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J/ApJ/448/179                  HST photometry in R136 (Hunter+ 1995)

The intermediate stellar mass population in R136 determined from Hubble Space Telescope planetary camera 2 images Hunter D.A., Shaya E.J., Holtzman J.A., Light R.M., Earl J., Oneil Jr. <Astrophys. J. 448, 179 (1995)> =1995ApJ...448..179H
ADC_Keywords: Magellanic Clouds ; Photometry ; Clusters, open Keywords: Hertzsprung-Russell diagram - Magellanic Clouds - open clusters and associations: individual (R136) - stars: evolution - stars: luminosity function, mass function Abstract: We have analyzed Hubble Space Telescope (HST) images of the compact, luminous star cluster R136 in the LMC that were taken with the refurbished HST and new Wide Field/Planetary Camera. These images allow us to examine the stellar population in a region of unusually intense star formation at a scale of 0.01pc. We have detected stars to 23.5 in F555W and have quantified the stellar population to an M_555.0 of 0.9 or a mass of 2.8M. Comparisons of HR diagrams with isochrones that were constructed for the HST flight filter system from theoretical stellar evolutionary tracks reveal massive stars, a main sequence to at least 2.8M, and stars with M_555.0≥0.5 still on pre-main sequence tracks. The average stellar population is fit with a 3-4Myr isochrone. Contrary to expectations from star formation models, however, the formation period for the massive stars and lower mass stars appear to largely overlap. We have measured the IMF for stars 2.8-15M in three annuli from 0.5-4.7pc from the center of the cluster. The slopes of the IMF in all three annuli are the same within the uncertainties, thus, showing no evidence for mass segregation beyond 0.5pc. Furthermore, the combined IMF slope, -1.22±0.06, is close to a normal Salpeter IMF. The lower mass limit must be lower than the limits of our measurements: ≤2.8M beyond 0.5pc and ≤7M within 0.1pc. This is contrary to some predictions that the lower mass limit could be as high as 10M in regions of intense massive star formation. Integrated properties of R136 are consistent with its being comparable to a rather small globular cluster when such clusters were the same age as R136. From the surface brightness profile, an upper limit for core radius of 0.02pc is set. Within a radius of 0.4pc we estimate that there have been roughly 20 crossing times and relaxation should be well along. Within 0.5pc crowding prevents us from detecting the intermediate mass population, but there is a hint of an excess of stars brighter than M_555.0=-5 and of a deficit in the highest mass stars between 0.6pc and 1.2pc. This would be consistent with dynamical segregation. Objects: ---------------------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------------------- 05 38 42.8 -69 06 03 R 136 = RMC 136 = HD 38268 ---------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 98 3623 The photometry
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 6 I6 --- Star Star identification number 8- 13 F6.1 pix Xpos *X pixel coordinate 15- 20 F6.1 pix Ypos *Y pixel coordinate 22- 27 F6.2 mag F336W []?=100.00 F336W magnitude 29- 34 F6.2 mag e_F336W []?=100.00 F336W magnitude uncertainty 36- 41 F6.2 mag F555W []?=100.00 F555W magnitude 43- 48 F6.2 mag e_F555W []?=100.00 F555W magnitude uncertainty 50- 55 F6.2 mag F814W []?=100.00 F814W magnitude 57- 62 F6.2 mag e_F814W []?=100.00 F814W magnitude uncertainty 64- 71 F8.2 mag F336W-F555W []?=100.00 F336W-F555W color 73- 80 F8.2 mag e_F336W-F555W []?=100.00 F336W-F555W color uncertainty 82- 89 F8.2 mag F555W-F814W []?=100.00 F555W-F814W color 91- 98 F8.2 mag e_F555W-F814W []?=100.00 F555W-F814W color uncertainty
Note on Xpos, Ypos: The X,Y coordinates are those in the short exposure F555W image, and the coordinate system is indicated in Figure 2 of the printed paper.
Origin: AAS CD-ROM series, Volume 5, 1995 Lee Brotzman [ADS] 10-Oct-95
(End) [CDS] 29-Jan-1996
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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