Scaled solar tracks and isochrones in a large region  of 
the <i>Z</i>–<i>Y</i> plane

Context. Lithium is a fragile element, which is easily destroyed in the stellar interior. The existence of lithium-rich giants still represents a challenge for stellar evolution models. Aims. We have collected a large database of high-resolution stellar spectra of 824 candidate thick-disk giants having 2 MASS photometry and proper motions measured by the Southern Proper-Motion Program (SPM). In order to investigate the nature of Li-rich giants, we searched this database for giants presenting a strong Li I resonance line. Methods. We performed a chemical abundance analysis on the selected stars with the MOOG code along with proper ATLAS-9 model atmospheres. The iron content and atmospheric parameters were fixed by using the equivalent width of a sample of Fe lines. We also derive abundances for C, N, and O and measure or derive lower limits on the 12 C/ 13 C isotopic ratios, which is a sensible diagnostic of the stars evolutionary status. Results. We detected five stars with a lithium abundance higher than 1.5, i.e. Li-rich according to the current definition. One of them (SPM-313132) has A(Li) > 3.3 and, because of this, belongs to the group of the rare super Li-rich giants. Its kinematics makes it a likely thin-disk member and its atmospheric parameters are compatible with it being a 4 M star either on the red giant branch (RGB) or the early asymptotic giant branch. This object is the first super Li-rich giant detected at this phase. The other four are likely low-mass thick-disk stars evolved past the RGB luminosity bump, as determined from their metallicities and atmospheric parameters. The most evolved of them lies close to the RGB-tip. It has A(Li) > 2.7 and a low 12 C/ 13 C isotopic ratio, close to the cool bottom processing predictions.

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“…5 stellar evolutionary tracks (Bertelli et al 2008(Bertelli et al , 2009) of metallicity appropriate to our stars. While the arguments in Sect.…”

Section: Discussionmentioning

confidence: 99%

Lithium-rich giants in the Galactic thick disk

Monaco

Villanova

Bidin

et al. 2011

A&A

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“…We will not review the physics of these stellar tracks here but we just mention that over the years, these models were calculated including semi-convection in massive stars (e.g., Chiosi & Summa 1970), ballistic-convective overshooting from the core (Bressan, Chiosi & Bertelli 1981), overshooting from the the bottom of the convective envelope (Alongi et al 1991), turbulent diffusion from the convective core and convective shells Deng, Bressan & Chiosi (1996a,b); Salasnich, Bressan & Chiosi (1999), plus several additional improvements and revisions (Alongi et al 1993; Fagotto et al 1994b;Bertelli et al 1994;Fagotto et al 1994a,a;Bertelli & Nasi 2001;Bertelli et al 2003Bertelli et al , 2008Bertelli et al , 2009. The stellar models in use are those by Bertelli et al (2008Bertelli et al ( , 2009), which cover a wide grid of helium Y , metallicity Z, and enrichment ratio ∆Y /∆Z. The associated isochrones include the effect of mass loss by stellar wind and the thermally pulsing AGB phase according to the models calculated by Marigo & Girardi (2007).…”

Section: Sources Of Stellar Tracks Isochrones Ssps In Different Phomentioning

confidence: 99%

“…The code in use is the last version of YZVAR developed over the years by the Padova group and already used in many studies (for instance Chiosi & Greggio 1981;Chiosi et al 1986Chiosi et al , 1989Bertelli et al 1995;Ng et al 1995;Aparicio et al 1996;Bertelli & Nasi 2001;Bertelli et al 2003) and recently extended to obtain isochrones and SSPs in a large region of the Z−Y plane. The details on the interpolation scheme at given ∆Y /∆Z are given in Bertelli et al (2008Bertelli et al ( , 2009). The present isochrones and SSPs are in the Johnson-Cousins-Glass system as defined by Bessell (1990) and Bessell & Brett (1988).…”

Section: Sources Of Stellar Tracks Isochrones Ssps In Different Phomentioning

confidence: 99%

Spiral arm kinematics for Milky Way stellar populations

Pasetto

Natale

Kawata

et al. 2016

Mon. Not. R. Astron. Soc.

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We present a new theoretical population synthesis model (the Galaxy Model) to examine and deal with large amounts of data from surveys of the Milky Way and to decipher the present and past structure and history of our own Galaxy.We assume the Galaxy to consist of a superposition of many composite stellar populations belonging to the thin and thick disks, the stellar halo and the bulge, and to be surrounded by a single dark matter halo component. A global model for the Milky Way's gravitational potential is built up self-consistently with the density profiles from the Poisson equation. In turn, these density profiles are used to generate synthetic probability distribution functions (PDFs) for the distribution of stars in colour-magnitude diagrams (CMDs). Finally, the gravitational potential is used to constrain the stellar kinematics by means of the moment method on a (perturbed)-distribution function. Spiral arms perturb the axisymmetric disk distribution functions in the linear response framework of density-wave theory where we present an analytical formula of the so-called 'reduction factor' using Hypergeometric functions.Finally, we consider an analytical non-axisymmetric model of extinction and an algorithm based on the concept of probability distribution function to handle colour magnitude diagrams with a large number of stars. A genetic algorithm is presented to investigate both the photometric and kinematic parameter space.This galaxy model represents the natural framework to reconstruct the structure of the Milky Way from the heterogeneous data set of surveys such as Gaia-ESO, SEGUE, APOGEE2, RAVE and the Gaia mission.

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“…3 www.oa-teramo.inaf.it/BASTI (Pietrinferni et al 2004). 4 stev.oapd.inaf.it/YZVAR/cgi-bin/form (Bertelli et al 2008). 5 www.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/en/cfht 6 www.ast.obs-mip.fr/projets/espadons/espadons.html archive (Piskunov et al 1995;Ryabchikova et al 1999;Kupka et al 1999) and of the model atmospheres calculated with the LLmodels stellar model atmosphere code (Shulyak et al 2004).…”

Section: From Observationsmentioning

confidence: 99%

A seismic and gravitationally bound double star observed byKepler

Appourchaux

Antia

Ball

et al. 2015

A&A

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Context. Solar-like oscillations have been observed by Kepler and CoRoT in many solar-type stars, thereby providing a way to probe stars using asteroseismology. Aims. The derivation of stellar parameters has usually been done with single stars. The aim of the paper is to derive the stellar parameters of a double-star system (HIP 93511), for which an interferometric orbit has been observed along with asteroseismic measurements. Methods. We used a time series of nearly two years of data for the double star to detect the two oscillation-mode envelopes that appear in the power spectrum. Using a new scaling relation based on luminosity, we derived the radius and mass of each star. We derived the age of each star using two proxies: one based upon the large frequency separation and a new one based upon the small frequency separation. Using stellar modelling, the mode frequencies allowed us to derive the radius, the mass, and the age of each component. In addition, speckle interferometry performed since 2006 has enabled us to recover the orbit of the system and the total mass of the system. Results. From the determination of the orbit, the total mass of the system is 2.34 +0.45 −0.33 M . The total seismic mass using scaling relations is 2.47 ± 0.07 M . The seismic age derived using the new proxy based upon the small frequency separation is 3.5 ± 0.3 Gyr. Based on stellar modelling, the mean common age of the system is 2.7-3.9 Gyr. The mean total seismic mass of the system is 2.34-2.53 M consistent with what we determined independently with the orbit. The stellar models provide the mean radius, mass, and age of the stars as R A = 1.82−1.87 R , M A = 1.25−1.39 M , Age A = 2.6-3.5 Gyr; R B = 1.22−1.25 R , M B = 1.08−1.14 M , Age B = 3.35-4.21 Gyr. The models provide two sets of values for Star A: [1.25-1.27] M and [1.34-1.39] M . We detect a convective core in Star A, while Star B does not have any. For the metallicity of the binary system of Z ≈ 0.02, we set the limit between stars having a convective core in the range [1.14-1.25] M .

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Scaled solar tracks and isochrones in a large region of the Z–Y plane

Cited by 401 publications

References 135 publications

Lithium-rich giants in the Galactic thick disk

Lithium-rich giants in the Galactic thick disk

Spiral arm kinematics for Milky Way stellar populations

A seismic and gravitationally bound double star observed byKepler

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