J/AcA/65/233 OGLE Magellanic Clouds anomalous Cepheids (Soszynski+, 2015)
The OGLE collection of variable stars.
Anomalous Cepheids in the Magellanic Clouds.
Soszynski I., Udalski A., Szymanski M.K., Pietrzynski G., Wyrzykowski L.,
Ulaczyk K., Poleski R., Pietrukowicz P., Kozlowski S., Skowron J., Mroz P.,
Pawlak M.
<Acta Astron., 65, 233-250 (2015)>
=2015AcA....65..233S 2015AcA....65..233S (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Stars, variable
Keywords: Cepheids - stars: oscillations - stars: Population II -
Magellanic Clouds
Abstract:
We present a collection of 250 anomalous Cepheids (ACs) discovered in
the OGLE-IV fields toward the Large (LMC) and Small Magellanic Cloud
(SMC). The LMC sample is an extension of the OGLE-III Catalog of ACs
published in 2008, while the SMC sample contains the first known bona
fide ACs in this galaxy. The total sample is composed of 141 ACs in
the LMC and 109 ACs in the SMC. All these stars pulsate in single
modes: fundamental (174 objects) or first overtone (76 objects).
Additionally, we report the discovery of four ACs located in the
foreground of the Magellanic Clouds. These are the first unambiguously
identified fundamental-mode ACs known in the Galactic field.
We demonstrate that the coefficients φ21 and φ31 determined by
the Fourier light curve decomposition are useful discriminators
between classical Cepheids and ACs, at least in the LMC and in the
field of the Milky Way. In the SMC, the light curve shapes and mean
magnitudes of short-period classical Cepheids make them similar to
ACs, which is a source of difficulties in the discrimination of both
classes of pulsators. The presence of unidentified ACs in the catalogs
of classical Cepheids may be partly responsible for the observed
non-linearity of the period-luminosity relation observed for
short-period Cepheids in the SMC. We compare spatial distributions of
ACs, classical Cepheids and RR Lyr stars. We show that the
distribution of ACs resembles that of old stars (RR Lyr variables),
although in the LMC there are visible structures typical for young
population (classical Cepheids): the bar and spiral arms. This may
suggest that ACs are a mixture of relatively young stars and mergers
of very old stars.
Description:
Time-series I and V-band photometry of the Magellanic Clouds was
obtained in the years 2010-2015 using the 32-chip mosaic CCD camera
mounted at the focus of the 1.3-m Warsaw Telescope located at Las
Campanas Observatory in Chile. The observatory is operated by the
Carnegie Institution for Science. The OGLE- IV camera has a total
field of view of 1.4 square degrees and pixel scale of 0.26".
The OGLE-IV fields cover approximately 650 square degrees in both
Clouds and a region between both galaxies, the so-called Magellanic
Bridge. For each field we obtained from 90 (in sparse regions far from
the centers of the Magellanic Clouds) to over 750 observing points (in
the densest fields) in the Cousins I-band and from several to over 260
points in the Johnson V-band. Data reduction of the OGLE images was
performed using the Difference Image Analysis technique (Alard and
Lupton 1998ApJ...503..325A 1998ApJ...503..325A, Wozniak 2000). Detailed descriptions of the
instrumentation, photometric reductions and astrometric calibrations
of the OGLE-IV data are provided by Udalski et al. (2015,
Cat. J/AcA/50/421).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
lident.dat 106 146 LMC identification of stars
lacepf.dat 98 102 LMC parameters of fundamental-mode anomalous
Cepheids (2019 version)
lacep1o.dat 98 44 LMC parameters of first-overtone anomalous
Cepheids (2019 version)
lremarks.dat 67 5 LMC remarks on selected objects (2019 version)
sident.dat 106 122 SMC identification of stars (2019 version)
sacepf.dat 98 79 SMC parameters of fundamental-mode anomalous
Cepheids (2019 version)
sacep1o.dat 98 43 SMC parameters of first-overtone anomalous
Cepheids (2019 version)
sremarks.dat 66 42 SMC remarks on selected objects (2019 version)
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See also:
J/AcA/58/163 : VI light curves of LMC classical Cepheids (Soszynski+, 2008)
J/AcA/58/293 : Type-II and anomalous Cepheids in LMC (Soszynski+, 2008)
J/AcA/58/313 : LMC Cepheids in OGLE and MACHO data (Poleski+, 2008)
J/AcA/59/1 : LMC RR Lyrae stars VI light curves (Soszynski+, 2009)
J/AcA/59/239 : LMC long-period variables VI light curves (Soszynski+, 2009)
J/AcA/59/335 : LMC R CBr stars VI light curves (Soszynski+, 2009)
J/AcA/60/1 : LMC delta Scuti stars VI light curves (Poleski+, 2010)
J/AcA/60/17 : VI light curves of SMC classical Cepheids (Soszynski+, 2010)
J/AcA/60/91 : VI light curves of SMC type II Cepheids (Soszynski+, 2010)
J/AcA/60/165 : VI light curves of SMC RR Lyrae (Soszynski+, 2010)
J/AcA/60/179 : LMC double periodic variables VI light curves (Poleski+, 2011)
J/AcA/61/1 : VI light curves of Galactic Bulge RR Lyrae (Soszynski+, 2011)
J/AcA/61/103 : VI light curves of LMC eclipsing binaries (Szymanski+, 2011)
J/AcA/61/217 : VI light curves of SMC long-period variables (Soszynski+, 2011)
J/AcA/61/285 : VI light curves of Galactic Bulge Cepheids (Soszynski+, 2011)
J/AcA/63/115 : OLGE-III Galactic disk eclipsing binaries (Pietrukowicz+, 2013)
J/AcA/63/323 : OGLE-III SMC eclipsing binary stars (Pawlak+, 2013)
Byte-by-byte Description of file: lident.dat sident.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Star Star's ID
20- 21 A2 --- Mode [F 1O] Mode of pulsations (F, 1O)
24- 25 I2 h RAh Right ascension, equinox J2000.0 (hours)
27- 28 I2 min RAm Right ascension, equinox J2000.0 (minutes)
30- 34 F5.2 s RAs Right ascension, equinox J2000.0 (seconds)
36 A1 --- DE- Declination, equinox J2000.0 (sign)
37- 38 I2 deg DEd Declination, equinox J2000.0 (degrees)
40- 41 I2 arcmin DEm Declination, equinox J2000.0 (arc minutes)
43- 46 F4.1 arcsec DEs Declination, equinox J2000.0 (arc seconds)
49- 64 A16 --- OGLE4 OGLE-IV ID
66- 80 A15 --- OGLE3 OGLE-III ID
82- 96 A15 --- OGLE2 OGLE-II ID
98-106 A9 --- OName Other designation (from GCVS)
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Byte-by-byte Description of file: lacep1o.dat lacepf.dat sacep1o.dat sacepf.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Star Star's ID
20- 25 F6.3 mag <Imag> Intensity mean I-band magnitude
27- 32 F6.3 mag <Vmag> ?=- Intensity mean V-band magnitude
34- 43 F10.7 d Per Period
45- 53 F9.7 d e_Per Uncertainty of period
56- 65 F10.5 d T0 Time of maximum brightness (HJD-2450000)
68- 72 F5.3 mag IAmp I-band amplitude (maximum-minimum)
75- 79 F5.3 --- R21 Fourier coefficient R_21
81- 85 F5.3 --- phi21 Fourier coefficient phi_21
88- 92 F5.3 --- R31 Fourier coefficient R_31
94- 98 F5.3 --- phi31 ?=- Fourier coefficient phi_31
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Byte-by-byte Description of file: lremarks.dat sremarks.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Star Star's ID
19- 67 A49 --- Rem Remarks
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History:
* 03-Jan-2017: Copied at ftp://ftp.astrouw.edu.pl/ogle/ogle4/OCVS/lmc/acep/
and ftp://ftp.astrouw.edu.pl/ogle/ogle4/OCVS/smc/acep/
* 30-Sep-2019: updated version
(End) Patricia Vannier [CDS] 13-Jun-2016