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J/AJ/137/3869       Radio SNRs in 4 irregular galaxies      (Chomiuk+, 2009)

A search for radio supernova remnants in four irregular galaxies. Chomiuk L., Wilcots E.M. <Astron. J., 137, 3869-3883 (2009)> =2009AJ....137.3869C
ADC_Keywords: Supernova remnants ; Radio sources ; Morphology Keywords: galaxies: individual (NGC 1569, NGC 2366, NGC 4214, NGC 4449) - radio continuum: galaxies - supernova remnants Abstract: We survey four nearby irregular galaxies for radio supernova remnants (SNRs) using deep (1σ∼20uJy), high-resolution (∼20pc) Very Large Array continuum data at 20, 6, and 3.6cm. We identify discrete sources in these galaxies and use radio spectral indices and Hα images to categorize them as SNRs, HII regions, or background radio galaxies. Our classifications are generally in good agreement with the literature. We identify a total of 43 SNR candidates: 23 in NGC 1569, seven in NGC 4214, five in NGC 2366, and eight in NGC 4449. Only one SNR - the well-studied object J1228+441 in NGC 4449 - is more luminous at 20cm than Cas A. By comparing the total thermal flux density in each galaxy with that localized in HII regions, we conclude that a significant fraction must be in a diffuse component or in low-luminosity HII regions. Description: All radio data used here were obtained with the VLA of the National Radio Astronomy Observatory (NRAO). All VLA data are publicly available through the NRAO Archive, obtained by other investigators between 1983 and 2002, with the exception of the C-band data for NGC 2366, which were obtained by the present authors in 2006. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table4.dat 106 46 20cm sources in NGC 1569 table5.dat 106 29 20cm sources in NGC 4214 table6.dat 106 24 20cm sources in NGC 2366 table7.dat 106 30 20cm sources in NGC 4449
Byte-by-byte Description of file: table?.dat
Bytes Format Units Label Explanations
1- 8 A8 --- [CW2009] Source name, N1569-NN, N4214-NN, N2366-NN, or N4449-NN 9 A1 --- n_[CW2009] [*] Variable source (1) 11- 12 I2 h RAh Right ascension (J2000) 14- 15 I2 min RAm Right ascension (J2000) 17- 21 F5.2 s RAs Right ascension (J2000) 23 A1 --- DE- Declination sign (J2000) 24- 25 I2 deg DEd Declination (J2000) 27- 28 I2 arcmin DEm Declination (J2000) 30- 33 F4.1 arcsec DEs Declination (J2000) 35- 38 F4.1 arcsec amaj Major axis 39 A1 --- --- [/] 40- 43 F4.1 arcsec amin Minor axis 45- 49 F5.2 mJy S20cm Flux density at 20cm (1.5GHz) 51- 54 F4.2 mJy e_S20cm rms uncertainty on S20cm 56 A1 --- l_S6cm Limit flag on S6cm (5GHz) 57- 60 F4.2 mJy S6cm Flux density at 6cm 62- 65 F4.2 mJy e_S6cm ? rms uncertainty on S6cm 67 A1 --- l_S3.6cm Limit flag on S3.6cm (8.3GHz) 68- 71 F4.2 mJy S3.6cm ?=- Flux density at 3.6cm 73- 77 F5.3 mJy e_S3.6cm ? rms uncertainty on S3.6cm 79 A1 --- l_alpha Limit flag on alpha 80- 84 F5.2 --- alpha Spectral index α [S∝nuα] 86- 89 F4.2 --- e_alpha ? rms uncertainty on alpha 91- 93 A3 --- Ha [Yes/No ] Hα emission? 95-105 A11 --- Class Classification (2) 106 A1 --- n_Class [ab] Note (1)
Note (1): Notes as follows: * = The flux of this source is time variable and, therefore, given the different epochs of the flux measurements, the spectral index is not trustworthy. a = This source is actually likely an SNR based on [FeII] and Pabeta emission in Labrie & Pritchet (2006ApJS..166..188L). b = Additional data in the literature lend credence to this characterization; see Section 6. Note (2): Classification as follows: Bkg = no apparent Hα emission associated with it Bkg (>R_25) = no apparent Hα emission associated with it, source located beyond the galaxy's optical diameter SNR = has α≤-0.2 and Hα emission associated with it H II = has α>-0.2 and Hα emission associated with it
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 16-Sep-2011
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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