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We analyze the accretion properties of 21 low mass T Tauri stars using adataset of contemporaneous near ultraviolet (NUV) through optical observationsobtained with the Hubble Space Telescope Imaging Spectrograph (STIS) and theground based Small and Medium Aperture Research Telescope System (SMARTS), aunique dataset because of the nearly simultaneous broad wavelength coverage.Our dataset includes accreting T Tauri stars (CTTS) in Taurus, Chamaeleon I,$\eta$ Chamaeleon and the TW Hydra Association. For each source we calculatethe accretion rate by fitting the NUV and optical excesses above thephotosphere, produced in the accretion shock, introducing multiple accretioncomponents characterized by a range in energy flux (or density) for the firsttime. This treatment is motivated by models of the magnetospheric geometry andaccretion footprints, which predict that high density, low filling factoraccretion spots co-exist with low density, high filling factor spots. Byfitting the UV and optical spectra with multiple accretion components, we canexplain excesses which have been observed in the near infrared. Comparing ourestimates of the accretion rate to previous estimates, we find somediscrepancies; however, they may be accounted for when considering assumptionsfor the amount of extinction and variability in optical spectra. Therefore, weconfirm many previous estimates of the accretion rate. Finally, we measureemission line luminosities from the same spectra used for the accretion rateestimates, to produce correlations between accretion indicators (H$\beta$, CaII K, C II] and Mg II) and accretion properties obtained simultaneously.

Accretion Rates for T Tauri Stars Using Nearly Simultaneous Ultraviolet and Optical Spectra