HD 196761

HD 196761 is the Henry Draper Catalogue designation for a G-type main-sequence star in the constellation Capricornus. With an apparent magnitude of 6.37 it is near the limit of what can be seen with the naked eye, but according to the Bortle Scale it may be possible to view it at night from rural skies. Based upon parallax measurements by the Hipparcos spacecraft, it is located about 47 light years from the Solar System.^[1]

HD 196761

Observation data Epoch J2000      Equinox J2000
Constellation	Capricornus
Right ascension	20h 40m 11.75616s[1]
Declination	−23° 46′ 25.9178″[1]
Apparent magnitude (V)	6.37[2]
Characteristics
Spectral type	G8V[3]
U−B color index	1.393[4]
B−V color index	0.719[5]
Astrometry
Radial velocity (Rv)	–45.3[6] km/s
Proper motion (μ)	RA: +501.45[1] mas/yr Dec.: +461.36[1] mas/yr
Parallax (π)	69.53 ± 0.40 mas[1]
Distance	46.9 ± 0.3 ly (14.38 ± 0.08 pc)
Absolute magnitude (MV)	5.58[7]
Details
Mass	0.81 ± 0.03[8] M☉
Radius	0.88[9] R☉
Surface gravity (log g)	4.54[3] cgs
Temperature	5,457[7] K
Metallicity [Fe/H]	-0.30[7] dex
Rotational velocity (v sin i)	3.50[10] km/s
Age	5.63[11] Gyr
Other designations
CD−24° 16193, GJ 796, HD 196761, HIP 101997, HR 7898, LTT 8172, SAO 189549.[2]
Database references
SIMBAD	data

It has a stellar classification of G8V with about 88%^[9] of the radius of the Sun and 81%^[8] of the Sun's mass. Compared to the Sun, this star has about half the proportion of elements other than hydrogen and helium.^[7][12] The projected rotational velocity of the star's equator is a relatively leisurely 3.50 km/s.^[10] This star has been examined for an infrared excess that could indicate the presence of a circumstellar disk of dust, but as of 2015 none has been detected.^[11]

The space velocity components of this star are U = −59, V = 20 and W = 4 km/s. It is presently following an orbit through the Milky Way that has an eccentricity of 0.18, bringing it as close as 24.27 kly (7.44 kpc) and as distant as 34.6 kly (10.6 kpc) from the Galactic Center. The inclination of this orbit will carry HD 196761 no more than 0.65 kly (0.20 kpc) from the plane of the galactic disk.^[7]

References

1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
2. "LHS 3570 -- High proper-motion Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2010-02-20.
3. Gray, R. O.; et al. (July 2006). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc-The Southern Sample". The Astronomical Journal. 132 (1): 161–170. arXiv:astro-ph/0603770. Bibcode:2006AJ....132..161G. doi:10.1086/504637. S2CID 119476992.
4. Rufener, F. (October 1976). "Second catalogue of stars measured in the Geneva Observatory photometric system". Astronomy & Astrophysics Supplement Series. 26: 275–351. Bibcode:1976A&AS...26..275R.
5. van Leeuwen, Floor (2007). Hipparcos, the new Reduction of the Raw data. Astrophysics and Space Science Library. Vol. 474. pp. 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. ISBN 978-1-4020-6341-1. S2CID 18759600. {{cite book}}: |journal= ignored (help)
6. Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". In Batten, Alan Henry; Heard, John Frederick (eds.). Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. University of Toronto: International Astronomical Union. Bibcode:1967IAUS...30...57E.
7. Holmberg, J.; Nordström, B.; Andersen, J. (July 2009). "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics". Astronomy and Astrophysics Supplement Series. 501 (3): 941–947. arXiv:0811.3982. Bibcode:2009A&A...501..941H. doi:10.1051/0004-6361/200811191. S2CID 118577511.
8. Santos, N. C.; et al. (July 2001), "The metal-rich nature of stars with planets", Astronomy and Astrophysics, 373 (3): 1019–1031, arXiv:astro-ph/0105216, Bibcode:2001A&A...373.1019S, doi:10.1051/0004-6361:20010648, S2CID 119347084.
9. Johnson, H. M.; Wright, C. D. (1983). "Predicted infrared brightness of stars within 25 parsecs of the Sun". Astrophysical Journal Supplement Series. 53: 643–711. Bibcode:1983ApJS...53..643J. doi:10.1086/190905.
10. Martínez-Arnáiz, R.; et al. (September 2010), "Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter" (PDF), Astronomy and Astrophysics, 520: A79, arXiv:1002.4391, Bibcode:2010A&A...520A..79M, doi:10.1051/0004-6361/200913725, S2CID 43455849, archived from the original (PDF) on 2017-09-22, retrieved 2018-11-04.
11. Moro-Martín, A.; et al. (March 2015), "Does the Presence of Planets Affect the Frequency and Properties of Extrasolar Kuiper Belts? Results from the Herschel Debris and Dunes Surveys", The Astrophysical Journal, 801 (2): 28, arXiv:1501.03813, Bibcode:2015ApJ...801..143M, doi:10.1088/0004-637X/801/2/143, S2CID 55170390, 143.
12. The metallicity of the star is −0.30, so the proportion of metals is given by:

    10^−0.30 = 0.501

    or 50%.