T Chamaeleontis

A visual band light curve for T Chamaeleontis, plotted from AAVSO data [1]
Observation data Epoch J2000.0       Equinox J2000.0 ( ICRS)
Constellation	Chamaeleon
Right ascension	11h 57m 13.52451s [2]
Declination	−79° 21′ 31.5305″ [2]
Apparent magnitude (V)	10.05 - 14.50 [3]
Characteristics
Evolutionary stage	T Tauri star [4]
Spectral type	K0e [5]
U−B color index	+0.63 [6]
B−V color index	+1.14 [6]
J−K color index	+1.67 [7]
Variable type	Orion variable [8]
Astrometry
Radial velocity (Rv)	13.8±0.1 [9] km/s
Proper motion (μ)	RA: −41.586  mas/ yr [2] Dec.: −8.655  mas/ yr [2]
Parallax (π)	9.7356 ± 0.0332  mas [2]
Distance	335 ± 1  ly (102.7 ± 0.4  pc)
Absolute magnitude (MV)	+6.55 [10]
Details
Mass	0.65 [11]  M☉
Radius	0.65±0.09 [12]  R☉
Luminosity	0.29 [13]  L☉
Surface gravity (log g)	4.50 [13]  cgs
Temperature	5,111 [14]  K
Metallicity [Fe/H]	+0.09±0.15 [15]  dex
Rotational velocity (v sin i)	39±3 [16] km/s
Age	12.7 [17]  Myr
Other designations
T Cha, HIP 58285, TYC 9419-1187-1, GSC 09419-01187, 2MASS J11571348-7921313
Database references
SIMBAD	data

T Chamaeleontis (T Cha), also known as HIP 58285, is a T Tauri star located in the southern circumpolar constellation Chamaeleon. It has an apparent magnitude that ranges from 10.05 to 14.50, ^[3] which is below the limit for naked eye visibility. Gaia DR3 parallax measurements place the object 335 light years away ^[2] and it is currently receding with a heliocentric radial velocity of 13.8  km/s. ^[9] At its current distance, T Cha's average brightness is diminished by 0.31 magnitudes due to extinction from interstellar dust. It has an average absolute magnitude of +6.55. ^[10]

History

The object was first suspected to be a RW Aurigae-type star since 1949. ^[18] It was categorized as a T-Tauri star in 1975. In the same year, it was suspected to be variable and the variability was confirmed in 1976. ^[19] A 1993 paper said that it might be a weak-lined YY Orionis star. ^[20] T Cha might be either a member of the young ε Chamaeleontis association or the slightly older η Chamaeleontis association. ^{[17] [9]} T Cha is an Orion variable that fluctuates between 10.05 and 14.5. ^{[3] [8]}

Physical characteristics

T Cha has a stellar classification of K0e, ^[5] indicating that it is a K-type star with emission lines in its spectrum. It is currently on the T Tauri stage, ^[4] accreting matter at a rate of 3.16×10⁻⁹ to 1.26×10⁻⁸  M_☉/yr. ^[21] It has 65% the mass of the Sun ^[11] but the radius is highly uncertain. Estimates range from 0.65 to 4.36 times the radius of the Sun. ^{[22] [12]} It radiates 29% the luminosity of the Sun ^[13] from its photosphere at an effective temperature of 5,111  K, ^[14] giving it an orange hue. T Cha has a poorly constrained metallicity of [Fe/H] = +0.09 ^[15] and it spins modestly with a projected rotational velocity of 39  km/s. ^[16]

References