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J/ApJ/788/40  Late-type targets in Taurus, Cha I, and Upper Sco (Todorov+, 2014)

A search for companions to brown dwarfs in the Taurus and Chamaeleon star-forming regions. Todorov K.O., Luhman K.L., Konopacky Q.M., McLeod K.K., Apai D., Ghez A.M., Pascucci I., Robberto M. <Astrophys. J., 788, 40 (2014)> =2014ApJ...788...40T (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Stars, dwarfs ; Stars, late-type ; Spectral types Keywords: binaries: visual - brown dwarfs - stars: formation - stars: low-mass - stars: pre-main sequence Abstract: We have used WFPC2 on board the Hubble Space Telescope to obtain images of 47 members of the Taurus and Chamaeleon I star-forming regions that have spectral types of M6-L0 (M∼0.01-0.1 M). An additional late-type member of Taurus, FU Tau (M7.25+M9.25), was also observed with adaptive optics at Keck Observatory. In these images, we have identified promising candidate companions to 2MASS J04414489+2301513 (ρ=0.105"/15 AU), 2MASS J04221332+1934392 (ρ=0.05"/7 AU), and ISO 217 (ρ=0.03"/5 AU). We reported the first candidate in a previous study, showing that it has a similar proper motion as the primary in images from WFPC2 and Gemini adaptive optics. We have collected an additional epoch of data with Gemini that further supports that result. By combining our survey with previous high-resolution imaging in Taurus, Chamaeleon I, and Upper Sco (τ∼10 Myr), we measure binary fractions of 14/93=0.15-0.03+0.05 for M4-M6 (M∼0.1-0.3 M) and 4/108=0.04-0.01+0.03 for >M6 (M≲0.1 M) at separations of >10 AU. Given the youth and low density of these regions, the lower binary fraction at later types is probably primordial rather than due to dynamical interactions among association members. The widest low-mass binaries (>100 AU) also appear to be more common in Taurus and Chamaeleon I than in the field, which suggests that the widest low-mass binaries are disrupted by dynamical interactions at >10 Myr, or that field brown dwarfs have been born predominantly in denser clusters where wide systems are disrupted or inhibited from forming. Description: To characterize the multiplicity of low-mass stars and brown dwarfs in Taurus and Chamaeleon I, we combine the results from our survey with those from previous high-resolution images in these regions. The latter were collected with WFPC2 (Kraus et al. 2006ApJ...649..306K), Keck speckle imaging (Konopacky et al. 2007ApJ...663..394K), and Keck AO imaging (Kraus & Hillenbrand 2012, J/ApJ/757/141) in Taurus and with WFPC2 (Neuhauser et al. 2002A&A...384..999N), the Advanced Camera for Surveys on Hubble (Luhman 2007, J/ApJS/173/104), and AO at the Very Large Telescope (Ahmic et al. 2007ApJ...671.2074A; Lafreniere et al. 2008ApJ...683..844L) in Chamaeleon I. For comparison to these two regions, we also have compiled binary data measured for late-type members of the Upper Sco association (τ∼11 Myr; Pecaut et al. 2012, J/ApJ/746/154) with WFPC2 and Keck AO (Kraus et al. 2005ApJ...633..452K; Biller et al. 2011ApJ...730...39B; Kraus & Hillenbrand 2012, J/ApJ/757/141). Objects: ------------------------------------------------------------- RA (ICRS) DE Designation(s) ------------------------------------------------------------- 04 41.0 +25 52 Taurus = NAME Tau Region 11 06 48 -77 18.0 Chamaeleon I = NAME Cham I 16 12 -23.4 Upper Sco = NAME USco ------------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table4.dat 80 201 Late-type Targets of Multiplicity Surveys in Taurus, Cha I, and Upper Sco
See also: VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006) J/AJ/120/479 : Low-mass stars in the Upper Sco association (Ardila+, 2000) J/ApJ/578/914 : Low-mass stars in Taurus (Hartmann, 2002) J/ApJ/645/676 : Spatial distribution of brown dwarfs in Taurus (Luhman+, 2006) J/ApJ/684/654 : Low-mass members of Chamaeleon I (Luhman+, 2008) J/ApJ/703/1511 : Wide binaries in Taurus and Upper Sco (Kraus+, 2009) J/ApJ/757/141 : Companion IR detection limits in young associations (Kraus+, 2011) J/MNRAS/418/1231 : New brown dwarfs in upper Sco (Dawson+, 2011) J/ApJ/745/119 : Close companions to young stars. I. ChaI + Tau (Nguyen+, 2012) J/ApJ/746/154 : Improved kinematic parallaxes for Sco-Cen members (Pecaut+, 2012) Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 17 A17 --- 2MASS 2MASS name (JHHMMSSss+DDMMSSs) (1) 19- 48 A30 --- OtherName Other source name 50- 54 A5 --- SpType Spectral type 56- 73 A18 arcsec rho Projected separation (2) 75- 80 A6 --- r_rho Reference on rho (3)
Note (1): 2MASS Point Source Catalog (Skrutskie et al. 2006AJ....131.1163S, Cat. VII/233). Note (2): Separations measured for resolved binaries and the detection limits for unresolved sources. The adopted limits are described in Section 4.4. Note (3): Reference as follows: 1 = this work; 2 = Kraus & Hillenbrand (2012, J/ApJ/757/141); 3 = Kraus et al. (2006ApJ...649..306K); 4 = Konopacky et al. (2007ApJ...663..394K); 5 = Luhman et al. (2009ApJ...691.1265L); 6 = Todorov et al. (2010ApJ...714L..84T); 7 = Luhman (2004ApJ...614..398L); 8 = Lafreniere et al. (2008ApJ...683..844L); 9 = Ahmic et al. (2007ApJ...671.2074A); 10 = Luhman (2007, J/ApJS/173/104); 11 = Neuhauser et al. (2002A&A...384..999N); 12 = Biller et al. (2011ApJ...730...39B); 13 = Kraus et al. (2005ApJ...633..452K).
History: From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 05-Jul-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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