Astronomy:16 Serpentis

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Short description: Binary star system in the constellation Serpens
16 Serpentis
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Serpens
Right ascension  15h 36m 29.57498s[1]
Declination 10° 00′ 36.5574″[1]
Apparent magnitude (V) 5.261[2]
Characteristics
Spectral type K0III: CN1 Ba0.7 Sr2[3]
U−B color index +0.66[4]
B−V color index +0.937[2]
Astrometry
Radial velocity (Rv)+2.94±0.13[1] km/s
Proper motion (μ) RA: 41.881[1] mas/yr
Dec.: −125.722[1] mas/yr
Parallax (π)14.3226 ± 0.1100[1] mas
Distance228 ± 2 ly
(69.8 ± 0.5 pc)
Orbit[5]
Period (P)5,324±19 d
Eccentricity (e)0.345±0.024
Periastron epoch (T)44,090±53
Argument of periastron (ω)
(secondary)
358±4°
Semi-amplitude (K1)
(primary)
3.86±0.09 km/s
Details
16 Ser A
Mass1.70[2] M
Radius8[6] R
Luminosity42.7[2] L
Surface gravity (log g)2.64±0.12[7] cgs
Temperature4,946±51[7] K
Metallicity [Fe/H]−0.13±0.06[7] dex
Rotational velocity (v sin i)1.4[6] km/s
Age2.40[2] Gyr
Other designations
16 Ser, BD+10°2884, FK5 3226, GC 20981, HD 139195, HIP 76425, HR 5802, SAO 101640[8]
Database references
SIMBADdata

16 Serpentis is a binary star[5] system in the Serpens Caput portion of the equatorial constellation of Serpens,[8] located 228 light years from the Sun. It is visible to the naked eye as a fain, orange-hued star with an apparent visual magnitude of 5.261.[2] The system is moving further from the Earth with a heliocentric radial velocity of +3 km/s.[1]

The variable radial velocity of this star was discovered at Lick Observatory and was announced by J. H. Moore in 1924. It is a single-lined spectroscopic binary with an orbital period of 14.58 years and an eccentricity of 0.345.[5] The visible component is an evolved giant star with a stellar classification of K0III: CN1 Ba0.7 Sr2.[3] This is a mild barium star[9] with the suffix notation above indicating associated abundance anomalies. The companion is a presumed white dwarf star that has already passed through its giant stage, during which time it enhanced the envelope of the companion with s-process elements. The pair form one of the widest barium star binaries known, which may account for the mildness of the barium anomaly.[5]

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 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. Bibcode2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 Luck, R. Earle (2015). "Abundances in the Local Region. I. G and K Giants". Astronomical Journal 150 (3): 88. doi:10.1088/0004-6256/150/3/88. Bibcode2015AJ....150...88L. ]
  3. 3.0 3.1 Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series 71: 245. doi:10.1086/191373. Bibcode1989ApJS...71..245K. 
  4. Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode1986EgUBV........0M. 
  5. 5.0 5.1 5.2 5.3 Griffin, R. F. (February 1991). "Spectroscopic binary orbits from photoelectric radial velocities. Paper 96: 16 Serpentis". The Observatory 111: 29–37. Bibcode1991Obs...111...29G. 
  6. 6.0 6.1 Massarotti, Alessandro et al. (January 2008). "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity". The Astronomical Journal 135 (1): 209–231. doi:10.1088/0004-6256/135/1/209. Bibcode2008AJ....135..209M. 
  7. 7.0 7.1 7.2 Prugniel, Ph. et al. (July 2011). "The atmospheric parameters and spectral interpolator for the MILES stars". Astronomy & Astrophysics 531: A165. doi:10.1051/0004-6361/201116769. Bibcode2011A&A...531A.165P. 
  8. 8.0 8.1 "16 Ser". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=16+Ser. 
  9. Tomkin, J.; Lambert, D. L. (1986). "Heavy-element abundances in the mild barium stars Omicron Virginis and 16 Serpentis". The Astrophysical Journal 311: 819. doi:10.1086/164821. Bibcode1986ApJ...311..819T.