Chi Serpentis

Chi Serpentis (χ Ser, χ Serpentis) is a solitary star^[14] in the Serpens Caput section of the equatorial constellation Serpens. Based upon an annual parallax shift of 14.84 mas as seen from Earth, it is located around 222 light years from the Sun. The star is bright enough to be faintly visible to the naked eye, having an apparent visual magnitude of +5.30.^[3]

Chi Serpentis

A light curve for Chi Serpentis plotted from TESS data[1]
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Serpens
Right ascension	15h 41m 47.41474s[2]
Declination	+12° 50′ 51.0937″[2]
Apparent magnitude (V)	+5.30[3]
Characteristics
Spectral type	A2 Vp MnEu(Sr)[4]
U−B color index	+0.04[3]
B−V color index	+0.04[3]
Variable type	α2 CVn[5]
Astrometry
Radial velocity (Rv)	+1.90±1.78[6] km/s
Proper motion (μ)	RA: +39.045[2] mas/yr Dec.: −2.923[2] mas/yr
Parallax (π)	14.7221 ± 0.0748 mas[2]
Distance	222 ± 1 ly (67.9 ± 0.3 pc)
Absolute magnitude (MV)	+1.10[7]
Details
Mass	2.11[8] M☉
Radius	1.9[9] R☉
Luminosity	26[10] L☉
Surface gravity (log g)	3.66±0.24[11] cgs
Temperature	9,557±274[11] K
Metallicity [Fe/H]	+0.35±0.13[11] dex
Rotation	1.5948[7] d
Rotational velocity (v sin i)	75[12] km/s
Age	212[8] Myr
Other designations
χ Ser, 20 Ser, BD+13° 2982, FK5 3243, HD 140160, HIP 76866, HR 5843, SAO 101683.[13]
Database references
SIMBAD	data

In 1966 it was listed as a suspected spectroscopic binary,^[15] but it is believed to be single.^[14] This is a chemically peculiar star Ap star with a stellar classification of A2 Vp MnEu(Sr),^[4] indicating the spectrum shows abnormal excesses of manganese and europium. The star has 2.11^[8] times the mass of the Sun and about 1.9 times the Sun's radius.^[9] It is radiating 26^[10] times the solar luminosity from its photosphere at an effective temperature of 9,557 K.^[11] At the age of 212 million years,^[8] it is spinning with a rotation period of 1.6 days.^[15]

Chi Serpentis is classified as an Alpha2 Canum Venaticorum type variable star,^[5] and its magnitude varies by 0.03 with a period of 1.5948 days.^[7] The pattern of variation in the spectrum suggest there are regions of enhanced strontium, chromium, iron, titanium, and magnesium on the surface of the star.^[16] The averaged quadratic field strength of the surface magnetic field is (859.1±712.3)×10⁻⁴ T.^[17]

References

1. MAST: Barbara A. Mikulski Archive for Space Telescopes, Space Telescope Science Institute, retrieved 8 December 2021.
2. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
3. Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
4. Loden, L. O. (July 1983), "A physical study of the Ursa Major cluster (with special attention to the peculiar A stars)", Astronomy and Astrophysics Supplement Series, 53: 33–42, Bibcode:1983A&AS...53...33L.
5. Hoffleit, D. (October 1982), "Variable stars in the General Catalogue of Trigonometric Parallaxes", Bulletin d'Information du Centre de Données Stellaires, 23: 53, Bibcode:1982BICDS..23...53H.
6. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
7. Adelman, Saul J. (2002), "On the Periods of the Magnetic CP Stars", Baltic Astronomy, 11: 475–485, Bibcode:2002BaltA..11..475A.
8. David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
9. Pasinetti Fracassini, L. E.; Pastori, L.; Covino, S.; Pozzi, A. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics, 367 (2) (3rd ed.): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
10. McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
11. 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.
12. Royer, F.; et al. (October 2012), "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i", Astronomy and Astrophysics, 393 (3): 897–911, arXiv:astro-ph/0205255, Bibcode:2002A&A...393..897R, doi:10.1051/0004-6361:20020943, S2CID 14070763.
13. "chi Ser", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2017-03-23.
14. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
15. Rajamohan, R.; Babu, G. S. D. (March 1978), "On the intrinsic rotation of magnetic variables", Monthly Notices of the Royal Astronomical Society, 182 (4): 773–776, Bibcode:1978MNRAS.182..773R, doi:10.1093/mnras/182.4.773.
16. Riabchikova, T. A. (February 1975), "The spectroscopic variable AP star chi Serpentis", Soviet Astronomy, 18: 451–453, Bibcode:1975SvA....18..451R.
17. Bychkov, V. D.; et al. (April 2009), "Catalogue of averaged stellar effective magnetic fields - II. Re-discussion of chemically peculiar A and B stars", Monthly Notices of the Royal Astronomical Society, 394 (3): 1338–1350, Bibcode:2009MNRAS.394.1338B, doi:10.1111/j.1365-2966.2008.14227.x, S2CID 120268049.