J/ApJ/707/1347 HST F160W photometry in RMC 136 (Andersen+, 2009)
The low-mass initial mass function in the 30 Doradus starburst cluster.
Andersen M., Zinnecker H., Moneti A., McCaughrean M.J., Brandl B.,
Brandner W., Meylan G., Hunter D.
<Astrophys. J., 707, 1347-1360 (2009)>
=2009ApJ...707.1347A 2009ApJ...707.1347A
ADC_Keywords: Clusters, globular ; Photometry, HST ; Stars, pre-main sequence ;
Magellanic Clouds
Keywords: globular clusters: individual (30 Doradus) - stars: formation -
stars: luminosity function, mass function - stars: pre-main sequence
Abstract:
We present deep Hubble Space Telescope NICMOS 2 F160W band
observations of the central 56"x57" (14pcx14.25pc) region around R136
in the starburst cluster 30 Dor (NGC 2070) located in the Large
Magellanic Cloud. Our aim is to derive the stellar initial mass
function (IMF) down to ∼1M☉ in order to test whether the IMF in
a massive metal-poor cluster is similar to that observed in nearby
young clusters and the field in our Galaxy. We estimate the mean age
of the cluster to be 3Myr by combining our F160W photometry with
previously obtained HST WFPC2 optical F555W and F814W band photometry
and comparing the stellar locus in the color-magnitude diagram with
main sequence and pre-main sequence isochrones. The color-magnitude
diagrams show the presence of differential extinction and possibly an
age spread of a few megayear. We convert the magnitudes into masses
adopting both a single mean age of 3Myr isochrone and a constant star
formation history from 2 to 4Myr. We derive the IMF after correcting
for incompleteness due to crowding. The faintest stars detected have a
mass of 0.5M☉ and the data are more than 50% complete outside a
radius of 5pc down to a mass limit of 1.1M☉ for 3Myr old
objects.
Description:
We have obtained HST/NICMOS Camera 2 images through the F160W band of
the central 56"x57" region around R136 in the 30 Dor cluster (HST
program ID 7370). The observations were centered on the cluster (R.A.,
decl.) = (05:38:43.3,-69:06:08) and on two adjacent control fields
centered on (05:38:42.4,-68:52:00), and (05:38:56.9,-68:52:00). The
observing dates were 1997 October 14 and 16. The field of view of the
256x256 pixel NICMOS Camera 2 is 19"x19" with a pixel scale of 0.075".
Objects:
-------------------------------------------
RA (2000) DE Designation(s)
-------------------------------------------
05 38 42.4 -69 06 03 RMC 136 = * 30 Dor
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 28 10108 The F160W band detected sources in R 136
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See also:
II/187 : 30 Doradus OB Associations (Parker 1992)
J/ApJS/191/160 : 3D spectroscopy in 30 Dor (Pellegrini+, 2010)
J/ApJ/703/736 : Clump properties in the LMC 30 Dor region (Pineda+, 2009)
J/ApJ/707/1347 : HST F160W photometry in RMC 136 (Andersen+, 2009)
J/AJ/131/2164 : X-ray sources in RMC 136 (Townsley+, 2006)
J/A+A/443/851 : Effective temperature of 30 Dor population (Selman+, 2005)
J/A+A/438/663 : JHKL photometry of 30 Dor (Maercker+, 2005)
J/ApJ/466/254 : NIR Imaging of R136 in 30 Dor (Brandl+ 1996)
J/AJ/107/1054 : UBV photometry of the 30 Dor region (Malumuth+, 1994)
J/ApJ/413/604 : 30 Dor (Hill+, 1993)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 F8.3 pix Xpix The center X pixel (1)
10- 17 F8.3 pix Ypix The center Y pixel (1)
19- 23 F5.2 mag F160W HST/NICMOS F160W band magnitude
25- 28 F4.2 mag e_F160W Error in F160Wmag
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Note (1): 1pix=0.075" and each position in a 3x3 mosaic centered on R136
(J053843.3-690608) was observed 4 times with small dithers of ∼16pix.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 04-Jan-2012