J/ApJS/99/551 BVI photometry of massive stars in M33 and M31 (Hunter+ 1995)
The massive star populations in ionized gas shells in M33 and M31
Hunter D.A., Boyd D.M., Hawley W.N.
<Astrophys. J. Suppl. Ser. 99, 551 (1995)>
=1995ApJS...99..551H 1995ApJS...99..551H
ADC_Keywords: Interstellar medium ; Photometry
Keywords: galaxies: individual (M31, M33) - galaxies: ISM -
galaxies: star clusters - galaxies: stellar content -
stars: early-type
Abstract:
We present BVI photometry of the massive stars in and around five
Halpha shells in M33 and two in M31. These data can be used to
statistically compare the stellar population with ionization and
formation requirements of the gas shell. We have counted the numbers
of massive stars encircled by the shells and embedded within the
gaseous structures and corrected these numbers statistically for
background and foreground interlopers. We find that the stellar
production exceeds the ionization requirements of the nebulae by
factors of 4-10. Thus, it is reasonable that the shells are
photoionized and that a large fraction of the ionizing photons escape
into the rest of the galaxy. We have also compared the number of
massive stars counted and extrapolated to 7M☉ with the number
required to form the shells according to a simple formation model.
With one exception, we find that the number of stars estimated to be
present exceeds the number required by the model for our assumptions
of age and ambient gas density. This comparison and the morphology
evident in Halpha images suggests that the modification of the
interstellar medium by the massive stars in these regions has been far
more complicated than is currently considered in formation models.
There is evidence for multiple, and to some extent discreet, events in
the production of the gas structures. A more detailed modeling will be
necessary to adequately account for the stellar populations and Halpha
morphology.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 71 2228 The photometry
table3.dat 47 24 The groups and reddening
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See also:
J/ApJS/122/431 : Star Clusters in M33. I. (Chandar+, 1999)
J/A+A/366/498 : HST VI photometry of M33 star clusters (Chandar+, 2001)
J/AJ/121/861 : BVI photometry of central part of M33 (Macri+, 2001)
J/AJ/121/870 : Variables in the central part of M33 BVI phot. (Macri+, 2001)
J/AJ/110/1649 : HST VI photometry near the M33 nucleus (Mighell+ 1995)
J/AJ/110/2715 : UBV photometry in NGC 6822, M31 and M33 (Massey+ 1995)
J/ApJ/324/172 : M31 UBVR photometry (Hodge+, 1988)
J/ApJS/118/177 : JHK photometry of M31 spiral arm (Kodaira+, 1998)
J/ApJ/504/113 : F175W and F275W photometry of M31 and M32 (Brown+, 1998)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Region The region in M33 or M31
10 I1 --- Group *Group identification number within region
11- 13 I3 --- Star Star identification number within the group
15- 21 F7.2 pix Xpos *X pixel coordinate
23- 29 F7.2 pix Ypos *Y pixel coordinate
31- 36 F6.2 mag Vmag V magnitude
38- 43 F6.2 mag e_Vmag Uncertainty in V
45- 50 F6.2 mag B-V *[]?=100.00 B-V color
52- 57 F6.2 mag e_B-V *[]?=100.00 Uncertainty in B-V color
59- 64 F6.2 mag V-I *[]?=100.00 V-I color
66- 71 F6.2 mag e_V-I *[]?=100.00 Uncertainty in V-I color
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Note on Group:
See Table 3 for descriptions of the groups.
Note on Xpos, Ypos:
The X,Y pixel coordinates are relative to the long V-band image
shown in figure 1 (plates 11-16) of the printed paper.
Note on B-V, e_B-V, V-I, e_V-I:
A magnitude of 100.00 indicates that the star was not measured
through that filter.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Region The region in M33 or M31
10 I1 --- Group Group identification number within region
13- 42 A30 --- Comment Comment on the group
44- 47 F4.2 --- E(B-V) []? Reddening
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Origin: AAS CD-ROM series, Volume 5, 1995 Lee Brotzman [ADS] 31-Aug-95
(End) [CDS] 02-Feb-1996