CT Chamaeleontis

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CT Chamaeleontis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Chamaeleon
Right ascension 11h 04m 09.131s[1]
Declination −76° 27′ 19.30″[1]
Apparent magnitude (V) 12.31 to 12.43[2]
Spectral type K7[1]
B−V color index −0.9[1]
V−R color index 0.8[1]
Variable type INB[2]
Radial velocity (Rv) 15.1 ± 0.5[1] km/s
Proper motion (μ) RA: −21.3 ± 4.6[3] mas/yr
Dec.: 6.3 ± 4.5[3] mas/yr
Distance 540 ± 100 ly
(165 ± 30[3] pc)
Age Myr
Other designations
CT Cha.
Database references
CT Chamaeleontis b
Exoplanet Comparison CT Chamaeleontis b.png
A size comparison between the colossal planet CT Chamaeleontis b and Jupiter.
Position (relative to CT Chamaleontis)
Epoch of observation 2006–2007
Angular distance 2.670 [3]
Position angle 300.7° [3]
Observed separation
~440 AU [3]
Spectral type M8–L0[3]
Mass 17 ± 6 MJup
Radius 2.2+0.81
Luminosity 0.002 L
Surface gravity (log g) 3.5 cgs
Temperature 2,600 ± 250 K
Age Myr
Other designations
CT Cha b.
Database references

CT Chamaeleontis (CT Cha) is a T Tauri star in the constellation of Chamaeleon.[1] It has an apparent visual magnitude which varies between 12.31 and 12.43.[2]

In 2006 and 2007, a faint companion was observed 2.7 arcseconds away from CT Chamaeleontis, using the Very Large Telescope at the European Southern Observatory. Since the object shares common proper motion with CT Chamaleontis, it is believed to be physically close to the star, with a projected separation of approximately 440 astronomical units. It is estimated to have a mass of approximately 17 Jupiter masses and is probably a brown dwarf or a planet.[3] The companion has been designated CT Chamaeleontis b.[4]

The CT Chamaeleontis system
Companion Mass Observed separation
Discovery year
b 17 ± 6 MJ 200 2008


  1. ^ a b c d e f g V* CT Cha -- T Tau-type Star, database entry, SIMBAD. Accessed on line October 1, 2008.
  2. ^ a b c CT Cha, database entry, The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line October 1, 2008.
  3. ^ a b c d e f g h i j Direct evidence of a sub-stellar companion around CT Cha, T. O. B. Schmidt et al., accepted for publication in Astronomy and Astrophysics, Bibcode2008arXiv0809.2812S, arXiv:0809.2812.
  4. ^ NAME CT Cha b -- Extra-solar Planet Candidate, database entry, SIMBAD. Accessed on line October 1, 2008.