Discovery of molecular hydrogen in a high-velocity cloud of the Galactic halo

We report the discovery of molecular hydrogen absorption in a Galactic high-velocity cloud (HVC) in the direction of the Large Magellanic Cloud. For the same HVC we derive an iron abundance which is half of the solar value. Thus, all evidence points to a Galactic origin for high-velocity cloud complex in front of the LMC.Comment: Published in Nature, this week; 14 pages, 3 figure

ORFEUS II echelle spectra: Absorption by H-2 in the LMC

We report the first detection of H-2 absorption profiles of LMC gas on the line of sight to star 3120 in the association LH 10 near the emission nebula N 11B. Transitions found in the Lyman band are used to derive a total column density N(H-2) = 6.6 x 10(18) cm(-2). Excitation temperatures of less than or equal to 50 K for levels J less than or equal to 1 and of similar or equal to 470 K for levels 2 less than or equal to J less than or equal to 4 of H-2 are derived. We conclude that moderate UV pumping influences the population even of the lowest rotational states in this LMC gas