Search Publications
Spatio-temporal bands of coronal bright points and their relation to solar torsional oscillations
Tsinamdzgvrishvili, Tamar; Chargeishvili, B. B.; Shergelashvili, Bidzina M. +1 more
Using automatic processing of daily FITS files from SOHO_EIT, we studied the temporal evolution of the latitudinal distribution of bright coronal points from 1995 to 2020. The study revealed homogeneous and inhomogeneous components of the latitudinal distribution. The homogeneous component has cyclical variations with a significant phase shift com…
X-Ray Redshifts of Obscured Chandra Source Catalog Active Galactic Nuclei
Buchner, Johannes; Peca, Alessandro; Cappelluti, Nico +2 more
We have computed obscured active galactic nuclei (AGN) redshifts using the XZ method, adopting a broad treatment in which we employed a wide-ranging data set and worked primarily at the XZ counts sensitivity threshold, culminating with a redshift catalog containing 121 sources that lack documented redshifts. We considered 363 obscured AGN from the…
The Open Cluster Chemical Abundances and Mapping Survey. V. Chemical Abundances of CTIO/Hydra Clusters Using The Cannon
Donor, John; Frinchaboy, Peter M.; Chojnowski, S. D. +2 more
Open clusters are key chemical and age tracers of Milky Way evolution. While open clusters provide significant constraints on galaxy evolution, their use has been limited due to discrepancies in measuring abundances from different studies. We analyze medium-resolution (R ~ 19,000) Cerro Tololo Inter-American Observatory/Hydra spectra of giant star…
Rings and arcs around evolved stars - III. Physical conditions of the ring-like structures in the planetary nebula IC 4406 revealed by MUSE
Guerrero, M. A.; Toalá, J. A.; Ramos-Larios, G. +2 more
We present the analysis of Very Large Telescope Multi Unit Spectroscopic Explorer (MUSE) observations of the planetary nebula (PN) IC 4406. MUSE images in key emission lines are used to unveil the presence of at least five ring-like structures north and south of the main nebula of IC 4406. MUSE spectra are extracted from the rings to unambiguously…
Hybrid Simulations of the Cusp and Dayside Magnetosheath Dynamics Under Quasi-Radial Interplanetary Magnetic Fields
Lavraud, B.; Zou, Y.; Chen, L. -J. +2 more
Under quasi-radial interplanetary magnetic fields (IMF), foreshock turbulence can have an impact on the magnetosheath and cusps depending on the location of the quasi-parallel shock. We perform three-dimensional simulations of Earth's dayside magnetosphere using the hybrid code HYPERS, and compare northward and southward quasi-radial IMF configura…
Reconciling Observational Challenges to the Impulsive-Piston Shock-Excitation Scenario. I. Kinematic Challenges
Grechnev, V. V.; Kiselev, V. I.; Uralov, A. M.
Until now, there is no consensus on the origin of coronal shock waves. Questions also remain about the patterns that govern the propagation of the presumably related disturbances observed in the extreme ultraviolet (EUV waves). We present arguments in favor of the initial excitation of the waves by the impulsive acceleration of erupting structures…
A low-frequency pilot survey of southern H II regions in the vela constellation
Bourke, Tyler L.; Dickey, John M.; Wong, O. Ivy +3 more
Atomic ionized regions with strong continuum emission are often associated with regions of high-mass star formation and low-frequency (<2 GHz) observations of these regions are needed to help build star formation models. The region toward the Vela Supernova Remnant is particularly interesting as it is a complex structure of recent supernova exp…
Double Shells of the Planetary Nebula NGC 7009 Minor Axis
Otsuka, Masaaki; Hyung, Siek; Lee, Seong-Jae
We analyzed the minor-axis spectra of the elliptical planetary nebula (PN) NGC 7009 observed with Keck HIRES with a 0.″862 × 10″ slit placed at about 7.″5 and 10″ away from the center and a 0.″862 × 14″ slit at the center. The mean densities derived from the integrated [S II] 6716/6731 Å fluxes along the Keck HIRES slit length indicate a density r…
The Influence of Localized Dynamics on Dusk-Dawn Convection in the Earth's Magnetotail
Case, N. A.; Grocott, A.; Lane, J. H.
Previous work has shown that earthward convective flow bursts in the magnetotail have a dusk-dawn (v⊥y) component that is controlled by the historical state of the Interplanetary Magnetic Field (IMF) By component. Here, we analyze 27 years of Cluster, THEMIS and Geotail plasma and magnetic field data and identify 1,639 magnet…
Solar Wind Velocities at Comets C/2011 L4 Pan-STARRS and C/2013 R1 Lovejoy Derived Using a New Image Analysis Technique
Jones, Geraint H.; Ramanjooloo, Yudish
The ion tails of bright comets have long been considered as a natural tracers of the solar wind (SW) near these objects. Studies of comets and their ion tails allow inexpensive monitoring of key SW structures in the inner heliosphere, much of which is otherwise only accessible by in situ SW spacecraft measurements. Here, we present a novel techniq…