0 Assigned ID: 860 ----- Attempting Submission 1 (Fri Apr 08 21:28:00 GMT 2016) ----- HST Phase I Proposal 860 (flat2_v0.apt) successfully submitted. Receipt: # 860-1 0 ----- Attempting Submission 1 (Tue Jul 19 16:11:47 GMT 2016) ----- HST Phase II Proposal 14695 (flat2_v0.apt.2016_07_18_16.aptbackup.apt) successfully submitted. Receipt: # 14695-1 ----- Attempting Submission 2 (Tue Jul 19 16:12:11 GMT 2016) ----- WFC3 Imaging of 24 um Dropout Protostars in Orion We propose WFC3 imaging of four unusual candidate protostars that were uncovered in Spitzer and Herschel observations of the Orion Molecular Cloud. These sources exhibited a combination of weak 24 um fluxes, modest to bright 70 um fluxes, low luminosities and bolometric temperatures, but comparatively bright emission between 3.6 and 8 um. Since they did not fall into one of the typical protostar classes, they were not targeted for futher study. A recent HST/WFC3 F160W snapshot survey serendiptiously imaged one of these sources, revealing a bipolar nebula with a broad dust lane and binary point sources. This suggest that the lack of 24 um emission might be due to dust clearing in the inner disk and envelope by the binary. We propose to image the remaining four other sources with WFC3 in the F160W band, all of which have been detected in lower resolution, ground-based H-band observations and three of which show some sign of extension in the H or Ks-band. F160W imaging is essential to understand the geometry and inclination of the envelope and interpret the SEDs. These data will place these objects into the context of our picture of protostellar evolution, and test the possibility that these are envelopes being cleared by the gravitational torques from binary systems. For each target we repeat the same observation in the F160W band. The observation consists of four separate dithers with Step 100 and 13 samples for a 600 second integration per exposure. A WFC3 line dither pattern with an angle of 41 degrees and a separation of 1.13 along the line is used to obtain sub-pixel sampling. The targets are identified from Spitzer coordinates. In two case, they have been shifted by about 20" to capture additional YSOs near the targets. Stellar Physics 12 false false false false false false SUPPORTED STAR YSO J2000 J2000 STAR YSO J2000 J2000 STAR YSO J2000 J2000 STAR YSO J2000 J2000 WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F160W POS-TARG DITHER 1.13306 LINE false false 4 41.788 LINE 1 false /Users/Tom/proposals/hst24/OP-cache/flat2_v0-v01.xml The scheduling data was generated by CASM 24.2. CASM was run in Phase II mode. 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