J/ApJ/799/153 Yellowballs in Milky Way project (Kerton+, 2015) ================================================================================ The Milky Way project: what are yellowballs? Kerton C.R., Wolf-Chase G., Arvidsson K., Lintott C.J., Simpson R.J. =2015ApJ...799..153K ================================================================================ ADC_Keywords: Milky Way ; Infrared sources Keywords: ISM: bubbles - stars: formation - stars: massive - stars: pre-main sequence - stars: protostars Abstract: Yellowballs are a collection of approximately 900 compact, infrared sources identified and named by volunteers participating in the Milky Way Project (MWP), a citizen science project that uses GLIMPSE/MIPSGAL images from Spitzer to explore topics related to Galactic star formation. In this paper, through a combination of catalog cross-matching and infrared color analysis, we show that yellowballs are a mix of compact star-forming regions, including ultra-compact and compact HII regions, as well as analogous regions for less massive B-type stars. The resulting MWP yellowball catalog provides a useful complement to the Red MSX Source survey. It similarly highlights regions of massive star formation, but the selection of objects purely on the basis of their infrared morphology and color in Spitzer images identifies a signature of compact star-forming regions shared across a broad range of luminosities and, by inference, masses. We discuss the origin of their striking mid-infrared appearance and suggest that future studies of the yellowball sample will improve our understanding of how massive and intermediate-mass star-forming regions transition from compact to more extended bubble-like structures. Description: We use the spatial distribution of yellowballs, cross-matches with existing catalogs of star formation tracers, and mid- and far-infrared photometry to show that the yellowballs identified in the MWP are a collection of objects tracing a compact, dense phase of massive (O and B type) star formation. This includes a mix of compact and ultra-compact HII regions as well as analogous regions for less massive B stars. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 54 928 Yellowballs identified by MWP participants table2.dat 79 928 Yellowball catalog matches and MIPSGAL 24{mu}m saturation table3.dat 77 183 Yellowball photometry -------------------------------------------------------------------------------- See also: II/311 : WISE All-Sky Data Release (Cutri+ 2012) J/ApJ/721/137 : The Bolocam Galactic Plane Survey (BGPS) (Bally+, 2010) J/ApJS/188/123 : The Bolocam Galactic Plane Survey. II. (Rosolowsky+, 2010) J/ApJS/195/14 : The Bolocam Galactic Plane Survey. V. (Schlingman+, 2014) J/A+A/549/A45 : ATLASGAL Compact Source Catalog: 330