Cloudshine: New Light on Dark Clouds

We present new deep near-infrared images of dark clouds in the Perseusmolecular complex. These images show beautiful extended emission which we modelas scattered ambient starlight and name ``cloudshine''. The brightness andcolor variation of cloudshine complicates the production of extinction maps,the best tracer of column density in clouds. However, since the profile ofreflected light is essentially a function of mass distribution, cloudshineprovides a new way to study the structure of dark clouds. Previous work hasused optical scattered light to study the density profile of tenuous clouds;extending this technique into the infrared provides a high-resolution view intothe interiors of very dense clouds, bypassing the complexities of using thermaldust emission, which is biased by grain temperature, or molecular tracers,which have complicated depletion patterns. As new wide-field infrared camerasare used to study star-forming regions at greater depth, cloudshine will bewidely observed and should be seen as a new high-resolution tool, rather thanan inconvenience.Comment: 6 pages with 3 figures, submitted to ApJ Letters v2: correct attribution of the Henyey-Greenstein function and other typos and minor word change