R Crucis

R Crucis

A visual band light curve for R Crucis, adapted from Dean et al. (1977)[1]
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]
Distanceapprox. 1,600 ly
(approx. 500 pc)
Details
Radius44.6[8] R☉
Surface gravity (log g)1.65[9] cgs
Temperature5,812±22[9] K
Metallicity [Fe/H]+0.06[9] dex
Other designations
R Cru, CD−60°4138, HD 107805, HIP 60455, SAO 251878[10]
Database references
SIMBADdata

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]

  1. ^ Cite error: The named reference Dean was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  3. ^ a b c d e Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference AAVSOR was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Houk1979 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Samus2017 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference moskalik2005 was invoked but never defined (see the help page).
  9. ^ a b c d Cite error: The named reference Usenko2014 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Moskalik2005 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Evans2016 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Engle2017 was invoked but never defined (see the help page).