Cafe-Club, Patrice THEULÉ (LAM): “Warm temperature formation of interstellar molecular hydrogen on a carbonaceous surface”

Patrice THEULÉ (LAM): “Warm temperature formation of interstellar molecular hydrogen on a carbonaceous surface”.

You can find the schedule of upcoming café-clubs and the video of old ones here.

Take care,
Carlo, Meriam, Mathilde

—————-
ABSTRACT

Molecular hydrogen is a key ingredient and the physics and chemistry of the interstellar medium. The micro-physics of its formation has huge implications on the galactic-scale star formation rate over cosmic times and  the interstellar medium phases large-scale organisation. Molecular hydrogen cooling lines are an important component of the interstellar medium cooling function, which regulates the star formation efficiency and molecular hydrogen shielding of the interstellar radiation field defines the extent of the molecular component in the ISM, where new stars are formed. We report the possibility to form molecular hydrogen  at warm temperature (up to 250 K) on surfaces exhibiting defects in laboratory. A gas of atomic hydrogen at few hundreds kelvins can overcome barriers of chemisorption sites of surface with defects at temperature up to 250 K, to recombine following a diffusion-reaction mechanism. Molecular hydrogen is detected by mass spectroscopy and the formation yield is given as a function of the surface temperature. Pushing the molecular hydrogen efficiency to warmer temperatures has a huge influence on the star formation efficiency in the Milky Way and in high-redshift galaxies.