Astronomy:Theta Normae
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Norma |
| Right ascension | 16h 15m 15.31794s[1] |
| Declination | −47° 22′ 19.2710″[1] |
| Apparent magnitude (V) | 5.13[2] |
| Characteristics | |
| Spectral type | B8 V[3] |
| B−V color index | −0.12[2] |
| Astrometry | |
| Radial velocity (Rv) | +1.4±4.2[4] km/s |
| Proper motion (μ) | RA: −34.771 mas/yr Dec.: −45.813 mas/yr |
| Parallax (π) | 9.2718 ± 0.1692[5] mas |
| Distance | 352 ± 6 ly (108 ± 2 pc) |
| Absolute magnitude (MV) | −0.23[6] |
| Details | |
| Mass | 3.6[7] M☉ |
| Radius | 3.05[8] R☉ |
| Luminosity | 184[9] L☉ |
| Surface gravity (log g) | 4.5[7] cgs |
| Temperature | 12,341[9] K |
| Rotation | 1.144[10] days |
| Rotational velocity (v sin i) | 109[10] km/s |
| Age | 17[7] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
θ Normae, Latinised as Theta Normae, is a binary star system in the constellation Norma. It has an apparent visual magnitude of 5.13[2] and is visible to the naked eye as a faint, blue-white-hued point of light. Based upon an annual parallax shift of 9.27 mas as seen from Earth,[5] this system is located about 352 light-years from the Sun. At that distance, the visual magnitude of these stars is diminished by an extinction of 0.45 due to interstellar dust.[12]
Chini et al. (2012) identified this as a single-lined spectroscopic binary system.[13] The visible component is a B-type main-sequence star with a stellar classification of B8 V.[3] It is about 17[7] million tears old, with 3.6 times the mass of the Sun[7] and 3.05 times the Sun's radius.[8] It is radiating about 184 times the Sun's luminosity from its photosphere at an effective temperature of 12,341 K.[9] It is a mercury-manganese star, a B to A-type star with overabundances of the chemical elements mercury and manganese. It takes 1.144 days to fully rotate and has a projected rotational velocity of 109 km/s, unusually fast of a HgMn star.[10]
This system displays an infrared excess, suggesting a debris disk is orbiting at a mean radius of 21.8 astronomical unit|AU with a temperature of 220 K.[8]
References
- ↑ 1.0 1.1 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.
- ↑ 2.0 2.1 2.2 Corben, P. M.; Stoy, R. H. (1968), "Photoelectric Magnitudes and Colours for Bright Southern Stars", Monthly Notes of the Astronomical Society of Southern Africa 27: 11, Bibcode: 1968MNSSA..27...11C.
- ↑ 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 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.
- ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 7.0 7.1 7.2 7.3 7.4 Gullikson, Kevin et al. (2016), "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars", The Astronomical Journal 152 (2): 40, doi:10.3847/0004-6256/152/2/40, Bibcode: 2016AJ....152...40G.
- ↑ 8.0 8.1 8.2 Cotten, Tara H.; Song, Inseok (July 2016), "A Comprehensive Census of Nearby Infrared Excess Stars", The Astrophysical Journal Supplement Series 225 (1): 24, doi:10.3847/0067-0049/225/1/15, 15, Bibcode: 2016ApJS..225...15C.
- ↑ 9.0 9.1 9.2 McDonald, I. et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society 427 (1): 343–57, doi:10.1111/j.1365-2966.2012.21873.x, Bibcode: 2012MNRAS.427..343M.
- ↑ 10.0 10.1 10.2 Monier, Richard (2025-07-09), "The Far Ultraviolet Spectrum of the Newly Discovered HgMn Star HD 145842 (θ Nor)", Research Notes of the AAS 9 (7): 167, doi:10.3847/2515-5172/adec7c, ISSN 2515-5172.
- ↑ "tet Nor". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=tet+Nor.
- ↑ Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters 38 (11): 694–706, doi:10.1134/S1063773712110035, Bibcode: 2012AstL...38..694G.
- ↑ Chini, R. et al. (2012), "A spectroscopic survey on the multiplicity of high-mass stars", Monthly Notices of the Royal Astronomical Society 424 (3): 1925–1929, doi:10.1111/j.1365-2966.2012.21317.x, Bibcode: 2012MNRAS.424.1925C.
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