Reclassification of Cepheids in the <i>Gaia</i> Data Release 2

Ripepi, V.; Molinaro, R.; Musella, I.; Marconi, M.; Leccia, S.; Eyer, L.

doi:10.1051/0004-6361/201834506

Cited by 122 publications

(141 citation statements)

References 67 publications

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“…The coefficients of these relations at varying the ML relation and the efficiency of the superadiabatic convection, are reported in Table 11 and Table 12 for F and FO models, respectively. To derive the Wesenheit magnitude we adopt the relation provided by Ripepi et al (2019) < W >=< G > −1.9 < G BP − G RP >. Both the PLC and the PW relations hold for each individual pulsator thus allowing us to derive individual distances of observed Cepheids in the Gaia database.…”

Section: The Period-radius and The Period-mass-radius Relationsmentioning

confidence: 99%

“…In this context, the Gaia mission (Gaia Collaboration et al 2016) is producing a 3D-map of 1 billion stars of the Milky Way with unprecedented accuracy. Focusing on pulsating stars, after the recent Data Release 2 (Gaia Collaboration et al 2018;Holl et al 2018), a large sample of Cepheids, observed in three photometric bands (G, G BP and G RP ) complemented with accurate parallaxes and proper motions, is available to the scientific community (Clementini et al 2019;Ripepi et al 2019), and the future releases will provide also radial velocity time series. This important database represents a challenging benchmark for testing the physical and numerical assumptions of current pulsation models.…”

Section: Introductionmentioning

confidence: 99%

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An Extended Theoretical Scenario for Classical Cepheids. I. Modeling Galactic Cepheids in the Gaia Photometric System

Somma

Marconi

Molinaro

et al. 2020

ApJS

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We present a new extended and detailed set of models for Classical Cepheid pulsators at solar chemical composition (Z = 0.02, Y = 0.28) based on a well tested nonlinear hydrodynamical approach. In order to model the possible dependence on crucial assumptions such as the Mass-Luminosity relation of central Helium burning intermediate-mass stars or the efficiency of superadiabatic convection, the model set was computed by varying not only the pulsation mode and the stellar mass but also the Mass-Luminosity relation and the mixing length parameter that is used to close the system of nonlinear hydrodynamical and convective equations. The dependence of the predicted boundaries of the instability strip as well as of both light and radial velocity curves on the assumed Mass-Luminosity and the efficiency of superadiabatic convection is discussed. Nonlinear Period-Mass-Luminosity-Temperature,

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Section: The Period-radius and The Period-mass-radius Relationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An Extended Theoretical Scenario for Classical Cepheids. I. Modeling Galactic Cepheids in the Gaia Photometric System

Somma

Marconi

Molinaro

et al. 2020

ApJS

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“…In the case of the inner disk cepheids the A K s values from col. 3 in Table 3 in I19 based on the Cardelli et al (1989) reddening law were taken, converted to A V using A K s /A V = 0.114 and then converted to E(B − V) using a specific reddening of 3.1. The pulsation type listed in Col. 3 is from the independent classification by Ripepi et al (2019). The adopted distance (d) is listed in Col. 6 based on the reference in Col. 7.…”

Section: The Samplementioning

confidence: 99%

“…The analysis by Ripepi et al (2019) on the classification of CCs addresses one of the issues that also affected the analysis in G18. The classification as CCs was taken from the literature in that paper and the origin of this classification is sometimes hard to trace.…”

Section: Introductionmentioning

confidence: 99%

Analysing the spectral energy distributions of Galactic classical Cepheids

Groenewegen

2020

A&A

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Spectral energy distributions (SEDs) were constructed for a sample of 477 classical cepheids (CCs); including stars that have been classified in the literature as such but are probably not. The SEDs were fitted with a dust radiative transfer code. Four stars showed a large mid-or far-infrared excess and the fitting then included a dust component. These comprise the well-known case of RS Pup, and three stars that are (likely) Type-II cepheids (T2Cs), AU Peg, QQ Per, and FQ Lac. The infrared (IR) excess in FQ Lac is reported for the first time in this work. The remainder of the sample was fitted with a stellar photosphere to derive the best-fitting luminosity and effective temperature. Distance and reddening were taken from the literature. The stars were plotted in a Hertzsprung-Russell diagram (HRD) and compared to evolutionary tracks for cepheids and theoretical instability strips. For the large majority of stars, the position in the HRD is consistent with the instability strip for a CC or T2C. About 5% of the stars are outliers in the sense that they are much hotter or cooler than expected. A comparison to effective temperatures derived from spectroscopy suggests in some cases that the photometrically derived temperature is not correct and that this is likely linked to an incorrectly adopted reddening. Two three-dimensional reddening models have been used to derive alternative estimates of the reddening for the sample. There are significant systematic differences between the two estimates with a non-negligible scatter. In this work the presence of a small near-infrared (NIR) excess, as has been proposed in the literature for a few well-known cepheids, is investigated. Firstly, this was done by using a sample of about a dozen stars for which a mid-infrared spectrum is available. This data is particularly constraining as the shape of the observed spectrum should match that of the photosphere and any dust spectrum, both dust continuum and any spectral features of, for example, silicates or aluminium oxide. This comparison provides constraints on the dust composition, in agreement with a previous work in the literature. Secondly, the SEDs of all stars were fitted with a dust model to see if a statistically significant better fit could be obtained. The results were compared to recent work. Eight new candidates for exhibiting a NIR excess are proposed, solely based on the photometric SEDs. Obtaining mid-infrared spectra would be needed to confirm this excess. Finally, period-bolometric luminosity and period-radius relations are presented for samples of over 370 fundamental-mode CCs.

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“…New streams, kinematic substructures and past accretion events have been found (Helmi et al, 2017;Koppelman et al, 2018), from the inner galaxy to the outer halo, and studies of dwarf galxies in the local group were carried out as well (Fritz et al, 2018). Various tracers were used to further explore the galaxtic structure, such as cepheids to trace the warp of the galactic disk (Ripepi et al, 2019).…”

Section: The Second Gaia Data Releasementioning

confidence: 99%

Gaia: The Galaxy in six (and more) dimensions

Pancino¹

2020

Advances in Space Research

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The ESA cornerstone mission Gaia was successfully launched in 2013, and is now scanning the sky to accurately measure the positions and motions of about two billion point-like sources of 3 V 20.5 mag, with the main goal of reconstructing the 6D phase space structure of the Milky Way. The typical uncertainties in the astrometry will be in the range 30-500 µas. The sky will be repeatedly scanned (70 times on average) for five years or more, adding the time dimension, and the Gaia data are complemented by mmag photometry in three broad bands, plus line-of-sight velocities from medium resolution spectroscopy for brighter stars. This impressive dataset is having a large impact on various areas of astrophysics, from solar system objects to distant quasars, from nearby stars to unresolved galaxies, from binaries and extrasolar planets to light bending experiments. This invited review paper presents an overview of the Gaia mission and describes why, to reach the goal performances in astrometry and to adequately map the Milky Way kinematics, Gaia was also equipped with state-of-the-art photometers and spectrographs, enabling us to explore much more than the 6D phase-space of positions and velocities. Scientific highlights of the first two Gaia data releases are briefly presented.

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Reclassification of Cepheids in the Gaia Data Release 2

Cited by 122 publications

References 67 publications

An Extended Theoretical Scenario for Classical Cepheids. I. Modeling Galactic Cepheids in the Gaia Photometric System

An Extended Theoretical Scenario for Classical Cepheids. I. Modeling Galactic Cepheids in the Gaia Photometric System

Analysing the spectral energy distributions of Galactic classical Cepheids

Gaia: The Galaxy in six (and more) dimensions

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