ORFEUS II echelle spectra: Absorption by H₂ in the LMC
de Boer, K. S. · Richter, P. · Bomans, D. J. · Heithausen, A. · Koornneef, J.
Original · EN
We present the first detection of molecular hydrogen (H₂) UV absorption profiles on the line of sight to the LMC. The star LH 10:3120 in the LMC was measured with the ORFEUS telescope and the Tuebingen echelle spectrograph during the space shuttle mission of Nov./Dec. 1996. 16 absorption lines from the Lyman band are used to derive the column densities of H₂ for the lowest 5 rotational states in the LMC gas. For these states we find a total column density of N(H₂)=6.6 x 10¹8 cm-2 on this individual line of sight. We obtain equivalent excitation temperatures of T < 50 K for the rotational ground state and T = 470 K for 0 < J < 6 by fitting the population densities of the rotational states to theoretical Boltzmann distributions. We conclude that UV pumping dominates the population of the higher rotational levels, as known from the H₂ gas in the Milky Way. (Research supported in part by the DARA)
English translation
This paper has no Arabic translation yet. Be the first: it takes a few seconds, and the result is stored for every future reader.