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Context. The [Mg/Fe] abundance ratios are a fundamental fossil signature to trace the chemical evolution of the disc. Despite of the huge observational and theoretical effort, discrepancies between models and data are still present and…

Astrophysics of Galaxies · Physics 2022-07-20 Marco Palla , Pablo Santos-Peral , Alejandra Recio-Blanco , Francesca Matteucci

A comparison is made between the age-metallicity relation obtained from four different types of studies: F and G stars in the Solar Neighbourhood, analysis of open clusters, galactic structure studies with the stellar population synthesis…

Astrophysics · Physics 2009-10-30 G. Carraro , Y. K. Ng , L. Portinari

We find that hot jupiter host stars within the T$_\mathrm{eff}$ range 5900-6300K show lower Li abundances, by 0.14 dex, than stars without detected planets. This offset has a significance at the level 7$\sigma$, pointing to a stronger…

I briefly introduce a database of models that describe the evolution of star clusters in several broad-band photometric systems. Models are based on the latest Padova stellar evolutionary tracks - now including the alpha-enhanced case and…

Astrophysics · Physics 2007-05-23 Leo Girardi

Deriving the metallicity, [Fe/H], in low-resolution spectra of carbon-enhanced metal-poor (CEMP) stars is a tedious task that, owing to the large number of line blends, often leads to uncertainties on [Fe/H] exceeding 0.25dex. The CEMP…

Solar and Stellar Astrophysics · Physics 2020-02-12 D. Singh , C. J. Hansen , J. S. Byrgesen , M. Reichert , H. M. Reggiani

Comparing models and data of pulsating stars is a powerful way to understand the stellar structure better.\beta Hyi is an evolved solar-type pulsator with mixed modes in its frequency spectrum, making it very interesting for asteroseismic…

Solar and Stellar Astrophysics · Physics 2015-05-20 I. M. Brandão , G. Dogan , J. Christensen-Dalsgaard , M. S. Cunha , T. R. Bedding , T. S. Metcalfe , H. Kjeldsen , H. Bruntt , T. Arentoft

We investigate the age-chemical abundance structure of the outer Galactic disc at a galactocentric distance of r > 10 kpc as recently revealed by the SDSS/APOGEE survey. Two sequences are present in the [alpha/Fe]-[Fe/H] plane with…

We investigate the intrinsic scatter in the chemical abundances of a sample of metal-poor ([Fe/H]<-2.5) Milky Way halo stars. We draw our sample from four historic surveys and focus our attention on the stellar Mg, Ca, Ni, and Fe…

Astrophysics of Galaxies · Physics 2020-11-04 Louise Welsh , Ryan Cooke , Michele Fumagalli

As part of an ongoing program to measure detailed chemical abundances in nearby galaxies, we use a sample of young to intermediate age clusters in the Large Magellanic Cloud with ages of 10 Myr to 2 Gyr to evaluate the effect of isochrone…

Solar and Stellar Astrophysics · Physics 2015-06-04 J. E. Colucci , R. A. Bernstein

We present a new comprehensive collection of stellar evolutionary tracks and isochrones for rotating low- and intermediate-mass stars assembled with the updated version of PARSEC V2.0. This version includes our recent calibration of the…

Solar and Stellar Astrophysics · Physics 2022-09-21 C. T. Nguyen , G. Costa , L. Girardi , G. Volpato , A. Bressan , Y. Chen , P. Marigo , X. Fu , P. Goudfrooij

We investigate stellar elemental abundance patterns at z = 0 in 8 low-mass (M_* = 10^6 - 10^9 M_sun) galaxies in the Feedback in Realistic Environments (FIRE-2) cosmological simulations. Using magnesium (Mg) as a representative…

Models of the chemical evolution of our Galaxy are extended to include radial migration of stars and flow of gas through the disc. The models track the production of both iron and alpha elements. A model is chosen that provides an excellent…

Astrophysics · Physics 2015-05-13 Ralph Schoenrich , James Binney

The physical processes driving chemical evolution in the Milky Way can be probed using the distribution of abundances in low-mass FGK type stars in space phase at different times. During their final stages of evolution stars experience…

Solar and Stellar Astrophysics · Physics 2020-01-15 Paula Jofre , Holly Jackson , Marcelo Tucci Maia

We present a fully differential chemical abundance analysis using very high-resolution (R >~ 85,000) and very high signal-to-noise (S/N~800 on average) HARPS and UVES spectra of 7 solar twins and 95 solar analogs, 24 are planet hosts and 71…

Solar and Stellar Astrophysics · Physics 2015-05-19 J. I. Gonzalez Hernandez , G. Israelian , N. C. Santos , S. Sousa , E. Delgado-Mena , V. Neves , S. Udry

Despite the extensive study of lithium depletion during pre-main-sequence contraction, studies of individual stars show discrepancies between ages determined from the HR diagram and ages determined from lithium depletion (Song et al. 2002,…

Solar and Stellar Astrophysics · Physics 2015-05-18 Jennifer C. Yee , Eric L. N. Jensen

The pre-main-sequence evolution of low-mass stars and brown dwarfs is studied numerically starting from the formation of a protostellar/proto-brown dwarf seed and taking into account the mass accretion onto the central object during the…

Solar and Stellar Astrophysics · Physics 2017-09-20 Eduard Vorobyov , Vardan Elbakyan , Takashi Hosokawa , Yuya Sakurai , Manuel Guedel , Harold Yorke

The ages of the oldest and most metal-poor stars in the Milky Way bear important information on the age of the Universe and its standard model. We analyze a sample of 28 extremely metal-poor field stars in the solar vicinity culled from the…

Solar and Stellar Astrophysics · Physics 2022-12-07 Anastasiia Plotnikova , Giovanni Carraro , Sandro Villanova , Sergio Ortolani

We derive age constraints for 1639 red giants in the APOKASC sample for which seismic parameters from Kepler, as well as effective temperatures, metallicities and [alpha/Fe] values from APOGEE DR12 are available. We investigate the relation…

We present a survey of lithium abundances in 185 main- sequence field stars with Teff between 5600 and 6600 K and [Fe/H] from -1.4 to +0.2 based on high-resolution spectra of 130 stars and a reanalysis of data from Lambert et al. (1991).…

Astrophysics · Physics 2009-11-06 Y. Q. Chen , P. E. Nissen , T. Benoni , G. Zhao

We explore the redshift evolution of the metal content of damped Lyman alpha systems (DLAs) with new observations of four absorbers at z < 1.5 . The main conclusion is that the column density--weighted mean metallicity, [<Zn/H>] = -1.03 +/-…

Astrophysics · Physics 2009-10-30 Max Pettini , Sara L. Ellison , Charles C. Steidel , David V. Bowen