6 Hydrae

6 Hydrae
Observation data; Epoch J2000.0 Equinox J2000.0
Constellation	Hydra
Right ascension	08h 40m 01.47182s
Declination	−12° 28′ 31.3433″
Apparent magnitude (V)	4.98
Characteristics
Evolutionary stage	giant
Spectral type	K3 III
B−V color index	1.415±0.001
Astrometry
Radial velocity (Rv)	−7.8±0.6 km/s
Proper motion (μ)	RA: −81.619 mas/yr ; Dec.: −1.646 mas/yr
Parallax (π)	8.7394 ± 0.1769 mas
Distance	373 ± 8 ly ; (114 ± 2 pc)
Absolute magnitude (MV)	−0.40
Details
Radius	32.7+0.5; −2.6 R☉
Luminosity	267±6 L☉
Surface gravity (log g)	1.91 cgs
Temperature	4,080+173; −30 K
Metallicity	−0.21 dex
Other designations
	a Hya, 6 Hya, BD−11°2420, HD 73840, HIP 42509, HR 3431, SAO 154515
Database references
SIMBAD	data

6 Hydrae is a single^[7] star in the equatorial constellation of Hydra,^[6] located 373 light-years away from the Sun.^[1] It has the Bayer designation a Hydrae; 6 Hydrae is the Flamsteed designation. This object is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.98.^[2] It is moving closer to the Earth with a heliocentric radial velocity of −8 km/s.^[4] Eggen (1995) listed it as a proper motion candidate for membership in the IC 2391 supercluster.^[8]

This is an aging giant star with a stellar classification of K3 III,^[3] which indicates it has exhausted the hydrogen at its core and evolved away from the main sequence. As a consequence, it has expanded to 33^[1] times the radius of the Sun. The star is radiating 267^[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,080 K.^[1]

References

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l 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.
^ ^a ^b ^c ^d 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.
^ ^a ^b Houk, Nancy; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.
^ ^a ^b 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.
^ ^a ^b McWilliam, Andrew (December 1990), "High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances", Astrophysical Journal Supplement Series, 74: 1075–1128, Bibcode:1990ApJS...74.1075M, doi:10.1086/191527.
^ ^a ^b "6 Hya". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-04-23.
^ Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
^ Eggen, Olin J. (December 1995), "Reality Tests of Superclusters in the Young Disk Population", Astronomical Journal, 110: 2862, Bibcode:1995AJ....110.2862E, doi:10.1086/117734.

Zdroj:https://en.wikipedia.org?pojem=6_Hydrae
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[GaiaDR2-1] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l 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.

[Anderson2012-2] 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.

[houk1978-3] Houk, Nancy; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.

[deBruijne2012-4] 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.

[McWilliam1990-5] McWilliam, Andrew (December 1990), "High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances", Astrophysical Journal Supplement Series, 74: 1075–1128, Bibcode:1990ApJS...74.1075M, doi:10.1086/191527.

[SIMBAD-6] "6 Hya". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-04-23.

[Eggleton2008-7] Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.

[Eggen1995-8] Eggen, Olin J. (December 1995), "Reality Tests of Superclusters in the Young Disk Population", Astronomical Journal, 110: 2862, Bibcode:1995AJ....110.2862E, doi:10.1086/117734.

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Observation data Epoch J2000.0 Equinox J2000.0
Constellation	Hydra
Right ascension	08^h 40^m 01.47182^s^[1]
Declination	−12° 28′ 31.3433″^[1]
Apparent magnitude (V)	4.98^[2]
Characteristics
Evolutionary stage	giant
Spectral type	K3 III^[3]
B−V color index	1.415±0.001^[2]
Astrometry

Radial velocity (R_v)	−7.8±0.6^[4] km/s
Proper motion (μ)	RA: −81.619^[1] mas/yr Dec.: −1.646^[1] mas/yr
Parallax (π)	8.7394 ± 0.1769 mas^[1]
Distance	373 ± 8 ly (114 ± 2 pc)
Absolute magnitude (M_V)	−0.40^[2]

Details

Radius	32.7+0.5 −2.6^[1] `R`_☉
Luminosity	267±6^[1] `L`_☉
Surface gravity (log g)	1.91^[5] cgs
Temperature	4,080+173 −30^[1] K
Metallicity	−0.21^[5] dex

Other designations
a Hya, 6 Hya, BD−11°2420, HD 73840, HIP 42509, HR 3431, SAO 154515^[6]
Database references
SIMBAD	data