Credit: NASA, ESA/Hubble and the Hubble Heritage Team (STScI/AURA)
Fig. 2: Top: This plot is linking the depletion time and a specific combination of star formation rate (SFR) and stellar surface density. Each data point represents a grid cell of 1kpc x 1kpc size within different structures of the galaxies analysed.
Bottom: The optical image of one of the galaxies in the sample, NGC 5457. Coloured squares show grids cells, with 1 kpc on a side, in the arm (green), interarm (yellow) and bulge (red) regions.
The star formation rate in galaxies varies greatly both across different galaxy types and over galactic time scales. MPA astronomers have been trying to gain insight into how the interstellar medium may change in different galaxies by studying molecular gas in a wide variety of galaxies, ranging from gas-poor, massive ellipticals to strongly star-forming irregulars, and in environments ranging from inner bulges to outer disks. They find that the gas depletion time depends both on the strength of the local gravitational forces and the star formation activity inside the galaxy.
Guinevere Kauffmann and Mei-Ling Huang
Publications:Huang M.-L., Kauffmann G., 2014, MNRAS, 443, 1329
Huang M.-L., Kauffmann G., 2015, MNRAS, 450, 1375