J/ApJ/807/127 Properties of 70 RR Lyrae stars in the LMC bar (Muraveva+, 2015)
New near-infrared Period-Luminosity-Metallicity relations for RR Lyrae stars
and the outlook for Gaia.
Muraveva T., Palmer M., Clementini G., Luri X., Cioni M.-R.L.,
Moretti M.I., Marconi M., Ripepi V., Rubele S.
<Astrophys. J., 807, 127 (2015)>
=2015ApJ...807..127M 2015ApJ...807..127M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Magellanic Clouds ; Abundances, [Fe/H] ;
Photometry, infrared
Keywords: astrometry - distance scale - Magellanic Clouds -
methods: data analysis - stars: statistics -
stars: variables: RR Lyrae
Abstract:
We present results of the analysis of 70 RR Lyrae stars located in the
bar of the Large Magellanic Cloud (LMC). Combining the spectroscopically
determined metallicity of these stars from the literature with precise
periods from the OGLE III catalog (Soszynski et al. 2009, J/AcA/59/1)
and multi-epoch Ks photometry from the VISTA survey of the Magellanic
Clouds system, we derive a new near-infrared period-luminosity-metallicity
(PLKsZ) relation for RR Lyrae variables. In order to fit the relation we
use a fitting method developed specifically for this study. The zero-point
of the relation is estimated two different ways: by assuming the value
of the distance to the LMC and by using Hubble Space Telescope
parallaxes of five RR Lyrae stars in the Milky Way (MW). The
difference in distance moduli derived by applying these two approaches
is ∼0.2 mag. To investigate this point further we derive the PLKsZ
relation based on 23 MW RR Lyrae stars that had been analyzed in
Baade-Wesselink studies. We compared the derived PLKsZ relations for RR
Lyrae stars in the MW and LMC. Slopes and zero-points are different,
but still consistent within the errors. The shallow slope of the
metallicity term is confirmed by both LMC and MW variables. The
astrometric space mission Gaia is expected to provide a huge contribution
to the determination of the RR Lyrae PLKsZ relation; however,
calculating an absolute magnitude from the trigonometric parallax of
each star and fitting a PLKsZ relation directly to period and
absolute magnitude leads to biased results. We present a tool to
achieve an unbiased solution by modeling the data and inferring the
slope and zero-point of the relation via statistical methods.
Description:
In order to derive mean Ks magnitudes for the RR Lyrae stars in our
sample we used data from the VMC survey (Cioni et al. 2011A&A...527A.116C 2011A&A...527A.116C).
Started in 2009, the VMC survey covers a total area of 116 deg2 in the
LMC with 68 contiguous tiles. The survey is obtaining YJKs photometry.
The Ks-band photometry is taken in time-series mode over 12 (or more)
separate epochs and each single epoch reaches a limiting Ks magnitude
∼19.3 mag with a signal-to-noise ratio (S/N) ∼5 (see Figure 1 of
Moretti et al. 2014, J/MNRAS/437/2702). On the bright side, VMC is
limited by saturation at Ks∼11.4 mag. The majority of RR Lyrae stars
in our sample are located within the VMC tile LMC 5_5. Observations of
the tile LMC 5_5 were performed in 15 epochs taken in the period from
2010 October 30, to 2012 January 11.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 89 70 Properties of the 70 RR Lyrae Stars in the Bar
of the LMC Analyzed in This Paper
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See also:
J/A+AS/145/11 : AGAPEROS: variable stars in the LMC Bar (Melchior+, 2000)
J/AcA/53/93 : OGLE RR Lyrae in LMC (Soszynski+, 2003)
J/A+A/421/937 : Metal abundances of LMC RR Lyrae (Gratton+, 2004)
J/A+A/430/603 : BVI photometry of LMC bar variables (Di Fabrizio+, 2005)
J/A+A/502/505 : Ks photometry of LMC RR Lyrae (Borissova+, 2009)
J/AcA/59/1 : VI light curves of LMC RR Lyrae stars (Soszynski+, 2009)
J/MNRAS/437/2702 : MC Cepheids, RR Lyrae stars and binaries (Moretti+, 2014)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Star Star identification from Di Fabrizio et al.
(2005, J/A+A/430/603) (ANNNNN, BNNNNN) (1)
8- 27 A20 --- OGLE OGLE identification (2)
29 I1 h RAh Hour of Right Ascension (J2000)
31- 32 I2 min RAm Minute of Right Ascension (J2000)
34- 38 F5.2 s RAs Second of Right Ascension (J2000)
40 A1 --- DE- Sign of the Declination (J2000)
41- 42 I2 deg DEd Degree of Declination (J2000)
44- 45 I2 arcmin DEm Arcminute of Declination (J2000)
47- 50 F4.1 arcsec DEs Arcsecond of Declination (J2000)
52- 55 A4 --- Type [RRc RRab] Subtype of RR Lyr star
57- 61 F5.2 [Sun] [Fe/H] Metallicity from Gratton et al.
(2004, J/A+A/421/937)
63- 66 F4.2 [Sun] e_[Fe/H] Uncertainty in [Fe/H]
68- 76 F9.7 d Per Period (2)
78- 83 F6.3 mag Ksmag Dereddened mean Ks magnitude (3)
85- 89 F5.3 mag e_Ksmag Uncertainty in Ksmag
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Note (1): [DCM2005] A-NNNNN and [DCM2005] B-NNNNN in Simbad.
Note (2): From the OGLE III catalog (Soszynski et al. 2009, J/AcA/59/1).
Note (3): From the VMC data (Cioni et al. 2011A&A...527A.116C 2011A&A...527A.116C), determined from
the analysis of the light curve with GRATIS (custom software developed
at the Observatory of Bologna by P. Montegriffo; see, e.g.,
Clementini et al. 2000AJ....120.2054C 2000AJ....120.2054C).
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History:
From electronic version of the journal
(End) Prepared by Tiphaine Pouvreau [CDS] 20-Sep-2017