Forming High Mass Stars Probing the Formation Epoch

Forming HM Stars: Goals Probe epoch of stellar assembly for “isolated” HM stars Quantify cloud infall and disk accretion rates Locate and quantify associated stellar population Determine: linkage between outcome mass(es) and initial conditions relationship between accretion and outflow processes IMF for associated stellar population (unusual or not?)

Forming HM Stars: Measurements MCAO imaging at H & K bands CAO imaging at M and N bands High resolution M-band spectroscopy (R ~ 10 5 ) Proposed targets Proposed targets: Compact H II regions AO imaging can probe: – morphology of star-disk-envelope region – distribution; N(mass) for associated population – wind morphology High resolution spectroscopy can quantify: envelope infall rates disk accretion rates (?) wind momenta and energy

Probing the IMF: Current Status With current 6-10m class telescopes + HST: Extinction (A V > 100 mag) too great to enable imaging the forming star and its environs Angular resolution ~ 90 AU at 2 kpc (too low) Sensitivity too low for high resolution spectroscopy

Forming HM Stars: Need for GSMT With a 30m GSMT, K-band diffraction limit is 0.015” Disks & envelopes can be probed at 30 AU resolution at 2 kpc With a 30m GSMT, M-band limiting magnitude ~ 12 (?) Infall; disk accretion rates can be probed out to 10 kpc NB: these numbers need checking

Forming HM Stars: Requirements MCAO-fed near IR imager with ~1’ FOV –deliver Strehl ~ 0.6 at H-band CAO-fed mid-IR imager with ~ 10” FOV CAO-fed mid-IR spectrograph with R ~ 10 5

Forming HM Stars: Trades Ability to probe forming HM stars to larger distances increases as aperture increases –Angular resolution to probe at scales < 10 AU –Increased sample size by extending search volume Mid- IR performance enhanced by lower emissivity

Forming HM Stars: GSMT v NGST et al NGST is limited by “low” angular resolution no mid-IR high resolution imaging ALMA could provide a competitive; complementary tool provide direct measure of initial conditions in molecular gas image envelope and disk regions; quantify gas kinematics

Forming HM Stars: Needed Simulations Comparison of ALMA; GSMT capabilities Defining optimal probes of envelope; disk and wind kinematics