Search Publications
Parametric study of the kinematic evolution of coronal mass ejection shock waves and their relation to flaring activity
Kouloumvakos, Athanasios; Rouillard, Alexis P.; Warmuth, Alexander +2 more
Context. Coronal and interplanetary shock waves produced by coronal mass ejections (CMEs) are major drivers of space-weather phenomena, inducing major changes in the heliospheric radiation environment and directly perturbing the near-Earth environment, including its magnetosphere. A better understanding of how these shock waves evolve from the cor…
Chandra Observation of NGC 1559: Eight Ultraluminous X-Ray Sources Including a Compact Binary Candidate
Kong, Albert K. H.; Chu, You-Hua; Li, Kwan-Lok +1 more
Despite the 30 yr history of ultraluminous X-ray sources (ULXs) studies, issues such as the majority of their physical natures (i.e., neutron stars, stellar-mass black holes, or intermediate black holes) as well as the accretion mechanisms are still under debate. Expanding the ULX sample size in the literature is clearly a way to help. To this end…
Variations in the intermediate wind region of the blue supergiant 55 Cygni
Kraus, M.; Granada, A.; Arias, M. L. +6 more
Context. The quantitative near-infrared (NIR) spectroscopic synthesis is an important technique for determining wind properties of massive stars. The Brα line is an excellent mass-loss tracer and provides valuable information on the physical conditions of intermediate-wind regions. The knowledge of the wind properties gained by studying the NIR li…
Role of magnetic fields in the fragmentation of the Taurus B213 filament into Sun-type star-forming cores
Jose, Jessy; Eswaraiah, Chakali; Jiao, Sihan +1 more
Fragmentation is a key step in the process of transforming clouds (and their substructures, such as filaments, clumps and cores) into protostars. The thermal gas pressure and gravitational collapse are believed to be the primary agents governing this process, referred as thermal Jeans fragmentation. However, the contributions of other factors (suc…
Solar Energetic Particle Events with Short and Long Onset Times
Yashiro, Seiji; Nitta, Nariaki V.; Asai, Ayumi +1 more
Gradual solar energetic particle (SEP) events, usually attributed to shock waves driven by coronal mass ejections (CMEs), show a wide variety of temporal behaviors. For example, TO, the >10 MeV proton onset time with respect to the launch of the CME, has a distribution of at least an order of magnitude, even when the source region is not far fr…
Periodic changes in the morphology of the Galactic resonance rings
Melnik, A. M.; Dambis, A. K.; Podzolkova, E. N.
We study the periodic enhancement of either trailing or leading segments of the resonance elliptical rings in the dynamical model of the Galaxy which reproduces distributions of observed velocities derived from Gaia DR3 (EDR3) data along the Galactocentric distance. The model disc forms a nuclear ring, an inner combined ring, and outer resonance r…
Diagnostics from Polarization of Scattered Optical Light from Galactic Infrared Cirrus
Martin, Peter G.; Bowes, Shannon K.
We propose polarization of scattered optical light from intermediate Galactic latitude infrared cirrus as a new diagnostic to constrain models of interstellar dust and the anisotropic interstellar radiation field (aISRF). For single scattering by a sphere, with Mie scattering phase functions for intensity and polarized intensity for a dust model a…
Physics and Chemistry of Radiation Driven Cloud Evolution. [C II] Kinematics of IC 59, and IC 63
Soam, Archana; Andersson, B. -G.; Güsten, Rolf +5 more
We used high-resolution [C II] 158 µm mapping of two nebulae IC 59 and IC 63 from SOFIA/upGREAT in conjunction with ancillary data of the gas, dust, and polarization to probe the kinematics, structure, and magnetic properties of their photodissociation regions (PDRs). The nebulae are part of the Sh 2-185 H II region that is illuminated by th…
Surface activity of rapidly rotating stars from simultaneous X-ray and UV observations with AstroSat
Sairam, Lalitha; Pathak, Utkarsh; Singh, Kulinder Pal
Our study focuses on analysing the coronal, transition and chromospheric activity of four rapidly rotating stars located within 50 pc in the solar neighborhood. We have used the multi-wavelength capabilities of AstroSat to investigate the outer atmospheres of AB Dor, BO Mic, DG CVn and GJ 3331. These stars, classified as M and K type active stars,…
Solar Wind Protons in the Diamagnetic Cavity at Comet 67P/Churyumov-Gerasimenko
Nilsson, Hans; Goetz, Charlotte; Volwerk, Martin +5 more
The plasma environment at a comet can be divided into different regions with distinct plasma characteristics. Two such regions are the solar wind ion cavity, which refers to the part of the outer coma that does not contain any solar wind ions anymore; and the diamagnetic cavity, which is the region of unmagnetized plasma in the innermost coma. Fro…