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Neutrino and axion bounds from the globular cluster M5 (NGC 5904)
Nicolás Viaux, Márcio Catelan, Peter B. Stetson +4
The red-giant branch (RGB) in globular clusters is extended to larger brightness if the degenerate helium core loses too much energy in "dark channels." Based on a large set of arc…
Stellar Variability in the VVV survey
M. Catelan, D. Minniti, P. W. Lucas +34
The Vista Variables in the Vía Láctea (VVV) ESO Public Survey is an ongoing time-series, near-infrared (IR) survey of the Galactic bulge and an adjacent portion of the inner disk,…
Helium enhanced stars and multiple populations along the horizontal branch of NGC2808: direct spectroscopic measurements
A. F. Marino, A. P. Milone, N. Przybilla +15
We present an abundance analysis of 96 horizontal branch (HB) stars in NGC2808, a globular cluster exhibiting a complex multiple stellar population pattern. These stars are distrib…
RR Lyrae in the LMC: Insights Into the Oosterhoff Phenomenon
Charles A Kuehn, Horace A. Smith, Marcio Catelan +8
Although more than eight decades have passed since P. Th. Oosterhoff drew attention to differences in the properties of RR Lyrae variables in globular clusters, the origin and sign…
Symbiotic Stars in OGLE Data I. Large Magellanic Cloud Systems
R. Angeloni, C. E. Ferreira Lopes, N. Masetti +10
Symbiotic stars are long-orbital-period interacting-binaries characterized by extended emission over the whole electromagnetic range and by complex photometric and spectroscopic va…
VVV Survey Near-Infrared Photometry of Known Bulge RR Lyrae stars: the Distance to the Galactic Center and Absence of a Barred Distribution of the Metal-Poor Population
I. Dékány, D. Minniti, M. Catelan +4
We have combined optical and near-infrared data of known RR Lyrae (RRL) stars in the bulge in order to study the spatial distribution of its metal-poor component by measuring preci…
Discovery of New Companions to High Proper Motion Stars from the VVV Survey
Valentin D. Ivanov, Dante Minniti, Maren Hempel +14
[abridged] The severe crowding in the direction of the inner Milky Way suggests that the census of stars within a few tens of parsecs in that direction may not be complete. We sear…
Particle-physics constraints from the globular cluster M5: Neutrino Dipole Moments
Nicolás Viaux, Márcio Catelan, Peter B. Stetson +4
Stellar evolution is modified if energy is lost in a "dark channel" similar to neutrino emission. Comparing modified stellar evolution sequences with observations provides some of…
NGC 5694: another foster son of the Galactic Halo
A. Mucciarelli, M. Bellazzini, M. Catelan +5
We present the results of the analysis of high-resolution spectra obtained with UVES-FLAMES@VLT for six red giant branch stars in the outer-halo metal-poor ([Fe/H]I=-1.98 and [Fe/H…
Time-Series BVI Photometry for the Globular Cluster NGC 6981 (M72)
P. Amigo, P. B. Stetson, M. Catelan +2
We present new BVI photometry of the globular cluster NGC 6981 (M72), based mostly on ground-based CCD archive images. We present a new color-magnitude diagram (CMD) that reaches a…
The RR Lyrae variables and Horizontal Branch of NGC6656 (M22)
Andrea Kunder, Peter B. Stetson, Santi Cassisi +10
The first calibrated broadband UBVI time-series photometry is presented for the RR Lyrae variable stars in NGC6656 (M22), with observations spanning a range of twenty-two years. We…
Variable Stars in Large Magellanic Cloud Globular Clusters III: Reticulum
Charles A. Kuehn, Kyra Dame, Horace A. Smith +8
This is the third in a series of papers studying the variable stars in old globular clusters in the Large Magellanic Cloud. The primary goal of this series is to look at how the ch…
Spectroscopy of blue horizontal branch stars in NGC 6656 (M22)
C. Salgado, C. Moni Bidin, S. Villanova +2
Recent investigations revealed very peculiar properties of blue horizontal branch (HB) stars in ωCentauri, which show anomalously low surface gravity and mass compared to other clu…
The Globular Cluster NGC 6402 (M14). I. A New BV Color-Magnitude Diagram
C. Contreras Peña, M. Catelan, F. Grundahl +2
We present BV photometry of the Galactic globular cluster NGC 6402 (M14), based on 65 V frames and 67 B frames, reaching two magnitudes below the turn-off level. This represents, t…
Searching for variable stars in the VVV globular clusters
Javier Alonso-García, István Dékány, Márcio Catelan +2
The VVV is currently surveying the central regions of the Milky Way at near-infrared wavelengths, including 36 known Galactic globular clusters. We already have data in several fil…
The soundtrack of RR Lyrae in Omega Cen at high-frequency
A. Calamida, S. K. Randall, M. Monelli +8
We present preliminary Sloan u',g'-band light curves for a sample of known RR Lyrae variables in the Galactic globular cluster Omega Cen. Results are based on the partial reduction…
Fundamental properties of nearby stars and the consequences on DeltaY/DeltaZ
Aldo A. R. Valcarce, Márcio Catelan, José R. De Medeiros
One of the greatest difficulties in astrophysics is the determination of the fundamental stellar parameters (FSPs), one of which is the initial mass fraction of helium (Y). However…
Evidence for a Milky Way Tidal Stream Reaching Beyond 100 kpc
A. J. Drake, M. Catelan, S. G. Djorgovski +9
We present the analysis of 1,207 RR Lyrae found in photometry taken by the Catalina Survey's Mount Lemmon telescope. By combining accurate distances for these stars with measuremen…
Physical Parameters for RR Lyrae Stars in the SDSS Filter System
M. Catelan, G. I. Torrealba, C. Caceres +3
We present a calibration of the metallicity and physical parameters (temperature, luminosity, gravity, mass, radius) for RR Lyrae stars using the ugriz SDSS photometric system. Our…
Does the Oosterhoff Dichotomy Exist in The Andromeda Galaxy? I. The case of G11
Rodrigo Contreras Ramos, Gisella Clementini, Luciana Federici +8
We present the first evidence that Oosterhoff type II globular clusters exist in the Andromeda galaxy (M31). On the basis of time-series photometry of the moderately metal-poor ([F…
NGC5694: another extra-galactic globular cluster
A. Mucciarelli, M. Bellazzini, M. Catelan +5
We discuss the chemical composition of six giant stars of the outer Halo globular cluster NGC5694, through the analysis of UVES@FLAMES high-resolution spectra. The cluster has an a…
Multiple populations in Galactic globular clusters: a survey in the Strömgren system
J. Alonso-García, M. Catelan, P. Amigo +10
We are coming to believe that stellar populations in globular clusters are not as simple as they were once thought to be. A growing amount of photometric and spectroscopic evidence…
Theoretical Modeling of the RR Lyrae Variables in NGC 1851
Andrea Kunder, Maurizio Salaris, Santi Cassisi +5
The RR Lyrae instability strip (IS) in NGC 1851 is investigated, and a model is presented which reproduces the pulsational properties of the RR Lyrae population. In our model, a st…