AN ALTERNATIVE TO UNSEEN COMPANIONS TO T-TAURI STARS

Emission at infrared to millimeter wavelengths from the prototypical p re-main-sequence star T Tauri is consistent with the existence of a lo w-mass circumstellar disk around T Tauri. T Tauri's spectrum can be ch aracterized as flat, but with a significant dip at mid-infrared wavele ngths. Mid-infrared dips can result from gaps in the circumstellar dis k, and such gaps are thought to imply the existence of unseen companio ns which produce the gaps through gravitational effects. We show here that mid-infrared dips in T Tauri star spectra may have a more prosaic cause, and may be simply the result of dust grain opacity and the ver tical structure of a low-mass circumstellar disk without a gap.