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The Gaia-ESO Survey (GES) is a large public spectroscopic survey that was carried out using the multi-object FLAMES spectrograph at the Very Large Telescope. The survey provides accurate radial velocities, stellar parameters, and elemental…

In astrophysics, we often aim to estimate one or more parameters for each member object in a population and study the distribution of the fitted parameters across the population. In this paper, we develop novel methods that allow us to take…

Solar and Stellar Astrophysics · Physics 2018-06-19 Shijing Si , David A. van Dyk , Ted von Hippel , Elliot Robinson , Aaron Webster , David Stenning

We present UV-extended E-MILES stellar population synthesis models covering the spectral range 1680-50000A at moderately high resolution. We employ the NGSL space-based stellar library to compute spectra of single-age, single-metallicity…

Astrophysics of Galaxies · Physics 2016-12-06 A. Vazdekis , M. Koleva , E. Ricciardelli , B. Röck , J. Falcón-Barroso

Machine learning and artificial neural networks (ANNs) have increasingly become integral to data analysis research in astrophysics due to the growing demand for fast calculations resulting from the abundance of observational data.…

General Relativity and Quantum Cosmology · Physics 2023-09-11 Ioannis Liodis , Evaggelos Smirniotis , Nikolaos Stergioulas

The availability of asteroseismic constraints for tens of thousands of red giant (RG) stars has opened the door to robust age estimates, enabling time-resolved studies of different populations of stars in the Milky Way. This study leverages…

Recent results by Bensby and collaborators on the ages of microlensed stars in the Galactic bulge have challenged the picture of an exclusively old stellar population. However, these age estimates have not been independently confirmed. In…

Solar and Stellar Astrophysics · Physics 2015-05-13 G. Valle , M. Dell'Omodarme , P. G. Prada Moroni , S. Degl'Innocenti

Observational tests of stellar and Galactic chemical evolution call for the joint knowledge of a star's physical parameters, detailed element abundances, and precise age. For cool main-sequence (MS) stars the abundances of many elements can…

Solar and Stellar Astrophysics · Physics 2019-01-09 M. Fouesneau , H. -W. Rix , T. von Hippel , D. W. Hogg , H. Tian

We want to study the effects of the formation of planets and planetary systems on the atmospheric Li abundance of planet host stars. In this work we present new determinations of lithium abundances for 326 Main Sequence stars with and…

We present lithium abundances for 119 main-sequence stars in the old open cluster NGC 188 (age = 6.3 Gyr), using high-resolution, high signal-to-noise ratio spectra from WIYN/Hydra. We observe the stars over multiple nights and measure…

Solar and Stellar Astrophysics · Physics 2025-09-19 Qinghui Sun , Constantine P. Deliyannis , Bruce A. Twarog , Barbara J. Anthony-Twarog

Jets of energetic particles, as seen in FR type-I and FR type-II sources, ejected from the center of Radio-Loud AGN affect the sources surrounding intracluster medium/intergalactic medium. Placing constraints on the age of such sources is…

The characteristic timescale ($\tau$) of continuum variability of the accretion disk in active galactic nuclei (AGNs) is known to be related to the thermal timescale, which is predicted to scale with AGN luminosity ($L$) and restframe…

Astrophysics of Galaxies · Physics 2025-03-26 Suyeon Son , Minjin Kim , Luis C. Ho

High-resolution CTIO 4-m/HYDRA spectroscopy of the super-metal-rich open cluster NGC 6253 ([Fe/H]=+0.43+/-0.01) has been used to study the stellar lithium (Li) abundances near the cluster's turnoff. NGC 6253 greatly expands the range of…

Solar and Stellar Astrophysics · Physics 2015-06-11 Jeffrey D. Cummings , Constantine P. Deliyannis , Barbara Anthony-Twarog , Bruce Twarog , Ryan M. Maderak

We test a scenario in which radial migration could affect the Li abundance pattern of dwarf stars in the solar neighbourhood. This may confirm that the Li abundance in these stars can not serve as a probe for the Li abundance in the…

In this study, we utilize a sample of 338 galaxies within the redshift range of $\rm 0.02<z<0.1$, drawn from the Sloan Digital Sky Survey (SDSS), for which there are available classifications, based on their emission line ratios. We,…

Astrophysics of Galaxies · Physics 2024-08-07 G. Mountrichas , A. Ruiz , I. Georgantopoulos , E. Pouliasis , A. Akylas , E. Drigga

Galactic archaeology relies on accurate stellar parameters to reconstruct the galaxy's history, including information on stellar ages. While the precision of data has improved significantly in recent years, stellar models used for age…

Solar and Stellar Astrophysics · Physics 2025-04-25 Leslie M. Morales , Jamie Tayar , Zachary R. Claytor

The lithium abundance in 62 halo dwarfs is determined from accurate equivalent widths reported in the literature and an improved infrared flux method (IRFM) temperature scale. The Li abundance of 41 plateau stars (those with Teff > 6000 K)…

Astrophysics · Physics 2009-11-10 Jorge Melendez , Ivan Ramirez

The degradation process of lithium-ion batteries is intricately linked to their entire lifecycle as power sources and energy storage devices, encompassing aspects such as performance delivery and cycling utilization. Consequently, the…

Machine Learning · Computer Science 2023-08-16 Yue Xiang , Bo Jiang , Haifeng Dai

We present estimates of stellar age and mass for 0.93 million Galactic disk main sequence turn-off and sub-giant stars from the LAMOST Galactic Spectroscopic Surveys. The ages and masses are determined by matching with stellar isochrones…

We address the existence and origin of the lithium (Li) desert, a region in the Li - T_eff plane sparsely populated by stars. Here we analyze some of the explanations that have been suggested for this region, including mixing in the late…

Solar and Stellar Astrophysics · Physics 2018-06-13 Claudia Aguilera-Gómez , Iván Ramírez , Julio Chanamé

We theoretically quantify the impact of observational errors on the recovered age for stars in MS and RGB phases. We adopted Teff, [Fe/H], Delta_nu and nu_max as observational constraints. Artificial stars were sampled from a reference…

Solar and Stellar Astrophysics · Physics 2018-12-19 G. Valle , M. Dell'Omodarme , P. G. Prada Moroni , S. Degl'Innocenti