HST/WFC3 Spectroscopy of < 400 AU Companions to Orion Young Stellar Objects

0 Assigned ID: 682 ----- Attempting Submission 1 (Fri Apr 08 18:45:57 GMT 2016) ----- HST Phase I Proposal 682 (HST_2016_vfnl.apt) successfully submitted. Receipt: # 682-1 ----- Attempting Submission 2 (Fri Apr 08 18:53:44 GMT 2016) ----- HST Phase I Proposal 682 (HST_2016_vfnl.apt) successfully submitted. Receipt: # 682-2 ----- Attempting Submission 3 (Fri Apr 08 19:16:05 GMT 2016) ----- HST Phase I Proposal 682 (HST_2016_vfnl.apt) successfully submitted. Receipt: # 682-3 ----- Attempting Submission 4 (Fri Apr 08 20:12:56 GMT 2016) ----- 0 ----- Attempting Submission 1 (Thu Jul 21 18:30:50 GMT 2016) ----- HST/WFC3 Spectroscopy of < 400 AU Companions to Orion Young Stellar Objects We propose WFC3 G141 grism spectroscopy of companions to young stellar objects (YSOs) in the Orion molecular cloud which were identified in a WFC3/HST 1.6 micron survey of 320 YSOs in Orion. We will target six close companions with separaitons < 400 AU which have F160W magnitudes between 17-19; these are too faint obtain spectra from ground-based telecopes using LGS AO. To determine spectral types and masses for these sources, we will use grism spectroscopy to detect broad water features in the photospheric spectrum. These observations are part of a coordinated spectroscopy campaign; the remaining companions have been/will be observed using spectrographs on ground-based telescopes as well as a HST (Cycle 22). These data will constrain the companion mass function at projected separations of 100-1000 AU from Orion young stellar objects. Given their faint magnitudes, as many as half of the companions may be below the Hydrogen burning limit. With spectra, we can determine whether or not there is an excess of sub-stellar companions relative to the field IMF at these separations; thereby testing whether the companions form from the fragmentation of the parental cloud or by fragmenation in protostellar disks. Furthermore, the HST survey showed that the observed fraction of stars with companions increases ~50% between low and high stellar density region in Orion; suggesting that the formation of multiple systems is dependent on the birth environment. With spectra, we can explore the physical mechanisms for this enhanced formation. G141 Grism Spectroscopy Stellar Physics 12 false false false false false false SUPPORTED STAR YSO J2000 J2000 F160W = 17.8 STAR YSO J2000 J2000 F160W = 20 STAR YSO J2000 J2000 F160W = 17.3 STAR YSO J2000 J2000 F160W = 17.3 STAR YSO J2000 J2000 F160W = 16.7 STAR YSO J2000 J2000 F160W = 18.8 WFC3/IR Spectroscopic No No G141 WFC3/IR Imaging No No F160W WFC3/IR Spectroscopic No No G141 WFC3/IR Imaging No No F160W WFC3/IR Spectroscopic No No G141 WFC3/IR Imaging No No F160W WFC3/IR Spectroscopic No No G141 WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F160W WFC3/IR Spectroscopic No No G141 WFC3/IR Spectroscopic No No G141 WFC3/IR Imaging No No F160W POS-TARG DITHER 3.604 LINE false false 2 82.75 LINE 1

false

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