15 Vulpeculae

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15 Vulpeculae
Vulpecula constellation map.svg
Red circle.svg
Location of 15 Vulpeculae (circled)
Observation data
Epoch J2000       Equinox J2000
Constellation Vulpecula
Right ascension 20h 01m 06.0486s [1]
Declination +27° 45′ 12.863″ [1]
Apparent magnitude  (V)4.66 [2] (4.62 - 4.67) [3]
Characteristics
Spectral type A4IIIm [3] or kA5hA7mA7 (IV–V) [4]
U−B color index +0.15 [5]
B−V color index +0.18 [5]
Variable type α2 CVn [3]
Astrometry
Radial velocity (Rv)−26.10 [6] km/s
Proper motion (μ)RA: 57.817±0.081 [1] mas/yr
Dec.: 3.994±0.085 [1] mas/yr
Parallax (π)13.4427±0.1050  mas [1]
Distance 243 ± 2  ly
(74.4 ± 0.6  pc)
Absolute magnitude  (MV)0.36 [2]
Details
Mass 2.41 [7]   M☉
Radius 4.43 [7] [a]   R☉
Luminosity 61.6 [7]   L☉
Surface gravity (log g)3.53 [7]   cgs
Temperature 7,685±100 [7]   K
Metallicity [Fe/H]+0.02 [2]   dex
Rotational velocity (v sin i)15.0 [8]  km/s
Other designations
15 Vul, NT Vul, BD+27°3587, FK5  1523, GC  27753, HD  189849, HIP  98543, HR  7653, SAO  88071 [9]
Database references
SIMBAD data

15 Vulpeculae is a variable star in the northern constellation of Vulpecula, located approximately 243 light years away based on parallax measurements. [1] It has the variable star designation NT Vulpeculae; 15 Vulpeculae is the Flamsteed designation. It is visible to the naked eye as a faint, white-hued star with a typical apparent visual magnitude of 4.66. [2] This object is moving closer to the Earth with a heliocentric radial velocity of −26 km/s. [6]

An ultraviolet band light curve for NT Vulpeculae, adapted from Kuvshinov et al. (1976) NTVulLightCurve.png
An ultraviolet band light curve for NT Vulpeculae, adapted from Kuvshinov et al. (1976)

The star is considered a marginal Am star with a stellar classification of A4 IIIm, [3] matching an evolved A-type giant star. However, Gray & Garrison (1989) found a class of kA5hA7mA7 (IV–V), [4] which matches a blend of subgiant and main sequence luminosity classes with the K-line (kA5) of an A5 star and the hydrogen (hA7) and metal (mA7) absorption lines of an A7 star. 15 Vulpeculae was a typical Am star when a main sequence, when evolving into a subgiant, it lost most of the peculiar properties of an Am star but still maintain some element abundance peculiarities. [7] The star is 2.4 times more massive than the Sun and has expanded to four times the Sun's diameter. [a] It is radiating 62 times the Sun's luminosity from its photosphere at an effective temperature of 7,685 K. [7] It is an Alpha2 Canum Venaticorum-type variable with magnitude ranging from 4.62 down to 4.67 over a period of 14 days. [3]

There is evidence that 15 Vulpeculae may have a companion star, given the high margins of error in the astrometric measurements taken by Gaia DR3, as well as its unusually slow projected rotational velocity, which could also be explained if the star is being viewed pole-on. [7]

Notes

  1. 1 2 Calculated, using the Stefan-Boltzmann law and the star's effective temperature and luminosity, with respect to the solar nominal effective temperature of 5,772  K :

References

  1. 1 2 3 4 5 6 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.
  2. 1 2 3 4 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. S2CID   119257644. Vizier catalog entry
  3. 1 2 3 4 5 Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  4. 1 2 Çay, İpek H.; Teker Yelkenci, Aysegul; Adelman, Saul J. (May 2016). "Elemental Abundance Analyses with DAO Spectrograms. XXXIX. The Am Stars 2 UMa and 15 Vul". Publications of the Astronomical Society of the Pacific. 128 (963): 054201. Bibcode:2016PASP..128e4201C. doi:10.1088/1538-3873/128/963/054201. S2CID   123542297.
  5. 1 2 Mermilliod, J. C. (2006). "VizieR Online Data Catalog: Homogeneous Means in the UBV System (Mermilliod 1991)". VizieR On-line Data Catalog: II/168. Originally Published in: Institut d'Astronomie. 2168. Bibcode:2006yCat.2168....0M. Vizier catalog entry
  6. 1 2 Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 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.
  7. 1 2 3 4 5 6 7 8 Çay, M. Taşkın; Çay, İpek H.; Civelekler, Betül (2025-01-13). "A critical evaluation of the elemental abundances and evolutionary status of 15 Vul (HD 189849): The first identification of an evolved Am star". Monthly Notices of the Royal Astronomical Society (Accepted manuscript). 537 (4): 3054–3065. arXiv: 2501.07504 . Bibcode:2025MNRAS.537.3054C. doi: 10.1093/mnras/staf034 . S2CID   275463214.
  8. ↑ Glebocki, R.; Gnacinski, P. (2005). "VizieR Online Data Catalog: Catalog of Stellar Rotational Velocities (Glebocki+ 2005)". VizieR On-line Data Catalog: III/244. Originally Published in: 2005csss...13..571G; 2005yCat.3244....0G. 3244. Bibcode:2005yCat.3244....0G. Vizier catalog entry
  9. ↑ "15 Vul". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2018-03-15.
  10. ↑ Kuvshinov, V. M.; Hildebrandt, G.; Schoeneich, W. (January 1976). "Photoelektrische Untersuchungen des Magnetfeldes und der Helligkeit der Am-Sterne 15 VUL und 68 Tau". Astronomische Nachrichten. 297 (4): 181–188. Bibcode:1976AN....297..181K. doi:10.1002/asna.19762970405.
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