J/AJ/165/28 1622 M33 cepheids parameters with CFHT/MegaCam (Adair+, 2023)
M33 Cepheids from CFHT/MegaCam Survey.
Adair S., Lee C.-H.
<Astron. J., 165, 28 (2023)>
=2023AJ....165...28A 2023AJ....165...28A
ADC_Keywords: Stars, variable; Photometry, VRI
Keywords: Triangulum Galaxy ; Cepheid variable stars ; Distance indicators
Abstract:
In this paper we analyze Sloan g,r,i archival imaging data of M33
taken by Hartman et al. using MegaCam at the Canada-France-Hawaii
Telescope. To determine the distance to the M33 galaxy, we performed
several analytical steps to identify its Cepheid population. We used
the Lomb-Scargle algorithm to find periodicity and visually identified
1989 periodic variable stars. Since Cepheids occupy a specific region
of the color-magnitude diagram, to differentiate Cepheids from other
variables we used the expected position of the Cepheid instability
strip to down-select Cepheids in M33 from other variables. This led to
our sample of 1622 variables, the largest Cepheid sample known in M33
to date. We further classified these Cepheids into different
subclasses, and used the fundamental mode Cepheids to estimate
distance moduli for M33 in different filters: µ=25.044±0.083mag
in the g filter, µ=24.886±0.074mag in the r filter, and
µ=24.785±0.068mag for the i filter. These results are in
agreement with previous results.
Description:
To investigate the Cepheids in M33, we utilized the archival
time-series observations with Canada France Hawaii Telescope (CFHT) by
Hartman et al. A 1deg2 region centered at M33 was monitored
repeatedly with the wide-imager MegaCam. Data was taken on 27 nights
between 2003 and 2005 in three optical filters g, r, and i. Each
exposure was ∼500s in g and ∼600s in r and i, with a median seeing of
0.95", 0.85", 0.77" in g, r, and i, respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 92 1622 Parameters of the Cepheids identified by this work
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See also:
J/AJ/121/870 : BVI photometry of Variables in M33 (Macri+, 2001)
J/ApJ/614/167 : Planetary nebulae in M33 (Ciardullo+, 2004)
J/ApJ/652/313 : BV phot. of a detached eclipsing binary in M33 (Bonanos+, 2006)
J/MNRAS/371/1405 : Variables in M33 (Hartman+, 2006)
J/A+A/476/73 : Calibration Cepheid Period/Luminosity relation (Fouque+, 2007)
J/ApJ/715/277 : Insights into the Cepheid distance scale (Bono+, 2010)
J/A+A/509/A70 : Study of an eclipsing binary in M31 (Vilardell+, 2010)
J/ApJ/724/799 : RR Lyrae variables in M33. II. (Yang+, 2010)
J/ApJS/193/26 : The M33 synoptic stellar survey. I. (Pellerin+, 2011)
J/AJ/145/106 : M31 Cepheid disk sample of 1st year of PS1 (Kodric+, 2013)
J/AJ/153/170 : M33 Synoptic Stellar Survey. II. Mira variables (Yuan+, 2017)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- ID [20018/350116] Identifier
8- 16 F9.6 deg RAdeg [23/24] Right Ascension in decimal degrees (J2000)
18- 26 F9.6 deg DEdeg [30/32] Declination in decimal degrees (J2000)
28- 35 F8.4 d g-Per [1.19/103] Period from g-band photometry
37- 44 F8.4 d r-Per [1.18/104] Period from r-band photometry
46- 53 F8.4 d i-Per [1.18/103] Period from i-band photometry
55- 60 F6.3 mag gmag [19/23.6] Mean apparent g-band magnitude
62- 67 F6.3 mag rmag [18.5/23.1] Mean apparent r-band magnitude
69- 74 F6.3 mag imag [18.2/22.9] Mean apparent i-band magnitude
76- 82 F7.5 mag A [0.004/1.23] Amplitude ratio from r-band
84- 89 F6.3 mag Wmag [17.2/22.5] Wesenheit magnitude from r and i-bands
91- 92 A2 --- Type Type classification (1)
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Note (1): Types as follows:
FM = Fundamental Mode type Cepheids (1131 occurrences)
FO = Ffirst Overtone type Cepheids (445 occurrences)
T2 = Type II Cepheids (46 occurrences)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 23-May-2023