WZ Cassiopeiae

WZ Cassiopeiae

WZ Cassiopeiae in optical light
Observation data
Epoch J2000      Equinox J2000
Constellation Cassiopeia
Right ascension 00h 01m 15.85680s[1]
Declination +60° 21′ 19.0259″[1]
Apparent magnitude (V) 7.04[2] (6.3 – 8.8)[3]
Characteristics
Spectral type C-N7 III: C2 2 Li 10[4]
U−B color index +4.29[5]
B−V color index +2.835±0.040[2]
Variable type SRb[3]
Astrometry
Radial velocity (Rv)−34.0±2[6] km/s
Proper motion (μ) RA: +10.7693[1] mas/yr
Dec.: −5.672[1] mas/yr
Parallax (π)2.1227 ± 0.0297 mas[1]
Distance1,540 ± 20 ly
(471 ± 7 pc)
Details
Radius~600[7] R☉
Luminosity12,400[8] L☉
Temperature3,095[8] K
Other designations
WZ Cas, BD+59°2810, HD 224855, HIP 99, SAO 21002[9]
Database references
SIMBADdata

WZ Cassiopeiae (WZ Cas) is a deep red hued star in the northern constellation of Cassiopeia. It is a variable star with a magnitude that ranges from 6.3 down to 8.8,[3] placing it near the limit of naked eye visibility at peak magnitude. The estimated distance to this star, as determined from its annual parallax shift of 2.1 mas,[1] is about 1,540 light years. It is moving closer to the Earth with a heliocentric radial velocity of −34 km/s.[6]

A visual band light curve for WZ Cassiopeiae, adapted from Lebzelter et al. (2005)[7]

This is an aging carbon star on the asymptotic giant branch.[7] Keenan (1993) assigned it a classification of C-N7 III: C2 2 Li 10, which indicates it is of the N star subtype in the revised Morgan–Keenan system, with a C2 strength index of 2 (a measure of the excess of carbon over oxygen) and an anomalously strong line of lithium at 6707 Å.[4] It is losing mass at the rate of 6.5×10−9 M☉ yr−1, which is on the low side for a star of this type. This is a semiregular variable of subtype SRb[3] with periods of 186 and 366 days due to radial pulsations.[7] It has expanded to around 600 times the Sun's radius and is radiating 12,400 times the Sun's luminosity[8] from its photosphere at a relatively cool[10] effective temperature of 3,095 K.[8]

A magnitude 8.4 B-type visual companion, designated HD 224869, is located at an angular separation of 58″. The difference in the radial velocities for the two stars – 20 km/s – is too large for them to be dynamically associated.[11]

  1. ^ a b c d e f Cite error: The named reference GaiaDR3 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference gcvs was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference keenan1993 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Mendoza1965 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference GCRV was invoked but never defined (see the help page).
  7. ^ a b c d Cite error: The named reference Lebzelter2005 was invoked but never defined (see the help page).
  8. ^ a b c d Cite error: The named reference bergeat 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 Alksnis1994 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Herbig1955 was invoked but never defined (see the help page).