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J/A+AS/92/625 Ionized nebulae in M31 (Walterbos+ 1992)
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The interstellar medium of M 31. III. Narrow-band imagery in H-alpha and SII.
Walterbos R.A.M., Braun R.
<Astron. Astrophys. Suppl. Ser. 92, 625 (1992)>
=1992A&AS...92..625W
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ADC_Keywords: Galaxies, nearby; Surveys; Nebulae; H II regions
Keywords: galaxies: M31, spiral - HII regions - supernova remnants -
planetary nebulae
Abstract:
Deep CCD imagery in H alpha and (SII) is presented of the major spiral arms
of M31 with particular attention given to the data reduction and the
analysis of the (SII)/H alpha flux ratios. A diffuse ionized gas noted in
the images is analyzed which shows higher (SII)/H alpha ratios, and 967
discrete nebulae are listed with gray-scale images, finding charts, and
absolute fluxes. The differential H-alpha luminosity function is found to
have a slope of -0.95 for brighter objects and flattens out below a
critical level. The curve is shown to correspond to the point at which
single-star ionization accounts for the H alpha luminosities and is
consistent with previous observations. The catalog of objects and fluxes is
the largest existing sample of this type, and the unresolved objects in the
sample are considered to be planetary nebulae.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2 213 967 Catalog of ionized nebulae in M31
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Byte-by-byte Description of file: table2
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Bytes Format Units Label Explanations
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2- 4 I3 --- ID []? Source ID in the catalog.
6- 7 I2 h RAh []? Right ascension 1950
9- 10 I2 min RAm []? Right ascension 1950
12- 17 F6.3 s RAs Right ascension 1950
19- 23 F5.3 s e_RAs rms uncertainty on right ascension
25 A1 --- DE- Declination sign
26- 27 I2 deg DEd []? Declination 1950
29- 30 I2 arcmin DEm []? DEclination 1950
32- 36 F5.2 arcsec DEs Declination 1950
38- 42 F5.2 arcsec e_DEs rms uncertainty on declination
44- 49 F6.2 arcsec MajAxis Source major axis. Nominally unresolved
sources have size 0.0
51- 54 F4.2 arcsec e_MajAxis rms uncertainty on source major axis or upper
limit for the size of unresolved sources
56- 61 F6.2 arcsec MinAxis Source minor axis. Nominally unresolved
sources have size 0.0
63- 66 F4.2 arcsec e_MinAxis rms uncertainty on source minor axis or upper
limit for the size of unresolved sources
68- 72 F5.1 deg PA Major axis position angle (east of north)
74- 77 F4.1 deg e_PA rms uncertainty on source minor axis
position angle
79- 83 F5.1 arcsec Rmin Minimum radius of the annular regions centered
on the source (1)
85- 89 F5.1 arcsec Rmax Maximum radius of the annular regions centered
on the source (1)
91- 97 F7.2 10-18W/m2 H-alp Integrated source flux in Halpha
(10^-15^ erg/cm2/s)
99-104 F6.2 10-18W/m2 e_H-alp rms uncertainty on Halpha flux
106-111 F6.2 10-18W/m2 [SII] Integrated source flux in the [SII] 6717
and 6731 Angstrom lines (10^-15^ erg/cm2/s)
Negative values correspond to 3 sigma
upper limits.
113-117 F5.2 10-18W/m2 e_[SII] rms uncertainty on [SII] flux
119-123 F5.2 arcmin X []? Major axis coordinate of the source
125-130 F6.2 arcmin Y []? Minor axis coordinate of the source
132-136 F5.2 arcmin R1 Radius within the galaxy of the spiral arm
"most likely" associated with the source (2)
138-142 F5.2 arcmin R2 Second possible radius (2)
144-148 F5.0 km/s V1 Radial heliocentric velocity corresponding to
the "most likely" radius R1 (2)
150-154 F5.0 km/s V2 Radial heliocentric velocity corresponding to
R2 (2)
156-160 F5.2 arcmin dY1 Minor axis offsets of the source position from
the "most likely" spiral arm
162-166 F5.2 arcmin dY2 Minor axis offsets of the source position
from the second arm
168-171 F4.2 --- tau1 Optical depth at Halpha along the source
line-of-sight using a fixed Galactic
foreground contribution and a variable
contribution from dust in M31, assuming a
source position at the middle of the
"most likely" spiral arm at the radius R1 (3)
173-176 F4.2 --- tau2 Like tau1 but at the radius R2
178-184 F7.1 10-18W/m2 H-alp' Optical-depth-corrected flux in Halpha
(10^-15^ erg/cm2/s) using the "most likely"
optical depth from tau1
186-190 F5.1 10-18W/m2 e_H-alp' rms uncertainty on H-alp'
192-197 F6.1 10-81W/m2 [SII]' Optical-depth-corrected flux in [SII] 6717
and 6731 Angstrom line (10^-15^ erg/cm2/s)
using the "most likely" optical depth tau1
199-203 F5.1 10-81W/m2 e_[SII]' rms uncertainty on [SII]'
205-210 A6 --- Xref Cross-reference ID to larger sources within
the catalog in which the listed entry
is embedded.
212-218 A7 --- Notes A lower case c means uncertain calibration,
S? implies that the source coincides with a
continuum source and may be a star, although
this is by no means certain, since often the
remaining Halpha signal is too strong to be
due to the faint star that is visible in the
red continuum. C1, C2, R1, R2, D1, and D2
indicate morphology, as described in the paper
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Note (1): Minimun and maximum radius of the annular regions centered on the
source and contained within an isolating box which were used to
determine the local background level and its uncertainty for extended
sources in the catalog. Sources with R_{min} = R_{max} = 0 were fitted
with an elliptical Gaussian.
Note (2): The values are based on the kinematic model of Braun (1991).
Note (3): Optical depths are based on integrations of high resolution HI data
(Braun 1990b) after correction for HI optical depth and calibrated with
dust-to-gas ratios of Braun and Walterbos (1991).
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Courtesy: Rene Walterbos <rwalterb@NMSU.Edu>
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(End) Patricia Bauer [CDS] 10-Jun-1994