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Title: THE MILKY WAY PROJECT: WHAT ARE YELLOWBALLS?

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 H II 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.
Authors:
 [1] ;  [2] ;  [3] ; ;  [4]
  1. Department of Physics and Astronomy, Iowa State University, 12 Physics Hall, Ames, IA 50011 (United States)
  2. Astronomy Department, Adler Planetarium, 1300 South Lake Shore Drive, Chicago, IL 60605 (United States)
  3. Trull School of Science and Mathematics, Schreiner University, 2100 Memorial Boulevard, Kerrville, TX 78028 (United States)
  4. Oxford Astrophysics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom)
Publication Date:
OSTI Identifier:
22364376
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 799; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; APPROXIMATIONS; COLOR; IMAGES; INFRARED RADIATION; LUMINOSITY; MASS; MILKY WAY; MORPHOLOGY; ORIGIN; PROTOSTARS; STAR EVOLUTION; STARS