Search Publications
New Constraints on the Nature and Origin of the Leading Arm of the Magellanic Stream
Richter, Philipp; Lockman, Felix J.; Fox, Andrew J. +5 more
We present a new precision measurement of gas-phase abundances of S, O, N, Si, Fe, P, Al, Ca as well as molecular hydrogen (H2) in the Leading Arm (region II, LA II) of the Magellanic Stream (MS) toward the Seyfert galaxy NGC 3783. The results are based on high-quality archival ultraviolet/optical/radio data from various different instr…
Optical High-resolution Spectroscopy of 14 Young α-rich Stars
Ishigaki, Miho N.; Matsuno, Tadafumi; Yong, David +1 more
We report chemical abundances of 14 young α-rich stars including neutron-capture elements based on high-quality optical spectra from HIRES/Keck I and differential line-by-line analysis. From a comparison of the abundance patterns of young α-rich stars to those of nearby bright red giants with a similar metallicity range (-0.7 < [Fe/H] < -0.2…
Investigating Galactic Supernova Remnant Candidates Using LOFAR
Gelfand, Joseph D.; Vink, Jacco; Hessels, Jason W. T. +3 more
We investigate six supernova remnant (SNR) candidates—G51.21+0.11, G52.37-0.70, G53.07+0.49, G53.41+0.03, G53.84-0.75, and the possible shell around G54.1+0.3—in the Galactic plane using newly acquired Low-Frequency Array High-band Antenna observations, as well as archival Westerbork Synthesis Radio Telescope and Very Large Array Galactic Plane Su…
Observing and Modeling the Gamma-Ray Emission from Pulsar/Pulsar Wind Nebula Complex PSR J0205+6449/3C 58
Torres, Diego F.; Li, Jian; Kerr, Matthew +4 more
We present the results of the analysis of eight years of Fermi-LAT data of the pulsar/pulsar wind nebula complex PSR J0205+6449/3C 58. Using a contemporaneous ephemeris, we carried out a detailed analysis of PSR J0205+6449 both during its off-peak and on-peak phase intervals. 3C 58 is significantly detected during the off-peak phase interval. We s…
The X-Ray Luminosity Function of Ultraluminous X-Ray Sources in Collisional Ring Galaxies
Wolter, Anna; Mapelli, Michela; Fruscione, Antonella
Ring galaxies are fascinating laboratories: a catastrophic impact between two galaxies (one not much smaller than the other) has produced fireworks, especially in the larger one, when hit roughly perpendicularly to the plane. We analyze the point sources produced by the starburst episode following the impact in the rings of seven galaxies and dete…
The Orbit of the Close Companion of Polaris: Hubble Space Telescope Imaging, 2007 to 2014
Mack, Jennifer; Schaefer, Gail H.; Nelan, Edmund P. +6 more
As part of a program to determine the dynamical masses of Cepheids, we have imaged the nearest and brightest Cepheid, Polaris, with the Hubble Space Telescope (HST) Wide Field Planetary Camera 2 and Wide Field Camera 3. Observations were obtained at three epochs between 2007 and 2014. In these images, as in HST frames obtained in 2005 and 2006, wh…
Magnification Bias of Distant Galaxies in the Hubble Frontier Fields: Testing Wave Versus Particle Dark Matter Predictions
Broadhurst, Tom; Windhorst, Rogier; Schive, Hsi-Yu +4 more
Acting as powerful gravitational lenses, the strong lensing galaxy clusters of the deep Hubble Frontier Fields (HFF) program permit access to lower-luminosity galaxies lying at higher redshifts than hitherto possible. We analyzed the HFF to measure the volume density of Lyman-break galaxies at z > 4.75 by identifying a complete and reliable sam…
Toward a Quantitative Model for Simulation and Forecast of Solar Energetic Particle Production during Gradual Events. I. Magnetohydrodynamic Background Coupled to the SEP Model
Gombosi, T. I.; Taktakishvili, A.; Roussev, I. I. +2 more
Solar energetic particles (SEPs) are an important aspect of space weather. SEP events possess a high destructive potential, since they may cause disruptions of communication systems on Earth and be fatal to crew members on board spacecraft and, in extreme cases, harmful to people on board high-altitude flights. However, currently the research comm…
Constraining the Solar Galactic Reflex Velocity using Gaia Observations of the Sagittarius Stream
Law, David R.; Majewski, Steven R.; Hayes, Christian R.
Because of its particular orientation around the Galaxy—i.e., in a plane nearly perpendicular to the Galactic plane and containing both the Sun and Galactic center—the Sagittarius (Sgr) stream provides a powerful means by which to measure the solar reflex velocity, and thereby infer the velocity of the Local Standard of Rest (LSR), in a way that i…
A Wide-field Map of Intracluster Globular Clusters in Coma
O'Neill, Conor R.; Madrid, Juan P.; Gagliano, Alexander T. +1 more
The large-scale distribution of globular clusters in the central region of the Coma cluster of galaxies is derived through the analysis of Hubble Space Telescope/Advanced Camera for Surveys data. Data from three different HST observing programs are combined in order to obtain a full surface density map of globular clusters in the core of Coma. A t…