iras data have shown that active k and m emission line dwarfs, the so-called flare stars, are brigther at ir wavelength than non emission line dwarfs of the same spectral type. the infrared excess, first appearing at wavelengths as short as 12 micron, becomes more prominent at 25 and 60 micron. several mechanisms and models can be invoked to explain the origin of the ir excess: (i) syncrotron radiation of relativistic electrons produced during flare and microflare activity; (ii) emission from a stellar wind favoured by the presence of a hot corona; (iii) circumstellar dust surroundings flare stars consistently with their young ages (post t-tauri phase) or originating from mass ejection episodes that are associated with strong flares. in order to choose the best model among the above possibilities, the reconstruction of the energy distribution from optical to radio spectral domains is vital and has already been done for a few sample objects, but using a limited spectral coverage. however, only a complete description of the far ir spectral region will allow us to discriminate among the above hypotheses, because only in the far ir region the slope of the spectrum changes significantly depending on the physical mechanism responsible for the emission. the improved sensitivity of iso, with respect to iras, will allow us to obtain much better values of the ir fluxes, and, more important, beyond the present 100 micron limit. at present, for most dme sources, only upper limits are known, within a typical 2 sigma error.
Instrument
PHT03 , PHT22
Temporal Coverage
1996-12-03T21:43:02Z/1997-01-18T00:54:39Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the world's first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
European Space Agency, 1999, Infrared Excess In Dme Stars Existence Of A Circumstellar Envelope For Flare Stars, 1.0, European Space Agency, https://doi.org/10.5270/esa-x9dnsd6
