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J/AJ/115/1840 BV photometry in Carina dwarf galaxy (Hurley-Keller+ 1998)
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The star formation history of the Carina dwarf galaxy.
Hurley-Keller D., Mateo M., Nemec J.
<Astron. J. 115, 1840 (1998)>
=1998AJ....115.1840H (SIMBAD/NED BibCode)
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ADC_Keywords: Galaxies, photometry ; Photometry, UBV
Keywords: galaxies: evolution - galaxies: stellar content
Abstract:
We have analyzed deep B and V photometry of the Carina dwarf
spheroidal galaxy reaching below the old main-sequence turnoff to
V~25. Using simulated color-magnitude diagrams to model a range of
star formation scenarios, we have extracted a detailed, global star
formation history. Carina experienced three significant episodes of
star formation at ~15, 7, and 3Gyr. Contrary to the generic picture of
galaxy evolution, however, the bulk of star formation, at least 50%,
occurred during the episode 7Gyr ago, which may have lasted as long as
2Gyr. For unknown reasons, Carina formed only 10%-20% of its stars at
an ancient epoch and then remained quiescent for more than 4 Gyr. The
remainder (~30%) formed relatively recently, only 3Gyr ago. Interest
in the local population of dwarf galaxies has increased lately because
of their potential importance in the understanding of faint galaxy
counts. We surmise that objects like Carina, which exhibits the most
extreme episodic behavior of any of the dwarf spheroidal companions to
the Galaxy, are capable of contributing to the observed excess of blue
galaxies at B~24 only if the star formation occurred instantaneously.
Objects:
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RA (1950) DE Designation(s)
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06 39 53 -50 56 59 Field 1
06 40 07 -50 52 52 Field 2
06 40 42 -50 52 18 Field 3
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
field1.dat 46 3051 Field 1 photometry
field2.dat 46 2233 Field 2 photometry
field3.dat 46 2025 Field 3 photometry
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See also:
J/AJ/114/1458 : The Carina Dwarf (Mighell 1997)
Byte-by-byte Description of file: field1.dat, field2.dat, field3.dat
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Bytes Format Units Label Explanations
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1 I1 --- Field Field number
3- 6 I4 --- Seq Sequential number
8- 13 F6.2 pix Xpos X position (1)
15- 20 F6.2 pix Ypos Y position (1)
22- 27 F6.3 mag Vmag V magnitude
29- 33 F5.3 mag e_Vmag rms uncertainty on Vmag
35- 40 F6.3 mag B-V B-V colour index
42- 46 F5.3 mag e_B-V rms uncertainty on B-V
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Note (1): X and Y positions origin is the down left corner of the field.
North to the top and west to the right. (1pix=0.58")
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History: Copied from
ftp://ra.astro.lsa.umich.edu/pub/get/denise/carina.phot
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(End) James Marcout, Patricia Bauer [CDS] 12-Aug-1998