Observations reveal critical interplay of interstellar dust, hydrogen

Intense molecular hydrogen formation shown in near infrared image of the reflection nebula IC 63 in the constellation Cassiopeia. The white bars represent polarization seen toward stars in the background of the nebula. The largest polarization shows the most intense emission, demonstrating that hydrogen formation influences alignment of the dust grain with a magnetic field. For astrophysicists, the interplay of hydrogen - the most common molecule in the universe - and the vast clouds of dust that fill the voids of interstellar space has been an intractable puzzle of stellar evolution. The dust, astronomers believe, is a key phase in the life cycle of stars, which are formed in dusty nurseries throughout the cosmos. But how the dust interacts with hydrogen and is oriented by the magnetic fields in deep space has proved a six-decade-long theoretical challenge. Now, an international team of astronomers reports key observations that confirm a theory devised by University of Wisconsin-Madison astrophysicist Alexandre Lazarian and Wisconsin graduate student Thiem Hoang.