Search Publications
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…
The Pivot Energy of Solar Energetic Particles Affecting the Martian Surface Radiation Environment
Wang, Yuming; Guo, Jingnan; Wimmer-Schweingruber, Robert F. +5 more
Space radiation is a major risk for humans, especially on long-duration missions to outer space, e.g., a manned mission to Mars. Galactic cosmic rays contribute a predictable radiation background; the main risk is due to the highly variable and currently unpredictable flux of solar energetic particles (SEPs). Such sporadic SEP events may induce ac…
Even Simpler Modeling of Quadruply Lensed Quasars (and Random Quartets) Using Witt's Hyperbola
Schechter, Paul L.; Wynne, Raymond A.
Witt (1996) has shown that, for an elliptical potential, the four images of a quadruply lensed quasar lie on a rectangular hyperbola that passes through the unlensed quasar position and the center of the potential as well. Wynne & Schechter (2018) have shown that, for the singular isothermal elliptical potential (SIEP), the four images also li…
FIFI-LS Observations of the Circumnuclear Ring— Probing the High-density Phase of the PDR
Poglitsch, A.; Looney, L. W.; Krabbe, A. +13 more
We investigate the nature of dense gas in the 3-10 pc circumnuclear ring (CNR) in the galactic center of the Milky Way, which is a structure that may be dynamically connecting the supermassive black hole Sgr A* with the central molecular zone at the 100 pc scale, and is the closest reservoir of molecular gas to the massive stars located within the…
Measuring the Absolute Total Intrinsic Redshifts (Surface Gravity Plus the Convective Blueshift) of the Main-sequence Stars and Red Giants using Gaia Data
Dai, De-Chang; Stojkovic, Dejan; Li, ZhiGang
We analyze the GAIA release II data to demonstrate how one can measure the absolute total intrinsic redshifts of the main-sequence stars and red giants. We remove the relative velocity components of the stars’ motion with respect to the Sun by doing the analysis in the local standard of the rest frame defined by the average stars’ motion. We provi…
High Confidence Optical Confirmations among the High Signal-to-noise Planck Cluster Candidates
Infante, L.; Hughes, John P.; Doze, Peter +3 more
We report on newly identified galaxy clusters from the high signal-to-noise (>5σ) end of the second all-sky Planck Sunyaev-Zel’dovich (SZ) catalog (PSZ2). The clusters are identified in deep, optical imaging from the Kitt Peak National Observatory 4 m Mayall telescope taken between 2014 and 2017. Here we focus on the highest richness systems, a…
Ionization Mechanisms in Quasar Outflows
Veilleux, Sylvain; Rupke, David S. N.; Hinkle, Jason T.
The various ionization mechanisms at play in active galactic nuclei (AGN) and quasars have been well studied, but relatively little has been done to separately investigate the contributions of these ionization mechanisms within the host galaxy and outflowing components. Using Gemini integral field spectroscopy data, we study the ionization propert…
Exposure Experiments of Amorphous Silicates and Organics to Cometary Ice and Vapor Analogs
Takigawa, Aki; Kimura, Yuki; Davidsson, Björn +2 more
Hydration is a major mineral alteration process in primitive asteroids and it might occur in comet nuclei; however, it is poorly understood at low temperatures, especially below the freezing point of water. Long-duration experiments were performed with exposures of amorphous silicate nanoparticles and organic compounds (glycine and ribose) to D