J/A+AS/110/81       Methanol masers towards IRAS sources (van der Walt+ 1995)
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New detections of 51- 60  A+-methanol masers towards IRAS sources
    van der Walt D.J., Gaylard M.J., MacLeod G.C.
   <Astron. Astrophys. Suppl. Ser. 110, 81 (1995)>
   =1995A&AS..110...81V      (SIMBAD/NED BibCode)
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ADC_Keywords: Infrared sources ; Masers

Mission_Name: IRAS

Keywords: masers - ISM: clouds - ISM: molecules - radio lines: ISM


Abstract:
    We present the results of our second search for 6.7-GHz methanol
    masers towards colour-selected IRAS sources. Five hundred and twenty
    IRAS sources that meet the far-infrared colour criteria set by Wood &
    Churchwell (1989ApJ...340..265W) for ultra-compact HII regions were
    searched for 6.7-GHz methanol maser emission, to a sensitivity limit
    of 5Jy. Thirty one new maser sources were detected. We also compare
    the FIR colours of the newly detected maser sources with those
    detected by Schutte et al. (1993MNRAS.261..783S) and the IRAS
    counterparts of sources that have both methanol and hydroxyl maser
    emission. It was found that the average flux distribution of the newly
    detected sources differs significantly from that of all other known
    6.7-GHz methanol maser sources. It is argued that the differences may
    be due either to intrinsic differences between the three groups of
    sources or to interstellar extinction. An analysis of the relation
    between the 6.7-GHz maser and IRAS flux densities shows that the maser
    flux density is always less than the 100µm flux density while only
    three sources have a maser flux density greater than the 60µm flux
    density. Far-infrared pumping of the 6.7-GHz methanol masers is
    therefore in principle viable although it was found that the apparent
    maser efficiency will exceed 10 per cent for a significant number of
    sources in the case of FIR pumping by photons between 50 and 100µm.
    The overall detection rates on the IRAS [25-12] vs [60-12] two-colour
    diagram are also presented. Possible new search strategies for masers
    in colour-selected IRAS sources are discussed.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1            13      520   Source IRAS names
table2            75       31   Parameters of detected 6.668-GHz
                                  A+ -methanol masers


Byte-by-byte Description of file:  table1

   Bytes Format Units   Label     Explanations

       1  A1    ---     Note      [abcd] Characteristics (1)
   3- 13  A11   ---     IRAS      IRAS name (2)

Note (1): a: Sources with no upper limits at 12, 25, 60 & 100µm
          b: Sources with upper limit at 12 µm
          c: Sources with upper limit at 100 µm
          d: Sources with upper limits at 12 & 100 µm
Note (2): Misprint IRAS 06513-4316A for IRAS 16513-4316A



Byte-by-byte Description of file:  table2

   Bytes Format Units     Label     Explanations

   1- 11  A11   ---       IRAS      IRAS name (Cat. II/125)
  13- 14  I2    h         RAh       Right ascension (1950)
  16- 17  I2    min       RAm       Right ascension (1950)
  19- 22  F4.1  s         RAs       Right ascension (1950)
      24  A1    ---       DE-       Declination sign
  25- 26  I2    deg       DEd       Declination (1950)
  28- 29  I2    arcmin    DEm       Declination (1950)
  31- 32  I2    arcsec    DEs       Declination (1950)
  34- 39  F6.2  deg       GLON      Galactic longitude
  41- 45  F5.2  deg       GLAT      Galactic latitude
  47- 50  I4    km/s      Vmin      Velocity range (lower value)
  52- 55  I4    km/s      Vmax      Velocity range (upper value)
  57- 61  F5.1  Jy        Speak     Peak flux density
  63- 65  F3.1  Jy        e_Speak   rms uncertainty on Speak
  67- 71  F5.1  Jy.km/s   Ipeak     Integrated peak flux density
  73- 75  F3.1  Jy.km/s   e_Ipeak   rms uncertainty on Ipeak


History: Prepared via OCR at CDS.
  * 31-Oct-1997: two errors in table1 detected and corrected.
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(End)                           James Marcout, Patricia Bauer [CDS]  08-Apr-1997