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The Ages of Stars: The Horizontal Branch
M. Catelan
Horizontal branch (HB) stars play a particularly important role in the "age debate," since they are at the very center of the long-standing "second parameter" problem. In this revi…
The Globular Cluster NGC 5286. I. A New CCD BV Color-Magnitude Diagram
M. Zorotovic, M. Catelan, M. Zoccali +5
We present BV photometry of the Galactic globular cluster NGC 5286, based on 128 V frames and 133 B frames, and covering the entire face of the cluster. Our photometry reaches almo…
Stellar Evolution and Variability in the Pre-ZAHB Phase
V. Silva Aguirre, M. Catelan, A. Weiss +1
One of the most dramatic events in the life of a low-mass star is the He flash, which takes place at the tip of the RGB and is followed by a series of secondary flashes before the…
The Period-Luminosity Relation of RR Lyrae Stars in the SDSS Photometric System
C. Cáceres, M. Catelan
We provide the first detailed study of the RR Lyrae period-luminosity (PL) relation in the ugriz bandpasses of the Sloan Digital Sky Survey (SDSS) filter system. We argue that tigh…
A Semi-Empirical Study of the Mass Distribution of Horizontal Branch Stars in M3 (NGC 5272)
A. A. R. Valcarce, M. Catelan
Horizontal branch (HB) stars in globular clusters offer us a probe of the mass loss mechanisms taking place in red giants. For M3 (NGC 5272), different shapes for the HB mass distr…
The RR Lyrae Period-Luminosity-(Pseudo-)Color and Period-Color-(Pseudo-)Color Relations in the Strömgren Photometric System: Theoretical Calibration
C. Cortés, M. Catelan
We present a theoretical calibration of the RR Lyrae period-luminosity-color and period-color-color relations in the multiband uvby Stroemgren photometric system. Our theoretical w…
The Globular Cluster M15. I. Identification, Discovery, and Period Determination of Variable Stars
T. M. Corwin, J. Borissova, P. B. Stetson +4
We present new CCD photometry for variables in the globular cluster M15. Our photometry was obtained using both the image subtraction package ISIS and DAOPHOT/ALLFRAME. The d…
On the newly discovered Canes Venatici II dSph galaxy
C. Greco, M. Dall'Ora, G. Clementini +11
We report on the detection of variable stars in the Canes Venatici II (CVn II) dwarf spheroidal galaxy, a new satellite of the Milky Way recently discovered by the Sloan Digital Sk…
Multimodal Horizontal Branches: Empirical Evidence and Possible Evolutionary Scenarios
M. Catelan
We review the available empirical evidence for the presence of "gaps" and multimodal distributions among horizontal branch (HB) stars, along with some of the theoretical scenarios…
Meet the COG's
Martin Altmann, Marcio Catelan, Manuela Zoccali
Kinematics combined with detailed element abundances provide the method of analysis of stellar populations using as much available information as possible, in contrast to other met…
Binaries among Extreme Horizontal Branch Stars in Globular Clusters
C. Moni Bidin, M. Catelan, S. Villanova +4
Following a review of our present knowledge about blue subdwarf stars in globular clusters, we present an overview of the results of searches for close binaries among these stars,…
A Search for EHB Pulsators in the Globular Cluster NGC 6752
M. Catelan, G. E. Prieto, M. Zoccali +8
We describe the status of a project whose main goal is to detect variability along the extreme horizontal branch of the globular cluster NGC 6752. Based on Magellan 6.5m data, prel…
Variable Stars in the Newly Discovered Milky Way Dwarf Spheroidal Satellite Canes Venatici I
Charles Kuehn, Karen Kinemuchi, Vincenzo Ripepi +11
We have identified 23 RR Lyrae stars and 3 possible Anomalous Cepheids among 84 candidate variables in the recently discovered Canes Venatici I dwarf spheroidal galaxy. The mean pe…
Horizontal Branch Stars and the Ultraviolet Universe
M. Catelan
Extremely hot horizontal branch (HB) stars and their progeny are widely considered to be responsible for the "ultraviolet upturn" (or UVX) phenomenon observed in elliptical galaxie…
The Peculiar Horizontal Branch Morphology of the Galactic Globular Clusters NGC 6388 and NGC 6441: new insights from UV observations
G. Busso, S. Cassisi, G. Piotto +9
In this paper we present multiband optical and UV Hubble Space Telescope photometry of the two Galactic globular clusters NGC 6388 and NGC 6441. We have obtained the first UV color…
Variable stars in the Fornax dSph Galaxy. I. The Globular Cluster Fornax 4
C. Greco, G. Clementini, M. Catelan +8
Variable stars have been identified for the first time in Fornax 4, the globular cluster located near the center of the Fornax dwarf spheroidal galaxy. By applying the image subtra…
Structure and Evolution of Low-Mass Stars: An Overview and Some Open Problems
M. Catelan
A review is presented of some of the ingredients, assumptions and techniques that are used in the computation of the structure and evolution of low-mass stars. Emphasis is placed o…
Updated Electron-Conduction Opacities: The Impact on Low-Mass Stellar Models
S. Cassisi, A. Y. Potekhin, A. Pietrinferni +2
We review the theory of electron-conduction opacity, a fundamental ingredient in the computation of low-mass stellar models; shortcomings and limitations of the existing calculatio…
Image-Subtraction Photometry of Variable Stars in the Globular Clusters NGC 6388 and NGC 6441
T. M. Corwin, A. N. Sumerel, B. J. Pritzl +4
We have applied Alard's image subtraction method (ISIS v2.1) to the observations of the globular clusters NGC 6388 and NGC 6441 previously analyzed using standard photometric techn…
Near-Field Cosmology with Horizontal Branch and RR Lyrae Stars
M. Catelan
The importance of horizontal branch and RR Lyrae stars is discussed in the context of cosmological arguments for the formation of the Galactic halo and its satellite dwarf galaxies…
New Metallicities of RR Lyrae Stars in omega Centauri: Evidence for a Non He-Enhanced Metal-Intermediate Population
A. Sollima, J. Borissova, M. Catelan +4
We present new spectroscopic metal abundances for 74 RR Lyrae stars in omega Cen obtained with FLAMES. The well-known metallicity spread is visible among the RR Lyrae variables. Th…
WLM-1: A Non-Rotating, Gravitationally Unperturbed, Highly Elliptical Extragalactic Globular Cluster
Andrew W. Stephens, Marcio Catelan, Roxana P. Contreras
Globular clusters have long been known for presenting (at times) significant deviations from spherical symmetry. While rotation has been the main proposed explanation, other compli…
Completing the Census of (Bright) Variable Stars in Galactic Globular Clusters
M. Catelan, H. A. Smith, B. J. Pritzl +15
We present a long-term project aimed at completing the census of (bright) variable stars in Galactic globular clusters. While our main aim is to obtain a reliable assessment of the…
Homogeneous Photometry V: The Globular Cluster NGC 4147
P. B. Stetson, M. Catelan, H. A. Smith
New BVRI broad-band photometry and astrometry are presented for the globular cluster NGC 4147, based upon measurements derived from 524 ground-based CCD images mostly either donate…