TUNA Lunch Talk:

Ting-Wen Lan

Johns Hopkins University

Exploring the diffuse interstellar bands with the Sloan Digital Sky Survey

May 12

12:10PM, Room 230, NRAO, Edgemont Road


Diffuse interstellar bands (DIBs) are absorption features, observed ubiquitously in the interstellar medium (ISM). Their nature is one of the longest unsolved problems in astronomy since their discovery in 1920s. I will present new results of their properties derived from an analysis that makes use of about half of a million of SDSS quasar, galaxy, and stellar spectra. This large dataset allows us to characterize 20 DIBs and map out their distribution on the sky. With this new DIB sky map, we are able to study how DIBs correlate with other ISM tracers such as dust, atomic hydrogen, and molecular hydrogen. Our results show that each DIB has a different correlation with atomic and molecular hydrogen which can be parametrized by a simple formula. Finally, I will discuss that the parametrization applied to all the DIBs is sufficient to reproduce a large collection of observational results reported in the literature.

The DIB sky map can be viewed here http://www.pha.jhu.edu/~tlan/DIB_SDSS/ .