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Close binary evolution based on Gaia DR2. The origin of late WC-type Wolf-Rayet stars with low luminosity
Meynet, Georges; Qin, Ying; Ekström, Sylvia +8 more
Context. The observed late-type WC Wolf-Rayet stars (WC7-9) with low luminosity below log L/L⊙ < 5.4 in the HR diagram cannot be reproduced satisfactorily by the evolutionary track of single stars. The mass transfer due to Roche lobe overflow drastically modifies the internal structure and surface compositions of two components. Ther…
Transient two-pole accretion in the polar V496 UMa
Garnavich, P. M.; Kennedy, M. R.; Littlefield, C.
We report XMM-Newton and TESS observations of V496 UMa, an AM Herculis-type cataclysmic variable. The XMM-Newton observation reveals that at times, two poles on the white dwarf accrete simultaneously, but accretion on to the secondary magnetic pole is erratic and can nearly cease in less than one binary orbit (1.5 h). Modelling of the X-ray spectr…
Impacts of zonal winds on planetary oscillations and Saturn ring seismology
Fuller, Jim; Dewberry, Janosz W.; Mankovich, Christopher R.
The excitation of density and bending waves in Saturn's C ring by planetary oscillation modes presents a unique opportunity to learn about gas giant interiors and rotation. However, theoretical complications related to Saturn's rapid and differential rotation pose a barrier to the full utilization of ring wave detections. We calculate oscillation …
Mechanical Properties of Cometary Surfaces
Vincent, Jean-Baptiste; Biele, Jens; Knollenberg, Jörg
Mechanical properties, in particular, strength (tensile, shear, compressive) and porosity, are important parameters for understanding the evolution and activity of comets. However, they are notoriously difficult to measure. Unfortunately, neither Deep Impact nor other comet observations prior to Rosetta provided firm data on the strength of cometa…
Fundamental effective temperature measurements for eclipsing binary stars - II. The detached F-type eclipsing binary CPD-54 810
Maxted, P. F. L.; Southworth, J.; Tan, T. G. +2 more
CPD-54 810 is a double-lined detached eclipsing binary containing two mid-F type dwarfs on an eccentric 26-d orbit. We perform a combined analysis of the extensive photometry obtained by the TESS space mission along with previously published observations to obtain a full orbital and physical solution for the system. We measure the following model-…
Overexpansion-dominated coronal mass ejection formation and induced radio bursts
Song, H. Q.; Cheng, X.; Ding, M. D. +1 more
Aims: Coronal mass ejections (CMEs) are the most fascinating explosions in the Solar System. Their formation is still not fully understood, however.
Methods: We investigated a well-observed CME on 2021 May 7 that showed a typical three-component structure and was continuously observed from 0 to 3 R⊙ by a combination of SDO/AIA…
The Ice Composition Close to the Surface of Comet 67P/Churyumov-Gerasimenko
Altwegg, Kathrin; Rubin, Martin; Läuter, Matthias +1 more
The relation between ice composition in the nucleus of comet 67P/Churyumov-Gerasimenko on the one hand and relative abundances of volatiles in the coma on the other hand is important for the interpretation of density measurements in the environment of the cometary nucleus. For the 2015 apparition, in situ measurements from the two ROSINA (Rosetta …
Perfecting Our Set of Spectrophotometric Standard DA White Dwarfs
Rest, Armin; Matheson, Thomas; Raddi, Roberto +17 more
We verified for photometric stability a set of DA white dwarfs with Hubble Space Telescope magnitudes from the near-ultraviolet to the near-infrared and ground-based spectroscopy by using time-spaced observations from the Las Cumbres Observatory network of telescopes. The initial list of 38 stars was whittled to 32 final ones, which comprise a hig…
Unbound Close Stellar Encounters in the Solar Neighborhood
Hansen, Bradley M. S.
We present a catalog of unbound stellar pairs, within 100 pc of the Sun, that are undergoing close, hyperbolic, encounters. The data are drawn from the GAIA EDR3 catalog, and the limiting factors are errors in the radial distance and unknown velocities along the line of sight. Such stellar pairs have been suggested to be possible events associated…
Exploring the Fundamental Mechanism in Driving Highest-Velocity Ionized Outflows in Radio AGNs
Xue, Yongquan; Woo, Jong-Hak; He, Zhicheng +4 more
We investigate the ionized gas kinematics relationship with X-ray, radio and accreting properties using a sample of 348 nearby (z<0.4) SDSS-FIRST-X-ray detected AGNs. X-ray properties of our sample are obtained from XMM-Newton, Swift and Chandra observations. We unveil the ionized gas outflows in our sample manifested by the non-gravitational b…