2006A&A...448..655J


C.D.S. - SIMBAD4 rel 1.7 - 2019.07.20CEST22:56:50

2006A&A...448..655J - Astronomy and Astrophysics, volume 448, 655-663 (2006/3-3)

Improved kinematics for brown dwarfs and very low-mass stars in Chamaeleon I and a discussion of brown dwarf formation.

JOERGENS V.

Abstract (from CDS):

We present a precise kinematic study of very young brown dwarfs in the Cha I cloud based on radial velocities (RVs) measured with UVES at the VLT. The kinematics of the brown dwarfs in ChaI are compared to the kinematics of T Tauri stars in the same field, based on both UVES measurements for very low-mass ones and on RVs from the literature. More UVES spectra were taken compared with a former paper (Joergens & Guenther, 2001A&A...379L...9J), and the reduction of the spectra was improved, while studying the literature for RVs of T Tauri stars in ChaI led to a cleaned and enlarged sample of T Tauri stars. The result is an improved empirical RV distribution of brown dwarfs, as well as of T Tauri stars in ChaI. We found that the RVs of the nine brown dwarfs and very low-mass stars (M6-M8) in ChaI that were studied have a mean value of 15.7km/s and a dispersion measured in terms of a standard deviation of 0.9km/s, and they cover a total range of 2.6km/s. The standard deviation is consistent with the dispersion measured earlier in terms of fwhm of 2.1km/s. The studied sample of 25 T Tauri stars (G2-M5) has a mean RV of 14.7km/s, a dispersion in terms of standard deviation of 1.3km/s and in terms of fwhm of 3.0km/s, and a total range of 4.5km/s. The RV dispersion of the brown dwarfs is consistent within the errors with that of T Tauri stars, which is in line with the finding of no mass dependence in some theoretical models of the ejection-scenario for the formation of brown dwarfs. In contrast to current N-body simulations, we did not find a high-velocity tail for the brown dwarfs RVs. We found hints suggesting different kinematics for binaries compared to predominantly single objects in ChaI, as suggested by some models. The global RV dispersion for ChaI members (1.24km/s) is significantly lower than for Taurus members (2.0km/s), despite higher stellar density in ChaI showing that a fundamental increase in velocity dispersion with stellar density of the star-forming region is not established observationally. The RVs of brown dwarfs observed in ChaI are less dispersed than predicted by existing models for the ejection-scenario.

Abstract Copyright:

Journal keyword(s): stars: low-mass, brown dwarfs - techniques: radial velocities - stars: pre-main sequence - stars: formation

Simbad objects: 40

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Number of rows : 40

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2019
#notes
1 NAME Tau-Aur Region SFR 04 30 +25.0           ~ 1171 1
2 NAME Taurus Dark Cloud SFR 04 41.0 +25 52           ~ 3264 0
3 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 1885 1
4 V* SX Cha Or* 10 55 59.731 -77 24 39.91   15.88 16.71   12.35 M1.5+M3 78 0
5 V* SY Cha Or* 10 56 30.3882538728 -77 11 39.402450501         11.29 K5Ve 110 0
6 Sz 4 TT* 10 57 42.1008128649 -76 59 35.640039635   14.1 14.80   12.17 M4Ve 40 0
7 V* TW Cha TT* 10 59 01.0608276980 -77 22 40.946475900     13.40   11.68 K8Ve 113 0
8 Hen 3-545 TT* 10 59 06.9712894449 -77 01 40.309036535   12.91 11.136   9.596 K4Ve 182 0
9 V* CS Cha TT* 11 02 24.8849252208 -77 33 35.683462615   12.88 11.69   10.123 K2Ve 183 0
10 V* CT Cha Or* 11 04 09.0989057683 -76 27 19.326914289   13.44 13.00   10.89 K7Ve 105 1
11 Ass Cha T 2-21 TT* 11 06 15.3485848381 -77 21 56.737939872   12.58 11.01   9.35 G5Ve 121 0
12 [NC98] Cha HA 12 Em* 11 06 37.9644089837 -77 43 09.114902996     20.6   15.91 M6.5e 37 0
13 NAME Cha I MoC 11 06 48 -77 18.0           ~ 923 1
14 CHXR 74 TT* 11 06 57.3104472434 -77 42 10.645175426         13.66 M3Ve 42 0
15 [NC98] Cha HA 1 BD* 11 07 16.6694944374 -77 35 53.222755937   22.8 21.0   16.38 M8e 82 0
16 V* DI Cha TT* 11 07 20.72163 -77 38 07.2903   11.8 10.9     G2Ve 135 1
17 Ass Cha T 2-26 A ** 11 07 20.7272524388 -77 38 07.303742740   11.67 10.93     G0 132 0
18 V* VV Cha Or* 11 07 28.256 -76 52 11.90   16.06 14.80   12.19 M1.5+M3 59 0
19 CHXR 76 Or* 11 07 35.1777230466 -77 34 49.293344749   20.04 18.15   14.39 M4e 41 0
20 CHSM 10496 Em* 11 07 37.7397076094 -77 35 30.798281267   23.7 22.2   17.03 M7.75 38 0
21 V* HK Cha Or* 11 07 42.3440888366 -77 33 59.381952754   21.9 19.8   15.26 M5.25 75 0
22 [NC98] Cha HA 8 SB* 11 07 46.0905760052 -77 40 08.918571132   22.2 20.1   15.61 M5.75 42 1
23 V* HL Cha Or* 11 07 52.2571569898 -77 36 57.045566163   21.5 19.51   15.07 M5.5 44 0
24 Glass H Y*O 11 07 55.887 -77 27 25.75   15.30 13.49   11.04 K3Ve 48 0
25 Sz 23 Or* 11 07 58.0950734241 -77 42 41.351737085   15.8 18.04   14.63 M4Ve 56 0
26 V* VW Cha TT* 11 08 01.3974165580 -77 42 28.579297348 13.91 14.04 12.80   10.69 K7+M0 165 0
27 CHSM 12180 Em* 11 08 18.9689267002 -77 39 17.141407943   20.5 18.52   14.50 M5.5 39 0
28 ISO-ChaI 144 Em* 11 08 24.1180053004 -77 41 47.441399459   21.3 19.18   14.85 M5.5 46 0
29 V* HQ Cha Or* 11 08 39.5016839836 -77 34 16.747297668   21.7 19.75   15.06 M5.75 59 0
30 [CCE98] 1-74 TT* 11 09 17.6894816682 -76 27 57.916038219   15.48 13.92   11.72 K4Ve 40 0
31 V* VZ Cha Or* 11 09 23.7736314968 -76 23 20.855918834   13.82 12.94   12.14 K7e 121 0
32 V* WY Cha Or* 11 10 07.0323174364 -76 29 37.640377806   15.29 13.87   11.62 K8Ve 76 1
33 Glass Q Y*O 11 10 37.9009258039 -77 32 39.873598579   16.89 14.97   11.90 K5.5+K7 66 0
34 CHX 18N TT* 11 11 46.3366412620 -76 20 08.947142071   13.27 11.96   10.37 K5IVe 58 1
35 Sz 41 TT* 11 12 24.3971939698 -76 37 06.179976409   11.2 11.60   10.22 K7+M2.5 89 1
36 V* CV Cha TT* 11 12 27.7052551478 -76 44 22.298597430   12.02 10.98 10.51 9.76 G9Ve 168 1
37 CHX 21 X 11 12 42.10 -76 58 40.0           M1 21 0
38 HJM E 4-3 Y*O 11 12 42.1035695224 -76 58 40.105613409   14.74 13.29 12.98   K5Ve 13 0
39 Ass Cha T 2-54 TT* 11 12 42.6696152636 -77 22 22.928829312     11.103   9.653 G8+K7 76 2
40 HJM E 1-8 TT* 11 12 42.9823393023 -76 37 04.866099514         10.95 K3Ve 29 0

    Equat.    Gal    SGal    Ecl

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2019.07.20-22:56:50

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