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Formation of Isolated Radio Type II Bursts at Low Frequencies
Pohjolainen, Silja; Talebpour Sheshvan, Nasrin
The first appearance of radio type II burst emission at decameter-hectometer (DH) waves typically occurs in connection, and often simultaneously, with other types of radio emissions. As type II bursts are signatures of propagating shock waves that are associated with flares and coronal mass ejections (CMEs), a rich variety of radio emissions can b…
The Structure of the Cusp Diamagnetic Cavity and Test Particle Energization in the GAMERA Global MHD Simulation
Merkin, V.; Otto, A.; Nykyri, K. +4 more
Electrons with energies ≥40 keV can be found at low density in many different regions of Earth's magnetosphere. A litany of fundamental questions in space physics have focused on the acceleration mechanism of these particles, given that the sources of plasma are the relatively cool ionosphere and solar wind (∼1-100s eV). Upgraded global solar wind…
The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XXII. Relative ages of multiple populations in five globular clusters
Piotto, G.; Nardiello, D.; Lucertini, F.
Aims: We present a new technique to estimate the relative ages of multiple stellar populations hosted by the following five globular clusters: NGC 104 (47 Tuc), NGC 6121 (M 4), NGC 6352, NGC 6362, and NGC 6723.
Methods: We used the catalogs of the database HST UV Globular Cluster Survey to create color-magnitude and two-color diagrams of…
Probing Upflowing Regions in the Quiet Sun and Coronal Holes
Hara, Hirohisa; Sterling, Alphonse C.; Orozco Suárez, David +5 more
Recent observations from Parker Solar Probe have revealed that the solar wind has a highly variable structure. How this complex behaviour is formed in the solar corona is not yet known, since it requires omnipresent fluctuations, which constantly emit material to feed the wind. In this article we analyse 14 upflow regions in the solar corona to fi…
Gas and stellar dynamics in Stephan's Quintet. Mapping the kinematics in a closely interacting compact galaxy group
Eckart, A.; Sánchez-Monge, Á.; Yttergren, M. +4 more
In nearby compact galaxy groups we can study the complex processes of galaxy interactions at high resolution and obtain a window into a time in the history of the Universe when the galaxies were closely spaced and the intergalactic medium was awash with gas. Stephan's Quintet is a nearby compact galaxy group and a perfect laboratory for studying t…
NGC 6124: a young open cluster with anomalous- and fast-rotating giant stars
Pereira, C. B.; Holanda, N.; Drake, N. A. +5 more
We present the results of a chemical analysis of fast and anomalous rotator giants members of the young open cluster NGC 6124. For this purpose, we carried out abundances of the mixing sensitive species such as Li, C, N, Na, and 12C/13C isotopic ratio, as well as other chemical species for a sample of four giants among the se…
The Spatial Distributions of Blue Main-sequence Stars in Magellanic Cloud Star Clusters
Deng, Licai; de Grijs, Richard; Li, Chengyuan +1 more
The color-magnitude diagrams of young star clusters show that, particularly at ultraviolet wavelengths, their upper main sequences (MSs) bifurcate into a sequence comprising the bulk population and a blue periphery. The spatial distribution of stars is crucial to understanding the reasons for these distinct stellar populations. This study uses hig…
The Astrophysical Variance in Gaia-Radial Velocity Spectrometer Spectra
Rampalli, Rayna; Ness, Melissa; Wylie, Shola
Large surveys are providing a diversity of spectroscopic observations with Gaia alone set to deliver millions of Ca-triplet-region spectra across the Galaxy. We aim to understand the dimensionality of the chemical abundance information in the Gaia-Radial Velocity Spectrometer (RVS) data to inform galactic archeology pursuits. We fit a quadratic mo…
Electric field measurements at the plasma frequency around comet 67P by RPC-MIP on board Rosetta
Palmerio, E.; Nilsson, H.; Henri, P. +7 more
Context. The Mutual Impedance Probe (RPC-MIP) carried by the Rosetta spacecraft monitored both the plasma density and the electric field in the close environment of comet 67P/Churyumov-Gerasimenko (67P), as the instrument was operating alternatively in two main modes: active and passive. The active mode is used primarily to perform plasma density …
The Origins and Geological Histories of Deimos and Phobos: Hypotheses and Open Questions
Head, James W.; Ramsley, Kenneth R.
Quantitative measurements and photographic imaging of the moons of Mars set limits on several key geological conclusions-such as the orbits of the moons. Other examples include their estimated bulk densities where Phobos has a density of ∼1.876 g/cm3 and Deimos has a lower and less certain density of ∼1.48 g/cm3. Imaging data…