Matthias Sonnleitner, Monika Ritsch-Marte, Helmut Ritsch
Black-body radiation around hot objects induces AC Stark shifts of the energy levels of nearby atoms and molecules. These shifts are roughly proportional to the fourth power of the temperature and induce a force decaying with the third power of the distance from the object's surface. We explicitly calculate the resulting attractive black-body optical dipole force for ground state hydrogen atoms. Surprisingly this force can surpass the repulsive radiation pressure and actually pull the atoms towards the surface with a force stronger than gravity. We exemplify the dominance of the "black-body force" over gravity for hydrogen in a cloud of hot dust particles. These forces, which have been neglected to date, appear highly relevant in various astrophysical scenarios, in particular since analogous results hold for a wide class of broadband radiation sources.
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http://arxiv.org/abs/1302.3031
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