J/A+AS/92/625 Ionized nebulae in M31 (Walterbos+ 1992)
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 1992A&AS...92..625W
ADC_Keywords: Galaxies, nearby; Surveys; Nebulae; H II regions
Keywords: galaxies: M31, spiral - HII regions - supernova remnants -
planetary nebulae
Abstract:
Deep CCD imagery in Hα 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]/Hα flux ratios. A diffuse ionized gas
noted in the images is analyzed which shows higher [SII]/Hα
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 Hα 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.dat 213 967 Catalog of ionized nebulae in M31
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Byte-by-byte Description of file: table2.dat
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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 (4)
51- 54 F4.2 arcsec e_MajAxis rms uncertainty on source major axis (4)
56- 61 F6.2 arcsec MinAxis Source minor axis (4)
63- 66 F4.2 arcsec e_MinAxis rms uncertainty on source minor axis (4)
68- 72 F5.1 deg PA Major axis position angle (east of north)
74- 77 F4.1 deg e_PA rms uncertainty on PA
79- 83 F5.1 arcsec Rmin Minimum radius of annular region (1)
85- 89 F5.1 arcsec Rmax Maximum radius of annular region (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 [SII] source flux (5)
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 at R1 (2)
150-154 F5.0 km/s V2 Radial heliocentric velocity at 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 at radius R1 (3)
173-176 F4.2 --- tau2 Optical depth at Halpha at radius R2 (3)
178-184 F7.1 10-18W/m2 H-alp' Optical-depth-corrected flux in Halpha (6)
186-190 F5.1 10-18W/m2 e_H-alp' rms uncertainty on H-alp'
192-197 F6.1 10-18W/m2 [SII]' Optical-depth-corrected flux in [SII] (6)
199-203 F5.1 10-18W/m2 e_[SII]' rms uncertainty on [SII]'
205-207 I3 --- Xref ? Cross-reference ID to larger sources within
the catalog in which the listed entry
is embedded.
209-210 A2 --- Morph [CDR123 ] Morphology (7)
212-213 A2 --- Notes [cS? ] Notes (8)
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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 Rmin = Rmax = 0 were fitted
with an elliptical Gaussian.
Note (2): The values are based on the kinematic model of Braun
(1991ApJ...372...54B 1991ApJ...372...54B).
Note (3): optical depth 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 specified radius. Optical depths are based on
integrations of high resolution HI data (Braun 1990ApJS...72..761B 1990ApJS...72..761B)
after correction for HI optical depth and calibrated with dust-to-gas
ratios of Braun and Walterbos (1992ApJ...386..120B 1992ApJ...386..120B).
Note (4): Nominally unresolved sources have size 0.0; the rms values
contain then an upper limit for the size of unresolved source.
Note (5): Integrated source flux in the [SII] (6717 and 6731 Angstrom
lines, expressed in 10-15 erg/cm2/s). Negative values correspond
to 3σ upper limits.
Note (6): flux expressed in 10-15 erg/cm2/s, using the "most likely"
optical depth from tau1
Note (7): Morphology is defined as a letter
C = center brightened
D = diffuse
R = ring
followed by a number (1 for best classification quality).
Note (8): the symbols are:
c (lower case) 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.
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Courtesy: Rene Walterbos
History:
* 24-Jul-2002: table2 reformatted, to put the morphology in dedicated
columns; ReadMe was updated accordingly. (Francois Ochsenbein, CDS)
(End) Patricia Bauer [CDS] 10-Jun-1994