AAS 204th Meeting, June 2004
Session 62 Protoplanets, Star Formation and Debris Disks
Poster, Wednesday, June 2, 2004, 10:00am-7:00pm, Ballroom

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[62.09] Cold Ice Towards the McNeil Nebula (IRAS 05436-0007)

E.L. Gibb, T.W. Rettig, S.D. Brittain (Univ. of Notre Dame), T. Simon (Univ. of Hawaii), C. Kulesa (Univ. of Arizona)

The infrared source IRAS 05436-0007, also known as the McNeil Nebula, located in the Lynds 1630 cloud in Orion, was reported to have brightened substantially between October 2003 and January 2004. It has been suggested that this brightening resulted from rapid accretion of circumstellar material in a rare FU Orionis type eruption. An alternative explanation may be that McNeil’s Nebula has cleared much of the surrounding material to reveal a young protostar. We obtained infrared observations of this source from 2-5~\mum with NIRSPEC at the W. M. Keck Observatory and SpeX at the Infrared Telescope Facility. These data indicate a substantial column density (\tau~0.6) of water and CO ice. The 3.0~\mum profile is consistent with cold (~10~K) amorphous water ice. The 4.67~\mum CO ice feature is dominated by a cold (<20~K) apolar component with a small contribution from a cold polar (H2O:CO) ice mixture. Superposed on the CO ice are broad gas phase CO emission lines (Rettig et al. 2004), indicating the presence of hot gas close to the star, and narrow CO absorption lines consistent with cooler gas in the surrounding nebulosity.

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