Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Crux |
Right ascension | 12h 23m 37.68840s[2] |
Declination | −61° 37′ 44.8570″[2] |
Apparent magnitude (V) | 6.89[3] |
Characteristics | |
Spectral type | F6-G2Ib-II[4] or F7Ib/II[5] |
B−V color index | 0.67±0.02[3] |
Variable type | δ Cep[6] |
Astrometry | |
Radial velocity (Rv) | −13.5±3.0[3] km/s |
Proper motion (μ) | RA: -9.404[2] mas/yr Dec.: −0.430[2] mas/yr |
Parallax (π) | 1.98 ± 0.54 mas[7] |
Distance | approx. 1,600 ly (approx. 500 pc) |
Details | |
Radius | 44.6[8] R☉ |
Surface gravity (log g) | 1.65[9] cgs |
Temperature | 5,812±22[9] K |
Metallicity [Fe/H] | +0.06[9] dex |
Other designations | |
Database references | |
SIMBAD | data |
R Crucis is a variable star in the southern constellation of Crux. It has a yellow-white hue and is often too faint to see with the naked eye, having an apparent visual magnitude that fluctuates around 6.89.[3] This object is located at a distance of approximately 1,600 light years from the Sun based on parallax,[7] but it is drifting closer with a radial velocity of −13.5 km/s.[3]
This is a Classical Cepheid, or Delta Cephei variable, that ranges in brightness from visual magnitude 6.40 down to 7.23 with a period of 5.82575 days.[6] It is a supergiant star with a stellar classification that varies over each pulsation cycle, giving it a class range of F6-G2Ib-II.[4] The star has a mean radius 44.6 times the radius of the Sun (44.6 R☉), but the radius varies by 5 R☉ during each pulsation.[11] It has a near solar metallicity and the atmospheric abundances indicate it is likely past first dredge-up.[9]
A candidate companion star has been detected at an angular separation of 7.6″, which corresponds to a projected separation of 6,330 AU. The Hubble WFC3 shows a closer companion at a separation of 1.9″.[12] The system is a source for X-ray emission but the contributing component is unclear.[13]
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