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J/ApJS/178/1    Distribution of HII regions in disk galaxies   (Sanchez+, 2008)
The fractal distribution of H II regions in disk galaxies.
    Sanchez N., Alfaro E.J.
   <Astrophys. J. Suppl. Ser., 178, 1-19 (2008)>
   =2008ApJS..178....1S
ADC_Keywords: Galaxy catalogs ; H II regions

Keywords: catalogs - galaxies: structure, ISM: H II regions - stars: formation


Abstract:
    It is known that interstellar gas has a fractal structure in a wide
    range of spatial scales with a fractal dimension that seems to be a
    constant around Df∼2.7. It is expected that stars forming from this
    fractal medium exhibit similar fractal patterns. Here we address this
    issue by quantifying the degree to which star-forming events are
    clumped. We develop, test, and apply a precise and accurate technique
    to calculate the correlation dimension Dc of the distribution of HII
    regions in a sample of disk galaxies.

Description:
    We have compiled literature data for positions of HII regions in
    external galaxies. Here we present the set of HII region catalogues
    for a sample of 101 disk galaxies (93 spirals and 8 irregulars). For
    each galaxy several properties are given including the calculated
    fractal (correlation) dimension of the distribution of HII regions.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table2.dat        80      101   Properties of the galaxies in the sample
table3.dat        41      101   Calculated fractal dimensions
hii/*             21      101   HII regions individual data


Byte-by-byte Description of file: table2.dat

   Bytes Format Units   Label     Explanations

   1- 10  A10   ---     Name      Galaxy name
  13- 16  A4    ---     MType     Morphological Hubble type
  19- 23  F5.1  deg     PA        Position angle
  26- 29  F4.1  deg     IA        Inclination angle
  32- 34  F3.1  ---     TType     Morphological de Vaucouleurs type
  37- 38  I2    ---     Arm       ? Spiral arm class
  41- 45  F5.1  Mpc     Dist      Distance to the galaxy
  48- 53  F6.2  mag     BMAG      ? B-band absolute magnitude
  56- 60  F5.2  kpc     R25       25mag/arcsec2 isophotal radius
  63- 67  F5.1  km/s    Vrot      ? Maximum rotation velocity
                                    corrected for inclination
  69- 80  A12   ---     FileName  Name of the file containing the HII region
                                   data, in the "hii" subdirectory


Byte-by-byte Description of file: table3.dat

   Bytes Format Units   Label     Explanations

   1- 10  A10   ---     Name      Galaxy name
  13- 16  I4    ---     HII       Number of catalogued HII regions
  19- 22  F4.2  ---     Dc        Calculated correlation (fractal) dimension
  25- 28  F4.2  ---     e_Dc      Estimated uncertainty in Dc
  31- 34  F4.2  kpc     Rmin      Minimum spatial scale of the distribution
  37- 41  F5.2  kpc     Rmax      Maximum spatial scale of the distribution


Byte-by-byte Description of file: hii/*

   Bytes Format Units   Label   Explanations

   1-  7  F7.2  kpc     Xpos    X position of HII region with respect to
                                 the galaxy centre
  11- 17  F7.2  kpc     Ypos    Y position of HII region with respect to
                                 the galaxy centre
      21  I1    ---     Flag    [0/1] HII region excluded (0) or included (1)
                                      in the calculation of Dc


Acknowledgements:
    Nestor Sanchez, nestor(at)iaa.es
(End)                                      Patricia Vannier [CDS]    08-Sep-2008