J/AJ/115/592 VI photometry of NGC 2157 (Fischer+, 1998)
Mass segregation in young Large Magellanic Cloud clusters. I. NGC 2157.
Fischer P., Pryor C., Murray S., Mateo M., Richtler T.
<Astron. J. 115, 592 (1998)>
=1998AJ....115..592F 1998AJ....115..592F (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Clusters, open ; Photometry, VRI
Mission_Name: HST
Keywords: galaxies: star clusters - globular clusters: individual (NGC 2157) -
Magellanic Clouds
Abstract:
We have carried out Wide Field Planetary Camera 2 V- and I-band
imaging of the young LMC cluster NGC 2157. Construction of a
color-magnitude diagram and isochrone fitting yield an age of
τ=108yr, a reddening E(B-V)=0.1, and a distance modulus of
18.4mag. Our data cover the mass range 0.75M☉≤m≤5.1M☉.
We find that the cluster mass function changes significantly from the
inner regions to the outer regions, becoming steeper (larger number of
low-mass stars relative to high-mass stars) at larger radii. The age
of NGC 2157 is comparable to its two-body relaxation timescale only in
the cluster core. The observed steepening of the mass function at
larger radii is therefore most likely an initial condition of the
cluster stars. Such initial conditions are predicted in models of
cluster star formation in which dissipative processes act more
strongly upon more massive stars.
Objects:
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RA (2000) DE Designation(s)
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05 57 35.0 -69 11 48 NGC 2157
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 40 3074 Cluster Planerary Camera (PC) photometry
table2.dat 40 1904 Cluster Wide Field Planerary Camera 2
(WF2) photometry
table3.dat 40 1274 Cluster WF3 photometry
table4.dat 40 1675 Cluster WF4 photometry
table5.dat 40 218 Background PC photometry
table6.dat 40 1029 Background WF2 photometry
table7.dat 40 971 Background WF3 photometry
table8.dat 40 914 Background WF4 photometry
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See also:
VII/183 : Cluster System of the LMC (Kontizas+ 1990)
Byte-by-byte Description of file: table?.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq Sequential number
6- 11 F6.2 pix xpos x position (1)
13- 18 F6.2 pix ypos y position (1)
20- 24 F5.2 mag V0 Dereddenned V magnitude (2)
26- 29 F4.2 mag e_V0 rms uncertainty on V0
31- 35 F5.2 mag (V-I)0 Dereddenned V-I index (2)
37- 40 F4.2 mag e_(V-I)0 rms uncertainty on (V-I)0
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Note (1): The cluster center is located in the Planetary Camera (PC) frame.
Note (2): Reddening correction of E(B-V)=0.1.
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History: From AJ electronic version
(End) James Marcout, Patricia Bauer [CDS] 09-Mar-1999