The Dust Forecast, Predicting the Dust Attenuation in Spiral Disk Galaxies

2018-06-02T05:20:44Z (GMT) by B.W. Holwerda W.C. Keel

Interstellar dust is still a dominant uncertainty in Astronomy, limiting precision in e.g.,
cosmological distance estimates and models of how light is re-processed within a galaxy.

When a foreground galaxy serendipitously overlaps a more distant one, the latter back-
lights the dusty structures in the nearer foreground galaxy. Such an overlapping or

occulting galaxy pair can be used to measure the distribution of dust in the closest

galaxy with great accuracy. The STARSMOG program uses Hubble to map the dis-
tribution of dust in foreground galaxies in fine (<100 pc) detail. Integral Field Unit

(IFU) observations will map the effective extinction curve, disentangling the role of
fine-scale geometry and grain composition on the path of light through a galaxy. The
overlapping galaxy technique promises to deliver a clear understanding of the dust in
galaxies: geometry, a probability function of dimming as a function of galaxy mass and
radius, and its dependence on wavelength.