16 Serpentis

Binary star system in the constellation Serpens

16 Serpentis
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Serpens
Right ascension	15^h 36^m 29.57498^s^[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 (R_v)	+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]
Distance	228 ± 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
Mass	1.70^[2] `M`_☉
Radius	8^[6] `R`_☉
Luminosity	42.7^[2] `L`_☉
Surface gravity (log g)	2.64±0.12^[7] cgs
Temperature	4,946±51^[7] K
Metallicity [Fe/H]	−0.13±0.06^[7] dex
Rotational velocity (v sin i)	1.4^[6] km/s
Age	2.40^[2] Gyr

Other designations
16 Ser, BD+10°2884, FK5 3226, GC 20981, HD 139195, HIP 76425, HR 5802, SAO 101640^[8]
Database references
SIMBAD	data

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

^ ^a ^b ^c ^d ^e ^f ^g 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.
^ ^a ^b ^c ^d ^e ^f Luck, R. Earle (2015). "Abundances in the Local Region. I. G and K Giants". Astronomical Journal. 150 (3). 88. arXiv:1507.01466. Bibcode:2015AJ....150...88L. doi:10.1088/0004-6256/150/3/88. S2CID 118505114.]
^ ^a ^b Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373.
^ Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
^ ^a ^b ^c ^d Griffin, R. F. (February 1991). "Spectroscopic binary orbits from photoelectric radial velocities. Paper 96: 16 Serpentis". The Observatory. 111: 29–37. Bibcode:1991Obs...111...29G.
^ ^a ^b 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. Bibcode:2008AJ....135..209M. doi:10.1088/0004-6256/135/1/209.
^ ^a ^b ^c Prugniel, Ph.; et al. (July 2011). "The atmospheric parameters and spectral interpolator for the MILES stars". Astronomy & Astrophysics. 531: A165. arXiv:1104.4952. Bibcode:2011A&A...531A.165P. doi:10.1051/0004-6361/201116769. S2CID 54940439.
^ ^a ^b "16 Ser". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-03-22.
^ Tomkin, J.; Lambert, D. L. (1986). "Heavy-element abundances in the mild barium stars Omicron Virginis and 16 Serpentis". The Astrophysical Journal. 311: 819. Bibcode:1986ApJ...311..819T. doi:10.1086/164821.

Constellation of Serpens

Stars

Bayer	α (Unukalhai) β (Chow) γ (Ainalhai) δ ε ζ η θ (Alya) ι κ (Gudja) λ μ ν ξ ο π ρ σ τ¹ τ² τ³ τ⁴ τ⁵ τ⁶ τ⁷ τ⁸ υ φ χ ψ ω
Flamsteed	3 4 5 6 7 8 10 11 (A¹) 14 16 25 (A²) 29 36 (b) 39 40 43 45 46 47 59 (d) 60 (c) 61 64 3 Her 47 Oph
Variable	R W X RT UZ VV VY WX AA AN AO AP AR AU BQ CT CV CW EG FH FI FK FL FQ FR LV LW LX MR MS MT MV MY NN NO NQ NW OO OU PS QV QX QY V382 V411
HR	5665 5690 5692 5706 5711 5740 5745 5783 5796 5831 5850 5859 5861 5874 5909 5913 5931 5992 6005 6011 6014 6016 6449 6496 6544 6562 6568 6600 6620 6666 6681 6755 6756 6757 6785 6830 6840 6843 6858 6890 6898 6928 6993 (e) 6999 7008 7048 7076 7144
HD	135061 135615 136027 136118 138085 142245 143436 145936 146740 157969 168112 168443 168746 (Alasia) 175541 (Kaveh)
Other	ADS 9544 AS 296 9 11 22 23 27 Gliese 701 Gliese 710 GJ 1224 GX 17+2 IRAS 18418-0440 MWC 297 MWC 922 PG 1510+234 PG 1605+072 PSR B1534+11 PSR J1719−1438 Ross 508 Serpens FIRS 1 Serpens SVS 20 Serpens X-1 W40 IRS 1A South

Exoplanets	CoRoT-9b CoRoT-11b CoRoT-22b CoRoT-23b CoRoT-27b HD 168746 b (Onasilos) HD 175541 b (Kavian) ω Serpentis b

Star
clusters

NGC	NGC 6535 NGC 6539 NGC 6604 NGC 6605
Other	IC 4756 Messier 5 Messier 16 Serpens OB2 Serpens South Palomar 5

Nebulae

Other	Abell 41 Eagle Nebula L134 L183 L483 Serpens cloud Sh2-54 Westerhout 40 Red Square Nebula S68

Galaxies

NGC	5887 5910 5911 5913 5919 5920 5921 5926 5928 5931 5936 5937 5940 5942 5941 5944 5951 5953 5954 5952 5956 5955 5957 5960 5962 5964 5970 5972 5975 5977 5980 5983 5984 5988 5991 5990 5994 5996 5997 6003 6004 6008 6006 6007 6009 6012 6010 6014 6020 6017 6018 6021 6022 6023 6027 6027a 6027b 6027c 6027d 6027e 6029 6033 6037 6036 6051 6063 6065 6066 6070 6080 6100 6118 6172
Other	317 318 321 323.1 324 326 Arp 72 Arp 220 4C 11.50 CGCG 049-033 Hoag's Object IC 4537 IC 4588 IRAS 15107+0724 NRAO 530 PDS 456 PG 1553+113 PGC 54493 PKS 1546+027

NGC