Tidal Tales of Dark Gas: Searching for SQUARE_BRACKET_OPENCIISQUARE_BRACKET_CLOSE in CO-Deficient Star Forming Tidal Tails

How is star formation in tidal debris affected by gas properties? Toprobe the molecular gas properties of 3 tidal tail regions, we proposeto use the PACS spectrometer on Herschel to observe the CII 158micron line. Two particular tidal tail regions of interest are ClumpII in the M81 group and the western tail of NGC 2782. These tworegions are HIrich and have young blue stars or star clustersdetected in optical broadband and narrowband Halpha imaging; however,observations of CO 10 show nondetections down to low limits. Incontrast to these two regions, the base of the eastern tail of NGC2782 is rich in HI and CO and has young star clusters. Although thenondetection of CO suggests that there is no molecular gas in ClumpII and NGC 2782W, we expect the molecular gas to have a higherfraction of dark gas or mostly unobservable molecular hydrogen andC+. One way to observe this dark gas is to use the far infraredfine structure line of CII at 158 microns. Using these CIIobservations and previous data in optical, nearinfrared,submillimeter, and radio, we will compare the measurements of gas andyoung stars in Clump II and NGC 2782W to those in NGC 2782E to examinethe dependence of star formation in tidal tail regions on gas properties. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]