Theta2 Crucis

Theta² Crucis

Observation data Epoch J2000      Equinox J2000
Constellation	Crux
Right ascension	12^h 04^m 19.2155^s[1]
Declination	−63° 09′ 56.559″[1]
Apparent magnitude (V)	4.718[2]
Characteristics
Spectral type	B2 IV[2]
U−B color index	−0.61[3]
B−V color index	−0.08[3]
Variable type	Beta Cephei variable
Astrometry
Radial velocity (Rv)	+16.3[4] km/s
Proper motion (μ)	RA: −17.19[1] mas/yr Dec.: −0.01[1] mas/yr
Parallax (π)	4.33 ± 0.53[1] mas
Distance	approx. 750 ly (approx. 230 pc)
Details
Rotational velocity (v sin i)	23[5] km/s
Other designations
HR 4603, CD-62 610, HD 104841, SAO 251717, HIP 58867.[2]

Theta² Crucis (θ² Cru / Theta² Crucis) is a spectroscopic binary star in the constellation Crux. This pair of stars complete an orbit every 3.4280 days and they have a low orbital eccentricity that is close to 0.0.^[6] Theta² Crucis is located at about 750 light-years from the Sun.^[1]

The system has a combined mean apparent magnitude of +4.72^m. Since a member of the system is a β Cephei-type variable star, the magnitude is not fixed but varies slightly between +4.70^m and +4.74^m. The period of this variability is 0.0889 days.^[7] The system is categorized as is a blue-white subgiant with a stellar classification of B2 IV.

References

1. Perryman, M. A. C.; et al. (April 1997). "The HIPPARCOS Catalogue". Astronomy & Astrophysics 323: L49–L52. Bibcode:1997A&A...323L..49P.
2. "V* tet02 Cru -- Spectroscopic binary". SIMBAD Astronomical Database. Centre de Données astronomiques de Strasbourg. Retrieved 2010-05-19.
3. Johnson, H. L.; Iriarte, B.; Mitchell, R. I.; Wisniewskj, W. Z. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory 4 (99). Bibcode:1966CoLPL...4...99J.
4. Wilson, Ralph Elmer (1953). General Catalogue of Stellar Radial Velocities. Washington: Carnegie Institution of Washington. Bibcode:1953QB901.W495.....
5. Bernacca, P. L.; Perinotto, M. (1970). "A catalogue of stellar rotational velocities". Contributi Osservatorio Astronomico di Padova in Asiago 239 (1). Bibcode:1970CoAsi.239....1B.
6. Batten, A. H. (1967). "Sixth catalogue of the orbital elements of spectroscopic binary systems". Publications of the Dominion Astrophysical Observatory, Victoria 13: 154–155. Bibcode:1967PDAO...13..119B.
7. Samus, N. N.; Durlevich, O. V.; et al. (January 2009). "General Catalogue of Variable Stars". VizieR. Retrieved 2010-05-19. Note: query for GCVS "tet 2 Cru".