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The white dwarf luminosity function, which provides information about their cooling, has been measured with high precision in the past few years. Simulations that include well known Standard Model physics give a good fit to the data. This…

High Energy Physics - Phenomenology · Physics 2015-06-15 Herbert K. Dreiner , Jean-François Fortin , Jordi Isern , Lorenzo Ubaldi

We present our final study of the white dwarf cooling sequence (WD CS) in the globular cluster NGC 6752. The investigation is the main goal of a dedicated Hubble Space Telescope large Program, for which all the observations are now…

47 Tucanae is one of the most interesting and well observed and theoretically studied globular clusters. This allows us to study the reliability of our understanding of white dwarf cooling sequences, to confront different methods to…

Astrophysics of Galaxies · Physics 2015-06-23 Enrique García-Berro , Santiago Torres , Leandro G. Althaus , Marcelo M. Miller Bertolami

The Canada-France Brown Dwarf Survey is a wide eld survey for cool brown dwarfs conducted with the MegaCam camera on the CFHT telescope. Our objectives are to nd ultracool brown dwarfs and to constrain the eld brown dwarf mass function from…

Astrophysics · Physics 2009-11-13 C. Reyle , P. Delorme , X. Delfosse , T. Forveille , C. Willott , L. Albert , E. Artigau

We present new cooling models for carbon-oxygen white dwarfs with both H- and He-atmospheres, covering the whole relevant mass range, to extend our updated BaSTI (a Bag of Stellar Tracks and Isochrones) stellar evolution archive. They have…

Solar and Stellar Astrophysics · Physics 2021-12-22 Maurizio Salaris , Santi Cassisi , Adriano Pietrinferni , Sebastian Hidalgo

We present the white dwarf sequence of the globular cluster M4, based on a 123 orbit Hubble Space Telescope exposure, with limiting magnitude V = 30, I = 28. The white dwarf luminosity function rises sharply for I >25.5, consistent with the…

Microlensing events observed in the line of sight toward the LMC indicate that a significant fraction of the mass of the dark halo of the Galaxy is probably composed of white dwarfs. In addition, white dwarf sequences have now be observed…

Astrophysics · Physics 2009-10-31 D. Saumon , S. B. Jacobson

The GSC-II white dwarf survey was designed to identify faint and high proper motion objects, which we used to define a new and independent sample of cool white dwarfs. With this survey we aim to derive new constraints on the halo white…

In this paper, we present for the first time a proper-motion-selected white dwarf (WD) sample of the old Galactic open cluster M 67, down to the bottom of the WD cooling sequence (CS). The color-magnitude diagram is based on data collected…

The shape of the luminosity function of white dwarfs (WDLF) is sensitive to the characteristic cooling time and, therefore, it can be used to test the existence of additional sources or sinks of energy such as those predicted by alternative…

Solar and Stellar Astrophysics · Physics 2020-10-14 Jordi Isern

We present Spitzer 5-15 micron spectroscopy of one cool white dwarf and 3.6-8 micron photometry of 51 cool white dwarfs with T_eff < 6000 K. The majority of our targets have accurate BVRIJHK photometry and trigonometric parallax…

Solar and Stellar Astrophysics · Physics 2011-02-11 Mukremin Kilic , Piotr M. Kowalski , William T. Reach , Ted von Hippel

(Abridged Abstract) A favored interpretation of recent microlensing measurements towards the Large Magellanic Cloud implies that a large fraction (i.e. 10--50%) of the mass of the galactic halo is composed of white dwarfs. We compare model…

Astrophysics · Physics 2009-10-30 David S. Graff , Gregory Laughlin , Katherine Freese

The ACS Survey of Galactic Globular Clusters, an HST Treasury Project, will deliver high quality, homogeneous photometry of 65 globular clusters. This paper introduces a new collection of stellar evolution tracks and isochrones suitable for…

Astrophysics · Physics 2010-11-05 A. Dotter , B. Chaboyer , D. Jevremovic , E. Baron , J. W. Ferguson , A. Sarajedini , J. Anderson

We present an alternative interpretation of the nature of the extremely cool, high-velocity white dwarfs identified by Oppenheimer et al (2001) in a high-latitude astrometric survey. We argue that the velocity distribution of the majority…

Astrophysics · Physics 2009-11-06 I. Neill Reid , Kailash C. Sahu , Suzanne L. Hawley

A new method is presented to compute age estimates from theoretical isochrones using temperature, luminosity and metallicity data for individual stars. Based on Bayesian probability theory, this method avoids the systematic biases affecting…

Astrophysics · Physics 2009-11-10 Frederic Pont , Laurent Eyer

We present the results of a deep Hubble Space Telescope (HST) exposure of the nearby globular cluster NGC6397, focussing attention on the cluster's white dwarf cooling sequence. This sequence is shown to extend over 5 magnitudes in depth,…

Brown dwarfs can serve as both clocks and chemical tracers of the evolutionary history of the Milky Way due to their continuous cooling and high sensitivity of spectra to composition. We focus on brown dwarfs in globular clusters that host…

Solar and Stellar Astrophysics · Physics 2022-05-11 Roman Gerasimov , Adam J. Burgasser , Derek Homeier , Luigi R. Bedin , Jon M. Rees , Michele Scalco , Jay Anderson , Maurizio Salaris

We summarize recent improvements in model atmosphere and internal structure of faint white dwarfs. We derive an analytical cooling theory which illustrates the effects of various physical processes on the energy budget and the cooling…

Astrophysics · Physics 2007-05-23 Gilles Chabrier

We present new evolutionary stellar models suitable for old Population I clusters, discussing both the consequences of the most recent improvements in the input physics and the effect of element diffusion within the stellar structures.…

Astrophysics · Physics 2009-10-31 V. Castellani , S. Degl'Innocenti , M. Marconi

A detailed analysis of halo white dwarf candidates is presented, which is based on model atmosphere fits to observed energy distributions built from photoelectric or photographic magnitudes. Most of the candidates identified in reduced…

Astrophysics · Physics 2009-11-07 P. Bergeron