Contents of: VI/111/./abstract/TTSUJI_PROP_004.abs

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    We propose to extend spectrophotometry of M dwarf stars by PHOT-S
 with photometric calibration by PHOT-P to very late M dwarfs near the
 end of the main sequence. The purpose of our proposal is to clarify
 the infrared properties of very low mass stars (VLMSs) and establish
 the relationship of them to the basic physical properties of such
 stars. So far, little is known on the infrared spectra of M dwarfs
 (especially beyond 2.5 micron) because of their extreme faintness,
 but this knowledge should be very important to understand the
 atmospheric structure of M dwarfs and also as a basis of our future
 studies of brown dwarfs. We hope to obtain the infrared spectral
 energy distributions between 2.5 and 12 micron (except for a gap in
 5-6 micron) by PHOT-S with photometric calibration by PHOT-P, and also
 extend the photometry to IRAS bands. The major scientific goals by our
 observations are:
    1) To test the model atmospheres by comparing observed infrared
 flux with the predictions based on a new grid of  model atmospheres of
 VLMSs covering the Teff range between 1,000 and 4,000K for the
 metallicities of the disk and halo (see Sect.4), and to determine the
 basic physical parameters of the atmospheres of M (sub)dwarfs.
    2) To examine if there is any observational evidence such as
 silicate band at around 10 micron to show the dust formation in the
 dense and cool atmospheres of VLMSs.
    3) To explore a possibility if an indication of the temperature
 inversion due to coronal heating can be found in the infrared where
 opacity is increasing due to the quasi-continuous absorption by the
 collision induced dipole transitions of H2 molecule and if this can
 resolve some known inconsistencies between observations and model
 predictions.

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