J/A+A/592/A142   Reduced high-resolution HI and CO data cubes   (Roehser+, 2016)

High-resolution HI and CO observations of high-latitude intermediate-velocity clouds. Roehser T., Kerp J., Ben Bekhti N., Winkel B. <Astron. Astrophys. 592, A142 (2016)> =2016A&A...592A.142R 2016A&A...592A.142R (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Interstellar medium ; H I data ; Carbon monoxide ; Spectroscopy Keywords: instrumentation: high angular resolution - Galaxy: halo - ISM: clouds - ISM: structure - ISM: molecules Abstract: Intermediate-velocity clouds (IVCs) are HI halo clouds that are likely related to a Galactic fountain process. In-falling IVCs are candidates for the re-accretion of matter onto the Milky Way. Aims. We study the evolution of IVCs at the disk-halo interface, focussing on the transition from atomic to molecular IVCs. We compare an atomic IVC to a molecular IVC and characterise their structural differences in order to investigate how molecular IVCs form high above the Galactic plane. With high-resolution HI observations of the Westerbork Synthesis Radio Telescope and 12CO(1-0) and 13CO(1-0) observations with the IRAM 30m telescope, we analyse the small-scale structures within the two clouds. By correlating HI and far-infrared (FIR) dust continuum emission from the Planck satellite, the distribution of molecular hydrogen (H2) is estimated. We conduct a detailed comparison of the HI, FIR, and CO data and study variations of the XCO conversion factor. The atomic IVC does not disclose detectable CO emission. The atomic small-scale structure, as revealed by the high-resolution HI data, shows low peak HI column densities and low HI fluxes as compared to the molecular IVC. The molecular IVC exhibits a rich molecular structure and most of the CO emission is observed at the eastern edge of the cloud. There is observational evidence that the molecular IVC is in a transient and, thus, non- equilibrium phase. The average XCO factor is close to the canonical value of the Milky Way disk. We propose that the two IVCs represent different states in a gradual transition from atomic to molecular clouds. The molecular IVC appears to be more condensed allowing the formation of H2 and CO in shielded regions all over the cloud. Ram pressure may accumulate gas and thus facilitate the formation of H2. We show evidence that the atomic IVC will evolve also into a molecular IVC in a few Myr. Description: The spectral data cubes of the reduced high-resolution observations are provided for both clouds (mIVC and aIVC) in standard FITS format. For more details, compare with Table 1 of the corresponding publication. (1) The high-resolution 21-cm emission of neutral atomic hydrogen was observed with the Westerbork Synthesis Radio Telescope (Netherlands). The mIVC was covered with a single pointing, the aIVC with two pointings (denoted as aIVC1 and aIVC2). The Westerbork HI data is provided in Equatorial Coordinates with SIN projection, satisfying the WCS standard (Greisen & Calabretta, 2002A&A...395.1061G 2002A&A...395.1061G, Calabretta & Greisen, 2002A&A...395.1077C 2002A&A...395.1077C, Greisen et al., 2006A&A...446..747G 2006A&A...446..747G). (2) The rotational emission lines 12CO(1-0) and 13CO(1-0) were observed with the IRAM 30-m telescope (Spain) using the FTS spectrometer (Klein et. al, 2012A&A...542L...3K 2012A&A...542L...3K). For the aIVC, the empty 12CO(1-0) data cube is provided. The IRAM CO data is gridded in Equatorial Coordinates with GLS projection, satisfying the WCS standard. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file list.dat 138 6 List of fits datacubes fits/* . 6 Individual data cubes -------------------------------------------------------------------------------- Byte-by-byte Description of file: list.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 9 F9.5 deg RAdeg Right ascension (J2000) of data cube center 10- 18 F9.5 deg DEdeg Declination (J2000) of data cube center 20- 23 I4 pix Nx Number of pixels along X-axis 25- 28 I4 pix Ny Number of pixels along Y-axis 30- 32 I3 pix Nz Number of slices 34- 59 A26 --- Obs.Date Observation date (YYYY-MM-DDThh:mm:ss.ssssss) 61- 67 F7.2 km/s VLSRl Lower value of LSR velocity interval 69- 73 F5.2 km/s VLSRu Upper value of LSR velocity interval 75- 78 F4.2 km/s dVLSR Spectral resolution in LSR velocity 80- 85 I6 Kibyte size Size of FITS file 87-107 A21 --- FileName Name of the FITS file in subdirectory fits 109-138 A30 --- Title Title of the fits file -------------------------------------------------------------------------------- Acknowledgements: Tobias Roehser, troehser(at)astro.uni-bonn.de
(End) Patricia Vannier [CDS] 04-Aug-2016
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