No Excess of RR Lyrae Stars in the Canis Major Overdensity (2009)
Mateu, Cecilia, Vivas, A. Katherina, Zinn, Robert, Miller, Lissa, Abad, Carlos
Our multi-epoch survey of ~20 sq. deg. of the Canis Major overdensity has detected only 10 RR Lyrae stars (RRLS). We show that this number is consistent with the number expected from the Galactic...
Spectroscopy of Bright QUEST RR Lyrae Stars: Velocity Substructures toward Virgo (2008)
Vivas, A. Katherina, Jaffe, Yara, Zinn, Robert, Winnick, Rebeccah, Duffau, Sonia, Mateu, Cecilia
Using a sample of 43 bright (V
Hubble Spac e Telesc ope (2007)
J. N. Heasley, K. A. Janes, Robert Zinn, Carol A. Christian
We have observed the metal-rich globular clusters NGC 6624 and NGC 6637 (M69) using theplanetary camera of the WFPC2 on the Hubble Spac e Telesc ope (HST). Observations of the Ca II triplet lines in...
The Chemical Enrichment History of the Large Magellanic Cloud (2007)
Carrera, Ricardo, Gallart, Carme, Hardy, Eduardo, Aparicio, Antonio, Zinn, Robert
Ca II triplet spectroscopy has been used to derive stellar metallicities for individual stars in four LMC fields situated at galactocentric distances of 3\arcdeg, 5\arcdeg, 6\arcdeg\@ and 8\arcdeg\@...
The Infrared Ca II triplet as metallicity indicator (2007)
Carrera, Ricardo, Gallart, Carme, Pancino, Elena, Zinn, Robert
From observations of almost 500 RGB stars in 29 Galactic open and globular clusters, we have investigated the behaviour of the infrared Ca II triplet (8498, 8542 and 8662 \AA) in the age range...
Whiting 1: the youngest globular cluster associated with the Sgr dSph (2007)
Carraro, Giovanni, Zinn, Robert, Bidin, Christian Moni
Recently, Carraro (2005) drew attention to the remarkable star cluster Whiting 1 by showing that it lies about 40 kpc from the Sun and is therefore unquestionably a member of the Galactic halo...
Searching for RR Lyrae stars in the Canis Major Overdensity (2007)
Mateu, Cecilia, Vivas, A. Katherina, Zinn, Robert, Miller, Lissa
The Canis Major overdensity (CMa) was initially proposed to be the remnant of a tidally disrupting dSph galaxy. Since its nature is still subject of debate, the goal of the present work was to...
R. A. Méndez, C. Gallart, S. V. Duffau, G. Carraro, Robert Zinn, A. K. Vivas, ...
Confirmation of halo substructure using quest rr lyrae data: the new virgo stellar stream (VSS)
Sub-structures in the halo of the milky way (2006)
Jesús Hernández, A. Katherina Vivas, Yolimar Subero, Robert Zinn
Sub-structures in the halo of the milky way
Pont, Frederic, Zinn, Robert, Gallart, Carme, Hardy, Eduardo, Winnick, Rebeccah
Near infrared spectra were obtained for 117 red giants in the Fornax dwarf spheroidal galaxy with the FORS1 spectrograph on the VLT, in order to study the metallicity distribution of the stars and to...
Spectroscopy of quest RR Lyrae variables: The new virgo stellar stream (2006)
Duffau, Sonia, Zinn, Robert, Vivas, A. Katherina, Carraro, Giovanni, Méndez, René A., Winnick, Rebeccah, ...
Eighteen RR Lyrae variables (RRLs) that lie in the "12(h).4 clump" identified by the Quasar Equatorial Survey Team ( QUEST) have been observed spectroscopically to measure their radial velocities and...
The QUEST RR Lyrae Survey II: The Halo Overdensities in the First Catalog (2006)
Vivas, A. Katherina, Zinn, Robert
The first catalog of the RR Lyrae stars (RRLS) in the Galactic halo by the QUEST Survey has been searched for significant overdensities that may be debris from disrupted dwarf galaxies or globular...
Sub-structures in the halo of the milky way (2006)
Hernández, Jesús, Katherina Vivas, A., Subero, Yolimar, Zinn, Robert
Se describen los últimos resultados de la búsqueda QUEST de estrellas RR Lyrae. Esta búsqueda, la cual fue diseñada para encontrar y caracterizar sub-estructuras en el halo de nuestra Galaxia, ha...
Carraro, G., Duffau, S. V., Gallart, C., Méndez, R. A., Vivas, A. K., Winnick, R., ...
Se han obtenido observaciones espectroscópicas de dieciocho estrellas RR Lyrae (RRLs) que pertenecen al cúmulo de 12.4 hr", una prominente sobredensidad de halo en la exploración QUEST de RRLs....
Spectroscopy of QUEST RR Lyrae Variables: the new Virgo Stellar Stream (2005)
Duffau, Sonia, Zinn, Robert, Vivas, A. Katherina, Carraro, Giovanni, Mendez, Rene A., Winnick, Rebeccah, ...
Eighteen RR Lyrae variables (RRLs) that lie in the "$12\fh 4$ clump" identified by the QUEST survey have been observed spectroscopically to measure their radial velocities and metal abundances. Ten...
RR Lyrae search and stellar populations study in Canis Major: Preliminary Results (2005)
Mateu, Cecilia E., Vivas, A. Katherina, Zinn, Robert, Miller, Lissa
We present preliminary results of a RR Lyrae star search and stellar populations study performed in the Canis Major overdensity, spanning an area of 8.35sq deg. The observations were made in R and V...
VLT Spectroscopy of RR Lyrae Stars in the Sagittarius Tidal Stream (2004)
Vivas, A. Katherina, Zinn, Robert, Gallart, Carme
Sixteen RR Lyrae variables from the QUEST survey that lie in the leading arm of the tidal stream from the Sagittarius dSph galaxy have been observed spectroscopically to measure their radial...
Mapping Tidal Streams around Galactic Globular Clusters (2004)
Martinez-Delgado, David, Dinescu, Dana I., Zinn, Robert, Tuntsoff, Artyom, Cote, Patrick, Boyarchuck, Anastassia
The surroundings of globular clusters in the outer halo are one of the best places to look for the remnants of ancient dwarf satellites. The classical Searle & Zinn (1978) scenario of the formation...
Pont, Frederic, Zinn, Robert, Gallart, Carme, Hardy, Eduardo, Winnick, Rebeccah
Near infrared spectra were obtained for 117 red giants in the Fornax dwarf spheroidal galaxy with the FORS1 spectrograph on the VLT, in order to study the metallicity distribution of the stars and to...
The Selection of RR Lyrae Stars Using Single-epoch Data (2003)
Ivezic, Zeljko, Vivas, A. Katherina, Lupton, Robert H., Zinn, Robert
We utilize a complete sample of RR Lyrae stars discovered by the QUEST survey using light curves to design selection criteria based on SDSS colors. Thanks to the sensitivity of the u-g color to...
Halo Substructure in the QUEST RR Lyrae Survey (2003)
Zinn, Robert, Vivas, A. Katherina, Gallart, Carme, Winnick, Rebeccah
A survey of 380 sq. deg. of the sky with the 1m Schmidt telescope at the Observatorio Nacional de Llano del Halo and the QUEST camera has found 498 RR Lyrae variables lying from 4 to 60 kpc from the...
Velocities of RR Lyrae Stars in the Sagittarius Tidal Stream (2003)
Vivas, A. Katherina, Zinn, Robert, Gallart, Carme
We have measured radial velocities and metallicities of 16 RR Lyrae stars, from the QUEST survey, in the Sagittarius tidal stream at 50 kpc from the galactic center. The distribution of velocities is...
Pont, Frederic, Zinn, Robert, Gallart, Carme, Hardy, Eduardo, Winnick, Rebeccah
Near infrared spectra were obtained for 117 red giants in the Fornax dwarf spheroidal galaxy with the FORS1 spectrograph on the VLT, in order to study the metallicity distribution of the stars and to...
Pont, Frederic, Zinn, Robert, Gallart, Carme, Hardy, Eduardo, Winnick, Rebeccah
Near infrared spectra were obtained for 117 red giants in the Fornax dwarf spheroidal galaxy with the FORS1 spectrograph on the VLT, in order to study the metallicity distribution of the stars and to...
RR Lyrae Stars in the Halo: Tracers of Streams of Debris of Disrupted Galaxies (2002)
Vivas, A. Katherina, Zinn, Robert
We discuss the first part of a survey for RR Lyrae variables in the galactic halo that is being made with the 1m Schmidt telescope at the Venezuelan National Observatory. So far the survey has...
Demarque, Pierre, Zinn, Robert, Lee, Young-Wook, Yi, Sukyoung
A grid of synthetic horizontal-branch (SHB) models based on HB evolutionary tracks with improved physics has been constructed to reconsider the theoretical calibration of the dependence of M_v(RR) on...