47 Capricorni

47 Capricorni is a variable star located around 1,170[1] light years from the Sun in the southern constellation Capricornus,[6] near the northern border with Aquarius. It has the variable star designation of AG Capricorni and a Bayer designation of c2 Capricorni;[7] 47 Capricorni is the Flamsteed designation. This object is visible to the naked eye as a dim, red-hued point of light with an apparent visual magnitude that varies between 5.90 and 6.14. The star is receding from the Earth with a heliocentric radial velocity of +20 km/s.[5]

This article is about c2 Capricorni. For other stars with this Bayer designation, see c Capricorni.
47 Capricorni
Observation data
Epoch J2000      Equinox J2000
Constellation Capricornus
Right ascension  21h 46m 16.26887s[1]
Declination −09° 16′ 33.3799″[1]
Apparent magnitude (V) 6.00[2] (5.90 - 6.14)[3]
Characteristics
Evolutionary stage giant
Spectral type M2III[4]
B−V color index 1.629±0.010[2]
Variable type SRb[3]
Astrometry
Radial velocity (Rv)+19.80±0.89[5] km/s
Proper motion (μ) RA: +18.731[1] mas/yr
Dec.: +8.387[1] mas/yr
Parallax (π)2.7933 ± 0.2052[1] mas
Distance1,170 ± 90 ly
(360 ± 30 pc)
Absolute magnitude (MV)−1.76[2]
Details
Radius102+11
−10[1] R☉
Luminosity1,940±162[1] L☉
Temperature3,784+188
−186[1] K
Other designations
c2 Cap, 47 Cap, AG Cap, BD−09°5833, HD 207005, HIP 107487, HR 8318, SAO 145648[6]
Database references
SIMBADdata

This is an aging red giant star with a stellar classification of M2III.[4] It is a semiregular variable star of subtype SRb with a period of 30.592 days and a maximum brightness of 5.9 magnitude.[3] With the supply of hydrogen at its core exhausted, the star has expanded to around 102[1] times the Sun's radius. It is radiating 1,940[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 3,784 K.[1]

References
  1. 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.
  2. 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.
  3. 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. 1. Bibcode:2009yCat....102025S.
  4. Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.
  5. Famaey, B.; et al. (2009). "Spectroscopic binaries among Hipparcos M giants,. I. Data, orbits, and intrinsic variations". Astronomy and Astrophysics. 498 (2): 627. arXiv:0901.0934. Bibcode:2009A&A...498..627F. doi:10.1051/0004-6361/200810698.
  6. "47 Cap". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2014-05-12.
  7. Kostjuk, N. D. (2002). "HD 207005". HD-DM-GC-HR-HIP-Bayer-Flamsteed Cross Index. Institute of Astronomy of Russian Academy of Sciences; CDS. IV/27A
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