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Gaia EDR3 comparative study of protoplanetary disk fractions in young stellar clusters
Mendigutía, I.; Huélamo, N.; Solano, E. +4 more
Context. The lifetime of protoplanetary disks around young stars limits the timescale of planet formation. A disk dissipation timescale ≤10 Myr was inferred from surveys that count the relative number of stars with disks - the disk fraction - in young stellar clusters with different ages. However, most previous surveys focused on the compact regio…
Implications of Kappa Suprathermal Halo of the Solar Wind Electrons
Pierrard, Viviane; Lazar, Marian; Stverak, Stepan
The electron velocity distributions measured in-situ in space plasmas reveal two central populations, a low-energy and highly dense (quasi-)thermal core, and a more diffuse but hotter suprathermal halo. Even if the core contributes much more to the total number density than the suprathermal particles, the energetic electrons play an important role…
The Pulsating Helium-atmosphere White Dwarfs. I. New DBVs from the Sloan Digital Sky Survey
Kepler, S. O.; Hermes, J. J.; Bell, Keaton J. +4 more
We present a dedicated search for new pulsating helium-atmosphere (DBV) white dwarfs from the Sloan Digital Sky Survey using the McDonald 2.1 m Otto Struve Telescope. In total we observed 55 DB and DBA white dwarfs with spectroscopic temperatures between 19,000 and 35,000 K. We find 19 new DBVs and place upper limits on variability for the remaini…
Flux emergence and generation of flare-productive active regions
Toriumi, Shin
Solar flares and coronal mass ejections are among the most prominent manifestations of the magnetic activity of the Sun. The strongest events of them tend to occur in active regions (ARs) that are large, complex, and dynamically evolving. However, it is not clear what the key observational features of such ARs are, and how these features are produ…
A Multi-Event Study of Early-Stage SEP Acceleration by CME-Driven Shocks—Sun to 1 AU
Zucca, Pietro; Kozarev, Kamen; Nedal, Mohamed +2 more
The solar corona between below 10 solar radii is an important region for early acceleration and transport of solar energetic particles (SEPs) by coronal mass ejection-driven shock waves. There, these waves propagate into a highly variable dynamic medium with steep gradients and rapidly expanding coronal magnetic fields, which modulates the particl…
A Photometric and Astrometric Study of the Open Clusters NGC 1664 and NGC 6939
Bilir, Selçuk; Yontan, Talar; Paunzen, Ernst +5 more
This study calculated astrophysical parameters, as well as kinematic and galactic orbital parameters, of the open clusters NGC 1664 and NGC 6939. The work is based on CCD ultraviolet, blue, and visual (UBV) and Gaia photometric and astrometric data from ground- and space-based observations. Considering Gaia Early Data Release 3 (EDR3) astrometric …
Parameters of the Galactic Spiral Density Wave from Masers with Parallax Errors Less Than 10\boldsymbol{%}
Bobylev, V. V.; Bajkova, A. T.
We have studied the kinematics of Galactic masers and radio stars with measured VLBI trigonometric parallaxes and proper motions. We have considered masers with relative trigonometric parallax errors less than 10${%}$ and determined the Galactic rotation parameters from them. In particular, the linear rotation velocity of the Galaxy at the solar d…
Intrinsic Shapes of Brightest Cluster Galaxies
Bender, Ralf; Thomas, Jens; Saglia, Roberto P. +5 more
We discuss the statistical distribution of galaxy shapes and viewing angles under the assumption of triaxiality by deprojecting observed surface brightness profiles of 56 brightest cluster galaxies (BCGs) coming from a recently published large deep-photometry sample. For the first time, we address this issue by directly measuring axis ratio profil…
Confirmation and characterisation of three giant planets detected by TESS from the FIES/NOT and Tull/McDonald spectrographs
Bieryla, Allyson; Quinn, Samuel N.; Cochran, William D. +37 more
We report the confirmation and characterisation of TOI-1820 b, TOI-2025 b, and TOI-2158 b, three Jupiter-sized planets on short-period orbits around G-type stars detected by TESS. Through our ground-based efforts using the FIES and Tull spectrographs, we have confirmed these planets and characterised their orbits, and find periods of around 4.9 d,…
AutoSourceID-Light. Fast optical source localization via U-Net and Laplacian of Gaussian
Groot, P. J.; Jóhannesson, G.; Vreeswijk, P. +9 more
Aims: With the ever-increasing survey speed of optical wide-field telescopes and the importance of discovering transients when they are still young, rapid and reliable source localization is paramount. We present AutoSourceID-Light (ASID-L), an innovative framework that uses computer vision techniques that can naturally deal with large amount…