16 Serpentis
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]
| 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[1] mas |
| 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 | |
| Database references | |
| SIMBAD | data |
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
- 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.
- 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.]
- 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.
- 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.
- 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.
- 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.
- "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.