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Center-to-limb Variation of Transition-region Doppler Shifts in Active Regions
Tripathi, Durgesh; Kashyap, Vinay L.; Ghosh, Avyarthana +2 more
Studying Doppler shifts provides deep insights into the flow of mass and energy in the solar atmosphere. We perform a comprehensive measurement of Doppler shifts in the transition region and its center-to-limb variation (CLV) in the strong-field regions (∣ B ∣ ≥ 50 G) of 50 active regions (ARs), using the Si IV 1394 Å line recorded by the Interfac…
The Pristine survey - XX. GTC follow-up observations of extremely metal-poor stars identified from Pristine and LAMOST
Sestito, Federico; Martin, Nicolas F.; Aguado, David S. +5 more
Ultra-metal-poor stars ($\rm {[Fe/H]} \lt -4.0$) are very rare, and finding them is a challenging task. Both narrow-band photometry and low-resolution spectroscopy have been useful tools for identifying candidates, and in this work, we combine both approaches. We cross-matched metallicity-sensitive photometry from the Pristine survey with the low-…
Application of Deep Reinforcement Learning to Major Solar Flare Forecasting
Moon, Yong-Jae; Yi, Kangwoo; Jeong, Hyun-Jin
In this study, we present the application of deep reinforcement learning to the forecasting of major solar flares. For this, we consider full-disk magnetograms at 00:00 UT from the Solar and Heliospheric Observatory/Michelson Doppler Imager (1996-2010) and the Solar Dynamics Observatory/Helioseismic and Magnetic Imager (2011-2019), as well as Geos…
Surrounded by Giants: Habitable Zone Stability Within the HD 141399 System
Kane, Stephen R.
The search for exoplanets has revealed a diversity of planetary system architectures, the vast majority of which diverge significantly from the template of the solar system. In particular, giant planets beyond the snow line are relatively rare, especially for low-mass stars, placing the solar system within a small category of systems with multiple…
In-orbit performance of LE onboard Insight-HXMT in the first 5 years
Li, Xiaobo; Zhang, Shuang-Nan; Tuo, Youli +18 more
The low-energy X-ray telescope (LE) is a main instrument of the Insight-HXMT mission and consists of 96 swept charge devices covering the 1–10 keV energy band. The energy gain and resolution are continuously calibrated by analyzing Cassiopeia A (Cas A) and blank sky data, while the effective areas are also calibrated with the observations of the C…
The Yarkovsky effect and bulk density of near-Earth asteroids from Gaia DR3
Oszkiewicz, Dagmara; Tanga, Paolo; Carry, Benoit +3 more
Aims: The primary objective of this study is to utilize Gaia DR3 asteroid astrometry to detect the Yarkovsky effect, a non-gravitational acceleration that affects the orbits of small asteroids. We then computed the bulk densities for the sample of objects for which we obtained an estimation of the Yarkovsky effect.
Methods: We used the v…
Multiwavelength observations of PSR J2021+4026 across a mode change reveal a phase shift in its X-ray emission
Harding, A. K.; Kerr, M.; Marelli, M. +6 more
Context. We have investigated the multiwavelength emission of PSR J2021+4026, the only isolated γ-ray pulsar known to be variable, which in October 2011 underwent a simultaneous change in γ-ray flux and spin-down rate, followed by a second mode change in February 2018. Multiwavelength monitoring is crucial to understand the physics behind these ev…
An imaged 15 MJup companion within a hierarchical quadruple system
Henning, T.; Janson, M.; Langlois, M. +20 more
Context. Since 2019, the direct imaging B-star Exoplanet Abundance STudy (BEAST) at SPHERE@VLT has been scanning the surroundings of young B-type stars in order to ascertain the ultimate frontiers of giant planet formation. Recently, the 17−4+3 Myr HIP 81208 was found to host a close-in (∼50 au) brown dwarf and a wider (∼230 …
A survey for variable young stars with small telescopes: VI - Analysis of the outbursting Be stars NSW 284, gaia 19eyy, and VES 263
De, Kishalay; Hillenbrand, Lynne A.; Eislöffel, Jochen +44 more
This paper is one in a series reporting results from small telescope observations of variable young stars. Here, we study the repeating outbursts of three likely Be stars based on long-term optical, near-infrared, and mid-infrared photometry for all three objects, along with follow-up spectra for two of the three. The sources are characterized as …
Artificial neural network for star tracker centroid computation
Zapevalin, P. R.; Novoselov, A.; Zharov, V. E.
We propose a unique dataset with star images, their centroids, and a new centroid algorithm based on machine learning, that significantly improves star image centroid performance. The centroid of the star image is the subpixel coordinates on the image plane corresponding to the assumed point source of the light (a star). We have compiled and open-…