2008A&A...491..311S


Query : 2008A&A...491..311S

2008A&A...491..311S - Astronomy and Astrophysics, volume 491, 311-320 (2008/11-3)

Direct evidence of a sub-stellar companion around CT Chamaeleontis.

SCHMIDT T.O.B., NEUHAEUSER R., SEIFAHRT A., VOGT N., BEDALOV A., HELLING Ch., WITTE S. and HAUSCHILDT P.H.

Abstract (from CDS):

In our ongoing search for close and faint companions around T Tauri stars in the Chamaeleon star-forming region, we here present observations of a new common proper motion companion to the young T-Tauri star and Chamaeleon member CT Cha and discuss its properties in comparison to other young, low-mass objects and to synthetic model spectra from different origins. Common proper motion of the companion and CT Cha was confirmed by direct Ks-band imaging data taken with the VLT Adaptive Optics (AO) instrument NACO in February 2006 and March 2007, together with a Hipparcos binary for astrometric calibration. An additional J-band image was taken in March 2007 to obtain color information for a first classification of the companion. Moreover, AO integral field spectroscopy with SINFONI in J, and H+K bands was obtained to deduce physical parameters of the companion, such as temperature and extinction. Relative flux calibration of the bands was achieved using photometry from the NACO imaging data. We found a very faint (Ks=14.9mag, Ks0=14.4mag) object, just ∼2.67" northwest of CT Cha corresponding to a projected separation of ∼440AU at 165±30pc. We show that CT Cha A and this faint object form a common proper motion pair and that the companion is by ≥4σ significance not a stationary background object. The near-infrared spectroscopy yields a temperature of 2600±250K for the companion and an optical extinction of AV=5.2±0.8mag, when compared to spectra calculated from Drift-Phoenix model atmospheres. We demonstrate the validity of the model fits by comparison to several other well-known young sub-stellar objects. We conclude that the CT Cha companion is a very low-mass member of Chamaeleon and very likely a physical companion to CT Cha, as the probability for a by chance alignment is ≤0.01. Due to a prominent Pa-β emission in the J-band, accretion is probably still ongoing onto the CT Cha companion. From temperature and luminosity (log(Lbol/L)=-2.68±0.21), we derive a radius of R=2.20–0.60+0.81RJup. We find a consistent mass of M=17±6MJup for the CT Cha companion from both its luminosity and temperature when placed on evolutionary tracks. Hence, the CT Cha companion is most likely a wide brown dwarf companion or possibly even a planetary mass object.

Abstract Copyright:

Journal keyword(s): stars: pre-main sequence - stars: planetary systems: formation - stars: individual: CT Cha

Simbad objects: 19

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Number of rows : 19
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 * 54 Psc B BD* 00 39 18.91 +21 15 16.8           T7.5 72 1
2 2MASS J01415823-4633574 BD* 01 41 58.2329929560 -46 33 57.347594316           L0gamma 67 0
3 V* V2384 Ori EB* 05 35 21.8473218600 -05 46 08.571352260       19.21 17.28 M7 97 1
4 HD 42581B BD* 06 10 34.80 -21 52 00.0           T6.5 493 0
5 V* CT Cha B LM* 11 04 08.44 -76 27 18.0           M8 46 0
6 V* CT Cha Or* 11 04 09.0989256840 -76 27 19.329779664   13.44 13.00   10.89 K7Ve 126 0
7 HD 96675 Y*O 11 05 57.8105960448 -76 07 48.884316960   7.82 7.68   8.48 B5V 79 0
8 CHXR 73B LM* 11 06 28.49 -77 37 34.2           M9.5+ 32 0
9 CHXR 73 Y*O 11 06 28.7641341696 -77 37 33.140151012         15.78 M3e 48 1
10 NAME Cha 1 MoC 11 06 48 -77 18.0           ~ 1110 1
11 NAME Chamaeleon Region SFR 11 55 -78.0           ~ 770 0
12 2MASS J12043036+3212595 BD* 12 04 30.3584978184 +32 12 59.523701148           L0e 21 0
13 HD 132347 ** 14 59 29.23211 -30 42 41.5076           A3mA5-F0 25 0
14 HD 137013 PM* 15 24 47.8171229616 -32 08 29.789031552   9.39 8.73     G3V 16 0
15 V* GQ Lup Or* 15 49 12.1053805848 -35 39 05.058139788 12.19 12.76 11.66 11.15   K7Ve 278 1
16 UScoCTIO 134 LM* 16 06 48.1814420832 -22 30 40.025477124           M8.00 15 0
17 2MASS J16071478-2321011 BD* 16 07 14.78112 -23 21 01.1052           L0 21 0
18 NAME Upper Sco Association As* 16 12 -23.4           ~ 1286 1
19 * eps Ind B BD* 22 04 10.5951812451 -56 46 58.239102418     24.12 20.8 15.60 T1V+T6V 157 1

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2023.06.04-18:54:56

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