Atividade nas Estrelas Secundárias de Variáveis Cataclísmicas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

- Activity in the secondary star is an important ingredient for the removal of orbital angular momentum in cataclysmic variables. The magnetic-breaking of the secondary due to a stellar wind interacting with the interstellar medium, together with the emission of gravitational waves, define the evolutive fate of such binaries. However, the direct observation of activity in the secondary is difficult because this object may be orders of magnitude fainter than the other sources of radiation in the system. In this work, we adopted an alternative approach to estimate the effects of the activity in the system s brightness as a whole: we have observed field red and brown dwarfs aiming to quantify their activity and estimate their importance face to other sources of radiation in the system. Even though most of the observed objects showed activity only at the 0.1% - 1% level in the I and H bands, two of them showed noticeable flaring activity: 2MASS J0331302-304238 and LHS 1070. In the first object, we observed a 0.15 mag I band flare. In the second, besides the descend of a long (hours time-scale) I band flare with a few tenths of mag amplitude, we observed an impressive 5 mag amplitude flare in the B band. Photometric activity at this level was not known before for LHS 1070. We identified component B of the system has the emitting object. We calculated that the energetic event would be easily observed in the light curve of an AM Her system at low state. We also show that such events might be observed in VY Scl systems at low state. In SW Sex, the observational conditions are less favorable due to the strong influence of the accretion disk.

ASSUNTO(S)

estrelas secundárias variáveis cataclísmicas stars explosão atividade estelar cataclysmic variables stellar activity flare estrelas secondary stars

ACESSO AO ARTIGO

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