X Cancri

Not to be confused with χ (Chi) Cancri.
X Cancri
Location of X Cancri (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Cancer
Right ascension 08h 55m 22.88194s[1]
Declination +17° 13′ 52.5830″[1]
Apparent magnitude (V) 5.52 – 7.50[2]
Characteristics
Spectral type C-N4.5 C25.5 MS3[3]
B−V color index +2.975±0.039[4]
Variable type SRb[2]
Astrometry
Radial velocity (Rv)−5.0±0.7[4] km/s
Proper motion (μ) RA: −2.076[1] mas/yr
Dec.: +6.457[1] mas/yr
Parallax (π)1.7500 ± 0.0356 mas[1]
Distance1,860 ± 40 ly
(570 ± 10 pc)
Absolute magnitude (MV)−4.96[5]
Details
Radius208[6] R☉
Luminosity4,646[6] L☉
Surface gravity (log g)−0.014[6] cgs
Temperature3,239[6] K
Metallicity [Fe/H]−0.3[7] dex
Other designations
X Cnc, BD+17°1973, GC 12322, HD 76221, HIP 43811, HR 3541, SAO 98230[8]
Database references
SIMBADdata

X Cancri is a variable star in the northern constellation of Cancer.[8] It has a red hue and is visible to the naked eye at its brightest. The distance to this object is approximately 1,860 light years based on parallax measurements, but is drifting closer with a radial velocity of −5 km/s. It lies very close to the ecliptic and so is subject to lunar occultations.[9]

A visual band light curve for X Cancri, adapted from Percy et al. (2001)[10]

This object is a carbon star – an aging red giant star on the asymptotic giant branch that has a higher abundance of carbon than oxygen in its atmosphere[5] – and is one of the brightest carbon stars in the sky.[11] It has a carbon star spectral classification of C-N4.5 C25.5 MS3.[3] The first C indicates that it is a carbon star, and the N5 that it is a fairly cool strongly red AGB star. The C2 index indicates the strength of the Swan bands on a scale of one to eight, which shows the relative abundance of carbon vs oxygen. The MS index, not to be confused with an MS spectral class, indicates the strength of the SiC2 bands on a scale of one to seven. These bands are thought to be very sensitive to temperature.[12]

This is a semiregular variable star of subtype SRb that ranges in brightness from visual magnitude 5.52 down to 7.50 with a period of 193 days.[2] Fourier analysis has shown that the star also pulsates with periods of 350 and 1,870 days.[13]

The angular diameter of X Cancri has been measured using both lunar occultations and very long baseline interferometry, both methods giving a diameter around 8 mas.[14]

  1. ^ a b c d e Cite error: The named reference GaiaDR3 was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference Samus2017 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference barnbaum1996 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference guandalini2013 was invoked but never defined (see the help page).
  6. ^ a b c d Cite error: The named reference Mcdonald was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Lambert1986 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Schmidtke2011 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Percy was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Upgren1973 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference keenan1993 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference kiss1999 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference richichi2002 was invoked but never defined (see the help page).