X Caeli

This article is about γ² Caeli. For other stars with this Bayer designation, see γ Caeli.

X Caeli is a binary star^[11] system in the southern constellation of Caelum. It has the Bayer designation Gamma² Caeli, which is Latinized from γ² Caeli and abbreviated Gamma² Cae or γ² Cae; X Caeli is the system's variable star designation. This system is barely visible to the naked eye with a combined apparent visual magnitude of 6.32.^[1] Based upon an annual parallax shift of 9.7 mas,^[2] it is located at a distance of 336 light-years (103 pc) from Earth. The system is moving further away from the Sun with a radial velocity of +6 km/s.^[7]

X Caeli

Observation data Epoch J2000      Equinox J2000
Constellation	Caelum[1]
Right ascension	05h 04m 26.157s[2]
Declination	−35° 42′ 18.38″[2]
Apparent magnitude (V)	6.28 – 6.39[3] (6.43 + 9.65)[4]
Characteristics
Spectral type	F2 IV/V[5]
B−V color index	0.311±0.006[1]
Variable type	δ Sct[6]
Astrometry
Radial velocity (Rv)	+6.4±0.8[7] km/s
Proper motion (μ)	RA: +28.361 mas/yr[2] Dec.: +40.338 mas/yr[2]
Parallax (π)	9.7026±0.0221 mas[2]
Distance	336.2 ± 0.8 ly (103.1 ± 0.2 pc)
Absolute magnitude (MV)	1.36[1]
Details
X Cae A
Mass	1.52[8] M☉
Radius	3.43±0.32[9] R☉
Luminosity	23.65[1] L☉
Surface gravity (log g)	3.80[8] cgs
Temperature	7,227±246[8] K
Rotational velocity (v sin i)	69.0±1.0[9] km/s
Age	961[8] Myr
Other designations
γ2 Cae, γ2 Caeli, X Caeli, BD+27°2400, GC 6214, HD 32846, HIP 23596, HR 1653, SAO 195534, CCDM 05044-3542, WDS J05044-3542AB[10]
Database references
SIMBAD	data

Properties

A visual-band light curve for X Caeli, adapted from Mantegazza and Poretti (1996)^[12]

The yellow-white-hued primary, component A, has an apparent magnitude of +6.32 and stellar classification of F2 IV/V,^[5] showing mixed traits of an F-type main-sequence star and a subgiant. The spectral lines display a narrow absorption core that suggests the presence of a circumstellar shell.^[12]

This star is classified as a Delta Scuti variable with a brightness varies from magnitude 6.28 to 6.39 over a period of 3.25 hours. A 2000 observing campaign identified at least six independent pulsation modes for this variation.^[9][13] It has 1.5^[8] times the mass of the Sun and 3.4 times the Sun's radius.^[9] This star is radiating 24^[1] times the luminosity of the Sun from its photosphere at an effective temperature of 7,227 K.^[8] It is nearly a billion years old,^[8] with a relatively high rate of rotation, showing a projected rotational velocity of 69 km/s.^[9]

The companion star, component B, has an apparent magnitude of +9.65 and, as of 2000, is at an angular separation of 0.890″ along a position angle of 183°.^[4] The orbital period for this binary star system is unknown.^[11]