Astronomy:Gamma2 Normae
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Norma |
| Right ascension | 16h 19m 50.42227s[1] |
| Declination | −50° 09′ 19.8223″[1] |
| Apparent magnitude (V) | 4.02[2] |
| Characteristics | |
| Spectral type | K0III[3] |
| U−B color index | +1.16[2] |
| B−V color index | +1.08[2] |
| Astrometry | |
| Radial velocity (Rv) | −28.9±0.7[4] km/s |
| Proper motion (μ) | RA: −159.71[1] mas/yr Dec.: −52.25[1] mas/yr |
| Parallax (π) | 25.33 ± 0.20[1] mas |
| Distance | 129 ± 1 ly (39.5 ± 0.3 pc) |
| Absolute magnitude (MV) | 1.057[5] |
| Details | |
| Mass | 2.16[5] M☉ |
| Luminosity | 51[6] L☉ |
| Surface gravity (log g) | 2.80[5] cgs |
| Temperature | 4,699[5] K |
| Metallicity [Fe/H] | 0.23[5] dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
| ARICNS | data |
Gamma2 Normae, Latinized from γ2 Nor, is the brightest star in the southern constellation of Norma. Its apparent magnitude is 4.02[2] – making it a faint star but visible to the naked eye. Based upon an annual parallax shift of 25.33 mas as seen from Earth,[1] this star is located roughly 129 light years from the Sun. It is moving closer to the Sun with a radial velocity of −29 km/s.[4]
This is an evolved, yellow-hued giant of spectral type K0 III[3] around 2.16[5] times as massive as the Sun that has swollen to a diameter 10 times that of the Sun.[8] It is a red clump star on the horizontal branch, which indicates it is generating energy through helium fusion at its core.[9] The star is radiating 51[6] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,699 K.[5]
Gamma2 Normae is a close double, with a magnitude 10 companion. The pair has been previously identified as a binary star system,[10] but the second release of Gaia data showed the companion star to be much more distant. Another 16-magnitude star, with a temperature of 5,972 K, is listed 20" away with nearly the same parallax and proper motion as Gamma2 Normae.[11]
γ1 Nor is a yellow supergiant located nearby on the celestial sphere, but is much further away from Earth and nearly a magnitude fainter.
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): 653–64. 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.
- ↑ 4.0 4.1 Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters 32 (11): 759–771, doi:10.1134/S1063773706110065, Bibcode: 2006AstL...32..759G.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 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 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ "* gam02 Nor". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+gam02+Nor.
- ↑ Kaler, James B.. "Gamma-2 Normae". Stars. University of Illinois. http://stars.astro.illinois.edu/sow/gamma2nor.html. Retrieved 23 March 2015.
- ↑ Laney, C. D. et al. (January 2012), "A new Large Magellanic Cloud K-band distance from precision measurements of nearby red clump stars", Monthly Notices of the Royal Astronomical Society 419 (2): 1637–1641, doi:10.1111/j.1365-2966.2011.19826.x, Bibcode: 2012MNRAS.419.1637L.
- ↑ 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.
- ↑ 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.
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