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Analysis of photospheric magnetic fields in AR 12546: a case study
Abdelkawy, Ali G. A.; Shaltout, Abdelrazek M. K.
We investigate high-resolution observations with the spectropolarimeter (SP) aboard the Hinode satellite of the Solar Optical Telescope (SOT) of a positive polarity sunspot of an active region (AR) (NOAA 12546). We present a case study for the properties of the thermal, magnetic field, and plasma flows as a function of the optical depth from the i…
Solar Physics in the 2020s: DKIST, Parker Solar Probe, and Solar Orbiter as a Multi-Messenger Constellation
Müller, D.; Parenti, S.; Andretta, V. +21 more
The National Science Foundation (NSF) Daniel K. Inouye Solar Telescope (DKIST) has started operations at the summit of Haleakalā (Hawai'i). DKIST joins the nominal science phases of the NASA and ESA Parker Solar Probe and Solar Orbiter encounter missions. By combining in-situ measurements of the near-Sun plasma environment and detailed remote obse…
Identifying the population of T-Tauri stars in Taurus: UV–optical synergy
Arun, R.; Mathew, Blesson; Ujjwal, K. +9 more
With the third data release of the Gaia mission, Gaia DR3 with its precise photometry and astrometry, it is now possible to study the behavior of stars at a scale never seen before. In this paper, we developed new criteria to identify T-Tauri stars (TTS) candidates using UV and optical color-magnitude diagrams (CMDs) by combining the GALEX and Gai…
Iron Kα echoes from the circumnuclear disk orbiting Sgr A⋆
Haardt, Francesco; Ponti, Gabriele; Stel, Giovanni
Context. Molecular clouds in the Galactic center (GC) reprocess radiation from past outbursts of nearby high-energy sources, generating a bright Fe Kα fluorescence at 6.4 keV. The closest clouds to the GC are only ≃1.5 pc from Sgr A⋆, forming a torus-like structure known as the circumnuclear disk (CND). The study of fluorescence emissio…
Linear and nonlinear kinetic Alfvén waves at Venus
Fichtner, H.; Lazar, M.; Moslem, W. M. +1 more
Space observations show that Venus suffers significant atmospheric erosion caused by the solar wind forcing. Plasma acceleration is found to be one of the main mechanisms contributing to the global atmospheric loss at Venus through its magnetotail. Motivated by these observations, we propose that kinetic Alfvén waves (KAW) may be a possible candid…
New constraints on decaying dark matter from INTEGRAL/SPI
Santangelo, A.; Ducci, L.; Malyshev, D. +1 more
Based on almost 20 yr of data collected by the high-resolution spectrometer SPI on board the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), we present constraints on a decaying dark matter particle undergoing a decay into two bodies, at least one of which is a photon, manifesting itself via a narrow line-like spectral feature. Our ON-…
Kinetic study of ion acoustic waves in Venusian ionosphere
Lakhina, G. S.; Kamalam, T.; Singh, S. V. +1 more
Kinetic dispersion of the ion acoustic waves has been explored for an unmagnetized five component plasma system comprising of Venusian protons, Venusian oxygen ions, Venusian electrons, solar wind protons, and kappa electrons. The solar wind protons and electrons are assumed to be streaming along the ambient magnetic field. The plasma parameters f…
Modeling of geocoronal solar wind charge exchange events detected with Suzaku
Miyoshi, Yoshizumi; Ezoe, Yuichiro; Ishikawa, Kumi +2 more
A model of geocoronal solar wind charge exchange (SWCX) emission was built and compared to five Suzaku detections of bright geocoronal SWCX events. An exospheric neutral hydrogen distribution model, charge exchange cross-sections, solar wind ion data taken with the ACE and WIND satellites, and magnetic field models of the Earth's magnetosphere are…
TU Tau B: The Peculiar "Eclipse" of a Possible Proto-barium Giant
Walker, Gary; Gray, Richard O.; Corbally, Christopher J. +26 more
TU Tau (=HD 38218 = HIP 27135) is a binary system consisting of a C-N carbon star primary and an A-type secondary. We report on new photometry and spectroscopy which tracked the recent disappearance of the A-star secondary. The dimming of the A star was gradual and irregular, with one or more brief brightenings, implying the presence of nonhomogen…
Classifying Interplanetary Discontinuities Using Supervised Machine Learning
Munteanu, Costel; Dumitru, Daniel
Directional discontinuities (DDs) are defined as abrupt changes of the magnetic field orientation. We use observations from ESA's Cluster mission to compile a database of events: Four thousand two hundred and sixteen events are identified in January-April 2007, and 5,194 in January-April 2008. Localized time scale images depicting angular changes …