Theta1 Crucis (θ1 Cru, Theta1 Crucis) is a spectroscopic binary star system in the southern constellation of Crux. It is visible to the naked eye with an apparent visual magnitude of 4.30m.[2] The distance to this star, as determined using parallax measurements,[1] is around 235 light years.
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Crux |
| Right ascension | 12h 03m 01.50130s[1] |
| Declination | −63° 18′ 46.5406″[1] |
| Apparent magnitude (V) | 4.30[2] |
| Characteristics | |
| Spectral type | A3(m)A8-A8[3] |
| U−B color index | +0.03[2] |
| B−V color index | +0.28[2] |
| Astrometry | |
| Radial velocity (Rv) | −2.4[4] km/s |
| Proper motion (μ) | RA: −152.35[1] mas/yr Dec.: +7.00[1] mas/yr |
| Parallax (π) | 13.88 ± 0.15 mas[1] |
| Distance | 235 ± 3 ly (72.0 ± 0.8 pc) |
| Absolute magnitude (MV) | +1.29[5] |
| Orbit[6] | |
| Period (P) | 24.4828 d |
| Eccentricity (e) | 0.61 |
| Periastron epoch (T) | 2419453.3470 JD |
| Argument of periastron (ω) (secondary) | 358.9° |
| Semi-amplitude (K1) (primary) | 46.1 km/s |
| Semi-amplitude (K2) (secondary) | 56.1 km/s |
| Details | |
| Mass | 1.57[7] M☉ |
| Luminosity | 81[8] L☉ |
| Surface gravity (log g) | 3.76[7] cgs |
| Temperature | 7341±250[7] K |
| Age | 1.1[7] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
The pair orbit each other closely with a period of 24.5 days and an eccentricity of 0.61.[6] The primary component is an Am star, which is a chemically peculiar A-type star that shows anomalous variations in absorption lines of certain elements.[10] It has a stellar classification of A3(m)A8-A8.[3] With a mass 157% times that of the Sun,[7] it radiates 81[8] times the Sun's luminosity from its outer atmosphere at an effective temperature of 7341 K.[7] Unusually for a fully radiative A-type star, X-ray emissions have been detected, which may instead be coming from the orbiting companion.[11]
References
edit- ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
- ^ a b c d Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
- ^ a b Houk, N.; Cowley, A. P. (1975), University of Michigan Catalogue of two-dimensional spectral types for the HD stars, vol. 1, Bibcode:1975mcts.book.....H.
- ^ Wilson, Ralph Elmer (1953), "General Catalogue of Stellar Radial Velocities", Carnegie Institute Washington D.C. Publication, Washington: Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W.
- ^ Eggen, Olin J. (July 1998), "The Age Range of Hyades Stars", The Astronomical Journal, 116 (1): 284–292, Bibcode:1998AJ....116..284E, doi:10.1086/300413.
- ^ a b Pourbaix, D.; Tokovinin, A. A.; Batten, A. H.; Fekel, F. C.; Hartkopf, W. I.; et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy & Astrophysics, 424 (2): 727–732, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213, S2CID 119387088.
- ^ a b c d e f 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, S2CID 33401607.
- ^ a b McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
- ^ "tet01 Cru". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-10-06.
{{cite web}}: CS1 maint: postscript (link) - ^ Renson, P.; Manfroid, J. (May 2009), "Catalogue of Ap, HgMn and Am stars", Astronomy and Astrophysics, 498 (3): 961–966, Bibcode:2009A&A...498..961R, doi:10.1051/0004-6361/200810788.
- ^ Schröder, C.; Schmitt, J. H. M. M. (November 2007), "X-ray emission from A-type stars", Astronomy and Astrophysics, 475 (2): 677–684, Bibcode:2007A&A...475..677S, doi:10.1051/0004-6361:20077429.