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Old & young stars in DustPedia galaxies and their role in dust heating

Updated: Apr 9, 2020


Within the framework of the DustPedia project we investigate the properties of cosmic dust and its interaction with the stellar radiation (originating from different stellar populations) for 814 galaxies in the nearby Universe. We use the galaxy SED fitting code CIGALE, properly adapted to include the state-of-the-art dust model THEMIS.

Template SEDs for the six main morphological classes as derived by CIGALE.

Using the DustPedia photometry we determine the physical properties of the galaxies, such as, the dust and stellar mass, the star-formation rate, the bolometric luminosity as well as the unattenuated and the absorbed by dust stellar light, for both the old (> 200 Myr) and young (< 200 Myr) stellar populations.


On average, young stars are very efficient in heating the dust, with absorption fractions reaching as high as ~77% of the total, unattenuated luminosity of this population. On the other hand, the maximum absorption fraction of old stars is ~24%. Dust heating in early-type galaxies is mainly due to old stars, up to a level of ~90%. Young stars progressively contribute more for `typical' spiral galaxies and they become the dominant source of dust heating for Sm type and irregular galaxies, donating up to ~60% of their luminosity to this purpose.

Left: Ratio of the unattenuated luminosity of the old and the young stellar components to the bolometric luminosity (red and blue circles, respectively; top-left panel) along with the respective stacked-bar plots of the mean values (bottom-left panel). Right: Ratio of the attenuated luminosity of the old and the young stellar components to the bolometric luminosity (red and blue circles, respectively) together with the ratio of the dust luminosity to the bolometric luminosity (orange circles; top-right panel) along with the respective stacked-bar plots of the mean values (bottom-right panel). Square symbols in the top panels are the median values for a specific Hubble stage bin.

If you are interested in this work and want to learn more, then please follow this link by clicking here.

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