.
- ^ Houk, N.; Smith-Moore, M. (1988), Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars, vol. 4, Bibcode:1988mcts.book.....H.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ "nu. Cap", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2017-05-13.
- ^ a b "Naming Stars". IAU. Retrieved 16 December 2017.
- ^ 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.
- ^ Pratt, John (March 11, 2013). "Zodiac Stars". Archived from the original on 2013-11-24. Retrieved 27 June 2014.
- ^ 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.
- ^ 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.
- ^ 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) - ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
