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Tropopause and lower stratosphere winds and eddy fluxes on Saturn as seen by Cassini imaging
Del Genio, Anthony D.; Barbara, John M.
An automated cloud feature tracking algorithm is applied to 2004 Cassini Imaging Science Subsystem images of Saturn's southern hemisphere and equatorial region (5°N-70°S) in continuum, methane band, and ultraviolet filters to derive zonal wind profiles and eddy momentum fluxes from the middle troposphere cloud tops to the lower stratosphere. Zonal…
Thermophysical Characterization of Cyclic Frost Formation in the Subsurface and Nominal Water Activity on Comets: Case Study of 67P/Churyumov-Gerasimenko
Shi, Xian; Hu, Xuanyu
We use a generic thermophysical model to study in detail the formation of water-ice frost in the near-surface layers of comet 67P/Churyumov-Gerasimenko. We show that nightly frost formation is a common phenomenon. In particular, while abrupt landscapes may be conducive to frost formation, they are not a requisite condition. We show that the proces…
Sustaining Star Formation in the Galactic Star Cluster M 36?
Chen, Wen Ping; Gao, Yu; Sun, Yan +3 more
We present comprehensive characterization of the Galactic open cluster M 36. Some 200 member candidates, with an estimated contamination rate of ∼8%, have been identified on the basis of proper motion and parallax measured by the Gaia DR2. The cluster has a proper motion grouping around ( ${\mu }_{\alpha }\cos \delta =-0.15\pm 0.01$ <!-- -->…
Saturn's Nightside Ring Current During Cassini's Grand Finale
Roussos, E.; Cowley, S. W. H.; Bunce, E. J. +7 more
During Cassini's Grand Finale proximal orbits, the spacecraft traversed the nightside magnetotail to ∼21 Saturn radii. Clear signatures of Saturn's equatorial current sheet are observed in the magnetic field data. An axisymmetric model of the ring current is fitted to these data, amended to take into account the tilt of the current layer by solar …
Debris discs in binaries: morphology and photometric signatures
Kral, Q.; Olofsson, J.; Thebault, P.
Context. Since about half of all main-sequence stars reside in multiple star systems, it is important to consider the effect of binarity on the evolution of planetesimal belts in these complex systems.
Aims: We aim to see whether debris belts evolving between two stars may be impacted by the presence of the companion and whether this leaves a…
Bayes-based Orbital Elements Estimation in Triple Hierarchical Stellar Systems
Mendez, Rene A.; Orchard, Marcos E.; Silva, Jorge F. +1 more
Under certain rather prevalent conditions (driven by dynamical orbital evolution), a hierarchical triple stellar system can be well approximated, from the standpoint of orbital parameter estimation, as two binary star systems combined. Even under this simplifying approximation, the inference of orbital elements is a challenging technical problem b…
Exploring sub-MeV sensitivity of AstroSat–CZTI for ON-axis bright sources
Rao, A. R.; Bhalerao, Varun; Mithun, N. P. S. +5 more
The Cadmium–Zinc–Telluride Imager (CZTI) onboard AstroSat is designed for hard X-ray imaging and spectroscopy in the energy range of 20–100 keV. The CZT detectors are of 5-mm thickness and hence have good efficiency for Compton interactions beyond 100 keV. The polarisation analysis using CZTI relies on such Compton events and have been verified ex…
Redshift identification of X-ray-selected active galactic nuclei in the J1030 field: searching for large-scale structures and high-redshift sources
Prandoni, I.; Bolzonella, M.; Vignali, C. +23 more
We publicly release the spectroscopic and photometric redshift catalog of the sources detected with Chandra in the field of the z = 6.3 quasar SDSS J1030+0525. This is currently the fifth-deepest extragalactic X-ray field, and reaches a 0.5-2 keV flux limit of f0.5 − 2 = 6 × 10−17 erg s−1 cm−2. Using two…
Dynamics of Sunspot Shock Waves in the Chromosphere and Transition Region
Kayshap, Pradeep; Tripathi, Durgesh; Jelínek, P.
We study the dynamics of shock waves observed in the umbra of a sunspot using the spectroscopic observations from the Interface Region Imaging Spectrograph. The presence of a shock significantly deforms the shape of the spectral lines of Mg II, C II, and Si IV. We found that C II 1335.71 Å and Si IV 1393.75 Å show double-peaked profiles that chang…
Multi-band observations of Swift J0840.7−3516: A new transient ultra-compact X-ray binary candidate
Campana, S.; Rea, N.; Esposito, P. +5 more
We report on multi-band observations of the transient source Swift J0840.7−3516, which was detected in outburst in 2020 February by the Neil Gehrels Swift Observatory. The outburst episode lasted just ∼5 days, during which the X-ray luminosity quickly decreased from LX ≈ 3 × 1037 d102 erg s−1 …