36 G. Doradus

36 G. Doradus (HD 40409) is a suspected astrometric binary^[8] star system in the southern constellation of Dorado. It is a faint system but visible to the naked eye with an apparent visual magnitude of 4.65.^[2] Based upon an annual parallax shift of 36.60 mas,^[1] it is located 89 light years away from the Sun. It is moving further away with a heliocentric radial velocity of +25 km/s.^[2] The system has a relatively high proper motion, traversing the celestial sphere at the rate of 0.57 arcseconds per year along a position angle of 14.51°.^[9]

36 G. Doradus

Observation data Epoch J2000      Equinox J2000
Constellation	Dorado
Right ascension	05h 54m 06.05459s[1]
Declination	−63° 05′ 23.2090″[1]
Apparent magnitude (V)	4.65[2]
Characteristics
Spectral type	K2 III[3]
B−V color index	1.022±0.045[2]
Astrometry
Radial velocity (Rv)	+25.1±0.8[2] km/s
Proper motion (μ)	RA: +148.129 mas/yr[1] Dec.: +550.143 mas/yr[1]
Parallax (π)	36.5981 ± 0.0924 mas[1]
Distance	89.1 ± 0.2 ly (27.32 ± 0.07 pc)
Absolute magnitude (MV)	2.56[2]
Details[4]
Mass	1.28±0.03[5] M☉
Radius	4.76±0.14 R☉
Luminosity	9.68±0.40[5] L☉
Surface gravity (log g)	3.020±0.155 cgs
Temperature	4,807±62 K
Metallicity [Fe/H]	+0.141±0.035 dex
Age	7.91[6] Gyr
Other designations
CD−63°218, FK5 2452, GJ 9194, HD 40409, HIP 27890, HR 2102, SAO 249390[7]
Database references
SIMBAD	data

Based on the stellar classification of K2 III assigned by Gray et al. (2006),^[3] the visible component is a K-type giant star. In contrast, Keenan and McNeil (1989) gave it a somewhat less evolved classification of K2 III–IV.^[10] It is about eight billion years old^[6] with 28% more mass than the Sun,^[5] and has expanded to 4.76 times the Sun's radius. The star is radiating 10^[5] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,807 K.^[4]

References

1. 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.
2. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
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. Ottoni, G.; Udry, S.; Ségransan, D.; Buldgen, G.; Lovis, C.; Eggenberger, P.; Pezzotti, C.; Adibekyan, V.; Marmier, M.; Mayor, M.; Santos, N. C.; Sousa, S. G.; Lagarde, N.; Charbonnel, C. (2022-01-01), "CORALIE radial-velocity search for companions around evolved stars (CASCADES). I. Sample definition and first results: Three new planets orbiting giant stars", Astronomy and Astrophysics, 657: A87, arXiv:2201.01528, Bibcode:2022A&A...657A..87O, doi:10.1051/0004-6361/202040078, ISSN 0004-6361 36 G. Doradus' database entry at VizieR.
5. Malla, Sai Prathyusha; Stello, Dennis; Montet, Benjamin T; Huber, Daniel; Hon, Marc; Bedding, Timothy R; Reyes, Claudia; Hey, Daniel R (2024-11-01), "Benchmarking the spectroscopic masses of 249 evolved stars using asteroseismology with TESS", Monthly Notices of the Royal Astronomical Society, 534 (3): 1775–1786, arXiv:2409.11736, Bibcode:2024MNRAS.534.1775M, doi:10.1093/mnras/stae2179, ISSN 0035-8711
6. Wittenmyer, Robert A.; Liu, Fan; Wang, Liang; Casagrande, Luca; Johnson, John Asher; Tinney, C. G. (July 2016), "The Pan-Pacific Planet Search. V. Fundamental Parameters for 164 Evolved Stars", The Astronomical Journal, 152 (1): 15, arXiv:1605.00323, Bibcode:2016AJ....152...19W, doi:10.3847/0004-6256/152/1/19, S2CID 55991800, 19.
7. "HD 40409". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-07-16.
8. 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.
9. Bakos, Gáspár Á.; et al. (July 2002), "Revised Coordinates and Proper Motions of the Stars in the Luyten Half-Second Catalog", The Astrophysical Journal Supplement Series, 141 (1): 187–193, arXiv:astro-ph/0202164, Bibcode:2002ApJS..141..187B, doi:10.1086/340115, S2CID 36667868.
10. 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.