Search Publications
Matching Globular Cluster Models to Observations
Rui, Nicholas Z.; Rodriguez, Carl L.; Chatterjee, Sourav +4 more
As ancient, gravitationally bound stellar populations, globular clusters represent abundant, vibrant laboratories, characterized by high frequencies of dynamical interactions, coupled to complex stellar evolution. Using surface brightness and velocity dispersion profiles from the literature, we fit 59 Milky Way globular clusters to dynamical model…
Measurements of Photospheric and Chromospheric Magnetic Field Structures Associated with Chromospheric Heating over a Solar Plage Region
Kitai, Reizaburo; Kleint, Lucia; Schad, Thomas A. +6 more
In order to investigate the relation between magnetic structures and the signatures of heating in plage regions, we observed a plage region with the He I 1083.0 nm and Si I 1082.7 nm lines on 2018 October 3 using the integral field unit mode of the GREGOR Infrared Spectrograph (GRIS) installed at the GREGOR telescope. During the GRIS observation, …
New Hydrodynamic Solutions for Line-driven Winds of Hot Massive Stars Using the Lambert W-function
Hillier, D. J.; Najarro, F.; Gormaz-Matamala, A. C. +3 more
Hot massive stars present strong stellar winds that are driven by absorption, scattering, and reemission of photons by the ions of the atmosphere (line-driven winds). A better comprehension of this phenomenon, and a more accurate calculation of hydrodynamics and radiative acceleration, is Required to reduce the number of free parameters in spectra…
LoCuSS: The Splashback Radius of Massive Galaxy Clusters and Its Dependence on Cluster Merger History
Smith, Graham P.; Babul, Arif; Finoguenov, Alexis +4 more
We present the direct detection of the splashback feature using the sample of massive galaxy clusters from the Local Cluster Substructure Survey (LoCuSS). This feature is clearly detected (above 5σ) in the stacked luminosity density profile obtained using the K-band magnitudes of spectroscopically confirmed cluster members. We obtained the best-fi…
Energetic Proton Propagation and Acceleration Simulated for the Bastille Day Event of 2000 July 14
Downs, Cooper; Riley, Pete; Schwadron, Nathan A. +9 more
This work presents results from simulations of the 2000 July 14 ("Bastille Day") solar proton event. We used the Energetic Particle Radiation Environment Model (EPREM) and the CORona-HELiosphere (CORHEL) software suite within the SPE Threat Assessment Tool (STAT) framework to model proton acceleration to GeV energies due to the passage of a CME th…
Spectroscopic Confirmation of the Sixth Globular Cluster in the Fornax Dwarf Spheroidal Galaxy
Caldwell, Nelson; Mateo, Mario; Bailey, John I., III +5 more
The Fornax dwarf spheroidal galaxy has an anomalous number of globular clusters, five, for its stellar mass. There is a longstanding debate about a potential sixth globular cluster (Fornax 6) that has recently been "rediscovered" in DECam imaging. We present new Magellan/M2FS spectroscopy of the Fornax 6 cluster and Fornax dSph. Combined with lite…
Extragalactic Magnetism with SOFIA (Legacy Program) - II: A Magnetically Driven Flow in the Starburst Ring of NGC 1097
Beckman, John E.; Hughes, Annie; Dale, Daniel +9 more
Galactic bars are frequent in disk galaxies and they may support the transfer of matter toward the central engine of active nuclei. The barred galaxy NGC 1097 has magnetic forces controlling the gas flow at several kpc scales, which suggest that magnetic fields (B-fields) are dynamically important along the bar and nuclear ring. However, the effec…
Compact Molecular Gas Distribution in Quasar Host Galaxies
Ho, Luis C.; Bauer, Franz E.; Shao, Yali +4 more
We use Atacama Large Millimeter/submillimeter Array CO (2-1) observations of six low-redshift Palomar-Green quasars to study the distribution and kinematics of the molecular gas of their host galaxies at kiloparsec-scale resolution. While the molecular gas content, molecular gas fraction, and star formation rates are similar to those of nearby mas…
Characterizing the Multiphase Origin of [C II] Emission in M101 and NGC 6946 with Velocity-resolved Spectroscopy
Bolatto, Alberto D.; Croxall, Kevin V.; Dale, Daniel A. +10 more
The [C II] fine-structure transition at 158 µm is frequently the brightest far-infrared line in galaxies. Due to its low ionization potential, C+ can trace the ionized, atomic, and molecular phases of the ISM. We present velocity-resolved [C II] and [N II] pointed observations from SOFIA/GREAT on ~500 pc scales in the nearby galax…
The X-Ray Bursts of XTE J1739-285: A NICER Sample
Chakrabarty, Deepto; Arzoumanian, Zaven; Güver, Tolga +10 more
In this work, we report on observations with the Neutron Star Interior Composition Explorer of the known neutron star X-ray transient XTE J1739-285. We observed the source in 2020 February and March, finding it in a highly active bursting state. Across a 20 day period, we detected 32 thermonuclear X-ray bursts, with an average burst recurrence tim…