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Cygnus-X Survey 3.6μm=Blue, 5.8μm=Green, 24μm =Red Cyg OB2 W75N DR22 DR21 Cyg OB9 S106 AFGL 2591 DR23 DR20 AFGL 2636 Joseph L. Hora 1 , Rob Gutermuth 2 , Sean Carey 3 , Don Mizuno 4 , Kathleen Kraemer 5 , Sylvain Bontemps 6 , S. Thomas Megeath 7 , Nicola Schneider 8 , Frederique Motte 8 , Eric Keto 1 , Howard A. Smith 1 , Lori E. Allen 1,9 , Robert Simon 10 , Stephan Price 5 , Joseph Adams 11 , Giovanni G. Fazio 1, X. Koenig 1 The Spitzer Legacy Survey of the Cygnus-X region The Spitzer Legacy Survey of the Cygnus-X region We describe the first data delivery from the Spitzer Legacy Survey of the Cygnus-X region, which is a massive star formation complex containing the richest known concentration of massive protostars and the largest OB association within 2 kpc. This unbiased survey of 24 square degrees in Cygnus-X with the Spitzer IRAC and MIPS instruments has the sensitivity to detect young stars to a limit of 0.5 M . The data release consists of a source catalog and mosaics of the images in each band that combine all of the frames obtained in the various observation epochs. The source catalog contains the band-merged Spitzer 3.6, 4.5, 5.8, 8.0, and 24 μm photometry as well as the 2MASS J, H, and Ks bands. A preliminary source classification using this data set has yielded over 2000 deeply embedded and Class I YSO candidates, and over 12000 Class II candidate objects. Our reduction pipelines use artifact-correction methods which improve the quality of the full mosaic. The Cygnus-X survey is an important part of the Spitzer legacy in the study of star formation, and has provided a data set that will be key in future investigations carried out with the warm Spitzer, Herschel, and JWST missions, as well as ground- based observations. Abstract Abstract Affiliations: 1 Harvard-Smithsonian Center for Astrophysics, 2 Smith College/FCRAO, 3 Spitzer Science Center, 4 Boston College, 5 Air Force Research Lab, 6 Observatoire de Bordeaux, 7 University of Toledo, 8 CEA/Saclay, 9 NOAO, 10 University of Cologne, 11 Cornell University. The IRAC observations were obtained using 12s High Dynamic Range (HDR) mode. All frames were combined into mosaics with WCSmosaic (Gutermuth et al. 2008) such that rotation, spatial scale distortion, and subpixel offset resampling are all performed in one transformation, to minimize smoothing. Automated source detection and aperture photometry were performed using PhotVis version 1.10 (Gutermuth et al. 2008). The MIPS data was reduced using the same techniques as in the MIPSGAL Legacy program (Mizuno et al. 2008, Carey et al. 2009). The MIPSGAL pipeline performs many of the same operations as the standard SSC pipeline, but it has several modifications appropriate for bright, saturation-filled regions of the sky, and an improved droop correction and mitigation of other artifacts such as “jailbar” and latent images. Classification of sources is performed using the multi-phase mid-IR colors method explained and justified in detail in Gutermuth et al. (2008), but updated to account for complications found in the more active and typically more distant regions of the survey (Gutermuth et al. 2009). In summary, the method uses the numerous available flux ratios, or colors, to identify and classify YSOs as robustly as possible while mitigating the effects of contamination and reddening. Contamination arises from sources with excess IR emission, including star-forming galaxies, broad-line active galactic nuclei, and unresolved shock emission from outflows. The YSOs are classified into the canonical categories of Class I (protostars with infalling envelopes, including flat spectrum objects) and Class II (pre-main sequence stars with optically thick disks) YSOs (Allen et al. 2004), with supplemental categories of deeply embedded sources and the transitional disks (see Table 1). There are approximately 3.6 million sources in the full catalog of 2MASS/IRAC/MIPS sources. Table 1. Source summary The Point Source Catalog References Allen et al. 2004, ApJS, 154, 363 Carey, S. et al. 2009, PASP, 121, 76 Gutermuth, R. et al. 2004, ApJS, 154, 374 Gutermuth, R. et al. 2008, ApJ, 674, 336 Gutermuth, R. et al. 2009, submitted Mizuno, D. et al., 2008, PASP, 120, 1028 Reach et al. 2005, PASP, 117, 978 Acknowledgements This work is in part based on observations made with the Spitzer Space Telescope, operated by JPL/Caltech under NASA contract 1407. Support for this work was provided by NASA through Contract #1256790 issued by JPL/Caltech. The images at left show the spatial distribution of the candidate Class I and Class II sources, plotted on the 3.6 μm image of the Cygnus-X region. The strongest concentration of Class I sources are along filaments and in the densest parts of star- forming regions. The Class II objects are also clustered around the filaments and HII regions, but are not as tightly grouped as the Class I sources. There is a large cluster in the Cyg OB2 region, and large clusters in the DR21/22,W75N, and AFGL 2591 regions. The image at the bottom shows the space density of all objects classified as YSO candidates, from <0.1 to >100 parsec -2 . The highest density regions are in the regions listed above, and near IRAS 20306+4005. Distribution of YSOs Class I Class II IRAC color-color plots. Top left: the [3.6] - [4.5] versus [5.8] - [8.0] colors. All sources detected in the four bands are plotted as black points. The classified objects have been plotted as colored symbols as follows: red triangles = deeply embedded, red squares = Class I; green squares = Class II; orange squares = transition objects; blue squares = AGN galaxies; magenta squares = PAH-dominated colors (including galaxies); cyan squares = H 2 - dominated colors (possible outflows). Top right: similar to the figure on the left, except showing the [3.6] - [4.5] versus [4.5] - [5.8] colors. Bottom left: same as others, except the [3.6] - [4.5] versus [4.5] - [24] colors are plotted. DR21 DR21 Cyg OB2 Cyg OB2 DR22 DR22 W75 N W75 N Cyg OB2 DR22 DR21 W75 N Poster 4.5, Reionization to Exoplanets: Spitzer's Growing Legacy, 26-28 October 2009, Pasadena, CA IRAS20306+4005 IRAS20306+4005 IRAS20306+4005 IRAS 20306+4005 IRAC color-magnitude plots. Left: [4.5] versus [3.6] - [4.5] colors. The sources detected in the four bands are plotted as black points. In addition, the classified objects have been plotted as colored symbols as follows: red triangles = deeply embedded; red squares = Class I; green squares = Class II; orange squares = transition objects; blue squares = AGN galaxies; magenta squares = PAH-dominated colors (including galaxies); cyan squares = H2 - dominated colors (possible outflows). Right: same except showing [4.5] versus [4.5] - [8.0] colors.
