J/MNRAS/429/903 New brown dwarf discs in Upper Scorpius (Dawson+, 2013)
New brown dwarf discs in Upper Scorpius observed with WISE.
Dawson P., Scholz A., Ray T.P., Marsh K.A., Wood K., Natta A., Padgett D.,
Ressler M.E.
<Mon. Not. R. Astron. Soc., 429, 903-914 (2013)>
=2013MNRAS.429..903D 2013MNRAS.429..903D
ADC_Keywords: Clusters, open ; Photometry, infrared
Keywords: techniques: photometric -
open clusters and associations: individual: Upper Scorpius -
infrared: stars
Abstract:
We present a census of the disc population for UKIDSS selected brown
dwarfs in the 5-10Myr old Upper Scorpius OB association. For 116
objects originally identified in UKIDSS, the majority of them not
studied in previous publications, we obtain photometry from the
Wide-Field Infrared Survey Explorer data base. The resulting
colour-magnitude and colour-colour plots clearly show two separate
populations of objects, interpreted as brown dwarfs with discs (class
II) and without discs (class III). We identify 27 class II brown
dwarfs, 14 of them not previously known. This disc fraction (27 out of
116, or 23%) among brown dwarfs was found to be similar to results for
K/M stars in Upper Scorpius, suggesting that the lifetimes of discs
are independent of the mass of the central object for low-mass stars
and brown dwarfs. 5 out of 27 discs (19%) lack excess at 3.4 and
4.6µm and are potential transition discs (i.e. are in transition
from class II to class III). The transition disc fraction is
comparable to low-mass stars. We estimate that the time-scale for a
typical transition from class II to class III is less than 0.4Myr for
brown dwarfs. These results suggest that the evolution of brown dwarf
discs mirrors the behaviour of discs around low-mass stars, with disc
lifetimes of the order of 5-10Myr and a disc clearing time-scale
significantly shorter than 1Myr.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 85 27 *Positions, UKIDSS Z and J photometry, WISE W1, W2,
W3 and W4 photometry of the 27 class II objects
table3.dat 85 89 *Positions, UKIDSS Z and J photometry, WISE W1, W2,
W3 and W4 photometry of the 89 class III objects
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Note on table2.dat and table3.dat: Objects are listed in order of decreasing
mass, based on their Z magnitude. Coordinates are J2000.
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
II/328 : AllWISE Data Release (Cutri+ 2013)
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
Byte-by-byte Description of file: table2.dat table3.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- --- [2MASS]
7- 23 A17 --- 2MASS 2MASS name (JHHMMSSss+DDMMSSs)
25- 26 I2 h RAh Right ascension (J2000)
28- 29 I2 min RAm Right ascension (J2000)
31- 35 F5.2 s RAs Right ascension (J2000)
37 A1 --- DE- Declination sign (J2000)
38- 39 I2 deg DEd Declination (J2000)
41- 42 I2 arcmin DEm Declination (J2000)
44- 47 F4.1 arcsec DEs Declination (J2000)
49- 53 F5.2 mag Zmag UKIDSS Z magnitude
55- 59 F5.2 mag Jmag UKIDSS J magnitude
61- 65 F5.2 mag W1mag WISE W1 magnitude
67- 71 F5.2 mag W2mag WISE W2 magnitude
73- 77 F5.2 mag W3mag WISE W3 magnitude
78 A1 --- n_W3mag [a] a: S/N<5
80- 84 F5.2 mag W4mag WISE W4 magnitude
85 A1 --- n_W4mag [a] a: S/N<5
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 14-Mar-2014