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GLIMPSE results on the Mid IR Stellar and Diffuse Emission in the Galactic Plane

GLIMPSE is a survey that explores the stellar and diffuse emission in the Galactic plane using Spitzer/IRAC observations. It provides a catalog, archive, and Mosaicked Images in 4 bands. The data is available for free from the SSC website.

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GLIMPSE results on the Mid IR Stellar and Diffuse Emission in the Galactic Plane

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  1. GLIMPSE results on the Mid IR Stellar and Diffuse Emission in the Galactic Plane Robert Benjamin (UW-W) and the GLIMPSE teamwith special thanks to SSC and the IRAC team Spitzer Science Center 2005 ConferenceIR Diagnostics of Galaxy Evolution (Nov 14-16,2005)

  2. GLIMPSE(Galactic Legacy Infrared Mid-Plane Survey Extraordinaire) • PI:Ed Churchwell (UW-Madison) • GalacticSpitzer Legacy Program • Over 320,000 Spitzer /IRAC frames • bandsurveymicrons • GalacticLatitudeb| < 1 degree • GalacticLongitudel-65degrees • Totalsurveytimehours • Angular Resolution: <2 arcseconds (Almost) no extinction! Benjamin et al (2003) PASP, 115, 953 http://www.astro.wisc.edu/glimpse

  3. GLIMPSE Point Source Catalog and Archive l msel mbr msens Catalog Archive 3.55 mm 14.2 7.0 13.3-13.6 29.0 million 42.4 million4.49 mm 14.1 6.5 13.3-13.6 29.0 million 39.1 million5.66 mm 11.9 4.0 11.7-12.3 11.1 million 11.7 million7.84 mm 9.5 4.0 11.0-12.4 8.4 million 9.0 millionTOTAL 31 million 43 million Data Products • GLIMPSE Point Source Catalog (> 99.5% reliable) • GLIMPSE Point Source Archive (~5s) • Mosaicked Images in 4 bands • “Web Infrared Tool Shed” Mid-IR models of circumstellar dust and PDRs Note: ~85% of sources expected to be between K2 giants (d<7 kpc) and M5 giants (d<124 kpc). http://data.spitzer.caltech.edu/popular/glimpse

  4. Indebetouw et al. 2005, ApJ 619, 931• Extinction in mid IR is nearly flat across IRAC bands! A[3.6] /AK=0.56±0.06 A[4.5] /AK=0.56±0.08 A[5.8] /AK=0.43±0.10 A[8.0] /AK=0.43±0.10 Mean Free Path in Galactic ISM X-ray opacity (Benjamin 2004), UV/Optical (Clayton, Cardelli, Mathis 1989), IR (Li & Draine 2001) Assuming nH=1 cm-3

  5. RCW 79 IRAS 16205-5729(near RCW49) G311.5-0.3 GLIMPSE-C01 K Objects Uncovered by GLIMPSE 329 PAH Bubbles Churchwell et al (2005), in prep Supernova Remnant SurveyReach et al (2005), astro-ph/0510630 IR Dark Cloud SurveyDevine et al (2005), in prep New Planetary NebulaeCohen et al (2005), ApJ, 627, 446 24 New Mid IR Stellar BowshocksBenjamin et al (2005), in prep Large (R>9000 AU) Circumstellar Disk CandidateWalker et al (2005), in prep 92 New Open Stellar Clusters Mercer et al (2005), ApJ in press New Galactic Globular Cluster Kobulnicky et al (2005) AJ 129, 239

  6. • Edge-on spiral, face-on spiral, eight other candidates seen at l=317o b=-0.5o • “Transparency” of Galactic ISM at midplane relevant to search for “Zone of Avoidance” galaxies and using light profiles of external edge-on systems. Galaxy Cluster?

  7. Associated with Great Attractor? (10 kpc=30”) Galaxy Cluster?

  8. 10 deg to Galactic Center • Extinction still affects star counts for some small areas with dense CO clouds.• 25 % more stars to the left of Galactic Center (l=10-30) than to the right (l=350-330)

  9. Blueright of G.C. (l=350-295) Redleft of G.C. (l=10-65) • Galaxy approx. axisymmetric outside l=30o, but some enhancements, e.g. l=307o• Fit by N=No(l/lo)K1(l/l0) where lo=24±4o [4.5 band] (17-30o)

  10. ? Blueright of G.C. (l=350-295) Redleft of G.C. (l=10-65) Fits of data to n=no(S/So)-a yield aavg=1.83-1.95

  11. More sources: Faint and small l G.C. 54o 34o Molecular cloud/W41/W42 at l=23-25 Sun Fewer sources: Bright and large l Galactic Longitude

  12. Galactic structure parameters(Benjamin et al 2005 ApJL 630, 149) BAR Rbar=4.4±0.5 kpc fbar=44 ±10o M[4.5]=-2.15 ±0.2 mag (early K giants) DISK N=No(l/lo)K1(l/l0) lo=24±4o (17-30o) Rdisk=3.5 ±0.5 kpc SPIRAL ARMS Clear enhancement at l=306-309 (Centaurus) No enhancement at l= 49 (Sagittarius)

  13. l=30o l=-16o (344o) Credit: Robert Hurt (SSC/JPL/NASA) Galactic Longitude Asymmetry

  14. THANK YOU, SPITZER LEGACY PROGRAM! • Data is available to you now for FREE from SSC website. GLIMPSE: A Legacy for Galactic AND Extragalactic Research • GLIMPSE is uncovering a plethora of objects (clusters, star formation regions, PAH rings, planetary nebulae, SNR, mid IR stellar bowshocks, protostellar jets, other galaxies, etc.) that will provide detailed understanding of emission mechanisms for distant sources. • Mid IR star counts can now be used for the study of Galactic stellar structure to yield the scale-length of the stellar disk, the angle and size of the bar, and the locations of stellar spiral arms.* The bar seems to be enhanced in early K giants (lucky for us). • Coming up soon: • GLIMPSE II (the inner 20 degrees) • Refined Galactic modelling results (including amplitudes of bar/disk/arms). • Diffuse emission variation vs. location in Galaxy * [The length and] angle of the bar are also new”, said astronomer Michael Merrifield, “It’s a very different angle from the 10-30 degrees of previous analyses. In some sense, the new method is really pretty elegant but it’s at odds with previous estimates using different methods. Clearly, at least one of them is definitely wrong.” [discoverychannel.com, Sept 9, 2005] SSC website:data.spitzer.caltech.edu/popular/glimpseGLIMPSE website:www.astro.wisc.edu/glimpse(includes this talk)

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