Search Publications
Plasma Flows in the Cool Loop Systems
Wilhelm, Klaus; Rao, Yamini K.; Srivastava, Abhishek K. +2 more
We study the dynamics of low-lying cool loop systems for three data sets as observed by the Interface Region Imaging Spectrograph. Radiances, Doppler shifts, and line widths are investigated in and around observed cool loop systems using various spectral lines formed between the photosphere and transition region (TR). Footpoints of the loop thread…
A Search for Pulsed Very High-energy Gamma-Rays from 13 Young Pulsars in Archival VERITAS Data
Archer, A.; Benbow, W.; Bird, R. +58 more
We conduct a search for periodic emission in the very high-energy (VHE) gamma-ray band (E > 100 GeV) from a total of 13 pulsars in an archival VERITAS data set with a total exposure of over 450 hr. The set of pulsars includes many of the brightest young gamma-ray pulsars visible in the Northern Hemisphere. The data analysis resulted in nondetec…
Nonequilibrium Ionization Effects on Coronal Plasma Diagnostics and Elemental Abundance Measurements
Landi, Enrico; Shi, Tong; Manchester, Ward, IV
Plasma diagnostics and elemental abundance measurements are crucial to help us understand the formation and dynamics of the solar wind. Here we use a theoretical solar wind model to study the effect of nonequilibrium ionization (NEI) on plasma diagnostic techniques applied to line intensities emitted by the fast solar wind. We find that NEI almost…
A Sparkler in the Fireworks Galaxy: Discovery of an Ultraluminous X-Ray Transient with a Strong Oxygen Line in NGC 6946
Soria, Roberto; Wang, Junfeng; Wang, Chen
We discovered and studied an ultraluminous X-ray source (CXOU J203451.1+601043) that appeared in the spiral galaxy NGC 6946 at some point between 2008 February and 2012 May and has remained at luminosities ≈2-4 × 1039 erg s-1 in all observations since then. Our spectral modeling shows that the source is generally soft but wit…
Multiwavelength Modeling of the SED of Nova V339 Del: Stopping the Wind and Long-lasting Super-Eddington Luminosity with Dust Emission
Skopal, Augustin
During the classical nova outburst, the radiation generated by the nuclear burning of hydrogen in the surface layer of a white dwarf (WD) is reprocessed by the outer material into different forms at softer energies, whose distribution in the spectrum depends on the nova age. Using the method of multiwavelength modeling the spectral energy distribu…
The Plasma β Evolution through the Solar Corona during Solar Cycles 23 and 24
Dal Lago, Alisson; Vieira, Luis E. A.; Palacios, Judith +1 more
The plasma β is important in the investigation of interchanging roles of plasma and magnetic pressure in the solar atmosphere. It can help to describe features over the photosphere and their changes at different heights. The goal of this paper is to obtain the plasma β variations through the solar corona during solar cycles 23 and 24. The plasma β…
The Cluster-forming Site AFGL 5157: Colliding Filamentary Clouds and Star Formation
Dewangan, L. K.
We observationally investigate star formation process occurring in AFGL 5157 (area ∼13.5 pc × 13.5 pc) using a multi-wavelength approach. Embedded filaments are seen in the Herschel column density map, and one of them is identified as an elongated filamentary feature (FF) (length ∼8.3 pc; mass ∼1170 M ⊙). Five Herschel clumps (M cl…
Jovian Cosmic-Ray Protons in the Heliosphere: Constraints by Cassini Observations
Krupp, Norbert; Krimigis, Stamatios M.; Mitchell, Donald G. +5 more
Measurements of >82 MeV Galactic cosmic-ray (GCR) protons at Earth indicate that they may be mixed with protons that leak into the heliosphere from Jupiter’s magnetosphere (Jovian cosmic-ray protons (JCRPs)). A ∼400 day periodicity in these proton fluxes, which is similar to the synodic period between Jupiter and Earth, and an excess proton flu…
Morphological Classification of G-band Bright Points Based on Deep Learning
Yang, Yunfei; Feng, Song; Zhang, Xiaoli +4 more
The G-band bright points (GBPs) are driven by the granular convection flow, and appear with different morphologies in the quiet Sun, such as points, elongated chains, and knees. A point-like GBP represents a single slender flux tube, while the others represent the interaction of several slender flux tubes. This paper presents a deep-learning metho…
The Evolution of the Electron Number Density in the Coma of Comet 67P at the Location of Rosetta from 2015 November through 2016 March
Henri, P.; Edberg, N. J. T.; Rubin, M. +6 more
A comet ionospheric model assuming the plasma moves radially outward with the same bulk speed as the neutral gas and not being subject to severe reduction through dissociative recombination has previously been tested in a series of case studies associated with the Rosetta mission at comet 67P/Churyumov-Gerasimenko. It has been found that at low ac…