Interstellar medium in the M 43 nebula

Piotr Gnacinski

Published 2008-12-31, updated 2010-04-20Version 3

We present a list of interstellar absorption lines in the direction of HD 37061 in the M 43 nebula. Some of the absorption lines arise from atomic excited levels that are uncommon in interstellar clouds. The excited levels of Fe II are populated by fluorescence. We found a large number of H2 molecular absorption lines arising from vibrationally excited levels. The ortho/para H2 ratio is equal to 2.7. The H2 rotational temperature of vibrational levels 1 - 5 exceeds 2000 K.