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The Physics of Crystallization from Globular Cluster White Dwarf Stars in NGC 6397
(2009-03)
We explore the physics of crystallization in the deep interiors of white dwarf (WD) stars using the color-magnitude diagram and luminosity function constructed from proper- motion cleaned Hubble Space Telescope photometry ...
A Common, Non-Optimal Phenotypic Endpoint in Experimental Adaptations of Bacteriophage Lysis Time
(2012-03)
Optimality models of evolution, which ignore genetic details and focus on natural selection, are widely used but sometimes criticized as oversimplifications. Their utility for quantitatively predicting phenotypic evolution ...
The Massive Progenitor of the Type II-Linear Supernova 2009kr
(2010-05)
We present early-time photometric and spectroscopic observations of supernova (SN) 2009kr in NGC 1832. We find that its properties to date support its classification as Type II-linear (SN II-L), a relatively rare subclass ...
Independent Inactivation of Arginine Decarboxylase Genes by Nonsense and Missense Mutations Led to Pseudogene Formation in Chlamydia Trachomatis Serovar L2 and D Strains
(2009-07)
Chlamydia have reduced genomes that reflect their obligately parasitic lifestyle. Despite their different tissue tropisms, chlamydial strains share a large number of common genes and have few recognized pseudogenes, ...
Discovery of a Dynamical Cold Point in the Heart of the Sagittarius dSph Galaxy With Observations from the APOGEE Project
(2013-11)
The dynamics of the core of the Sagittarius (Sgr) dwarf spheroidal (dSph) galaxy are explored using high-resolution (R similar to 22,500), H-band, near-infrared spectra of over 1000 giant stars in the central 3 deg(2) of ...
Dark Stars: Improved Models And First Pulsation Results
(2015-02)
We use the stellar evolution code MESA to study dark stars (DSs). DSs, which are powered by dark matter (DM) self-annihilation rather than by nuclear fusion, may be the first stars to form in the universe. We compute stellar ...
KOI-54: The Kepler Discovery of Tidally Excited Pulsations and Brightenings in a Highly Eccentric Binary
(2011-11)
Kepler observations of the star HD 187091 (KIC 8112039, hereafter KOI-54) revealed a remarkable light curve exhibiting sharp periodic brightening events every 41.8 days with a superimposed set of oscillations forming a ...
Two Planets Orbiting The Recently Formed Post-Common Envelope Binary NN Serpentis
(2010-10)
Planets orbiting post-common envelope binaries provide fundamental information on planet formation and evolution. We searched for such planets in NN Ser ab, an eclipsing short-period binary that shows long-term eclipse ...
Rb-Rich Asymptotic Giant Branch Stars in the Magellanic Clouds
(2009-11)
We present high-resolution (R similar to 60,000) optical spectra of a carefully selected sample of heavily obscured and presumably massive O-rich asymptotic giant branch (AGB) stars in the Magellanic Clouds. We report the ...
Opinion dynamics of random-walking agents on a lattice
(2011-05)
The opinion dynamics of random-walking agents on finite two-dimensional lattices is studied. In the model, the opinion is continuous, and both the lattice and the opinion can be either periodic or nonperiodic. At each time ...