Search Publications
Average Radial Structures of Gas Convection in the Solar Granulation
Shimizu, T.; Oba, T.; Iida, Y.
Gas convection is observed in the solar photosphere as granulation, I.e., having highly time-dependent cellular patterns, consisting of numerous bright cells called granules and dark surrounding channels called intergranular lanes. Many efforts have been made to characterize the granulation, which may be used as an energy source for various types …
Low Water Outgassing from (24) Themis and (65) Cybele: 3.1 µm Near-IR Spectral Implications
Valtchanov, I.; Fornasier, S.; Küppers, M. +9 more
Asteroids (24) Themis and (65) Cybele have an absorption feature at 3.1 µm reported to be directly linked to surface water ice. We searched for water vapor escaping from these asteroids with the Herschel Space Observatory Heterodyne Instrument for the Far Infrared. While no H2O line emission was detected, we obtain sensitive 3σ wa…
Spatial Distribution of the Origin of Umbral Waves in a Sunspot Umbra
Kilcik, Ali; Yurchyshyn, Vasyl; Lim, Eun-Kyung +2 more
Umbral flashes (UFs) are emissions in the core of chromospheric lines caused by upward propagating waves steepening into shocks. UFs are followed by an expanding blueshifted umbral wave and redshifted plasma returning to the initial state. Here we use 5 s cadence images acquired at ±0.04 nm off the H ${}_{\alpha }$ line center by the Visible Imagi…
Interpreting Observations of Absorption Lines in the Circumgalactic Medium with a Turbulent Medium
Fumagalli, Michele; Buie, Edward, II; Scannapieco, Evan
Single-phase photoionization equilibrium (PIE) models are often used to infer the underlying physical properties of galaxy halos probed in absorption with ions at different ionization potentials. To incorporate the effects of turbulence, we use the Models of Agitated and Illuminated Hindering and Emitting Media (MAIHEM) code to model an isotropic …
Extratidal Stars and Chemical Abundance Properties of Two Metal-poor Globular Clusters M53 (NGC 5024) and NGC 5053
Lee, Jae-Joon; Lim, Dongwook; Chun, Sang-Hyun
We search for extratidal stars around two metal-poor Galactic globular clusters, M53 and NGC 5053, using the near-infrared APOGEE spectra. Applying the t-distributed stochastic neighbor embedding (t-SNE) algorithm on the chemical abundances and radial velocities results in identification of two isolated stellar groups composed of cluster member st…
Chandra Imaging of the Western Hotspot in the Radio Galaxy Pictor A: Image Deconvolution and Variability Analysis
Cheung, C. C.; Stawarz, Ł.; Siemiginowska, A. +3 more
Here we present an analysis of the X-ray morphology and flux variability of the particularly bright and extended western hotspot in the nearest powerful (FR II-type) radio galaxy, Pictor A, based on data obtained with the Chandra X-ray Observatory. The hotspot marks the position where the relativistic jet, which originates in the active nucleus of…
An XMM-Newton X-Ray View of Supernova Remnant W49B: Revisiting Its Recombining Plasmas and Progenitor Type
Chen, Yang; Sun, Lei
We present a comprehensive X-ray spectroscopy and imaging study of supernova remnant W49B using archival XMM-Newton observations. The overionization state of the shocked ejecta in W49B is clearly indicated by the radiative recombination continua of Si XIV, S XV, and Fe XXV, combined with the Lyα lines of Ca and Fe. The line flux images of W49B ind…
Accretion-driven Sources in Spatially Resolved Lyα Emitters
Hayes, Matthew; Östlin, Göran; Melinder, Jens +4 more
Lyα emission is a standard tracer of starburst galaxies at high redshift. However, a number of local Lyα emitters (LAEs) are X-ray sources, suggesting a possible origin of Lyα photons other than young, hot stars, and which may be active at much later ages relative to the parent starburst. Resolved, nearby LAEs offer the opportunity to discriminate…
Direct Imaging Discovery of a Young Brown Dwarf Companion to an A2V Star
Currie, Thayne; Wagner, Kevin; Apai, Dániel +3 more
We present the discovery and spectroscopy of HIP 75056Ab, a companion directly imaged at a very small separation of 0"125 to an A2V star in the Scorpius-Centaurus OB2 association. Our observations utilized Very Large Telescope/Spectro-Polarimetric High-contrast Exoplanet Research Experiment between 2015 and 2019, enabling low-resolution spectrosco…
Three Dusty Star-forming Galaxies at z ∼ 1.5: Mergers and Disks on the Main Sequence
Casey, Caitlin M.; Whitaker, Katherine E.; Cooray, Asantha +1 more
The main sequence of galaxies, a correlation between the star formation rates (SFRs) and stellar masses of galaxies, has been observed out to z ∼ 4. Galaxies within the scatter of the correlation are typically interpreted to be secularly evolving while galaxies with SFRs elevated above the main sequence are interpreted to be undergoing interaction…