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Resolving Red Giant Winds with the Hubble Space Telescope
Harper, Graham M.; Wood, Brian E.; Müller, Hans-Reinhard
We describe recent spectroscopic observations of red giant stars made by the Space Telescope Imaging Spectrograph (STIS) instrument on board the Hubble Space Telescope, which has provided spatially resolved observations of the warm chromospheric winds that predominate for early K to mid-M giants. The H I Lyα lines of a set of 11 red giants observe…
KIC 6362386: An Eclipsing Binary with γ Doradus–type Pulsations and Starspots
Zhang, Xiaobin; Zong, Weikai; Wang, Jiaxin +5 more
KIC 6362386 is an eclipsing binary system that exhibits both γ Doradus (γ Dor)–type pulsations and starspots. In this study, we investigated this binary system using the Kepler photometry and the spectroscopic data from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope. After employing the PHOEBE program for light-curve and radial-velo…
Primeros resultados del estudio observacional de estrellas masivas y centrales en cúmulos abiertos
González, J. F.; Alejo, A. D.; González, S. P.
Theoretical models show that binary and multiple stars play an important rol in the energetics of open clusters and therefore in their dynamical evolution, particulary in poor clusters dominated by one or a few central massive stars. In this work we present the results of our spectroscopic, astrometric and photometric analysis of four young open c…
JWST Resolves Collision-induced Absorption Features in White Dwarfs
Blouin, Simon; Dufour, Patrick; Kilic, Mukremin +2 more
Infrared-faint white dwarfs are cool white dwarfs exhibiting significant infrared flux deficits, most often attributed to collision-induced absorption (CIA) from H2–He in mixed hydrogen–helium atmospheres. We present James Webb Space Telescope (JWST) near- and mid-infrared spectra of three such objects using Near-Infrared Spectrograph (…
Solar Wind Turbulence and Complexity Probed with Rank-Ordered Multifractal Analysis (ROMA)
Voitcu, Gabriel; Echim, Marius; Munteanu, Costel +1 more
The Rank-Ordered Multifractal Analysis (ROMA) is a tool designed to characterize scale (in)variance and multifractality based on rank ordering the fluctuations in "groups" characterized by the same mono-fractal behavior (Hurst exponent). A range-limited structure-function analysis provides the mono-fractal index for each rank-ordered range of fluc…
Prolonged Fluvial Activity Revealed by Mapping and Analyses of Valley Networks in the Northwestern Hellas Region, Mars
Xiao, Long; Zhao, Jiannan; Shi, Yutong +4 more
Valley networks (VNs) on Mars are crucial for understanding the Martian hydrologic and climatic history. However, the limited resolution of remote sensing data hindered the complete identification of Martian VNs, affecting our understanding of the formation and duration of VNs as well as their climatic significance. In this study, we utilized high…
Observational Characteristics of Solar EUV Waves
Joshi, Bhuwan; Chen, P. F.; Awasthi, Arun Kumar +4 more
Extreme-ultraviolet (EUV) waves are one of the large-scale phenomena on the Sun. They are defined as large propagating fronts in the low corona with speeds ranging from a few tens km s‑1 to several 1000 km s‑1. They are often associated with solar filament eruptions, flares, and/or coronal mass ejections (CMEs). EUV waves exhibit various features,…
Chromospheric Mg I emission lines of pre-main-sequence stars
Itoh, Yoichi; Takagi, Yuhei; Yamashita, Mai
Context. To reveal details of the internal structure, the relationship between chromospheric activity and the Rossby number has been extensively examined for main-sequence stars. For active pre-main-sequence (PMS) stars, it is suggested that the level of activity be assessed using optically thin emission lines, such as Mg I. Aims. We aim to detect…
Statistical Investigation of Wave Propagation in the Quiet-Sun Using IRIS Spectroscopic Observations
Srivastava, A. K.; Scullion, E.; Kayshap, P. +2 more
In this analysis, we use spectroscopic observations of the quiet Sun made by the IRIS instrument and investigate wave propagation. We analyze various spectral lines formed in different atmospheric layers, such as the photosphere, chromosphere, and transition region. We examine the Doppler velocity time series at various locations in the quiet Sun …
Searching for planet-driven dust spirals in ALMA visibilities
Clarke, Cathie J.; Booth, Richard A.; Ribas, Álvaro +2 more
Atacama Large Millimetre/submillimetre Array (ALMA) observations of the thermal emission from protoplanetary disc dust have revealed a wealth of substructures that could evidence embedded planets, but planet-driven spirals, one of the more compelling lines of evidence, remain relatively rare. Existing works have focused on detecting these spirals …