We report the results of our HST snapshot survey with the ACS HRC PR200L prism , designed to measure the near-UV emission in a sample of nearby M dwarfs Based on observations made with the NASA/ESA Hubble Space Telescope , obtained at the Space Telescope Science Institute , which is operated by the Association of Universities for Research in Astronomy , Inc. , under NASA contract NAS 5-26555 .
These observations are associated with program 10525 . .
33 stars were observed , spanning the mass range from 0.1 - 0.6 solar masses ( T _ { eff } \sim 2200K - 4000K ) where the UV energy distributions vary widely between active and inactive stars .
These observations provide much-needed constraints on models of the habitability zone and the atmospheres of possible terrestrial planets orbiting M dwarf hosts , and will be useful in refining the target selection for future space missions such as TPF .
We compare our data with a new generation of M dwarf atmospheric models and discuss their implication for the chromospheric energy budget .
These NUV data will also be valuable in conjunction with existing optical , FUV and X-ray data to explore unanswered questions regarding the dynamo generation and magnetic heating in low-mass stars .