Zeta Hydri: Difference between revisions
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| names = {{odlist | B=ζ Hyi | CPD=−68° 169 | FK5=2191 | HD=17566 | HIP=12876 | HR=837 | SAO=248644 | GC=3354 }} |
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| names = [[Durchmusterung|CPD]]−68° 169, [[Fifth Fundamental Catalogue|FK5]] 2191, [[Boss General catalogue|GC]] 3354, [[Hipparcos catalogue|HIP]] 12876, [[Harvard Revised catalogue|HR]] 837, [[Henry Draper Catalogue|HD]] 17566, [[Smithsonian Astrophysical Observatory catalogue|SAO]] 248644 |
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'''Zeta Hydri''', [[Latinized]] from ζ Hydri, is a single,<ref name=Eggleton2008>{{citation | last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A. | title=A catalogue of multiplicity among bright stellar systems | journal=Monthly Notices of the Royal Astronomical Society | volume=389 | issue=2 | pages=869–879 | date=September 2008 | bibcode=2008MNRAS.389..869E | doi=10.1111/j.1365-2966.2008.13596.x | arxiv=0806.2878 | postscript=. }}</ref> white-hued [[star]] in the southern [[constellation]] of [[Hydrus (constellation)|Hydrus]]. It is faintly visible to the naked eye with an [[apparent magnitude]] of 4.83.<ref name=XHIP/> This distance to this star can be estimated from its annual [[stellar parallax|parallax shift]] of 11.47 [[milliarcsecond|mas]],<ref name=vanLeeuwen2007/> showing it to be about 284 [[light year]]s away. It is moving further away from the Sun with a [[radial velocity]] of +3.6 km/s.<ref name=Wilson1953/> |
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'''Zeta Hydri''' (ζ Hyi) is a class A2IV<ref name=XHIP/> (white subgiant) [[star]] in the [[constellation]] [[Hydrus (constellation)|Hydrus]]. Its apparent magnitude is 4.83<ref name=XHIP/> and it is approximately 284 light years away based on parallax.<ref name=vanLeeuwen2007/> |
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The [[spectrum]] of this star matches a [[stellar classification]] of A2 IV,<ref name=XHIP/> suggesting it is a [[subgiant star]] that is in the process of [[stellar evolution|evolving]] away from the [[main sequence]] as the supply of hydrogen at its code becomes exhausted. It has a high rate of spin, showing a [[projected rotational velocity]] of 116 km/s.<ref name=David2015/> This is giving the star a slight [[oblate spheroid|oblate shape]] with an [[equatorial bulge]] that is 5% larger than the polar radius.<ref name=belle>{{Cite journal | title=Interferometric observations of rapidly rotating stars | year=2012 | last1=Belle | first1=G. T. | journal=The Astronomy and Astrophysics Review | volume=20 | pages=51 | doi=10.1007/s00159-012-0051-2 | bibcode=2012A&ARv..20...51V | arxiv=1204.2572 }}</ref> It has 2.4 times the [[mass of the Sun]] and nearly four times the [[Sun's radius]].<ref name=AllendePrieto/> Zeta Hydri is radiating 80<ref name=XHIP/> times the [[Sun's luminosity]] into space from its [[photosphere]] at an [[effective temperature]] of 9,144 K.<ref name=David2015/> |
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==References== |
==References== |
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{{Stars of Hydrus}} |
{{Stars of Hydrus}} |
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[[Category:A-type subgiants]] |
[[Category:A-type subgiants]] |
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[[Category:Bayer objects|Hydri, Zeta]] |
[[Category:Bayer objects|Hydri, Zeta]] |
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[[Category:Durchmusterung objects]] |
[[Category:Durchmusterung objects]] |
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[[Category:Hipparcos objects|012876]] |
[[Category:Hipparcos objects|012876]] |
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[[Category:HR objects|0837]] |
[[Category:HR objects|0837]] |
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{{Subgiant-star-stub}} |
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Revision as of 20:02, 21 December 2017
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| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hydrus |
| Right ascension | 02h 45m 32.63435s[1] |
| Declination | −67° 36′ 59.8268″[1] |
| Apparent magnitude (V) | 4.83[2] |
| Characteristics | |
| Spectral type | A2IV[2] |
| U−B color index | +0.09[3] |
| B−V color index | +0.06[3] |
| Astrometry | |
| Radial velocity (Rv) | +3.60[4] km/s |
| Proper motion (μ) | RA: +66.41[1] mas/yr Dec.: +43.38[1] mas/yr |
| Parallax (π) | 11.47 ± 0.17 mas[1] |
| Distance | 284 ± 4 ly (87 ± 1 pc) |
| Absolute magnitude (MV) | 0.13[2] |
| Details | |
| Mass | 2.44[5] M☉ |
| Radius | 3.9[5] R☉ |
| Luminosity | 79.55[2] L☉ |
| Surface gravity (log g) | 3.72[6] cgs |
| Temperature | 9,144[6] K |
| Rotational velocity (v sin i) | 116[6] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Zeta Hydri, Latinized from ζ Hydri, is a single,[7] white-hued star in the southern constellation of Hydrus. It is faintly visible to the naked eye with an apparent magnitude of 4.83.[2] This distance to this star can be estimated from its annual parallax shift of 11.47 mas,[1] showing it to be about 284 light years away. It is moving further away from the Sun with a radial velocity of +3.6 km/s.[4]
The spectrum of this star matches a stellar classification of A2 IV,[2] suggesting it is a subgiant star that is in the process of evolving away from the main sequence as the supply of hydrogen at its code becomes exhausted. It has a high rate of spin, showing a projected rotational velocity of 116 km/s.[6] This is giving the star a slight oblate shape with an equatorial bulge that is 5% larger than the polar radius.[8] It has 2.4 times the mass of the Sun and nearly four times the Sun's radius.[5] Zeta Hydri is radiating 80[2] times the Sun's luminosity into space from its photosphere at an effective temperature of 9,144 K.[6]
References
- ^ a b c d e f Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. Vizier catalog entry
- ^ a b c d e f g 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. Vizier catalog entry
- ^ a b Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers. 42: 443. Bibcode:2014JAVSO..42..443M.Vizier catalog entry
- ^ a b Wilson, R. E. (1953). General Catalogue of Stellar Radial Velocities. Carnegie Institution of Washington. Bibcode:1953GCRV..C......0W. LCCN 54001336.
- ^ a b c 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. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A. Vizier catalog entry
- ^ a b c d e David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146. Vizier catalog entry
- ^ 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.
{{citation}}: CS1 maint: unflagged free DOI (link) - ^ Belle, G. T. (2012). "Interferometric observations of rapidly rotating stars". The Astronomy and Astrophysics Review. 20: 51. arXiv:1204.2572. Bibcode:2012A&ARv..20...51V. doi:10.1007/s00159-012-0051-2.
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