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Accretion Variability of the Multiple T Tauri System VW Cha
Pál, András; Ábrahám, Péter; Kóspál, Ágnes +5 more
Classical T Tauri stars are low-mass objects that are still accreting material from the surrounding circumstellar disk. The accretion process is essential in the formation of Sun-like stars and in setting the properties of the disk at the time when planet formation occurs. We constructed a complex data set in order to examine the accretion process…
Presence of clay minerals can obscure spectral evidence of Mg sulfates: implications for orbital observations of Mars
Milliken, Ralph E.; Sheppard, Rachel Y.; Robertson, Kevin M.
The martian crust is often viewed through the lens of its dominant secondary minerals, Noachian phyllosilicates and Hesperian sulfates, based on orbital spectral observations. However, the effects of surface exposure on the spectra of these hydrous minerals are not fully understood. We use an environmental chamber to measure changes in near-infrar…
Prospects for mapping temporal height variations of the seasonal CO2 snow/ice caps at the Martian poles by co-registration of MOLA profiles
Oberst, Jürgen; Schmidt, Frédéric; Steinbrügge, Gregor +3 more
We investigate the feasibility and demonstrate the merits of using Mars Orbiter Laser Altimeter (MOLA) profiles to retrieve seasonal height variations of CO2 snow/ice cap in Mars' polar areas by applying a co-registration strategy. We present a prototype analysis on the research region of [85.75°S, 86.25°S, 300°E, 330°E] that is located…
Statistical Analysis of the Distribution and Evolution of Mirror Structures in the Martian Magnetosheath
Jin, Taifeng; Lei, Li; Yiteng, Zhang +2 more
The mirror-mode structures in the Martian magnetosheath that were observed by Mars Atmosphere and Volatile Evolution during 2015-2018 are analyzed statistically. It is found that most mirror-mode events occurred close to the bow shock. Morphological categorization based on skewness of the magnetic field shows that ~46.57% of the observed mirror-mo…
Parameter Distributions for the Drag-Based Modeling of CME Propagation
Foldes, Raffaello; Pietropaolo, Ermanno; Paouris, Evangelos +7 more
In recent years, ensemble modeling has been widely employed in space weather to estimate uncertainties in forecasts. We here focus on the ensemble modeling of Coronal Mass Ejections (CME) arrival times and arrival velocities using a drag-based model, which is well-suited for this purpose due to its simplicity and low computational cost. Although e…
Periodic stellar variability from almost a million NGTS light curves
Jackman, James A. G.; Wheatley, Peter J.; Bayliss, Daniel +25 more
We analyse 829 481 stars from the Next Generation Transit Survey (NGTS) to extract variability periods. We utilize a generalization of the autocorrelation function (the G-ACF), which applies to irregularly sampled time series data. We extract variability periods for 16 880 stars from late-A through to mid-M spectral types and periods between ~0.1 …
Wide binaries from the H3 survey: the thick disc and halo have similar wide binary fractions
Conroy, Charlie; Ting, Yuan-Sen; Cargile, Phillip +8 more
Due to the different environments in the Milky Way's disc and halo, comparing wide binaries in the disc and halo is key to understanding wide binary formation and evolution. By using Gaia Early Data Release 3, we search for resolved wide binary companions in the H3 survey, a spectroscopic survey that has compiled ~150 000 spectra for thick-disc an…
X-ray activity of the young solar-like star Kepler-63 and the structure of its corona
Orlando, S.; Stelzer, B.; Coffaro, M.
The X-ray satellite XMM-Newton has so far revealed coronal cycles in seven solar-like stars. Of these, the youngest stars ϵ Eridani (~400 Myr) and ι Horologii (~600 Myr) display the shortest X-ray cycles and the smallest amplitudes, defined as the variation of the X-ray luminosity between the maximum and minimum of the cycle. The X-ray cycle of ϵ …
Search for Planets in Hot Jupiter Systems with Multi-Sector TESS Photometry. II. Constraints on Planetary Companions in 12 Systems
Maciejewski, G.
Uninterrupted observations from space-borne telescopes provide the photometric precision that is required to detect shallow transits of small planets missed by ground-based surveys. We used data from the Transiting Exoplanet Survey Satellite (TESS) to search for nearby planetary companions in 12 planetary systems with hot Jupiters: HD 2685, Qatar-…
Turin-SyCAT: A multifrequency catalog of Seyfert galaxies
Capetti, A.; Masetti, N.; Chavushyan, V. +3 more
Aims: We present the first release of Turin-SyCAT, a multifrequency catalog of Seyfert galaxies.
Methods: We selected Seyfert galaxies considering criteria based on radio, infrared, and optical properties and starting from sources belonging to hard X-ray catalogs and surveys. We visually inspected optical spectra available for all select…