| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hydra |
| Right ascension | 08h 41m 43.33591s [1] |
| Declination | −15° 56′ 36.1727″ [1] |
| Apparent magnitude (V) | 4.866 [2] |
| Characteristics | |
| Spectral type | K0 III CNII [3] |
| U−B color index | +0.92 [4] |
| B−V color index | +1.07 [4] |
| Astrometry | |
| Radial velocity (Rv) | −1.98±0.12 [1] km/s |
| Proper motion (μ) |
RA: 3.676
[1]
mas/
yr Dec.: -97.743 [1] mas/ yr |
| Parallax (π) | 15.9089 ± 0.1297 mas [1] |
| Distance | 205 ± 2
ly (62.9 ± 0.5 pc) |
| Absolute magnitude (MV) | +0.81 [5] |
| Details [6] | |
| Mass | 1.72±0.46 [7] M☉ |
| Radius | 11.10+0.15 −0.69 [1] R☉ |
| Luminosity | 54.445+0.536 −0.457 [1] L☉ |
| Surface gravity (log g) | 2.8 cgs |
| Temperature | 4,688±5 K |
| Metallicity [Fe/H] | −0.01 dex |
| Rotational velocity (v sin i) | 1.7 km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
9 Hydrae is a single [9] star in the equatorial constellation of Hydra, [8] located 205 light years away from the Sun. [1] It is visible to the naked eye as a faint, yellow-orange hued star with an apparent visual magnitude of 4.87. [2] This body is moving closer to the Sun with a heliocentric radial velocity of −2 km/s. [1]
This is an aging giant star with a stellar classification of K0 III CNII, [3] where the suffix notation indicates an overabundance of cyanogen in the spectrum. It is a red clump giant, [10] which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. The star has 1.7 [7] times the mass of the Sun but, as a consequence of evolving away from the main sequence, its envelope has swollen to 11 [1] times the Sun's radius. It is radiating 54 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,688 K. [6]
- ^ a b c d e f g h i j k 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 Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode: 2000A&A...355L..27H.
- ^ a b Houk, N.; Smith-Moore, M. (1988). "Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 4, Declinations -26°.0 to -12°.0". Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. 4. Bibcode: 1988mcts.book.....H.
- ^ a b Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode: 1966CoLPL...4...99J.
- ^ 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 Massarotti, Alessandro; Latham, David W.; Stefanik, Robert P.; Fogel, Jeffrey (2008). "Rotational and Radial Velocities for a Sample of 761 Hipparcos Giants and the Role of Binarity". The Astronomical Journal. 135 (1): 209–231. Bibcode: 2008AJ....135..209M. doi: 10.1088/0004-6256/135/1/209.
- ^ a b Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555–562. arXiv: astro-ph/9911002. Bibcode: 1999A&A...352..555A.
- ^ a b "9 Hya". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved April 26, 2019.
- ^ 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.
- ^ Alves, David R. (August 2000), "K-Band Calibration of the Red Clump Luminosity", The Astrophysical Journal, 539 (2): 732–741, arXiv: astro-ph/0003329, Bibcode: 2000ApJ...539..732A, doi: 10.1086/309278, S2CID 16673121.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hydra |
| Right ascension | 08h 41m 43.33591s [1] |
| Declination | −15° 56′ 36.1727″ [1] |
| Apparent magnitude (V) | 4.866 [2] |
| Characteristics | |
| Spectral type | K0 III CNII [3] |
| U−B color index | +0.92 [4] |
| B−V color index | +1.07 [4] |
| Astrometry | |
| Radial velocity (Rv) | −1.98±0.12 [1] km/s |
| Proper motion (μ) |
RA: 3.676
[1]
mas/
yr Dec.: -97.743 [1] mas/ yr |
| Parallax (π) | 15.9089 ± 0.1297 mas [1] |
| Distance | 205 ± 2
ly (62.9 ± 0.5 pc) |
| Absolute magnitude (MV) | +0.81 [5] |
| Details [6] | |
| Mass | 1.72±0.46 [7] M☉ |
| Radius | 11.10+0.15 −0.69 [1] R☉ |
| Luminosity | 54.445+0.536 −0.457 [1] L☉ |
| Surface gravity (log g) | 2.8 cgs |
| Temperature | 4,688±5 K |
| Metallicity [Fe/H] | −0.01 dex |
| Rotational velocity (v sin i) | 1.7 km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
9 Hydrae is a single [9] star in the equatorial constellation of Hydra, [8] located 205 light years away from the Sun. [1] It is visible to the naked eye as a faint, yellow-orange hued star with an apparent visual magnitude of 4.87. [2] This body is moving closer to the Sun with a heliocentric radial velocity of −2 km/s. [1]
This is an aging giant star with a stellar classification of K0 III CNII, [3] where the suffix notation indicates an overabundance of cyanogen in the spectrum. It is a red clump giant, [10] which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. The star has 1.7 [7] times the mass of the Sun but, as a consequence of evolving away from the main sequence, its envelope has swollen to 11 [1] times the Sun's radius. It is radiating 54 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,688 K. [6]
- ^ a b c d e f g h i j k 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 Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode: 2000A&A...355L..27H.
- ^ a b Houk, N.; Smith-Moore, M. (1988). "Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 4, Declinations -26°.0 to -12°.0". Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. 4. Bibcode: 1988mcts.book.....H.
- ^ a b Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode: 1966CoLPL...4...99J.
- ^ 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 Massarotti, Alessandro; Latham, David W.; Stefanik, Robert P.; Fogel, Jeffrey (2008). "Rotational and Radial Velocities for a Sample of 761 Hipparcos Giants and the Role of Binarity". The Astronomical Journal. 135 (1): 209–231. Bibcode: 2008AJ....135..209M. doi: 10.1088/0004-6256/135/1/209.
- ^ a b Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555–562. arXiv: astro-ph/9911002. Bibcode: 1999A&A...352..555A.
- ^ a b "9 Hya". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved April 26, 2019.
- ^ 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.
- ^ Alves, David R. (August 2000), "K-Band Calibration of the Red Clump Luminosity", The Astrophysical Journal, 539 (2): 732–741, arXiv: astro-ph/0003329, Bibcode: 2000ApJ...539..732A, doi: 10.1086/309278, S2CID 16673121.