New Metallicities of RR Lyrae Stars in ω Centauri: Evidence for a Non-He-enhanced Metal-intermediate Population

Sollima, A.; Borissova, J.; Catelan, M.; Smith, Horace A.; Minniti, D.; Cacciari, C.; Ferraro, F. R.

doi:10.1086/503099

Cited by 57 publications

(147 citation statements)

References 45 publications

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“…The histograms describe the distribution of the observed and simulated periods values for the metal rich component of the sample ([F e/H] > −1.4, top) and for the metal poor component ([F e/H] < −1.4, bottom ) respectively and shows the adequacy of the simulation. We remark that the two groups of RR Lyrae differing in metallicity described in Sollima et al (2006), according our interpretation, are also in different evolutionary stages. The metal richer stars are closer to their ZAHB phase, and the lower metallicity ones are in an advanced stage of their helium burning evolution, crossing the boundary of the instability strip from the blue side, as shown in Fig.6.…”

Section: Rr Lyraesupporting

confidence: 62%

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The mosaic multiple stellar populations in ω Centauri: the horizontal branch and the main sequence

Tailo

Criscienzo

D’Antona

et al. 2016

Mon. Not. R. Astron. Soc.

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We interpret the stellar population of ω Centauri by means of a population synthesis analysis, following the most recent observational guidelines for input metallicities, helium and [(C+N+O)/Fe] contents. We deal at the same time with the main sequences, sub-giant and horizontal branch data. The reproduction of the observed color magnitude features is very satisfying and bears interesting hints concerning the evolutionary history of this peculiar stellar ensemble. Our main results are: 1) no significant spread in age is required to fit the colour-magnitude diagram. Indeed we can use coeval isochrones for the synthetic populations, and we estimate that the ages fall within a ∼ 0.5 Gyr time interval; in particular the most metal rich population can be coeval (in the above meaning) with the others, if its stars are very helium-rich (Y∼0.37) and with the observed CNO enhancement ([(C+N+O)/Fe] = + 0.7); 2) a satisfactory fit of the whole HB is obtained, consistent with the choice of the populations providing a good reproduction of the main sequence and sub giant data. 3) the split in magnitude observed in the red HB is well reproduced assuming the presence of two stellar populations in the two different sequences observed: a metal poor population made of stars evolving from the blue side (luminous branch) and a metal richer one whose stars are in a stage closer to the zero age HB (dimmer branch). This modelization also fits satisfactorily the period and the [Fe/H] distribution of the RR Lyrae stars.

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Section: Rr Lyraesupporting

confidence: 62%

“…In Fig. 7 we compare the simulated RR Lyrae with the data by Sollima et al (2006), in the [Fe/H] vs logP plane. Filled and empty circles identify respectively RRab and RRc.…”

Section: Rr Lyraementioning

confidence: 99%

The mosaic multiple stellar populations in ω Centauri: the horizontal branch and the main sequence

Tailo

Criscienzo

D’Antona

et al. 2016

Mon. Not. R. Astron. Soc.

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“…In the case of the K s band, we add the RR Lyr stars from ω Cen (Sollima et al 2006a), which cover a much wider metallicity range. Based on this combined sample, only a very mild metallicity dependence is found, as shown in our Eq.…”

Section: Discussionmentioning

confidence: 99%

“…Although our results are very similar to those obtained by Bono et al (2003), Catelan et al (2004), and Sollima et al (2008), we cannot reach firm conclusions concerning the metallicity dependence of the period-luminosity relation in the J band based solely on these data. Therefore, to increase the sample size, we added the Sollima et al (2006a) dataset for ω Cen (Fig. 10, upper panel) to our K s band magnitudes and metallicities.…”

Section: Period-[fe/h] Relationsmentioning

confidence: 99%

“…The metallicity spread of the RR Lyrae variables is within the range −2.2 < [Fe/H] < −1.1. The ω Cen K s magnitudes given in Sollima et al (2006a) are dereddened using E(B − V) = 0.11, and their residuals are calculated by applying a correction for the LMC −ω Cen relative distance moduli and then the corresponding residuals are computed with respect to our own fits using Eq. (7).…”

Section: Period-[fe/h] Relationsmentioning

confidence: 99%

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Properties of RR Lyrae stars in the inner regions of the Large Magellanic Cloud

Borissova¹,

Rejkuba²,

Minniti

et al. 2009

A&A

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Context. RR Lyrae variable stars are the primary Population II distance indicator. Likewise, the Large Magellanic Cloud (LMC) constitutes a key step in the extragalactic distance scale. Aims. By combining near-IR photometry and spectroscopically measured metallicities for a homogeneous sample of 50 RR Lyr stars in the LMC, we investigate the metallicity dependence of the period-luminosity relation in the near-infrared (IR), use the newly derived relations to re-derive the distance to the LMC, and compare the distance moduli obtained from RR Lyr and red clump stars. Methods. This paper presents new (single-epoch) J-band and (multi-epoch) K s -band photometry of RR Lyr stars in 7 different LMC fields, observed with the near-IR camera SOFI at ESO's New Technology Telescope. Additional K s -band data for another two LMC fields were taken with the ISPI infrared array at CTIO's Blanco 4m telescope. The near-IR photometry was cross-correlated with the MACHO and OGLE databases, resulting in a catalog of 62 RR Lyr stars with BVRI JK s photometry. A subsample of 50 stars also has spectroscopically measured metallicities. Results. In the deep JK color-magnitude diagrams of 7 fields, red giant branch, red clump and RR Lyr stars are detected. The majority of RR Lyr stars are located within the instability strip with near-IR colors between 0.14 ≤ (J − K s ) 0 < 0.32. The period-luminosity relation only has a very mild dependence on metallicity in the K band, consistent with no dependence: M Ks = 2.11(±0.17) log P + 0.05(±0.07) [Fe/H] − 1.05. In the J band the currently available data do not allow firm conclusions regarding the metallicity dependence of the period-luminosity relation. Conclusions. The distance modulus of the LMC, derived using our near-IR period-luminosity-metallicity relation for RR Lyr stars, is (m − M) 0 = 18.53 ± 0.13, in very good agreement with the distance modulus from the red clump stars, 18.46 ± 0.07. However, LMC modulus derived from the RR Lyrae stars depends on the parallax of the star RR Lyrae.

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High-precision distance measurements with classical pulsating stars

Bhardwaj

2020

J Astrophys Astron

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New Metallicities of RR Lyrae Stars in ω Centauri: Evidence for a Non-He-enhanced Metal-intermediate Population

Cited by 57 publications

References 45 publications

The mosaic multiple stellar populations in ω Centauri: the horizontal branch and the main sequence

The mosaic multiple stellar populations in ω Centauri: the horizontal branch and the main sequence

Properties of RR Lyrae stars in the inner regions of the Large Magellanic Cloud

High-precision distance measurements with classical pulsating stars

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