J/A+A/284/233   Association of HII regions and IRAS PSC sources (Codella+ 1994)
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HII Regions and IRAS PSC sources: the realiability of the association
     CODELLA C., FELLI M., NATALE V.
    
    =1994A&A...284..233C
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ADC_Keywords: H II regions ; Infrared sources
Keywords: HII regions - radio   lines: interstellar - stars: formation
          infrared: continuum: ISM

File Summary:

Abstract:
The IRAS Point Source Catalogue has been compared with a catalogue of 462
(diffuse) HII regions detected in hydrogen radio recombination lines. To
distinguish the true IRAS counterpart of the HII region from chance
coincidences the distribution of offset and the position in colour-colour
plots as a function of F(60um) are investigated. It is found that sources
with F(60um) < 100 Jy have a high probability of being chance coincidences.
The far infrared properties of the HII regions are investigated for a
subsample of 252 IRAS PSC sources which have a high (> 80%) probability of
being true coincidences. The majority satisfy the Wood and Churchwell colour
criteria which identify ultracompact HII regions; therefore, these criteria
select ultracompact as well as more diffuse HII regions, or, alternatively,
diffuse HII and ultracompact HII regions may often be mixed, as predicted by
the sequential star formation theory. The luminosity of a single star
required to produce the observed HII line emission correlates very well with
the far infrared luminosity and is, on the average, higher than the observed
value. Consequently, the stars ionizing the extended HII regions can account
for the bulk of the observed FIR emission and no contribution from lower
mass stars of the cluster is necessary.

Keywords: HII regions - radio lines: interstellar - stars: formation -
infrared: continuum: ISM
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 FileName    Lrecl    Records    Explanations
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ReadMe          80          .    This file
table1         156        252    IRAS properties of HII regions
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Byte-by-byte Description of file: table1
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   Bytes Format  Units   Label    Explanations
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   1-  2  I2     h       RAh      Right Ascension (1950)
   4-  5  I2     min     RAm      Right Ascension (1950)
   7- 10  F4.1   s       RAs      Right Ascension (1950)
      13  A1     ---     DE-      Declination sign
  14- 15  I2     deg     DEd      Declination (1950)
  17- 18  I2     arcmin  DEm      Declination (1950)
  20- 21  I2     arcsec  DEs      Declination (1950)
  26- 32  F7.3   deg     GLON     Galactic longitude
  35- 41  F7.3   deg     GLAT     Galactic latitude
  49- 53  F5.2   kpc     d        []? Distance
  55- 58  I4     pc      z        []? Height from the galactic plane
  65- 75  A11    ---     IRAS     IRAS name
      81  A1     ---   l_F12      limit flag on F12 (upper limit)
  83- 90  E8.2   Jy      F12      IRAS flux density at 12 micron
      92  A1     ---   l_F25      limit flag on F25 (upper limit)
  94-101  E8.2   Jy      F25      IRAS flux density at 25 micron
     103  A1     ---   l_F60      limit flag on F60 (upper limit)
 105-112  E8.2   Jy      F60      IRAS flux density at 60 micron
     114  A1     ---   l_F100     limit flag on F100 (upper limit)
 116-123  E8.2   Jy      F100     IRAS flux density at 100 micron
     125  A1     ---   l_FIR      limit flag on FIR (upper limit)
 127-134  E8.2   W/m2    FIR      Integrated infrared flux
     136  A1     ---   l_LFIR     limit flag on LFIR (upper limit)
 138-145  E8.2   Sun     LFIR     []? IRAS luminosity
 148-156  A9     ---     R        Remarks: D    : double position
                                           UCHII: IRAS sources inside the WC box
                                           O    : observed UCHII region
                                                   (see text)
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(End)                                           Patricia Bauer [CDS] 25-Nov-1993