2010A&A...522A..13R


Query : 2010A&A...522A..13R

2010A&A...522A..13R - Astronomy and Astrophysics, volume 522, A13-13 (2010/11-1)

A magnetic field evolution scenario for brown dwarfs and giant planets.

REINERS A. and CHRISTENSEN U.R.

Abstract (from CDS):

Very little is known about magnetic fields of extrasolar planets and brown dwarfs. We use the energy flux scaling law presented by Christensen et al. to calculate the evolution of average magnetic fields in extrasolar planets and brown dwarfs under the assumption of fast rotation, which is probably the case for most of them. We find that massive brown dwarfs of about 70MJup can have fields of a few kilo-Gauss during the first few hundred Million years. These fields can grow by a factor of two before they weaken after deuterium burning has stopped. Brown dwarfs with weak deuterium burning and extrasolar giant planets start with magnetic fields between ∼100G and ∼1kG at the age of a few Myr, depending on their mass. Their magnetic field weakens steadily until after 10Gyr it has shrunk by about a factor of 10. We use observed X-ray luminosities to estimate the age of the known extrasolar giant planets that are more massive than 0.3MJup and closer than 20pc. Taking into account the age estimate, and assuming sun-like wind-properties and radio emission processes similar to those at Jupiter, we calculate their radio flux and its frequency. The highest radio flux we predict comes out as 700mJy at a frequency around 150MHz for τ Boob, but the flux is below 60mJy for the rest. Most planets are expected to emit radiation between a few Mhz and up to 100MHz, well above the ionospheric cutoff frequency.

Abstract Copyright:

Journal keyword(s): planets and satellites: magnetic fields - stars: activity - stars: magnetic field - brown dwarfs - stars: low-mass

Simbad objects: 22

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Number of rows : 22
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 HD 1237b Pl 00 16 12.6791488703 -79 51 04.244738563           ~ 56 1
2 * ups And b Pl 01 36 47.84216 +41 24 19.6443           ~ 263 1
3 * ups And d Pl 01 36 47.84216 +41 24 19.6443           ~ 158 1
4 * ups And c Pl 01 36 47.84216 +41 24 19.6443           ~ 152 1
5 * q01 Eri b Pl 01 42 29.3148822519 -53 44 26.991165270           ~ 33 1
6 HD 13445b Pl 02 10 25.9190575041 -50 49 25.467227759           ~ 95 1
7 * iot Hor PM* 02 42 33.4666679022 -50 48 01.055138166   5.97 5.40     F8V 367 1
8 * eps Eri b Pl 03 32 55.8449634 -09 27 29.731165           ~ 124 1
9 * eps Ret b Pl 04 16 29.0292136 -59 18 07.761375           ~ 47 1
10 * bet Gem b Pl 07 45 18.94987 +28 01 34.3160           ~ 30 1
11 HD 87883b Pl 10 08 43.1409121581 +34 14 32.148705342           ~ 30 1
12 * tau Boo b Pl 13 47 15.74340 +17 27 24.8552           ~ 262 1
13 HD 128311b Pl 14 36 00.5607343227 +09 44 47.453643485           ~ 67 1
14 HD 128311c Pl 14 36 00.5607343227 +09 44 47.453643485           ~ 56 1
15 HD 147513b Pl 16 24 01.2905970257 -39 11 34.734611237           ~ 46 1
16 HD 189733b Pl 20 00 43.7130382888 +22 42 39.071811263           ~ 1293 1
17 HD 192263b Pl 20 13 59.8455148268 -00 52 00.771665295           ~ 59 1
18 HD 204961b Pl 21 33 33.9749932664 -49 00 32.403471949           ~ 54 1
19 BD-15 6290b Pl 22 53 16.7323107416 -14 15 49.303409936           ~ 236 1
20 BD-15 6290c Pl 22 53 16.7323107416 -14 15 49.303409936           ~ 182 1
21 * 51 Peg b Pl 22 57 27.9804167474 +20 46 07.782240714           ~ 605 1
22 * gam Cep b Pl 23 39 20.9015326708 +77 37 56.505477975           ~ 74 1

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2022.10.06-19:20:02

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