Essential Ultraviolet Stellar Characterization for Guaranteed JWST Transiting Pl

JWST will launch during HST cycle 28 and begin a new era in atmosphericcharacterization for all types of exoplanets. Atmospheric spectroscopy of warmrocky planets, subNeptune, and Jupitermass planets will be obtained through arobust set of guaranteed transiting planet observations (the JWST ERS and GTOprograms). We propose to obtain temporallyresolved UV (11503200 Ang) stellarspectroscopy of the 13 JWST guaranteed time targets with no UV characterizationdata in the HST archive. Our proposed observations will provide the UV contextnecessary to determine the likelihood of atmospheric formation and retention,the identification and interpretation of atmospheric chemistry, and the impactsof stellar activity on the exoplanet atmospheric stability. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]