J/ApJ/468/633 Photometry in the M31 OB association NGC 206 (Hunter+ 1996)
The intermediate stellar mass population in the M31 OB association NGC 206.
Hunter D.A., Baum W.A., O'Neil E.J.Jr, Lynds R.
<Astrophys. J. 468, 633 (1996)>
=1996ApJ...468..633H 1996ApJ...468..633H
ADC_Keywords: Associations, stellar ; Photometry
Mission_Name: HST
Keywords: galaxies: individual: M 31 - galaxies: star clusters -
galaxies: stellar content - Hertzsprung-Russell diagrams -
open clusters and associations: individual: NGC 206
Abstract:
As part of our effort to determine what affects the star formation
process by looking at the products of that process, we have obtained
broadband Hubble Space Telescope images of the large OB association
NGC 206 in the nearby spiral galaxy M31. Our images cover
approximately the southern half of the association. We have detected
stars down to an F555W magnitude of 25.5 and measure stars on the main
sequence in NGC 206 to an MF555W,0 of -1 or a mass of ∼6M☉.
From a comparison with isochrones, ages up to about 8Myr are
plausible, and we adopt an age of 6Myr. For stellar masses
6-15M☉, we determine an initial mass function slope of
-1.4±0.5. This is close to the value for a Salpeter mass function,
although the uncertainty is large. The uncertainty in the slope
represents disagreement among the individual mass bins. In terms of
intermediate-mass stars (6-15M☉) the NGC 206 star formation
event appears to be typical of star formation processes in other
nearby galaxies, and it is part of a growing number of studies ,that
are finding similarities in the products of the star formation
processes in a wide variety of star formation events and galactic
environments. Nevertheless, the density of stars formed in NGC 206 is
much lower than that in giant H II regions such as NGC 604 in M33 or
30 Doradus in the LMC and in typical OB associations.
Objects:
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RA (2000) DE Designation(s)
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00 37 50.3 +40 27 54 NGC 206
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 81 15379 Cluster photometry
table3.dat 81 20343 Background field photometry
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See also:
J/ApJS/98/595 : OB associations in M31 (Hill+ 1995)
Byte-by-byte Description of file: table2.dat table3.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- ID Star identification number
8- 13 F6.1 pix xpos x pixel coordinate (1)
15- 20 F6.1 pix ypos y pixel coordinate (1)
22- 27 F6.2 mag F336W ?=100.00 F336W magnitude (2)
29- 34 F6.2 mag e_F336W ?=100.00 uncertainty in F336W magnitude (2)
36- 40 F5.2 mag F555W F555W magnitude
42- 45 F4.2 mag e_F555W uncertainty in F555W magnitude
47- 51 F5.2 mag F814W F814W magnitude
53- 56 F4.2 mag e_F814W uncertainty in F814W magnitude
58- 63 F6.2 mag F336W-F555W ?=100.00 F336W-F555W color (2)
65- 70 F6.2 mag e_F336W-F555W ?=100.00 uncertainty in F336W-F555W color (2)
72- 76 F5.2 mag F555W-F814W F555W-F814W color
78- 81 F4.2 mag e_F555W-F814W uncertainty in F555W-F814W color
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Note (1): 1 pix = 0.1". The region is centered near:
RA=00h40m28s, DE=+40°44.0' (2000), in table2.dat
RA=00h40m51s, DE=+40°41.3' (2000), in table3.dat
Note (2): A magnitude of 100.00 indicates that the star was not measured through
that filter.
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Acknowledgements: Brian Skiff
(End) Patricia Bauer [CDS] 11-Sep-1998