2019MNRAS.483..614Z


C.D.S. - SIMBAD4 rel 1.7 - 2021.05.06CEST00:11:14

2019MNRAS.483..614Z - Mon. Not. R. Astron. Soc., 483, 614-623 (2019/February-2)

Low-frequency GMRT observations of ultra-cool dwarfs.

ZIC A., LYNCH C., MURPHY T., KAPLAN D.L. and CHANDRA P.

Abstract (from CDS):

Observations of radio emission in about 10 per cent of ultra-cool dwarfs (UCDs) indicate the presence of strong, persistent magnetic fields in these stars. These results are in contrast to early theoretical expectations on fully convective dynamos, and to other tracers of magnetic activity, such as H αand X-ray luminosity. Radio-frequency observations have been key to physically characterizing UCD magnetospheres, although explaining the diverse behaviour within them remains challenging. Most radio-frequency studies of UCDs have been conducted in the 4-8 GHz band, where traditional radio interferometers are typically most sensitive. Hence, the nature of UCD radio emission at low frequencies (≲1.4 GHz) remains relatively unexplored, but can probe optically thick emission, and regions of lower magnetic field strengths - regimes not accessible to higher-frequency observations. In this work, we present the results from Giant Metrewave Radio Telescope observations of nine UCDs taken at ∼610 and 1300 MHz. These are the first observations of UCDs in this frequency range to be published in the literature. Using these observations, we are able to constrain the coronal magnetic field strength and electron number density of one of the targets to 1 ≲B ≲90 G and 4 <= log (Ne) <= 10, respectively. We do not detect the flaring emission observed at higher frequencies, to a limit of a few millijansky. These results show that some UCDs can produce low-frequency radio emission and highlight the need for simultaneous multiwavelength radio observations to tightly constrain the coronal and magnetospheric properties of these stars.

Abstract Copyright: © 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society

Journal keyword(s): stars: activity - brown dwarfs - stars: low-mass - stars: magnetic field - radio continuum: stars

Simbad objects: 21

goto Full paper

goto View the reference in ADS

Number of rows : 21

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 ICRF J002225.4+001456 BiC 00 22 25.4258623 +00 14 56.161217   21.1       ~ 105 1
2 ICRF J002914.2+345632 AGN 00 29 14.24246572 +34 56 32.2471186   20.2       ~ 122 1
3 2MASS J00345157+0523050 BD* 00 34 51.57696 +05 23 05.0964           T6.5 25 0
4 LSPM J0036+1821 BD* 00 36 16.1119130763 +18 21 10.291990145       18.451 16.053 L3.5 189 0
5 3C 48 QSO 01 37 41.2995845985 +33 09 35.079126038   16.62 16.20     ~ 2581 2
6 2MASS J03140344+1603056 BD* 03 14 03.4419804524 +16 03 05.475765117           L0 25 0
7 QSO B0319+12 QSO 03 21 53.10350836 +12 21 13.9537265   19 19     ~ 124 1
8 2MASS J03552337+1133437 BD* 03 55 23.3772215371 +11 33 43.796763263           L5gamma 92 0
9 QSO B0420-0127 QSO 04 23 15.80072776 -01 20 33.0654034   17.50 17.00 16.28   ~ 1092 3
10 2MASSI J0423485-041403 BD* 04 23 48.5838371891 -04 14 03.228116841           L6.5+T2 107 0
11 ICRF J054236.1+495107 Sy1 05 42 36.13789843 +49 51 07.2337251   18.45 17.80 17.210   ~ 1312 1
12 QSO J0738+1742 BLL 07 38 07.39374766 +17 42 18.9982302   16.76 16.22 15.78   ~ 907 1
13 LSPM J0746+2000 BD* 07 46 42.50553 +20 00 31.9757       17.9 15.034 L0+L1.5 173 1
14 SSSPM J0829-1309 BD* 08 28 34.1713208171 -13 09 19.842042734         16.07 L2 41 0
15 QSO J0902-1415 QSO 09 02 16.8309580146 -14 15 30.871869075   16.79 16.59 16.4   ~ 226 1
16 4C 12.46 BLL 13 09 33.93245071 +11 54 24.5531525 18.95 18.72 18.28 18.16   ~ 120 1
17 LP 497-33 ** 13 14 20.376648 +13 20 01.00608   16.8 15.83 14.9 11.94 M6.0V 63 0
18 3C 286 Sy1 13 31 08.2885060664 +30 30 32.960825107   17.51 17.25     ~ 3863 2
19 TVLM 513-46 LM* 15 01 08.1871800643 +22 50 02.120480463   21.4 15.09 18.0   M8.5V 149 0
20 4C 23.41 Rad 15 13 40.1857032 +23 38 35.200789   20       ~ 44 1
21 3C 468 Rad 23 48 36.10 +50 43 32.0           ~ 10 1

    Equat.    Gal    SGal    Ecl

To bookmark this query, right click on this link: simbad:objects in 2019MNRAS.483..614Z and select 'bookmark this link' or equivalent in the popup menu


2021.05.06-00:11:14

© Université de Strasbourg/CNRS

    • Contact