Search Publications
The Solar Neighborhood. XXI. Parallax Results from the CTIOPI 0.9 m Program: 20 New Members of the 25 Parsec White Dwarf Sample
Henry, Todd J.; Bergeron, P.; Dufour, P. +5 more
We present accurate trigonometric parallaxes for 20 new members of the 25 pc white dwarf (WD) sample as part of the Discovery and Evalution of Nearby Stellar Embers (DENSE) project.7 http://www.DenseProject.com Previously, there were a total of 112 WD systems with trigonometric parallaxes placin…
Tracers of Chromospheric Structure. I. Observations of Ca II K and Hα in M Dwarfs
Hawley, Suzanne L.; Walkowicz, Lucianne M.
We report on our observing program4This paper is based on observations obtained with the Apache Point Observatory 3.5 m telescope, which is owned and operated by the Astrophysical Research Consortium. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the Ca…
Population Parameters of Intermediate-Age Star Clusters in the Large Magellanic Cloud. I. NGC 1846 and its Wide Main-Sequence Turnoff
Chandar, Rupali; Goudfrooij, Paul; Puzia, Thomas H. +1 more
The Advanced Camera for Surveys onboard the Hubble Space Telescope has been used to obtain deep, high-resolution images of the intermediate-age star cluster NGC 1846 in the Large Magellanic Cloud. We present new color-magnitude diagrams (CMDs) based on F435W, F555W, and F814W imaging. We test the previously observed broad main-sequence turnoff (MS…
Early Optical Observations of Gamma-Ray Bursts by the TAROT Telescopes: Period 2001-2008
Klotz, A.; Gendre, B.; Atteia, J. L. +1 more
The Télescopes à Action Rapide pour les Objets Transitoires telescopes are two robotic observatories designed to observe the prompt optical emission counterpart and the early afterglow of gamma-ray bursts (GRBs). We present data acquired between 2001 and 2008 and discuss the properties of the optical emission of GRBs, noting various interesting re…
Testing Fundamental Physics with Distant Star Clusters: Analysis of Observational Data on Palomar 14
Djorgovski, S. G.; Côté, P.; Grebel, E. K. +6 more
We use the distant outer halo globular cluster Palomar 14 as a test case for classical versus modified Newtonian dynamics (MOND). Previous theoretical calculations have shown that the line-of-sight velocity dispersion predicted by these theories can differ by up to a factor of 3 for such sparse, remote clusters like Pal 14. We determine the line-o…
Nearby Young Stars Selected by Proper Motion. I. Four New Members of the β Pictoris Moving Group From The Tycho-2 Catalog
Lépine, Sébastien; Simon, Michal
We describe a procedure to identify stars from nearby moving groups and associations out of catalogs of stars with large proper motions. We show that from the mean motion vector of a known or suspected moving group, one can identify additional members of the group based on proper motion data and photometry in the optical and infrared, with minimal…
An Intensive Hubble Space Telescope Survey for z>1 Type Ia Supernovae by Targeting Galaxy Clusters
Gladders, M. D.; Panagia, N.; Stern, D. +58 more
We present a new survey strategy to discover and study high-redshift Type Ia supernovae (SNe Ia) using the Hubble Space Telescope (HST). By targeting massive galaxy clusters at 0.9 < z < 1.5, we obtain a twofold improvement in the efficiency of finding SNe compared to an HST field survey and a factor of 3 improvement in the total yield of SN…
Eight-Dimensional Mid-Infrared/Optical Bayesian Quasar Selection
Brandt, W. N.; Myers, Adam D.; Schneider, Donald P. +11 more
We explore the multidimensional, multiwavelength selection of quasars from mid-infrared (MIR) plus optical data, specifically from Spitzer-Infrared Array Camera (IRAC) and the Sloan Digital Sky Survey (SDSS). Traditionally, quasar selection relies on cuts in two-dimensional color space despite the fact that most modern surveys (optical and IR) are…
The ACS Nearby Galaxy Survey Treasury. I. The Star Formation History of the M81 Outer Disk
de Jong, Roelof S.; Williams, Benjamin F.; Dolphin, Andrew +16 more
The Advanced Camera for Surveys (ACS) Nearby Galaxy Survey Treasury is a large Hubble Space Telescope (HST)/ACS treasury program to obtain resolved stellar photometry for a volume-limited sample of galaxies out to 4 Mpc. As part of this program, we have obtained deep ACS imaging of a field in the outer disk of the large spiral galaxy M81. The fiel…
Star Formation History in the Small Magellanic Cloud: The Case of NGC 602
Degl'Innocenti, S.; Cignoni, M.; Tosi, M. +9 more
Deep Hubble Space Telescope/Advanced Camera for Surveys photometry of the young cluster NGC 602, located in the remote low-density "wing" of the Small Magellanic Cloud (SMC), reveals numerous pre-main-sequence (PMS) stars as well as young stars on the main sequence. The resolved stellar content thus provides a basis for studying the star formation…