Theta Circini , θ Cir , θ Compass is a double star in the constellation Compass north of Alpha Compass . [6] It is poorly visible to the naked eye, since it has a visible magnitude of 5.110. [2] Based on the annual parallax measurement [9] , an estimate was obtained of the distance from the Sun to a given star: 1,500 light years (460 pc ).
| θ Compass | |||
|---|---|---|---|
| Star | |||
| Observational data ( Age J2000.0 ) | |||
| Right ascension | |||
| Declination | |||
| Visible magnitude ( V ) | 5,110 [2] (5.90 + 5.90) [3] | ||
| Constellation | Compass | ||
| Astrometry | |||
| Radial velocity ( R v ) | 3.00 [1] km / s | ||
| Own movement (μ) | RA: -11.70 [1] Dec: -11.69 [1] | ||
| Parallax (π) | 2.16 ± 0.29 mas | ||
| Absolute magnitude (V) | −3.21 | ||
| Characteristics | |||
| Spectral class | B3 Ve [5] (B2 + B2) [3] | ||
| Color Index ( B - V ) | +0.00 [2] | ||
| Color Index ( U - B ) | -0.77 [1] | ||
| Variability | Shell Star [6] | ||
| physical characteristics | |||
| Weight | 9.3 ± 0.6 [7] M ☉ | ||
| Age | 27.1 ± 6.1 [7] Ma | ||
| Temperature | 19099 [2] K | ||
| Rotation | 195 ± 13 [8] km / s | ||
| |||
| Database Information | |||
| SIMBAD | data | ||
Theta Circular is an astrometric binary [10] star system with an orbital period of about 39.6 years, an eccentricity of about 0.3, and a major semi-axis of the orbit of 85.64 msd. [5] The pair of stars together has a spectral class B3 Ve, [5] which corresponds to a star of class B of the main sequence . [5] The index 'e' indicates that this object is a Be-star . In other classifications, the star has the designations B4 Vnp [7] and B4npe, [5] where the symbol 'n' indicates the presence of wide absorption lines due to rotation, the symbol 'p' indicates chemical peculiarity . The two components of a binary star probably have similar visible magnitudes, masses, and spectral classes. [5] The system as a whole behaves like a variable of the Gamma Cassiopeia type [6] and exhibits flares of amplitude up to 0.27 in magnitude. [eleven]
Notes
- ↑ 1 2 3 4 5 6 tet Cir - Star , Center de Données astronomiques de Strasbourg , < http://simbad.u-strasbg.fr/simbad/sim-id?Ident=tet+Cir > . Retrieved July 25, 2017.
- ↑ 1 2 3 4 Soubiran, C .; Le Campion, J.-F .; Cayrel de Strobel, G. & Caillo, A. (June 2010), " The PASTEL catalog of stellar parameters ", Astronomy and Astrophysics T. 515: A111 , DOI 10.1051 / 0004-6361 / 201014247
- ↑ 1 2 Cvetkovic, Z. & Ninkovic, S. (June 2010), “ On the Component Masses of Visual Binaries ”, Serbian Astronomical Journal T. 180: 71–80 , DOI 10.2298 / SAJ1080071C
- ↑ 1 2 3 4 Collaboration G. Gaia DR2 - 2018 .-- T. 1345. - P. 0.
- ↑ 1 2 3 4 5 6 Mason, Brian D .; Hartkopf, William I. & Tokovinin, Andrei (September 2010), " Binary Star Orbits. IV. Orbits of 18 Southern Interferometric Pairs ", The Astronomical Journal T. 140 (3): 735-743 , DOI 10.1088 / 0004-6256 / 140/3/735
- ↑ 1 2 3 Arnold, HJP; Doherty, Paul & Moore, Patrick (1999), The Photographic Atlas of the Stars , CRC Press, p. 176, ISBN 0750306548 , < https://books.google.com/books?id=YjcvJUfnWBAC&pg=PA176 >
- ↑ 1 2 3 Tetzlaff, N .; Neuhäuser, R. & Hohle, MM (January 2011), " A catalog of young runaway Hipparcos stars within 3 kpc from the Sun ", Monthly Notices of the Royal Astronomical Society T. 410 (1): 190-200 , DOI 10.1111 / j.1365-2966.2010.17434.x
- ↑ Frémat, Y .; Zorec, J .; Hubert, A.-M. & Floquet, M. (September 2005), " Effects of gravitational darkening on the determination of fundamental parameters in fast-rotating B-type stars ", Astronomy and Astrophysics T. 440 (1): 305–320 , DOI 10.1051 / 0004- 6361: 20042229
- ↑ van Leeuwen, F. (2007), " Validation of the new Hipparcos reduction ", Astronomy and Astrophysics T. 474 (2): 653–664 , DOI 10.1051 / 0004-6361: 20078357
- ↑ Mason, Brian D .; ten Brummelaar, Theo; Gies, Douglas R. & Hartkopf, William I. (July 1997), “A Speckle Survey of Southern Be Stars”, Be Star Newsletter T. 32: 9-10
- ↑ Adelman, SJ; Mayer, MR & Rosidivito, MA (December 2000), "On the Variability of O4-B5 Luminosity Class III-V Stars", Information Bulletin on Variable Stars (no. 5008): 1