J/AJ/108/1276 Clusters in GEHRs (Mayya, 1994)
Embedded clusters in giant extragalactic HII Regions. I. BVRHalpha photometry
Mayya Y.D.
<Astron. J. 108, 1276 (1994)>
=1994AJ....108.1276M 1994AJ....108.1276M (SIMBAD/NED Reference)
ADC_Keywords: H II regions ; Photometry, H-alpha ; Equivalent widths
Abstract:
Photometry in BVR continuum bands and in the emission line of Halpha+
[N II] are presented for a sample of H II complexes in disk, spiral arm
and nuclear regions of galaxies NGC 1365, 1566, 2366, 2903, 2997, 3351,
4303, 4449, and 5253. Main sources of errors on H II region photometry
are discussed. Errors due to background subtraction are parametrized
in terms of background nonuniformity and fractional background
contribution and are described separately in the Appendix. Our
photometric data are compared with the existing data in the literature.
Photometric properties of the sample regions are analyzed statistically
and its implications on star formation are briefly discussed. Colors
and Halpha+[N II] equivalent widths of nuclear H II regions are found
to be distinctly different from disk H II regions, suggesting different
star formation histories. We have identified a few high Halpha+[N II]
equivalent width regions, which are fainter than average in both
emission line and continuum fluxes, thus accounting for the low
frequency of occurence of such regions in flux limited samples.
Addresses:
Mayya Y.D.
Indian Institute of Astrophysics, Bangalore 560 034, India
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3 93 186 Photometric catalogue of H II regions
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Byte-by-byte Description of file: table3
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Bytes Format Units Label Explanations
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1- 12 A12 --- Gal Galaxies name (g for groups)
14- 15 I2 --- ID H II region numbers (1)
18- 20 I3 pix Xpos X pixel coordinate (2)
22- 24 I3 pix Ypos Y coordinate (2)
27 A1 --- dirRA [EW] Direction of RA position (3)
28- 30 I3 arcsec posRA ? Approximate right ascension position (3)
32 A1 --- dirDE [NS] Direction of DE position (3)
33- 35 I3 arcsec posDE ? Approximate declination position (3)
38- 41 F4.1 arcsec Diam Diam. of aperture for mag. extractions
43 A1 --- l_Vmag [>] Limiting character for V
44- 48 F5.2 mag Vmag V magnitude (4)
50- 54 F5.2 mag B-V []? B-V color (4)
56- 60 F5.2 mag V-R []? V-R color (4)
63- 68 F6.2 [mW/m2] Salpha Log of observed H_alpha+[N II] flux
70 A1 --- l_W(Ha) Limiting character for W(Ha)
71- 74 I4 0.1nm W(Ha) Emission equivalent width (5)
77 I1 --- Qual Index of photometric quality (6)
80- 93 A14 --- OtherID Id. from other authors when available (7)
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Note (1): H II region numbers as identified on the charts in the printed paper.
Note (2): X and Y pixel coordinates on the aligned CCD images, which are the
same as that appearing on the grid around identification charts.
For NGC 4449 the grids contain different pixel numbers than that
given in these columns for the reasons mentioned in the text.
Note (3): Approximate position of the H II region, along Right Ascension and
declination in seconds of arc, with respect to the galactic nucleus.
These were obtained by transforming X and Y assuming that the RA-DEC
axis is aligned with X-Y axis of the CCD. Since the alignment during
observations is only approximate (≤5deg), RA and DEC values away
from the center are less accurate, compared to those near the center
of the CCD. Thus the positions should be used only for identification
purposes. E, W, N, and S preceeding the numbers indicate respectively
whether the H II region is to the east, west, north or south of the
nucleus of the galaxy.
Note (4): V Magnitude, B-V and V-R colors of H II regions after subtracting
assumed background. The rms errors on the measured magnitudes are
in the range 0.05-0.10, as estimated from measurements on multiple
frames.
Note (5): H_alpha + [N II] emission equivalent width in A with R magnitude as
an estimate for the continuum at H_alpha, computed using the equation
W(Ha)=1.633E-11*F_alpha/10**(-0.4(R+48.6))
where, F_alpha is the H_alpha + [N II] flux in mW/m^2 (erg/s/cm^2).
The measurement errors are <20A. Note that the R band magnitudes used
in the above definition include emission from the nebular continuum
and lines.
Note (6): An index of photometric quality. It is an integer between 1 and 4
and gives a measure of the background domination for BVR
measurements. Higher the index, more sensitive are the colors to the
background measurement. See printed paper for details.
Note (7): Identification from other authors when available. For measurements
with bigger apertures, individual GEHRs enclosed within the aperture
are indicated. The notations used for identifications are:
CM Crillon and Monnet 1969, =1969A&A.....1..449C 1969A&A.....1..449C
HK Hodge and Kennicutt 1983, =1983AJ.....88..296H 1983AJ.....88..296H
HP Hawley and Phillips 1980, =1980ApJ...235..783H 1980ApJ...235..783H
AN Alloin and Nieto 1982, =1982A&AS...50..491A 1982A&AS...50..491A
Oka Oka et. al 1974, PASJ, 26, 289
Tpp Prabhu 1980, ApSpSci., 68, 519
L Lindblad, P.O. see Alloin et. al, 1981A&A...101..377A 1981A&A...101..377A
M McCall, Rybski, and Shields 1985, =1985ApJS...57....1M 1985ApJS...57....1M
RW Roy and Walsh: 1986MNRAS.223...39R 1986MNRAS.223...39R; 1987MNRAS.228..883R 1987MNRAS.228..883R;
1988MNRAS.234..977R 1988MNRAS.234..977R
WR Walsh and Roy: 1989MNRAS.239..297W 1989MNRAS.239..297W; 1989ApJ...341..722W 1989ApJ...341..722W
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Origin: AAS CD-ROM series, Volume 3, 1995
(End) Lee Brotzman [ADS] 31-Oct-1994, Patricia Bauer [CDS] 16-Feb-1995