HD 40657

HD 40657 is a single^[11] star in the equatorial constellation of Orion, near the constellation border with Monoceros. It has an orange hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.52.^[2] The star is located at a distance of approximately 289 light years from the Sun based on parallax.^[1] It is drifting further away with a radial velocity of +26 km/s.^[5]

HD 40657

Location of HD 40657 (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Orion
Right ascension	06h 00m 03.34979s[1]
Declination	−3° 04′ 27.3341″[1]
Apparent magnitude (V)	4.52[2]
Characteristics
Spectral type	K1.5III-IIIb CN-1[3]
U−B color index	+1.21[2]
B−V color index	+1.22[2]
Variable type	suspected[4]
Astrometry
Radial velocity (Rv)	+25.9±0.9[5] km/s
Proper motion (μ)	RA: +10.646[1] mas/yr Dec.: −73.589[1] mas/yr
Parallax (π)	11.2968 ± 0.2633 mas[1]
Distance	289 ± 7 ly (89 ± 2 pc)
Absolute magnitude (MV)	−1.00[6]
Details
Mass	1.68[7] M☉
Radius	25.06+0.84 −0.51[1] R☉
Luminosity	196.4±5.2[1] L☉
Surface gravity (log g)	2.42[8] cgs
Temperature	4,317+53 −80[1] K
Metallicity [Fe/H]	−0.48[6] dex
Rotational velocity (v sin i)	2.1[9] km/s
Age	2.27[7] Gyr
Other designations
NSV 2770, BD−03°1256, FK5 2457, GC 7587, HD 40657, HIP 28413, HR 2113, SAO 132732[10]
Database references
SIMBAD	data

This is an aging giant star with a stellar classification of K1.5III-IIIb CN-1,^[3] where the suffix notation indicates an underabundance of cyanogen in the spectrum. Having exhausted the supply of hydrogen at its core, this star cooled and expanded off the main sequence. At present it has 25 times the radius of the Sun.^[1]

HD 40657 is a suspected variable star with a brightness that has been measured ranging from magnitude 4.54 down to 4.58.^[4] It is an estimated 2.27^[7] billion years old with 1.68^[7] times the mass of the Sun and is spinning with a projected rotational velocity of 2.1 km/s.^[9] The star is radiating 196 times the Sun's luminosity from its swollen photosphere at an effective temperature of 4,317 K.^[1]

References

1. 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.
2. Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
3. Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". The Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373.
4. Samus, N. N.; et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. 5.1. 61 (1): 80–88. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. S2CID 125853869.
5. Wilson, R. E. (1953). "General Catalogue of Stellar Radial Velocities". Carnegie Institute Washington D.C. Publication. Carnegie Institution for Science. Bibcode:1953GCRV..C......0W. LCCN 54001336.
6. 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. Vizier catalog entry
7. 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.
8. Soubiran, Caroline; Le Campion, Jean-François; Brouillet, Nathalie; Chemin, Laurent (2016). "The PASTEL catalogue: 2016 version". Astronomy & Astrophysics. 591: A118. arXiv:1605.07384. Bibcode:2016A&A...591A.118S. doi:10.1051/0004-6361/201628497. S2CID 119258214.
9. De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (2014). "A catalog of rotational and radial velocities for evolved stars". Astronomy & Astrophysics. 561: A126. arXiv:1312.3474. Bibcode:2014A&A...561A.126D. doi:10.1051/0004-6361/201220762. S2CID 54046583. Vizier catalog entry
10. "HD 40657". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-12-31.
11. 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.