Search Publications
Galactic Planetary Nebulae as Probes of Radial Metallicity Gradients and Other Abundance Patterns
Haywood, Misha; Stanghellini, Letizia
We use planetary nebulae (PNe) as probes to determine the Galactic radial oxygen gradients and other abundance patterns. We select data homogeneously from recent data sets, including PNe at large Galactocentric distances. The radial oxygen gradient calculated for the general PN population, which probes the region from the Galactic center out to ∼2…
Galaxies Probing Galaxies in PRIMUS. I. Sample, Spectroscopy, and Characteristics of the z\sim 0.5 Mg II-absorbing Circumgalactic Medium
Moustakas, John; Coil, Alison L.; Diamond-Stanic, Aleksandar M. +2 more
The spectroscopy of background QSO sightlines passing close to foreground galaxies is a potent technique for studying the circumgalactic medium (CGM). However, QSOs are effectively point sources, limiting their potential to constrain the size of circumgalactic gaseous structures. Here we present the first large Keck/Low-resolution Imaging Spectrom…
The Araucaria Project: High-precision Cepheid Astrophysics from the Analysis of Variables in Double-lined Eclipsing Binaries
Udalski, Andrzej; Soszyński, Igor; Thompson, Ian B. +15 more
Based on new observations and improved modeling techniques, we have reanalyzed seven Cepheids in the Large Magellanic Cloud. Improved physical parameters have been determined for the exotic system OGLE LMC-CEP-1718 composed of two first-overtone Cepheids and a completely new model was obtained for the OGLE LMC-CEP-1812 classical Cepheid. This is n…
Does Circumgalactic O VI Trace Low-pressure Gas Beyond the Accretion Shock? Clues from H I and Low-ion Absorption, Line Kinematics, and Dust Extinction
Stern, Jonathan; Faucher-Giguère, Claude-André; Hennawi, Joseph F. +3 more
Large O VI columns are observed around star-forming low-redshift ∼ {L}* galaxies, with a dependence on impact parameter indicating that most {{{O}}}5+ particles reside beyond half the halo virial radius (≳ 100 {kpc}). In order to constrain the nature of the gas traced by {{O}} {{vi}}, we analyze additional observables of the…
Predicting Stellar-mass Black Hole Populations in Globular Clusters
Rodriguez, Carl L.; Chatterjee, Sourav; Weatherford, Newlin C. +1 more
Recent discoveries of black hole (BH) candidates in Galactic and extragalactic globular clusters (GCs) have ignited interest in understanding how BHs dynamically evolve in a GC and the number of BHs ({N}BH}) that may still be retained by today’s GCs. Numerical models show that even if stellar-mass BHs are retained in today’s GCs, they a…
An L Band Spectrum of the Coldest Brown Dwarf
Fortney, Jonathan J.; Freedman, Richard S.; Faherty, Jacqueline K. +10 more
The coldest brown dwarf, WISE 0855, is the closest known planetary-mass, free-floating object and has a temperature nearly as cold as the solar system gas giants. Like Jupiter, it is predicted to have an atmosphere rich in methane, water, and ammonia, with clouds of volatile ices. WISE 0855 is faint at near-infrared wavelengths and emits almost al…
Super-strong Magnetic Field in Sunspots
Okamoto, Takenori J.; Sakurai, Takashi
Sunspots are the most notable structure on the solar surface with strong magnetic fields. The field is generally strongest in a dark area (umbra), but sometimes stronger fields are found in non-dark regions, such as a penumbra and a light bridge. The formation mechanism of such strong fields outside umbrae is still puzzling. Here we report clear e…
Ages of the Bulge Globular Clusters NGC 6522 and NGC 6626 (M28) from HST Proper-motion-cleaned Color-Magnitude Diagrams
Vieira, R. G.; Bica, E.; Nardiello, D. +5 more
Bulge globular clusters (GCs) with metallicities [Fe/H] ≲ -1.0 and blue horizontal branches are candidates to harbor the oldest populations in the Galaxy. Based on the analysis of HST proper-motion-cleaned color-magnitude diagrams in filters F435W and F625W, we determine physical parameters for the old bulge GCs NGC 6522 and NGC 6626 (M28), both w…
The Anatomy of the Column Density Probability Distribution Function (N-PDF)
Goodman, Alyssa; Burkhart, Blakesley; Chen, Hope How-Huan +1 more
The column density probability distribution function (N-PDF) of Giant Molecular Clouds (GMCs) has been used as a diagnostic of star formation. Simulations and analytic predictions have suggested that the N-PDF is composed of a low-density lognormal component and a high-density power-law component tracing turbulence and gravitational collapse, resp…
A Large Moving Group within the Lower Centaurus Crux Association
Henning, Thomas; Goldman, Bertrand; Röser, Siegfried +2 more
Scorpius-Centaurus is the nearest OB association, and its hundreds of members are divided into subgroups, including the Lower Centaurus Crux (LCC). Here we study the dynamics of the LCC area. We report the revelation of a large moving group containing more than 1800 intermediate- and low-mass young stellar objects and brown dwarfs that escaped ide…