Schmidt’s Conjecture and Star Formation in Galactic Molecular Clouds and External Galaxies

Author(s)

Joao Alves, Charles Lada, Marco Lombardi, Jan Forbrich

Abstract

The star formation rate and its variation in time are intimately

connected to our understanding of the formation and evolution of the

Milky Way and external galaxies. Ever since the pioneering work of

Martin Schmidt a half-century ago there has been great interest in

finding an appropriate empirical relation that would directly link some

property of interstellar gas with the physical process of star formation

within it. Schmidt conjectured that this might take the form of a

relation between the rate of star formation and the surface density of

the interstellar gas. In this talk I will describe how recent

observations of nearby GMCs made with robust, high-dynamic range

Planck-Herschel-2MASS maps, are providing new insights into the nature

of this relationship. I will show that though a Schmidt relation is

observed within individual molecular clouds, there is no Schmidt law

that characterizes star formation between the clouds in the Milky Way.

Instead, a linear scaling exists between the total SFR and the amount of

dense gas within molecular clouds. This scaling may be the underlying

physical relationship that most directly connects star formation

activity with interstellar gas both between clouds in the Milky Way and

within and between external galaxies. Finally I will discuss the

implications of these results for the Kennicutt-Schmidt relation for

galaxies.

Organisation(s)

Department of Astrophysics

External organisation(s)

Harvard-Smithsonian Center for Astrophysics, Universitá degli Studi di Milano

Journal

IAU General Assembly Meeting

Volume

Pages

53581

Publication date

08-2015

Austrian Fields of Science 2012

103003 Astronomy, 103004 Astrophysics

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