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Giant Planet Atmospheres: Dynamics and Variability from UV to Near-IR Hubble and Adaptive Optics Imaging
Wong, Michael H.; Fletcher, Leigh N.; Simon, Amy A. +2 more
Each of the giant planets, Jupiter, Saturn, Uranus, and Neptune, has been observed by at least one robotic spacecraft mission. However, these missions are infrequent; Uranus and Neptune have only had a single flyby by Voyager 2. The Hubble Space Telescope, particularly the Wide Field Camera 3 (WFC3) and Advanced Camera for Surveys (ACS) instrument…
Fundamental stellar parameters of benchmark stars from CHARA interferometry. II. Dwarf stars
White, T. R.; Casagrande, L.; Nordlander, T. +3 more
Context. Stellar models applied to large stellar surveys of the Milky Way need to be properly tested against a sample of stars with highly reliable fundamental stellar parameters. We have established a programme aiming to deliver such a sample of stars.
Aims: Here we present new fundamental stellar parameters of nine dwarf stars that will be …
A Snowball in Hell: The Potential Steam Atmosphere of TOI-1266c
Batalha, Natasha E.; Mahadevan, Suvrath; Hedges, Christina +4 more
TOI-1266c is a recently discovered super-Venus in the radius valley orbiting an early M dwarf. However, its notional bulk density (~2.2 g cm-3) is consistent with a large volatile fraction, suggesting that it might have volatile reservoirs that have survived billions of years at more than twice Earth's insolation. On the other hand, the…
Predicting CME arrival time through data integration and ensemble learning
Xu, Yan; Jing, Ju; Wang, Haimin +7 more
The Sun constantly releases radiation and plasma into the heliosphere. Sporadically, the Sun launches solar eruptions such as flares and coronal mass ejections (CMEs). CMEs carry away a huge amount of mass and magnetic flux with them. An Earth-directed CME can cause serious consequences to the human system. It can destroy power grids/pipelines, sa…
Dynamical parallax, physical parameters, and evolutionary status of the components of the bright eclipsing binary α Draconis
Bodensteiner, J.; Bowman, D. M.; Tkachenko, A. +13 more
Aims: Both components of the bright eclipsing binary α Dra have been resolved using long baseline interferometry and the secondary component has been shown to contribute approximately 15% of the total flux; however, a spectroscopic detection of the companion star has so far been unsuccessful. We aim for a firm spectroscopic detection of the s…
On the Origin of the Dichotomy of Stellar Activity Cycles
Corsaro, Enrico; Bonanno, Alfio
The presence of possible correlations between stellar rotation rate Ω and the frequency of the activity cycle ω cyc is still much debated. We implement a new Bayesian classification algorithm based on a simultaneous regression analysis of multiple scaling laws and we demonstrate the existence of two different scalings in the ${\mathrm{l…
Lithium on the lower red giant branch of five Galactic globular clusters
Salaris, M.; Pancino, E.; Monaco, L. +3 more
Context. Lithium is one of the few elements produced during Big Bang nucleosynthesis in the early universe. Moreover, its fragility makes it useful as a proxy for stellar environmental conditions. As such, the lithium abundance in old systems is at the core of various astrophysical investigations.
Aims: Stars on the lower red giant branch are…
Asteroid astrometry by stellar occultations: Accuracy of the existing sample from orbital fitting
Tanga, P.; Spoto, F.; Herald, D. +2 more
Context. The technique of stellar occultations, greatly enhanced by the publication of the Gaia data releases, permits not only the determination of asteroid size and shape, but also the retrieval of additional, very accurate astrometry, with a possible relevant impact on the study of dynamical properties. The use of Gaia as reference catalogue an…
The GALAH Survey: A New Sample of Extremely Metal-poor Stars Using a Machine-learning Classification Algorithm
Lewis, Geraint F.; Spitler, Lee R.; Ting, Yuan-Sen +21 more
Extremely metal-poor (EMP) stars provide a valuable probe of early chemical enrichment in the Milky Way. Here we leverage a large sample of ~600,000 high-resolution stellar spectra from the GALAH survey plus a machine-learning algorithm to find 54 candidates with estimated [Fe/H] ≤-3.0, six of which have [Fe/H] ≤-3.5. Our sample includes ~20% main…
Asteroid phase curves using sparse Gaia DR2 data and differential dense light curves
Shevchenko, V.; Kwiatkowski, T.; Oszkiewicz, D. +10 more
The amount of sparse asteroid photometry being gathered by both space- and ground-based surveys is growing exponentially. This large volume of data poses a computational challenge owing to both the large amount of information to be processed and the new methods needed to combine data from different sources (e.g. obtained by different techniques, i…