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The 21 cm signal from the Epoch of Reionization should be observed within the next decade. While a simple statistical detection is expected with SKA pathfinders, the SKA will hopefully produce a full 3D mapping of the signal. To extract…

Cosmology and Nongalactic Astrophysics · Physics 2017-04-28 Hayato Shimabukuro , Benoit Semelin

RR Lyrae (RRL) are old, low-mass radially pulsating variable stars in their core helium burning phase. They are popular stellar tracers and primary distance indicators, since they obey to well defined period-luminosity relations in the…

Solar and Stellar Astrophysics · Physics 2023-06-28 Piero Trevisan , Mario Pasquato , Gaia Carenini , Nicolas Mekhael , Vittorio F. Braga , Giuseppe Bono , Mohamad Abbas

Aims. We present an innovative artificial neural network (ANN) architecture, called Generative ANN (GANN), that computes the forward model, that is it learns the function that relates the unknown outputs (stellar atmospheric parameters, in…

Instrumentation and Methods for Astrophysics · Physics 2016-10-19 C. Dafonte , D. Fustes , M. Manteiga , D. Garabato , M. A. Alvarez , A. Ulla , C. Allende Prieto

We present an Artificial Neural Network (ANN) model of photospheric lithium depletion in cool stars (3000 < Teff / K < 6500), producing estimates and probability distributions of age from Li I 6708A equivalent width (LiEW) and effective…

Solar and Stellar Astrophysics · Physics 2024-09-13 George Weaver , Robin D. Jeffries , Richard J. Jackson

A serious concern for semi-analytical galaxy formation models, aiming to simulate multi-wavelength surveys and to thoroughly explore the model parameter space, is the extremely time consuming numerical solution of the radiative transfer of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Laura Silva , Fabio Fontanot , Gian Luigi Granato

Modelling the complex physics of the Interstellar Medium (ISM) in the context of large-scale numerical simulations is a challenging task. A number of methods have been proposed to embed a description of the ISM into different codes. We…

Instrumentation and Methods for Astrophysics · Physics 2011-03-03 T. Grassi , E. Merlin , L. Piovan , U. Buonomo , C. Chiosi

Simulation of spectra of x-ray absorption spectroscopy (XAS) at the L-edge is a well-established and reliable computational tool that, in combination with experimental measurements, reveals details about the local electronic structure and…

Materials Science · Physics 2021-07-29 Johann Lueder

Artificial neural networks (ANN) have different applications in Astronomy, including data reduction and data mining. In this work we propose the use ANNs in the identification of stellar model solutions. We illustrate this method, by…

Solar and Stellar Astrophysics · Physics 2015-06-04 F. J. G. Pinheiro , T. Simas , J. Fernandes , R. Ribeiro

A new approach to estimating photometric redshifts - using Artificial Neural Networks (ANNs) - is investigated. Unlike the standard template-fitting photometric redshift technique, a large spectroscopically-identified training set is…

Astrophysics · Physics 2009-11-07 Andrew E. Firth , Ofer Lahav , Rachel S. Somerville

We calculate photometric redshifts from the Sloan Digital Sky Survey Data Release 2 Galaxy Sample using artificial neural networks (ANNs). Different input patterns based on various parameters (e.g. magnitude, color index, flux information)…

Astrophysics · Physics 2007-05-23 Lili Li , Yanxia Zhang , Yongheng Zhao , Dawei Yang

It has been demonstrated that the time variability of a star's brightness at different frequencies can be used to infer its surface gravity, radius, mass, and age. With large samples of light curves now available from Kepler and K2, and…

Solar and Stellar Astrophysics · Physics 2018-10-17 Melissa K. Ness , Victor Silva Aguirre , Mikkel N. Lund , Matteo Cantiello , Daniel Foreman-Mackey , David W. Hogg , Ruth Angus

Aiming to extend the census of RR Lyrae stars to highly reddened low-latitude regions of the central Milky Way, we performed a deep near-IR variability search using data from the VISTA Variables in the V\'ia L\'actea (VVV) survey of the…

Astrophysics of Galaxies · Physics 2020-07-29 István Dékány , Eva K. Grebel

Magnetic activity in stars manifests as dark spots on their surfaces that modulate the brightness observed by telescopes. These light curves contain important information on stellar rotation. However, the accurate estimation of rotation…

We determine the fundamental stellar parameters of altogether 20 double-mode RR Lyrae (RRd) stars from the Galactic Field and the Large Magellanic Cloud, following our approach employed on the field RRd star BS Comae. The stars were…

Solar and Stellar Astrophysics · Physics 2015-05-13 Istvan Dekany

RR Lyrae stars are useful chemical tracers thanks to the empirical relationship between their heavy-element abundance and the shape of their light curves. However, the consistent and accurate calibration of this relation across multiple…

Solar and Stellar Astrophysics · Physics 2022-05-31 István Dékány , Eva K. Grebel

Existing adaptive bias techniques, which seek to estimate free energies and physical properties from molecular simulations, are limited by their reliance on fixed kernels or basis sets which hinder their ability to efficiently conform to…

Statistical Mechanics · Physics 2018-04-04 Hythem Sidky , Jonathan K. Whitmer

Stellar metallicity strongly correlates with the presence of planets and their properties. To check for new correlations between stars and the existence of an orbiting planet, we determine precise stellar parameters for a sample of…

Solar and Stellar Astrophysics · Physics 2015-05-20 Sérgio G. Sousa , Nuno C. Santos , Garik Israelian , C. Lovis , Michel Mayor , Pedro B. Silva , Stephane Udry

High-resolution spectroscopic measurements of OB stars are important for understanding processes like stellar evolution, but require labor-intensive observations. In contrast, photometric missions like the Transiting Exoplanet Survey…

Solar and Stellar Astrophysics · Physics 2025-12-16 Rachel C. Zhang , Kaze W. K. Wong , Gonzalo Holgado , Matteo Cantiello

Detection of redshifted \ion{H}{i} 21-cm emission is a potential probe for investigating the Universe's first billion years. However, given the significantly brighter foreground, detecting 21-cm is observationally difficult. The Earth's…

Cosmology and Nongalactic Astrophysics · Physics 2024-01-30 Anshuman Tripathi , Abhirup Datta , Madhurima Choudhury , Suman Majumdar

We apply machine learning techniques in an attempt to predict and classify stellar properties from noisy and sparse time series data. We preprocessed over 94 GB of Kepler light curves from MAST to classify according to ten distinct physical…

Instrumentation and Methods for Astrophysics · Physics 2018-06-27 Trisha Hinners , Kevin Tat , Rachel Thorp