Query : 2006A&A...460L..35S

2006A&A...460L..35S - Astronomy and Astrophysics, volume 460, L35-38 (2006/12-3)

Simultaneous optical and X-ray observations of a giant flare on the ultracool dwarf LP 412-31.


Abstract (from CDS):

Cool stars are known to produce flares probably as a result of the magnetic reconnection in their outer atmospheres. We present simultaneous XMM-Newton optical V band and X-ray observations of the M8 dwarf LP412-31. During the observation a giant flare occurred, with an optical amplitude of 6mag and total energy of 3x1032erg in both the V band and soft X-rays. Both flare onset and flare decay were completely covered in both wavebands with a temporal resolution of 20s, allowing determination of the flare time scales, as well as a study of the temperature evolution of the flaring plasma. The data are consistent with an impulsive energy release followed by radiative cooling without any further energy release during the decay phase. Our analysis suggests that the optical flare originates from a small fraction of the surface of LP412-31, while the characteristic scale size of the flaring X-ray plasma is of the order of the stellar radius or larger. The absence of any small-scale variability in the light curve suggests a non-standard flare number energy distribution.

Abstract Copyright:

Journal keyword(s): X-rays: stars - stars: activity - stars: flare - stars: low-mass, brown dwarfs - stars: coronae - stars: individual: LP 412-31

Simbad objects: 3

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Number of rows : 3
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 G 272-61B Er* 01 39 01.6377185550 -17 57 01.001240728           M6V 832 0
2 LP 412-31 LM* 03 20 59.7114769400 +18 54 22.770750621   20.5 18.881 16.904 14.484 M8V 114 0
3 NAME Proxima Centauri Er* 14 29 42.9461331854 -62 40 46.164680672 14.21 12.95 11.13 9.45 7.41 M5.5Ve 1175 0

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