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Forming High Mass Stars

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:

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Forming High Mass Stars

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  1. Forming High Mass Stars Probing the Formation Epoch

  2. 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?)

  3. Forming HM Stars: Measurements • MCAO imaging at H & K bands • CAO imaging at M and N bands • High resolution M-band spectroscopy (R ~ 105) • 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

  4. Probing the IMF: Current Status With current 6-10m class telescopes + HST: • Extinction (AV > 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

  5. 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

  6. 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 ~ 105

  7. 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

  8. 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

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

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