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A fully kinetic perspective on weakly active comets: Asymmetric outgassing
Henri, Pierre; Galand, Marina; Divin, Andrey +3 more
The European Space Agency's Rosetta mission measured the complex plasma environment surrounding comet 67P/Churyumov-Gerasimenko for more than two years. In this work, the collisionless dynamics of the plasma interaction during the comet's weakly outgassing phases is investigated through a fully kinetic semi-implicit particle-in-cell approach. The …
Characteristics of decametric hectometric (DH) type IIs, CMEs and flares of geoeffective and non-geoeffective storm events in Solar Cycle 24
Pant, Charita; Pande, Bimal; Pande, Seema
In this paper, a statistical study on geoeffectiveness of CMEs integrated with decametric hectometric (DH) type-II radio bursts, association of Dst with plasma and interplanetary field parameters (T,V,P,
Observed dispersive properties of the slow magnetoacoustic waves propagating in coronal fan loops above sunspots
Zhao, Junwei; Chen, Ruizhu; Wang, Tongjiang
Recurrent and propagating intensity perturbations are frequently observed in extreme ultraviolet (EUV) channels along coronal fan loops above sunspots, and these perturbations are suggested to be slow magnetoacoustic waves. Numerous studies have been conducted to investigate their propagation speeds, damping, and excitation sources; however, there…
Serendipitous detection of an intense X-ray flare in the weak-line T Tauri star KM Ori with SRG/eROSITA
Arun, R.; Mathew, Blesson; Kartha, Sreeja S. +8 more
Weak-line T Tauri stars (WTTS) exhibit X-ray flares, likely resulting from magnetic reconnection that heats the stellar plasma to very high temperatures. These flares are difficult to identify through targeted observations. Here, we report the serendipitous detection of the brightest X-ray flaring state of the WTTS KM Ori in the eROSITA DR1 survey…
Temporal variability and obscuration effects in the X-ray emission of classical nova V339 Delphini (Nova Delphini 2013)
Cai, Yongzhi; Pei, Songpeng; Li, Qiang +4 more
In this study, we present a detailed analysis of public archival soft X-ray data on the classical nova V339 Delphini (Nova Del 2013) during its outburst, obtained using the Chandra High-Resolution Camera Spectrometer and Low Energy Transmission Grating, as well as XMM-Newton in 2013. The observations, spanning from days 85.2 to 112.0 after the opt…
A Simplified Theory of External Occulters for Solar Coronagraphs
Osterman, Steven N.; DeForest, Craig. E.; Erickson, Nicholas F. +3 more
We present a first-principles analytic treatment of modern multivane occulters in circular (coronagraph) and linear (heliospheric imager) geometry, develop a simplified theory that is useful for designing and predicting their performance, explain certain visual artifacts, and explore the performance limits of multivane occulters. Multivane occulte…
Unveiling VVV/WISE Mira variables on the far side of the Galactic disk: Distances, kinematics, and a new extinction law
Zoccali, M.; Contreras Ramos, R.; Salvo-Guajardo, C. +8 more
Context. The structure and kinematics of the Milky Way disk are largely inferred from the solar vicinity. To gain a comprehensive understanding, it is essential to find reliable tracers in less explored regions such as the bulge and the far side of the disk. Mira variables, which are well studied and bright standard candles, offer an excellent opp…
A Nonstop Aurora? The Intriguing Radio Emission from the Rapidly Rotating Magnetic Massive Star HR 5907
Wade, Gregg A.; Biswas, Ayan; Das, Barnali +2 more
HR 5907 (HD 142184) stands out among magnetic OB stars for its rapid rotation, exceptionally hard X-ray emission, and strong magnetic field. High-frequency (>5 GHz) radio emission from the star exhibits an approximately flat spectrum that can be attributed to gyrosynchrotron emission from a dense centrifugal magnetosphere. In a survey of radio …
Ubiquitous Small-scale Extreme-ultraviolet Upflow-like Events above Network Regions Observed by the Solar Orbiter/Extreme Ultraviolet Imager
Shen, Yuandeng; Hou, Zhenyong; Duan, Yadan +2 more
Universal small-scale solar activity in the quiet region is suggested to be a potential source of solar wind and the upper solar atmosphere. Here, with the high-resolution 174 Å imaging observations from the Solar Orbiter/Extreme Ultraviolet Imager, we investigate 59 EUV upflow-like events observed in the quiet Sun. Their average apparent (plane-o…
Pulsating ultraluminous X-ray sources: Modeling the thermal emission and polarization properties
Israel, G. L.; Turolla, R.; Pintore, F. +4 more
Context. Ultraluminous X-ray sources (ULXs) are enigmatic sources first discovered in the 1980s in external galaxies. They are characterized by their extraordinarily high X-ray luminosity, which often exceeds 1040 erg s‑1. Aims. Our study aims to obtain more information about pulsating ULXs (PULXs), first of all, their viewin…