J/ApJ/446/622 UV and optical imagery of LH 52 and LH 53 (Hill+ 1995)
UIT and optical imagery of Large Magellanic cloud associations
LH 52 and LH 53: ages and initial mass function slopes
Hill R.S., Cheng K.-P., Bohlin R.C., OConnell R.W., Roberts M.S.,
Smith A.M., Stecher T.P.
<Astrophys. J. 446, 622 (1995)>
=1995ApJ...446..622H 1995ApJ...446..622H
ADC_Keywords: Magellanic Clouds ; Clusters, open ; Photometry, ultraviolet
Misson_Name: Astro-1
Keywords: dust, extinction - Magellanic Clouds - open clusters and
associations: individual (LH 52, LH 53) - stars: luminosity
function, mass function - ultraviolet: stars
Abstract:
A 40' field including the stellar associations LH 52 and LH 53 and the
supernova remnant N49 in the Large Magellanic Cloud was observed by
the Ultraviolet Imaging Telescope (UIT) during the Astro-1 Space
Shuttle mission in 1990 December. The image in the 162 nm bandpass is
discussed together with ground-based BV data on subfields containing
LH 52 and LH 53. Point-spread function photometry in the 162nm, B,
and V bands is presented in the form of color-magnitude diagrams and
two-color diagrams, which are compared with stellar models. The
far-ultraviolet extinction curve of the dust in LH 52 is unusually
steep for the LMC. The most probable age of both associations is ∼10
Myr, which constrains the scenario for the evolution of the supergiant
Halpha shell LMC 4 by stochastic self-propagated star formation. The
initial mass function (IMF) slope for LH 52 is Gamma~-1, in
agreement with previous work, and the slope for LH 53, which is less
densely populated, is Gamma~-2. A similar relationship between
surface density of stars and IMF slope is reported for a UIT field
near 30 Dor. The ultraviolet morphology of N49, which is contained in
LH 53, is dominated by two bright features that straddle an X-ray
bright spot, consistent with an encounter between the blast wave and a
cloud. The estimated age of ∼10Myr for LH 53 implies an initial mass
of ∼20M☉ for the N49 progenitor star.
Objects:
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RA (2000) DE Designation(s)
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05 24 -66 24 LH 52 = NGC 1948
05 26 -66 14 LH 53
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 98 122 Ultraviolet sources in LH 52
table3.dat 118 201 Ultraviolet sources in LH 53
lh52_bv.dat 60 1048 BV photometry of LH 52
lh53_bv.dat 60 2227 BV photometry of LH 53
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Byte-by-byte Description of file: table2.dat table3.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID *Identification
6- 7 I2 h RAh Right ascension (J2000)
9- 10 I2 min RAm Right ascension (J2000)
12- 16 F5.2 s RAs Right ascension (J2000)
18 A1 --- DE- Declinatin sign
19- 20 I2 deg DEd Declination (J2000)
22- 23 I2 arcmin DEm Declination (J2000)
25- 28 F4.1 arcsec DEs Declination (J2000)
30- 36 F7.2 mag m162 *Magnitude at 162nm
38- 44 F7.3 mag e_m162 DAOPHOT-type internal error in m162
46- 52 F7.2 mag Bmag ?=99.99 Calibrated B magnitude
54- 60 F7.3 mag e_Bmag ?=99.999 DAOPHOT-type internal error in Bmag
62- 68 F7.2 mag Vmag ?=99.99 Calibrated V magnitude
70- 76 F7.3 mag e_Vmag ?=99.999 DAOPHOT-type internal error in V
78- 99 A22 --- Remark Remark on dup. matches or UIT image quality
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Note on ID:
IDs are derived from UIT photometry. Duplicates mean the same
ultraviolet source had more than one candidate match on the B
image, and the author could not decide between them. However,
coordinates are based on the B sources and can thus differ
between two appearances of the same ID.
Note on m162:
m162 = -2.5*alog10(f_B5) - 21.1, where f_B5 is the mean flux in
the UIT B5 bandpass in mW/m2/(0.1nm); the B5 centroid wavelength is
approximately 162nm.
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Byte-by-byte Description of file: lh52_bv.dat lh53_bv.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID Identification derived from V photometry
6- 7 I2 h RAh Right ascension (J2000)
9- 10 I2 min RAm Right ascension (J2000)
12- 16 F5.2 s RAs Right ascension (J2000)
18 A1 --- DE- Declination sign
19- 20 I2 deg DEd Declination (J2000)
22- 23 I2 arcmin DEm Declination (J2000)
25- 28 F4.1 arcsec DEs Declination (J2000)
30- 36 F7.2 mag Bmag B magnitude
38- 44 F7.3 mag e_Bmag DAOPHOT-like internal error
46- 52 F7.2 mag Vmag V magnitude
54- 60 F7.3 mag e_Vmag DAOPHOT-like internal error
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Origin: AAS CD-ROM series, Volume 5, 1995 Lee Brotzman [ADS] 10-Oct-95
(End) [CDS] 29-Jan-1996