English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

With the aim of constructing accurate 2D maps of the stellar massdistribution in nearby galaxies from S4G 3.6 and 4.5 micron images, we reporton the separation of the light from old stars from the emission contributed bycontaminants (e.g. hot dust and the 3.3 micron PAH feature). Results for asmall sample of six disk galaxies (NGC 1566, NGC 2976, NGC 3031, NGC 3184, NGC4321, and NGC 5194) with a range of morphological properties, dust contents andstar formation histories are presented to demonstrate our approach. We use anIndependent Component Analysis (ICA) technique designed to separatestatistically independent source distributions, maximizing the distinction inthe [3.6]-[4.5] colors of the sources. The technique also removes emission fromintermediate-age evolved red objects with a low mass-to-light ratio, such asasymptotic giant branch (AGB) and red supergiant (RSG) stars, revealing maps ofthe underlying old distribution of light with [3.6]-[4.5] colors consistentwith the colors of K and M giants. Contaminants are identified via comparisonto the non-stellar emission imaged at 8 microns, which is dominated by thebroad PAH feature. Using the measured 3.6/8 micron ratio to select theindividual contaminants, we find that hot dust and PAH together contributebetween ~5-15% to the integrated light at 3.6 microns, while light from regionsdominated by intermediate-age stars accounts for only 1-5%. Locally, however,the contribution from either contaminant can reach much higher levels; dustcontributes on average 22% to the emission in star-forming regions throughoutthe sample, while intermediate age-stars contribute upwards of 50% in localizedknots. The removal of these contaminants with ICA leaves maps of the oldstellar disk that retain a high degree of structural information and areideally suited for tracing the stellar mass, as will be the focus in acompanion paper.

astrophysical journal/the astrophysical journal

Reconstructing the stellar mass distributions of galaxies using S4G IRAC  3.6 and 4.5 micron images: I. Correcting for contamination by PAH, hot dust,  and intermediate age stars