High-resolution near-IR spectroscopy of protostars with large telescope's

It is now possible to measure absorption spectra of flat-spectrum and Class 1 protostars using D greater than or equal to 8m telescopes equipped with sensitive cryogenic IR spectrographs. For the first time ever, our latest high-resolution (R similar to 20, 000) Keck NIRSPEC data reveal that Class I protostars are indeed low-mass stars with pre-main-sequence or dwarf-like features. However, Class I and flat-spectrum protostars differ from T Tauri stars in that protostars have much higher IR veilings (r(k) greater than or equal to 1 - 3+) and they are rotating quickly, v sin i > 20 km s(-1). Interestingly, absorption spectra of low-mass protostars show stellar - not disk - absorption features. Our observations should also be able to probe whether protostellar photospheres have different physical structures than T Tauri stars, as predicted by theoretical models which account for accretion effects. There is much work to be done in this field, and the VLT can contribute immensely.