Cors Baade–wesselink Distance to the LMC NGC 1866 Blue Populous Cluster

Molinaro, R.; Ripepi, V.; Marconi, M.; Musella, I.; Brocato, E.; Mucciarelli, A.; Stetson, P. B.; Storm, J.; Walker, A. R.

doi:10.1088/0004-637x/748/1/69

Cited by 20 publications

(39 citation statements)

References 67 publications

(144 reference statements)

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“…Applying this relation, we obtain a distance modulus of 18.39 ± 0.03 mag for NGC1866. The shorter distance scale obtained from the BW calibration supports previous determinations based on this method in the literature (see, e.g., the discussion in Molinaro et al 2012, and references therein). On the other hand the application of the CORS version of the BW method by Molinaro et al (2012) to the NGC1866 Cepheids used in their work gives a distance modulus of 18.51 ± 0.03 mag.…”

Section: The Empirical Route To the Distance Of Ngc1866supporting

confidence: 87%

“…The uncertainties on the distance estimates based on BW techniques depend on the controversial issue of the adopted projection factor which converts the measured radial velocity into the pulsational one (see e.g. Barnes 2009;Storm et al 2011b;Molinaro et al 2012, and references therein). In Fig.…”

Section: The Empirical Route To the Distance Of Ngc1866mentioning

confidence: 99%

“…On the basis of such a tantalizing situation, we took advantage of assigned observing time at the ESO Very Large Telescope to perform an accurate photometric investigation of the cluster field, with the aim of securing suitable data constraining the light curves of all the member Cepheids. Moreover, to get accurate information about radial velocities and chemical abundances of the stars in NGC1866, we have performed FLAMES@VLT spectroscopic observations for 30 stars (19 belonging to the cluster and 11 to the LMC field), including 3 Cepheids (Mucciarelli et al 2011;Molinaro et al 2012). Mucciarelli et al (2011) found that, as far as the chemical composition is concerned, the cluster stars are reasonably homogeneous.…”

Section: Introductionmentioning

confidence: 99%

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The Cepheids of NGC 1866: a precise benchmark for the extragalactic distance scale and stellar evolution from modernUBVIphotometry

Musella¹,

Marconi²,

Stetson³

et al. 2016

Mon. Not. R. Astron. Soc.

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We present the analysis of multiband time-series data for a sample of 24 Cepheids in the field of the Large Magellanic Cloud cluster NGC1866. Very accurate BVI VLT photometry is combined with archival UBVI data, covering a large temporal window, to obtain precise mean magnitudes and periods with typical errors of 1-2% and of 1 ppm, respectively. These results represent the first accurate and homogeneous dataset for a substantial sample of Cepheid variables belonging to a cluster and hence sharing common distance, age and original chemical composition. Comparisons of the resulting multiband Period-Luminosity and Wesenheit relations to both empirical and theoretical results for the Large Magellanic Cloud are presented and discussed to derive the distance of the cluster and to constrain the mass-luminosity relation of the Cepheids. The adopted theoretical scenario is also tested by comparison with independent calibrations of the Cepheid Wesenheit zero point based on trigonometric parallaxes and Baade-Wesselink techniques. Our analysis suggests that a mild overshooting and/or a moderate mass loss can affect intermediate-mass stellar evolution in this cluster and gives a distance modulus of 18.50 ± 0.01 mag. The obtained V,I color-magnitude diagram is also analysed and compared with both synthetic models and theoretical isochrones for a range of ages and metallicities and for different efficiencies of core overshooting. As a result, we find that the age of NGC1866 is about 140 Myr, assuming Z = 0.008 and the mild efficiency of overshooting suggested by the comparison with the pulsation models.

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Section: The Empirical Route To the Distance Of Ngc1866supporting

confidence: 87%

Section: The Empirical Route To the Distance Of Ngc1866mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Cepheids of NGC 1866: a precise benchmark for the extragalactic distance scale and stellar evolution from modernUBVIphotometry

Musella¹,

Marconi²,

Stetson³

et al. 2016

Mon. Not. R. Astron. Soc.

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“…The dotted line depicts the linear relatios derived by Molinaro et al (2012) on the basis of the CORS Baade-Wesselink method applied to a sample of 11 Cepheids belonging to the young LMC blue populous cluster NGC 1866, while the dashed line is the relation derived by Gieren et al (1999) for a sample of both Galactic and Magellanic Cepheids. We note that the predicted PR relation based on the model fitting of SMC Cepheids suggests that at fixed period the radius is smaller for SMC Cepheids than for Galactic and LMC ones.…”

Section: The Period-radius Relationmentioning

confidence: 99%

The VMC survey – XXIII. Model fitting of light and radial velocity curves of Small Magellanic Cloud classical Cepheids

Marconi

Molinaro

Ripepi

et al. 2016

Mon. Not. R. Astron. Soc.

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We present the results of the χ 2 minimization model fitting technique applied to optical and near-infrared photometric and radial velocity data for a sample of 9 fundamental and 3 first overtone classical Cepheids in the Small Magellanic Cloud (SMC). The nearinfrared photometry (JK filters) was obtained by the European Southern Observatory (ESO) public survey "VISTA near-infrared Y, J, K s survey of the Magellanic Clouds system" (VMC). For each pulsator isoperiodic model sequences have been computed by adopting a nonlinear convective hydrodynamical code in order to reproduce the multifilter light and (when available) radial velocity curve amplitudes and morphological details. The inferred individual distances provide an intrinsic mean value for the SMC distance modulus of 19.01 mag and a standard deviation of 0.08 mag, in agreement with the literature. Moreover the instrinsic masses and luminosities of the best fitting model show that all these pulsators are brighter than the canonical evolutionary MassLuminosity relation (MLR), suggesting a significant efficiency of core overshooting and/or mass loss. Assuming that the inferred deviation from the canonical MLR is only due to mass loss, we derive the expected distribution of percentage mass loss as a function of both the pulsation period and of the canonical stellar mass. Finally, a good agreement is found between the predicted mean radii and current Period-Radius (PR) relations in the SMC available in the literature. The results of this investigation support the predictive capabilities of the adopted theoretical scenario and pave the way to the application to other extensive databases at various chemical compositions, including the VMC Large Magellanic Cloud pulsators and Galactic Cepheids with Gaia parallaxes.

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“…A well known potential problem related with the application of the BW technique is the uncertainty on the projection factor p (see, e.g. Molinaro et al 2012;Nardetto et al 2014, and references therein). In their analysis Feast et al (2008) derived and adopted a fixed pfactor = 1.23± 0.03.…”

Section: Absolute Calibration Of P L P Lc and P W Relationsmentioning

confidence: 99%

The VMC Survey – XIII. Type II Cepheids in the Large Magellanic Cloud★

Ripepi

Moretti

Marconi

et al. 2014

Monthly Notices of the Royal Astronomical Society

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The VISTA survey of the Magellanic Clouds System (VMC) is collecting deep K s -band time-series photometry of the pulsating variable stars hosted in the system formed by the two Magellanic Clouds and the Bridge connecting them. In this paper we have analysed a sample of 130 Large Magellanic Cloud (LMC) Type II Cepheids (T2CEPs) found in tiles with complete or near complete VMC observations for which identification and optical magnitudes were obtained from the OGLE III survey. We present J and K s light curves for all 130 pulsators, including 41 BL Her, 62 W Vir (12 pW Vir) and 27 RV Tau variables. We complement our near-infrared photometry with the V magnitudes from the OGLE III survey, allowing us to build a variety of PeriodLuminosity (P L), Period-Luminosity-Colour (P LC) and Period-Wesenheit (P W ) relationships, including any combination of the V, J, K s filters and valid for BL Her and W Vir classes. These relationships were calibrated in terms of the LMC distance modulus, while an independent absolute calibration of the P L(K s ) and the P W (K s , V ) was derived on the basis of distances obtained from Hubble Space T elescope parallaxes and Baade-Wesselink technique. When applied to the LMC and to the Galactic Globular Clusters hosting T2CEPs, these relations seem to show that: 1) the two population II standard candles RR Lyrae and T2CEPs give results in excellent agreement with each other; 2) there is a discrepancy of ∼0.1 mag between population II standard candles and Classical Cepheids when the distances are gauged in a similar way for all the quoted pulsators. However, given the uncertainties, this discrepancy is within the formal 1σ uncertainties.

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Cors Baade–wesselink Distance to the LMC NGC 1866 Blue Populous Cluster

Cited by 20 publications

References 67 publications

The Cepheids of NGC 1866: a precise benchmark for the extragalactic distance scale and stellar evolution from modernUBVIphotometry

The Cepheids of NGC 1866: a precise benchmark for the extragalactic distance scale and stellar evolution from modernUBVIphotometry

The VMC survey – XXIII. Model fitting of light and radial velocity curves of Small Magellanic Cloud classical Cepheids

The VMC Survey – XIII. Type II Cepheids in the Large Magellanic Cloud★

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