J/ApJ/824/74 OGLE LC classification of MC Cepheids (Garcia-Varela+, 2016)
The influential effect of blending, bump, changing period, and
eclipsing Cepheids on the Leavitt law.
Garcia-Varela A., Munoz J.R., Sabogal B.E., Vargas Dominguez S.,
Martinez J.
<Astrophys. J., 824, 74-74 (2016)>
=2016ApJ...824...74G 2016ApJ...824...74G (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Stars, variable
Keywords: Magellanic Clouds; methods: statistical; stars: variables: Cepheids
Abstract:
The investigation of the nonlinearity of the Leavitt law (LL) is a
topic that began more than seven decades ago, when some of the studies
in this field found that the LL has a break at about 10 days. The goal
of this work is to investigate a possible statistical cause of this
nonlinearity. By applying linear regressions to OGLE-II and OGLE-IV
data, we find that to obtain the LL by using linear regression, robust
techniques to deal with influential points and/or outliers are needed
instead of the ordinary least-squares regression traditionally used.
In particular, by using M- and MM-regressions we establish firmly and
without doubt the linearity of the LL in the Large Magellanic Cloud,
without rejecting or excluding Cepheid data from the analysis. This
implies that light curves of Cepheids suggesting blending, bumps,
eclipses, or period changes do not affect the LL for this galaxy. For
the Small Magellanic Cloud, when including Cepheids of this kind, it
is not possible to find an adequate model, probably because of the
geometry of the galaxy. In that case, a possible influence of these
stars could exist.
Description:
OGLE-II and OGLE-IV observations of Cepheid variables in the LMC and
SMC galaxies were collected with the 1.3m Warsaw telescope, at Las
Campanas Observatory, Chile (Udalski et al. 1999, J/AcA/49/223;
1999, J/AcA/49/437; 2015AcA....65....1U 2015AcA....65....1U). While Cepheid catalogs for
the OGLE-II fundamental mode contain 771 and 1319 stars for the LMC
and SMC, respectively, OGLE-IV has a nearly complete collection (2429
and 2739 for the LMC and SMC, respectively), covering practically the
whole Magellanic System with a time baseline of a little more than
five years (Soszynski et al. 2015AcA....65..329S 2015AcA....65..329S).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 52 2088 Bi-dimensional classification of OGLE-II
Magellanic Clouds Cepheids
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See also:
J/AcA/62/219 : OGLE: Gaia South Ecliptic Pole Field (Soszynski+, 2012)
J/AcA/60/17 : VI light curves of SMC classical Cepheids (Soszynski+, 2010)
J/other/A+ARV/17.251 : Stars observed with Doppler imaging (Strassmeier, 2009)
J/AcA/58/313 : LMC Cepheids in OGLE and MACHO data (Poleski+, 2008)
J/AcA/58/163 : VI light curves of LMC classical Cepheids (Soszynski+, 2008)
J/A+A/476/73 : Calibration of Cepheid Per/Lum relation (Fouque+, 2007)
J/AJ/131/2514 : Radial velocities of red giants in the SMC (Harris+, 2006)
J/AJ/128/2815 : ARAUCARIA project: NGC 6822 Cepheids (Pietrzynski+, 2004)
J/A+A/404/423 : BVI photometry of Galactic Cepheids (Tammann+, 2003)
J/AcA/51/221 : OGLE-II. Cepheids in IC 1613 (Udalski+, 2001)
J/AcA/49/543 : OGLE LMC + SMC Cepheids VI photometry (Pietrzynski+, 1999)
J/AcA/49/437 : BVI photometry of OGLE SMC Cepheids (Udalski+, 1999)
J/AcA/49/223 : BVI photometry of OGLE LMC Cepheids (Udalski+, 1999)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh [0/5] Hour of Right Ascension (J2000)
4- 5 I2 min RAm Minute of Right Ascension (J2000)
7- 11 F5.2 s RAs Second of Right Ascension (J2000)
13 A1 --- DE- [-] Sign of the Declination (J2000)
14- 15 I2 deg DEd [68/73] Degree of Declination (J2000)
17- 18 I2 arcmin DEm Arcminude of Declination (J2000)
20- 23 F4.1 arcsec DEs Arcsecond of Declination (J2000)
25- 32 A8 --- Field OGLE-II field (1)
34- 39 I6 --- ID [1/472701] OGLE-II identifier (1)
41- 48 F8.5 d Period [0.9/49.8] Period
50- 51 A2 --- Class The bi-dimensional class (2)
52 A1 --- f_Class "i" identifies the influential Cepheids
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Note (1): These data were reported for the LMC by
Udalski et al. (1999, J/AcA/49/223; in Simbad),
and for the SMC by Udalski et al. (1999, J/AcA/49/437;
in Simbad).
Note (2): We perform a bi-dimensional classification of the Cepheids in some of
the following groups: light curves with small ("1"), moderate ("2"),
or large ("3") dispersion. And light curves whose morphological shapes
are sinusoidal-like ("A"), sawtooth-like ("B"), or exhibit bumps,
i.e., showing the Hertzsprung progression ("C").
See section 4 for further explanations.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 16-Aug-2016