2019A&A...629A.145E


Query : 2019A&A...629A.145E

2019A&A...629A.145E - Astronomy and Astrophysics, volume 629A, 145-145 (2019/9-1)

Detection of new strongly variable brown dwarfs in the L/T transition.

ERIKSSON S.C., JANSON M. and CALISSENDORFF P.

Abstract (from CDS):


Context. Brown dwarfs in the spectral range L9-T3.5, within the so called L/T transition, have been shown to be variable at higher amplitudes and with greater frequency than other field dwarfs. This strong variability allows for the probing of their atmospheric structure in 3D through multi-wavelength observations for studying the underlying physical mechanisms responsible for the variability. The few known strongly variable dwarfs in this range have been extensively studied. Now, more variables such as these need to be discovered and studied to better constrain atmospheric models. This is also critical to better understand giant exoplanets and to shed light on a number of possible correlations between brown dwarf characteristics and variability.
Aims. Previous studies suggest an occurrence rate for strong variability (peak-to-peak amplitudes >2%) of up to ∼39% among brown dwarfs within the L/T transition. In this work, we aim to discover new strong variables in this spectral range by targeting ten previously unsurveyed brown dwarfs.
Methods. We used the NOTCam at the Nordic Optical Telescope to observe 11 targets, with spectral types ranging from L9.5 to T3.5, in the J-band during October 2017 and September 2018. Using differential aperture photometry, we then analysed the light curves for significant variability using Lomb-Scargle periodogram algorithms and least squares fitting.
Results. We report first discoveries of strong and significant variability in four out of the ten targets (false alarm probability <0.1%), measuring peak-to-peak amplitudes up to 10.7±0.4% in J for the T1 dwarf 2MASS J22153705+2110554, for which we observe significant light curve evolution between the 2017 and 2018 epochs. We also report a marginally significant detection of strong variability, and confirm that the well known 2MASS J01365662+0933473 is still strongly variable three years after the last reported epoch. Finally, we present an extensive multi-epoch catalogue of strong variables reported in the literature and discuss possible correlations that are identifiable from the catalogue.
Conclusions. We significantly add to the number of known strong variables, and through Poisson statistics infer an occurrence rate for strong variability among L9-T3.5 brown dwarfs of 40+32–19%, which is in agreement with previous estimates. The new variables identified in this work are also excellently suited for extensive multi-wavelength observations dedicated to probing the 3D structure of brown dwarf atmospheres.

Abstract Copyright: © ESO 2019

Journal keyword(s): brown dwarfs - stars: individual: 2MASS J22153705+2110554 - stars: variables: general - stars: low-mass - infrared: stars - techniques: photometric

VizieR on-line data: <Available at CDS (J/A+A/629/A145): table1.dat table2.dat lc/*>

CDS comments: Paragraph. 6. J0136+2650 is a probable misprint for SIMP J013656.5+093347.3.

Simbad objects: 37

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Number of rows : 37
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 2MASS J00132229-1143006 BD* 00 13 22.29720 -11 43 00.6168           T3pec 10 0
2 2MASS J00470038+6803543 BD* 00 47 00.38664 +68 03 54.3672           L9pec 77 0
3 2MASS J01352531+0205232 BD* 01 35 25.31112 +02 05 23.2440           L9.5 7 0
4 SIMP J013656.5+093347.3 BD* 01 36 56.5605419830 +09 33 47.311965969           T2.0 128 0
5 2MASS J01383648-0322181 BD* 01 38 36.48216 -03 22 18.1308           T3 13 0
6 SIMP J0150099+382725 BD* 01 50 09.97272 +38 27 25.9308           T0 13 0
7 2MASS J03162759+2650277 BD* 03 16 27.59976 +26 50 27.7548           T2.5 10 0
8 2MASS J04473039-1216155 BD* 04 47 30.396 -12 16 15.54           T2: 8 0
9 2MASS J05012406-0010452 BD* 05 01 24.0852555792 -00 10 45.591750444           L4gamma 55 0
10 V* AB Dor TT* 05 28 44.8712165880 -65 26 55.199147208 8.259 7.856 6.999 6.496 5.993 K0V 1020 0
11 2MASS J07584037+3247245 BD* 07 58 40.3517739525 +32 47 23.984796389           T0.0+T3.5 45 0
12 WISEA J085510.74-071442.5 BD* 08 55 10.83168 -07 14 42.5256           Y2 85 0
13 2MASS J10101480-0406499 BD* 10 10 14.80704 -04 06 49.9320           L6 60 0
14 NAME Luhman 16A BD* 10 49 14.0238534572 -53 19 05.005159625           L7.5 48 0
15 NAME Luhman 16B BD* 10 49 14.0744805001 -53 19 05.800116097           T0.5 59 0
16 NAME Luhman 16 ** 10 49 18.91536 -53 19 10.0776   16.86 16.20   14.95 L7.5+T0.5 94 0
17 2MASS J10521350+4422559 BD* 10 52 13.50504 +44 22 55.9128           L6.5+T1.5 33 0
18 TWA 41 BD* 11 47 24.21360 -20 40 20.4384           L7V 29 0
19 TWA 27B BD* 12 07 33.50 -39 32 54.4           L3 280 0
20 BD+13 2618C BD* 13 00 42.08415 +12 21 15.0536         23.28 T8.5p 128 0
21 2MASS J13243553+6358281 BD* 13 24 35.53752 +63 58 28.1532           L8.0+T3.5 49 0
22 WISE J140518.39+553421.3 BD* 14 05 18.39384 +55 34 21.3996           Y0(pec?) 51 0
23 2MASS J15164306+3053443 BD* 15 16 43.06536 +30 53 44.3436           L8.0+L9.5 33 0
24 SIMP J1619275+031350 BD* 16 19 27.51936 +03 13 50.7108           T2.5+T4.0 12 0
25 2MASS J16291840+0335371 BD* 16 29 18.40896 +03 35 37.1040           T2 26 0
26 WISE J173835.53+273259.0 BD* 17 38 35.53440 +27 32 59.0964           Y0 54 0
27 2MASS J21140802-2251358 BD* 21 14 08.02560 -22 51 35.8380           L7.5 111 0
28 2MASS J21324898-1452544 BD* 21 32 48.98088 -14 52 54.4872           T4 6 0
29 2MASS J21392216+0220185 * 21 39 22.1663287248 +02 20 18.574768464           ~ 5 0
30 CFBDS J213926+022023 BD* 21 39 26.76936 +02 20 22.6968           L8.5+T3.5 90 0
31 V* HN Peg B BD* 21 44 28.47168 +14 46 07.7988           T2.5 126 0
32 SIMP J2148357+223942 BD* 21 48 35.78208 +22 39 42.7284           T1 4 0
33 2MASS J22153705+2110554 BD* 22 15 37.05648 +21 10 55.4916           T0+T2? 11 0
34 2MASS J22282889-4310262 BD* 22 28 28.89432 -43 10 26.2740           T6.5 66 0
35 2MASS J22393718+1617127 BD* 22 39 37.18608 +16 17 12.7500           T3 15 0
36 2MASS J22443167+2043433 BD* 22 44 31.67376 +20 43 43.3020           L6-L8gamma 99 0
37 SIMP J2303292+315021 BD* 23 03 29.25624 +31 50 21.0084           T2 5 0

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