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This work presents an approach (fitCMD) designed to obtain a comprehensive set of astrophysical parameters from colour-magnitude diagrams (CMDs) of star clusters. Based on initial mass function (IMF) properties taken from isochrones, fitCMD…

Instrumentation and Methods for Astrophysics · Physics 2018-12-12 Charles Bonatto

We have developed a maximum-likelihood procedure to fit theoretical isochrones to the observed cluster color-magnitude diagrams of NGC 6866, an open cluster in the Kepler Spacecraft field of view. The Markov-Chain Monte Carlo algorithm…

Solar and Stellar Astrophysics · Physics 2015-06-19 Kenneth Janes , Sydney A. Barnes , Soeren Meibom , Sadia Hoq

The colour-magnitude diagrams of resolved single stellar populations, such as open and globular clusters, have provided the best natural laboratories to test stellar evolution theory. Whilst a variety of techniques have been used to infer…

Astrophysics · Physics 2009-11-13 X. Hernandez , D. Valls-Gabaud

We present updated stellar population models appropriate for old ages (>1 Gyr) and covering a wide range in metallicities (-1.5<[Fe/H]<0.3). These models predict the full spectral variation associated with individual element abundance…

Astrophysics of Galaxies · Physics 2018-02-28 Charlie Conroy , Alexa Villaume , Pieter van Dokkum , Karin Lind

Asteroseismic parameters allow us to measure the basic stellar properties of field giants observed far across the Galaxy. Most of such determinations are, up to now, based on simple scaling relations involving the large frequency…

We have used over 10,000 early-type galaxies from the 6dF Galaxy Survey (6dFGS) to construct the Fundamental Plane across the optical and near-infrared passbands. We demonstrate that a maximum likelihood fit to a multivariate Gaussian model…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Christina Magoulas , Matthew Colless , D. Heath Jones , Christopher M. Springob , Jeremy R. Mould

We consider from a general point of view the problem of determining the extinction in dense molecular clouds. We use a rigorous statistical approach to characterize the properties of the most widely used optical and infrared techniques,…

Astrophysics · Physics 2009-11-11 Marco Lombardi

We present a detailed discussion of how to obtain precise stellar photometry in crowded fields using images from multi-conjugate adaptive optics (MCAO) systems, with the intent of informing the scientific development of this key technology…

Instrumentation and Methods for Astrophysics · Physics 2017-04-12 P. Turri , A. W. McConnachie , P. B. Stetson , G. Fiorentino , D. R. Andersen , G. Bono , D. Massari , J. -P. Veran

New estimate of the distances of 36 nearby galaxies is presented. It is based on the calibration of the V- and I-band Period-Lumi- nosity relations for galactic Cepheids measured by the HIPPARCOS mission. The distance moduli are obtained in…

Astrophysics · Physics 2009-11-07 G. Paturel , P. Teerikorpi , G. Theureau , P. Fouque , I. Musella , J. N. Terry

The Gaia mission has provided highly accurate observations that have significantly reduced the scatter in the colour-magnitude diagrams of open clusters. As a result of the improved isochrone sequence of the open cluster M67, we have…

Solar and Stellar Astrophysics · Physics 2024-07-09 Claudia Reyes , Dennis Stello , Marc Hon , Regner Trampedach , Eric Sandquist , Marc Pinsonneault

Globular Clusters (GCs) in the Milky Way are the primary laboratories for establishing the ages of the oldest stellar populations and for measuring the color-magnitude relation of stars. In infrared (IR) color-magnitude diagrams (CMDs), the…

Solar and Stellar Astrophysics · Physics 2016-05-25 Matteo Correnti , Mario Gennaro , Jason S. Kalirai , Thomas M. Brown , Annalisa Calamida

Traditional binned statistics such as $\chi^2$ suffer from information loss and arbitrariness of the binning procedure. We point out that the underlying statistical quantity (the log likelihood $L$) does not require any binning beyond the…

We introduce new methods for robust high-precision photometry from well-sampled images of a non-crowded field with a strongly varying point-spread function. For this work, we used archival imaging data of the open cluster M37 taken by MMT…

Instrumentation and Methods for Astrophysics · Physics 2015-06-24 S. -W. Chang , Y. -I. Byun , J. D. Hartman

Many statistical models in cosmology can be simulated forwards but have intractable likelihood functions. Likelihood-free inference methods allow us to perform Bayesian inference from these models using only forward simulations, free from…

Cosmology and Nongalactic Astrophysics · Physics 2018-04-11 Justin Alsing , Benjamin Wandelt , Stephen Feeney

Recently, it has been noticed that the discrepancies in the integrated colour indices (CIs) between star clusters and models are mostly due to the projection of bright stars in the apertures. In order to reduce this problem, the method of…

Astrophysics of Galaxies · Physics 2025-06-12 Karolis Daugevičius , Eimantas Kriščiūnas , Erikas Cicėnas , Rima Stonkutė , Vladas Vansevičius

MAx is a new tool to estimate parameters from stellar spectra. It is based on the maximum likelihood method, with the likelihood compressed in a way that the information stored in the spectral fluxes is conserved. The compressed data are…

Astrophysics of Galaxies · Physics 2015-05-14 Paula Jofré , Ben Panter , Camilla Juul Hansen , Achim Weiss

The most fundamental problem in statistics is the inference of an unknown probability distribution from a finite number of samples. For a specific observed data set, answers to the following questions would be desirable: (1) Estimation:…

Statistics Theory · Mathematics 2013-01-23 Ali Kinkhabwala

Stellar population synthesis models can now reproduce the photometry of old stellar systems (age $>$ 2 Gyr) in the near-infrared (NIR) bands at 3.4 and 4.6$\mu$m (WISE W1 $\&$ W2 or IRAC 1 $\&$ 2). In this paper we derive stellar…

A maximum likelihood methodology for a general class of models is presented, using an approximate Bayesian computation (ABC) approach. The typical target of ABC methods are models with intractable likelihoods, and we combine an ABC-MCMC…

Methodology · Statistics 2016-08-16 Umberto Picchini , Rachele Anderson

(Abridged) We introduce a novel technique to construct spatially resolved maps of stellar mass surface density in galaxies based on optical and near IR imaging. We use optical/NIR colour(s) to infer effective stellar mass-to-light ratios…

Cosmology and Nongalactic Astrophysics · Physics 2011-03-28 Stefano Zibetti , Stephane Charlot , Hans-Walter Rix
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