2013ApJ...778...36R


Query : 2013ApJ...778...36R

2013ApJ...778...36R - Astrophys. J., 778, 36 (2013/November-3)

Discovery of a visual T-dwarf triple system and binarity at the L/T transition.

RADIGAN J., JAYAWARDHANA R., LAFRENIERE D., DUPUY T.J., LIU M.C. and SCHOLZ A.

Abstract (from CDS):

We present new high contrast imaging of eight L/T transition brown dwarfs (BDs) using the NIRC2 camera on the Keck II telescope. One of our targets, the T3.5 dwarf 2MASS J08381155+1511155, was resolved into a hierarchal triple with projected separations of 2.5±0.5 AU and 27±5 AU for the BC and A(BC) components, respectively. Resolved OSIRIS spectroscopy of the A(BC) components confirms that all system members are T dwarfs. The system therefore constitutes the first triple T-dwarf system ever reported. Using resolved photometry to model the integrated-light spectrum, we infer spectral types of T3±1, T3±1, and T4.5±1 for the A, B, and C components, respectively. The uniformly brighter primary has a bluer J - Ks color than the next faintest component, which may reflect a sensitive dependence of the L/T transition temperature on gravity, or alternatively divergent cloud properties among components. Relying on empirical trends and evolutionary models we infer a total system mass of 0.034-0.104 M for the BC components at ages of 0.3-3 Gyr, which would imply a period of 12-21 yr assuming the system semimajor axis to be similar to its projection. We also infer differences in effective temperatures and surface gravities between components of no more than ∼150 K and ∼0.1 dex. Given the similar physical properties of the components, the 2M0838+15 system provides a controlled sample for constraining the relative roles of effective temperature, surface gravity, and dust clouds in the poorly understood L/T transition regime. For an age of 3 Gyr we estimate a binding energy of ∼20 x1041 erg for the wide A(BC) pair, which falls above the empirical minimum found for typical BD binaries, and suggests that the system may have been able to survive a dynamical ejection during formation. Combining our imaging survey results with previous work we find an observed binary fraction of 4/18 or 22–8+10% for unresolved spectral types of L9-T4 at separations ≳ 0.''1. This translates into a volume-corrected frequency of 13–6+7%, which is similar to values of ∼9%-12% reported outside the transition. Our reported L/T transition binary fraction is roughly twice as large as the binary fraction of an equivalent L9-T4 sample selected from primary rather than unresolved spectral types (6–4+6%); however, this increase is not yet statistically significant and a larger sample is required to settle the issue.

Abstract Copyright:

Journal keyword(s): binaries: visual - brown dwarfs - stars: individual: 2MASS J08381155+1511155

Simbad objects: 56

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Number of rows : 56
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 2MASS J00001354+2554180 BD* 00 00 13.54488 +25 54 18.0648           T4.5 28 0
2 L 362-29 B BD* 00 04 34.8671722377 -40 44 06.463544237       19.61 16.88 L5+L5 100 0
3 LP 881-64 ** 00 24 44.1774908692 -27 08 25.263232614   17.18 15.338 13.502 11.403 M5.5/6Ve+M8.5Ve+M9/9.5V 130 0
4 2MASSI J0025036+475919 BD* 00 25 03.65928 +47 59 19.1868           L4: 16 0
5 2MASS J01191207+2403317 BD* 01 19 12.071 +24 03 31.71           T0.0+T4.0 7 0
6 SIMP J013656.5+093347.3 BD* 01 36 56.5605419830 +09 33 47.311965969           T2.0 113 0
7 BRLT 38 BD* 01 51 41.55936 +12 44 30.0768           T0.5 65 0
8 DENIS J020529.0-115925 BD* 02 05 29.3651195393 -11 59 29.721210536           L7V 145 0
9 2MASS J02474978-1631132 BD* 02 47 49.78680 -16 31 13.2780           T0.0+T7.0 12 0
10 2MASSI J0328426+230205 BD* 03 28 42.65592 +23 02 05.1900           L9.5 46 0
11 2MASS J03510423+4810477 BD* 03 51 04.23096 +48 10 47.7804           L6.5+T5.0 11 0
12 2MASS J03572695-4417305 BD* 03 57 26.9613211008 -44 17 30.532793208         17.86 L0beta 30 0
13 LP 714-37 ** 04 10 48.10248 -12 51 42.1488   18.4   15.0 12.99 M5.5+M8.0+M8.5 24 0
14 2MASSI J0423485-041403 BD* 04 23 48.5763811987 -04 14 03.246502948           L6.5+T2 116 0
15 2MASS J05185995-2828372 BD* 05 18 59.95656 -28 28 37.2720           L6+T4 34 0
16 2MASS J06020638+4043588 BD* 06 02 06.38496 +40 43 58.8900           T4.5 11 0
17 2MASS J07003664+3157266 BD* 07 00 36.7233300485 +31 57 25.462866965           L3+L6.5 36 0
18 2MASS J07420130+2055198 BD* 07 42 01.30152 +20 55 19.8840           T5 15 0
19 LSPM J0746+2000 BD* 07 46 42.50553 +20 00 31.9757       17.9 15.034 L0+L1.5 175 1
20 HD 64586 * 07 54 42.9946617984 +00 52 55.368453900   9.94 9.92     B9IV/V 5 0
21 2MASS J07584037+3247245 BD* 07 58 40.3517739525 +32 47 23.984796389           T0.0+T3.5 39 0
22 SDSS J083717.21-000018.0 BD* 08 37 17.20032 -00 00 19.3608           T1 45 0
23 2MASS J08381155+1511155 BD? 08 38 11.55336 +15 11 15.5112           ~ 8 0
24 2MASS J08503593+1057156 BD* 08 50 35.93400 +10 57 15.6168       22.466 20.349 L6.5+L8.5 74 0
25 2MASS J08564793+2235182 BD* 08 56 47.9153673048 +22 35 18.292009308           L3 20 0
26 BD+21 1974 * 09 07 55.6910292912 +20 53 49.529602572   10.69 9.13     A0V 4 0
27 2MASS J09083803+5032088 BD* 09 08 38.0091771633 +50 32 08.205341214           L8 37 0
28 HD 79108 PM* 09 12 12.8807934720 +03 52 01.121272932   6.127 6.131     A0V 72 0
29 2MASS J09153413+0422045 BD* 09 15 34.13712 +04 22 04.5948           L6 30 0
30 2MASSW J0920122+351742 BD* 09 20 12.23664 +35 17 42.9684           L5.5+L9 43 0
31 2MASS J09261537+5847212 BD* 09 26 15.37752 +58 47 21.2280           T3.5+T5 29 0
32 2MASS J10170754+1308398 BD* 10 17 07.5535371936 +13 08 39.784300548         17.418 L1.5+L3 28 0
33 2MASS J10210969-0304197 BD* 10 21 09.69240 -03 04 19.7904           T1+T4 70 0
34 HD 97334B BD* 11 12 25.6353966120 +35 48 12.742807176           L4.5+L6 72 0
35 2MASS J11463449+2230527 BD* 11 46 34.5341033040 +22 30 54.036482400           L3+L4 85 0
36 2MASS J12060248+2813293 BD* 12 06 02.48952 +28 13 29.3160           T2.0+T4.5 17 0
37 2MASS J12095613-1004008 BD* 12 09 56.13096 -10 04 00.8076           T2+T7.5 55 0
38 2MASS J12255432-2739466 BD* 12 25 54.32328 -27 39 46.6776           T5.5+T8 55 0
39 SIPS J1228-1547 BD* 12 28 15.23184 -15 47 34.2312       20.187 18.163 L5.5+L5.5 141 0
40 2MASSW J1239272+551537 BD* 12 39 27.31632 +55 15 37.3788           L5V 35 0
41 2MASS J12545393-0122474 BD* 12 54 53.9040607346 -01 22 47.399401142           T2e: 142 0
42 NAME Kelu-1 BD* 13 05 40.1642434199 -25 41 05.712165150         16.85 L2+L3.5 244 0
43 2MASS J14044948-3159330 BD* 14 04 49.48416 -31 59 33.0576           T1+T5 31 1
44 2MASS J14304358+2915405 BD* 14 30 43.5734270640 +29 15 40.718334672           L1.5V 16 0
45 DENIS J144137.2-094558 BD* 14 41 37.1567200536 -09 45 59.229849096       20.030 17.234 L1+L1 49 0
46 2MASSW J1449378+235537 BD* 14 49 37.8493181976 +23 55 37.884727668           L0V 14 0
47 2MASSI J1534498-295227 BD* 15 34 49.84080 -29 52 27.4188           T4.5+T5 61 0
48 2MASS J15530228+1532369 BD* 15 53 02.28072 +15 32 36.9132           T6.5+T7.5 46 0
49 2MASSI J1600054+170832 BD* 16 00 05.4775186992 +17 08 32.725071672           L1.5V 13 0
50 2MASSW J1728114+394859 BD* 17 28 11.50056 +39 48 59.3100           L5+L6.5 53 0
51 2MASS J17503293+1759042 BD* 17 50 32.93832 +17 59 04.2504           T3.5 48 0
52 SDSS J204749.59-071818.2 BD* 20 47 49.59816 -07 18 18.2592           L9.5 15 0
53 2MASSW J2101154+175658 BD* 21 01 15.44112 +17 56 58.6860           L7+L8 27 0
54 2MASS J21522609+0937575 BD* 21 52 26.09064 +09 37 57.5328           L6+L6 14 0
55 2MASS J22521073-1730134 BD* 22 52 10.7512306563 -17 30 13.889743018         17.9 L4.5+T3.5 47 0
56 2MASSI J2254188+312349 BD* 22 54 18.92016 +31 23 49.8300           T5.0 63 0

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2022.10.06-18:41:52

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