2015MNRAS.450.3490D

Query : 2015MNRAS.450.3490D

2015MNRAS.450.3490D - Mon. Not. R. Astron. Soc., 450, 3490-3502 (2015/July-2)

The number fraction of discs around brown dwarfs in Orion OB1a and the 25 Orionis group.

DOWNES J.J., ROMAN-ZUNIGA C., BALLESTEROS-PAREDES J., MATEU C., BRICENO C., HERNANDEZ J., PETR-GOTZENS M.G., CALVET N., HARTMANN L. and MAUCO K.

Abstract (from CDS):

We present a study of 15 new brown dwarfs belonging to the ∼ 7Myr old 25 Orionis group and Orion OB1a subassociation with spectral types between M6 and M9 and estimated masses between ∼ 0.07 and ∼ 0.01M☉. By comparing them through a Bayesian method with low-mass stars (0.8 ≲ M/M☉ ≲ 0.1) from previous works in the 25 Orionis group, we found statistically significant differences in the number fraction of classical T Tauri stars, Weak T Tauri stars, class II, evolved discs and purely photospheric emitters at both sides of the substellar mass limit. Particularly, we found a fraction of 3.9^+2.4_-1.6 percent low-mass stars classified as Classic T Tauri star and class II or evolved discs, against a fraction of 33.3^+10.8_-9.8 percent in the substellar mass domain. Our results support the suggested scenario in which the dissipation of discs is less efficient for decreasing mass of the central object.

Abstract Copyright: © 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2015)

Journal keyword(s): brown dwarfs - stars: low-mass - open clusters and associations: individual: 25 Orionis

VizieR on-line data: <Available at CDS (J/MNRAS/450/3490): table1.dat table2.dat table3.dat>

Nomenclature: Table 1: [DRB2015] NN (Nos 1-21).

CDS comments: [DRB2015] 1, 7, 11, 13, 16, 20 not created in Simbad (no coordinates provided in the article)

Simbad objects: 31

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Number of rows : 31
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 IC 348 OpC 03 44 31.1 +32 10 02           ~ 1476 1
2 V* GG Tau Or* 04 32 30.3506925552 +17 31 40.494063144 14.84 14.78 13.40 11.54   M0e+M2.0e 793 1
3 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 4971 0
4 WISE J052309.87+014251.0 LM* 05 23 09.87072 +01 42 51.0948           M7.5 1 0
5 WISE J052324.07+014727.3 LM* 05 23 24.07848 +01 47 27.3696           M8.0 1 0
6 2MASS J05233466+0150475 LM* 05 23 34.6567402872 +01 50 47.408850816           M6.0 2 0
7 WISE J052348.33+014832.9 LM* 05 23 48.33360 +01 48 32.9904           M8.0 1 0
8 NAME 25 Ori Group OpC 05 24 50.9 +01 41 38           ~ 195 1
9 WISE J052458.48+014400.2 LM* 05 24 58.48752 +01 44 00.2004           M8.5 1 0
10 SDSS J052603.59+004414.6 LM* 05 26 03.5854068624 +00 44 14.637222996           M7.5 1 0
11 [KPR2005] 18 OpC 05 26 10 +00 49.2           ~ 36 0
12 SDSS J052611.93+004915.4 LM* 05 26 11.9428247616 +00 49 15.443112648           M7.5 1 0
13 2MASS J05263562+0036016 LM* 05 26 35.6239198752 +00 36 01.648146996           M7.0 1 0
14 SDSS J052641.68+003813.6 LM* 05 26 41.68080 +00 38 13.6932           M8.0 1 0
15 2MASS J05273818+0057416 LM* 05 27 38.1886719864 +00 57 41.716087812           M7.0 1 0
16 2MASS J05274967+0112187 LM* 05 27 49.6488742656 +01 12 18.862755228           M7.5 1 0
17 2MASS J05291380+0051103 LM* 05 29 13.7976985248 +00 51 10.037994912           M7.0 1 0
18 SDSS J052930.01+004727.4 LM* 05 29 30.01608 +00 47 27.3984           M8.0 1 0
19 2MASS J05303544+0146298 LM* 05 30 35.4592568568 +01 46 30.104993424           M6.0 1 0
20 SDSS J053042.09+015134.1 LM* 05 30 42.09240 +01 51 34.1496           M8.0 1 0
21 Ass Ori OB 1b As* 05 34.0 -01 30           ~ 281 0
22 Cl Collinder 69 OpC 05 35 32.1 +09 44 02     2.8     ~ 369 0
23 NAME Ori I As* 05 38 -02.8           ~ 653 0
24 NAME sig Ori Cluster OpC 05 38 42 -02 36.0           ~ 623 0
25 * sig Ori Y*O 05 38 44.7653828520 -02 36 00.283179888 2.54 3.58 3.79 3.87 4.11 O9.5V+B0.2V(n) 855 0
26 V* TW Hya TT* 11 01 51.9053285064 -34 42 17.033218380   11.94 10.50 10.626 9.18 K6Ve 2144 1
27 NAME TW Hya Association As* 11 01.9 -34 42           ~ 1018 0
28 NAME Cha 1 MoC 11 06 48 -77 18.0           ~ 1266 1
29 NAME Upper Sco Association As* 16 12 -23.4           ~ 1586 1
30 Ass Ori OB 1a As* ~ ~           ~ 237 0
31 NAME Ori Belt reg ~ ~           ~ 83 0

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