Astronomy:Eta Normae
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Norma |
| Right ascension | 16h 03m 12.89783s[1] |
| Declination | −49° 13′ 46.9151″[1] |
| Apparent magnitude (V) | 4.65[2] |
| Characteristics | |
| Evolutionary stage | horizontal branch |
| Spectral type | G8III[3] |
| U−B color index | +0.64[2] |
| B−V color index | +0.92[2] |
| Astrometry | |
| Radial velocity (Rv) | −0.3±2.8[4] km/s |
| Proper motion (μ) | RA: 42.05[1] mas/yr Dec.: 9.14[1] mas/yr |
| Parallax (π) | 14.86 ± 0.25[1] mas |
| Distance | 219 ± 4 ly (67 ± 1 pc) |
| Absolute magnitude (MV) | 0.524[5] |
| Details | |
| Mass | 2.78[5] M☉ |
| Radius | 11.07+0.23 −0.09[6] R☉ |
| Luminosity | 71.9±3.1[6] L☉ |
| Surface gravity (log g) | 2.84[5] cgs |
| Temperature | 5052+16 −51[6] K |
| Metallicity [Fe/H] | −0.05[5] dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
Eta Normae, Latinized from η Normae, is a single[8] star in the southern constellation of Norma. It is visible to the naked eye as a faint, yellow-hued star with an apparent visual magnitude of 4.65.[2] The distance to this star is about 219 light years, based on parallax.[1] The Gamma Normids radiate from a position near this star.[9]
This is an aging giant star with a stellar classification of G8III,[3] having exhausted the supply of hydrogen at its core then swollen and cooled off the main sequence. At present it has a diameter of 11[6] times that of the Sun. It is a red clump[5] giant, meaning it is on the horizontal branch and is generating energy through core helium fusion. The star has 2.78[5] times the mass of the Sun and is radiating 72[6] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 5,052 K.[6] It is a source for X-ray emission.[10]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 2.3 Johnson, H. L. et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory 4 (99): 99, Bibcode: 1966CoLPL...4...99J.
- ↑ 3.0 3.1 Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 2, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode: 1978mcts.book.....H.
- ↑ 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, doi:10.1051/0004-6361/201219219, A61, Bibcode: 2012A&A...546A..61D.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Liu, Y. J. et al. (2007), "The abundances of nearby red clump giants", Monthly Notices of the Royal Astronomical Society 382 (2): 553–66, doi:10.1111/j.1365-2966.2007.11852.x, Bibcode: 2007MNRAS.382..553L.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ "eta Nor". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=eta+Nor.
- ↑ 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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E.
- ↑ Lunsford, Robert (2009), Meteors and How to Observe Them, Astronomers' Observing Guides, Springer Science & Business Media, pp. 76–77, ISBN 9780387094618, https://books.google.com/books?id=iu9XakR51EsC&pg=PA76.
- ↑ Haakonsen, Christian Bernt; Rutledge, Robert E. (September 2009), "XID II: Statistical Cross-Association of ROSAT Bright Source Catalog X-ray Sources with 2MASS Point Source Catalog Near-Infrared Sources", The Astrophysical Journal Supplement 184 (1): 138–151, doi:10.1088/0067-0049/184/1/138, Bibcode: 2009ApJS..184..138H.
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