16 Serpentis

16 Serpentis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
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 mas[1]
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]

  1. ^ a b c d e f g Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d e f Cite error: The named reference Luck2015 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference perkins1989 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference EgUBV was invoked but never defined (see the help page).
  5. ^ a b c d Cite error: The named reference Griffin1991 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Massarotti2008 was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference Prugniel was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Simbad was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Tomkin1986 was invoked but never defined (see the help page).