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Using up-to-date stellar models and isochrones we determine the age of 25 galactic halo clusters. The clusters are distributed into four groups according to metallicity. We measure the absolute age of a reference cluster in each group, and…

Astrophysics · Physics 2007-05-23 Maurizio Salaris , Achim Weiss

We have exploited the very precise parallaxes, proper motions and photometry of \textit{Gaia}\, Data Release~2 to study white dwarf members of the Hyades star cluster. Gaia photometry and parallaxes for the eight DA white dwarfs confirmed…

Solar and Stellar Astrophysics · Physics 2018-09-26 M. Salaris , L. R. Bedin , .

I propose and apply a method for deriving ages of the metal-poor globular clusters (GCs) in a distance-independent way, which is based on age indicator related to the main sequence in the two-color diagrams with U-B index. Age of the…

Astrophysics · Physics 2007-05-23 Valery V. Kravtsov

Cooling ages of white dwarfs are routinely determined by mapping effective temperatures and masses to ages using evolutionary models. Typically, the reported uncertainties on cooling ages only consider the error propagation of the…

Solar and Stellar Astrophysics · Physics 2025-03-12 Praneet Pathak , Simon Blouin , Falk Herwig

An analysis of ages, metallicities, and [alpha/Fe] ratios of globular cluster systems in early-type galaxies is presented, based on Lick index measurements summarized in Puzia et al. (2004, Paper I of this series). In the light of…

Relative ages for the globular cluster (GC) subpopulations in the Virgo giant elliptical galaxy M87 (NGC 4486) have been determined from Stroemgren photometry obtained with WFPC2 on board HST. Using a variety of population synthesis models,…

Astrophysics · Physics 2009-11-07 Andres Jordan , Patrick Cote , Michael J. West , R. O. Marzke

While the number of detected planets is continuously increasing since 1995, their impact on their central star still remain poorly understood. Yet, the presence of a massive close-in planet can strongly modify the surface angular velocity…

Earth and Planetary Astrophysics · Physics 2018-10-30 Florian Gallet , Philippe Delorme

We use 10 orbits of Advanced Camera for Surveys observations to reach the end of the white dwarf cooling sequence in the solar-metallicity open cluster NGC 2158. Our photometry and completeness tests show that the end falls at magnitude…

Astrophysics of Galaxies · Physics 2015-05-14 L. R. Bedin , M. Salaris , I. R. King , G. Piotto , J. Anderson , S. Cassisi

We present spectroscopic observations of a massive globular cluster in the dwarf irregular galaxy Sextans B, discovered by us on Hubble Space Telescope Wide Field and Planetary Camera 2 (HST WFPC2) images. Long-slit spectra were obtained…

Astrophysics · Physics 2009-11-13 M. E. Sharina , Th. H. Puzia , A. S. Krylatyh

In previous papers of the series we used a combination of optical and near-infrared colours to derive constraints on the relative age structure in globular cluster systems. Here, we present the details, strength and limitations of our…

Astrophysics · Physics 2009-11-10 Maren Hempel , Markus Kissler-Patig

We describe a new multi-colour proper motion survey for cool white dwarfs (CWDs). The observational database consists of ~300 digitally scanned Schmidt plates in ESO/SERC field 287. The entire survey procedure, from the raw Schmidt plate…

Astrophysics · Physics 2009-10-31 R. A. Knox , M. R. S. Hawkins , N. C Hambly

We have used new parallax measurements, obtained by the Hipparcos satellite, of fifteen nearby, metal-poor stars to re-define the subdwarf main-sequence. All of these stars have parallaxes determined to an accuracy of at least 12 %.…

Astrophysics · Physics 2009-10-30 I. Neill Reid

We present a photometric analysis of globular clusters (GCs) in the massive galaxy cluster MACS J0416.1-2403 (z = 0.397) using deep JWST/NIRCam imaging from the PEARLS program. PSF photometry was performed in the short wavelength filters…

In this third paper of a series on the precision of obtaining ages of stellar populations using the full spectrum fitting technique, we examine the precision of this technique in deriving possible age spreads within a star cluster. We test…

Astrophysics of Galaxies · Physics 2021-05-12 Randa Asa'd , Paul Goudfrooij , A. M. As'ad , H. G. El-Mir , L. Begum , A. Aljasmi , O. Almatroushi

The termination in the white dwarf luminosity function is a standard diagnostic tool for measuring the total age of nearby stellar populations. In this paper, an algorithm is presented for inverting the full white dwarf luminosity function…

Astrophysics of Galaxies · Physics 2015-06-16 Nicholas Rowell

The age difference between the two main globular cluster sub-populations in the Virgo giant elliptical galaxy, NGC 4472 (M 49), has been determined using HST WFPC2 images in the F555W and F814W filters. Accurate photometry has been obtained…

Astrophysics · Physics 2009-10-31 Thomas H. Puzia , Markus Kissler-Patig , Jean P. Brodie , John P. Huchra

Recent work on globular cluster systems in dwarf galaxies outside the Local Group is reviewed. Recent large imaging surveys with the Hubble Space Telescope and follow-up spectroscopy with 8-m class telescopes now allow us to compare the…

Astrophysics · Physics 2007-05-23 Bryan W. Miller

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 are essential probes of stellar and planetary formation, yet their low luminosities pose challenges for detection at large Galactic distances. The James Webb Space Telescope (JWST), with its unprecedented near-infrared…

Solar and Stellar Astrophysics · Physics 2025-10-03 Zhijun Tu , Shu Wang , Xiaodian Chen , Jifeng Liu

Using multi-wavelength imaging from the Wide Field Camera 3 on the Hubble Space Telescope we study the stellar cluster populations of two adjacent fields in the nearby face-on spiral galaxy, M83. The observations cover the galactic centre…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 N. Bastian , A. Adamo , M. Gieles , H. J. G. L. M. Lamers , S. S. Larsen , E. Silva-Villa , L. J. Smith , R. Kotulla , I. S. Konstantopoulos , G. Trancho , E. Zackrisson
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