Theta1 Crucis

For other stars with the name θ Crucis, see Theta Crucis.
θ1 Crucis
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]
Distance235 ± 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
Mass1.57[7] M☉
Luminosity81[8] L☉
Surface gravity (log g)3.76[7] cgs
Temperature7341±250[7] K
Age1.1[7] Gyr
Other designations
θ1 Cru, CPD−62° 2543, HD 104671, HIP 58758, HR 4599, SAO 251705.[9]
Database references
SIMBADdata

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.

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]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Mermilliod1986 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Houk1975 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference gcsrv was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Eggen1998 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Pourbaix2004 was invoked but never defined (see the help page).
  7. ^ a b c d e f Cite error: The named reference David2015 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Mcdonald2012 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Renson2009 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Schroeder2007 was invoked but never defined (see the help page).