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Detecting Dark Clouds in the Galactic Plane with 2MASS data By : Luis Mercado In collaboration with the part of GLIMPSE team (Christer Watson, Ed Churchwell and Bob Benjamin)
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Detecting Dark Clouds in the Galactic Plane with 2MASS data By : Luis Mercado

Feb 01, 2016

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Detecting Dark Clouds in the Galactic Plane with 2MASS data By : Luis Mercado. In collaboration with the part of GLIMPSE team (Christer Watson, Ed Churchwell and Bob Benjamin). Introduction / Background. What are Dark Clouds and why study them? Optically thick at visual and IR wavelengths - PowerPoint PPT Presentation
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  • Detecting Dark Clouds in the Galactic Plane with 2MASS dataBy : Luis MercadoIn collaboration with the part of GLIMPSE team (Christer Watson, Ed Churchwell and Bob Benjamin)

  • Introduction / BackgroundWhat are Dark Clouds and why study them?Optically thick at visual and IR wavelengthsStar Formation RegionsGLIMPSE & SIRTF Infrared SurveysMSX (8 micron) Showed dark clouds to be thicker than previously believed2MASS 2 Micron All-Sky Survey

  • 2MASS DatabaseImaged entire sky in near infrared with J, H & K filtersUsed data to produce point source catalog with over 300 million sourcesOur selection criteria:Artifact flagsMagnitude errors < 0.15 magsMag limits:14.3 for H, 13.5 for K

  • Our TechniqueH-K grid pixels represent average color excess over a radius of 1.2Stellar density grid pixels represent number of stars over radius of 1.2Unsharp Masking used Gaussian to smooth image and create contrast image

  • Smoothing ProcessContrast =Image - Background_____________________Background1.2 radius for image2.0 radius for smoothing

  • Our TechniqueH-K grid pixels represent average color excess over a radius of 1.2Stellar density grid pixels represent number of stars over radius of 1.2Unsharp Masking used Gaussian to smooth image and create contrast imageBest technique: product of color and density contrasts

  • What it all looks like

  • Above: Product of density and color contrast.

    Below:MSX image of same field (l = 1015).Notice the correlation between the dark blue objects on the contrast plot and high absorption areas (dark clouds) in the MSX image.

  • 2MASS three color image of test field.Also plotted are contours obtained from our selection method for the corresponding area.

  • Results / ConclusionsDark Clouds are identifiable with 2MASS dataFound technique that proves thisColor excess and stellar density are both used as indicators380 dark clouds were detected in l = 10- 40 range with our techniqueSince we only see foreground stars, information about the clouds is limited

  • What Now?Develop catalogue of Dark Clouds for publishingPresent work at AAS meetingUse data on future research missions such as SIRTF

  • THE END

  • ProblemsLeft: Histogram of # of dark clouds detected vs. galactic longitude. Notice a rise in detections at high longitudes, opposite to what would be expectedRight: Plot of noise and density versus longitude. Notice the similar behavior. It turns out noise seems to be proportional to the density, but in an unexpected way.