J/ApJ/591/L111 Period of Cepheids in M 83 (Bonanos+, 2003)
Reanalysis of Very Large Telescope data for M83 with image subtraction-Ninefold
increase in number of Cepheids.
Bonanos A.Z., Stanek K.Z.
<Astrophys. J. 591, L111 (2003)>
=2003ApJ...591L.111B 2003ApJ...591L.111B
ADC_Keywords: Stars, variable
Keywords: Cepheids - distance scale - galaxies: individual (M83)
Abstract:
We apply the image-subtraction method in order to reanalyze the
ESO Very Large Telescope data on M83 (NGC 5236), obtained and
analyzed by Thim et al. (2003ApJ...590..256T 2003ApJ...590..256T). Whereas Thim et al.
(2003ApJ...590..256T 2003ApJ...590..256T) found 12 Cepheids with periods between 12 and
55 days, we find 112 Cepheids with periods ranging from 7 to 91 days
as well as 60 other variables. These include two candidate eclipsing
binaries, which, if confirmed, would be the first optically
discovered outside the Local Group. We thus demonstrate that the
image-subtraction method is much more powerful for detecting
variability, especially in crowded fields. However, Hubble Space
Telescope observations are necessary to obtain a Cepheid
period-luminosity distance not dominated by blending and crowding.
We propose a "hybrid" approach, in which numerous Cepheids are
discovered and characterized using large ground-based telescopes
and then followed up with the Hubble Space Telescope to obtain
precise distances.
Description:
We have retrieved the M83 data obtained by the FOcal Reducer/low
dispersion Spectrograph 1 (FORS1) on the ESO VLT, from the ESO/Space
Telescope-European Coordinating Facility (ST-ECF) Science Archive.
The field of view is 6.8'x6.8', with a pixel scale of 0.2"/pix.
The 2048x2048 Tektronix CCD has 24µm pixels. There are 34 epochs
in the V band spanning a period of 1.5yr, from 2000 January to 2001
July. Each epoch consists of three to four subexposures of 400 or
500s. More details are given by Thim et al. (2003ApJ...590..256T 2003ApJ...590..256T).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 62 112 Cepheids in M83
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Hour of Right Ascension (J2000)
4- 5 I2 min RAm Minute of Right Ascension (J2000)
7- 10 F4.1 s RAs Second of Right Ascension (J2000)
12 A1 --- DE- Sign of the Declination (J2000)
13- 14 I2 deg DEd Degree of Declination (J2000)
16- 17 I2 arcmin DEm Arcminute of Declination (J2000)
19- 22 F4.1 arcsec DEs Arcsecond of Declination (J2000)
24- 29 F6.3 d Per Period
31- 37 F7.2 pix Xpix The X pixel coordinate on the reference image
39- 45 F7.2 pix Ypix The Y pixel coordinate on the reference image
47- 61 A15 --- Comm Additional comments (1)
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Note (1): Names and periods of Cepheids found by Thim et al.,
2003ApJ...590..256T 2003ApJ...590..256T.
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Nomenclature Notes:
Objects are identified as [BS2003] JHHMMSS.s+DDMMSS.s in Simbad
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 26-Sep-2003