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The young stellar population in NGC 247. Main properties and hierarchical clustering
Baume, G.; Rodríguez, M. J.; Feinstein, C.
Aims: We seek to investigate the characteristics of the young stellar population in the spiral galaxy NGC 247. In particular, we focused our attention in its hierarchical clustering distributions and the properties of the smallest groups.
Methods: We used multiband Hubble Space Telescope (HST) data from three fields covering more than ha…
A black box for dark sector physics: predicting dark matter annihilation feedback with conditional GANs
Lewis, Geraint F.; List, Florian; Bhat, Ishaan
Traditionally, incorporating additional physics into existing cosmological simulations requires re-running the cosmological simulation code, which can be computationally expensive. We show that conditional Generative Adversarial Networks (cGANs) can be harnessed to predict how changing the underlying physics alters the simulation results. To illus…
Variability of Intra-D Ring Azimuthal Magnetic Field Profiles Observed on Cassini's Proximal Periapsis Passes
Dougherty, M. K.; Cowley, S. W. H.; Bunce, E. J. +4 more
We overview the properties of the azimuthal magnetic fields observed during the periapsis passes of the final 23 orbits of the Cassini spacecraft, including the partial orbit at end of mission, on near equatorial field lines passing inside of Saturn's D ring. The signatures are variable in form and amplitude, though generally approximately symmetr…
Asteroseismic constraints on active latitudes of solar-type stars: HD 173701 has active bands at higher latitudes than the Sun
Chaplin, William J.; Davies, Guy R.; Miglio, Andrea +6 more
We present a new method for determining the location of active bands of latitude on solar-type stars, which uses stellar-cycle-induced frequency shifts of detectable solar-like oscillations. When near-surface activity is distributed in a non-homogeneous manner, oscillation modes of different angular degree and azimuthal order will have their frequ…
Resonant instabilities of kinetic Alfvén waves in the Earth's magnetosphere with superthermal electrons
Lakhina, G. S.; Singh, S. V.; Barik, K. C.
A theoretical plasma model for the generation of kinetic Alfvén waves (KAWs), having background Maxwellian ions, κ-electrons, and drifting Maxwellian beam ions, is discussed. The ion beam streams along the ambient magnetic field, whereas velocity shear is perpendicular to it. The role played by nonthermal electrons in the excitation of resonant KA…
Ultraviolet observation of Enceladus' plume in transit across Saturn, compared to Europa
Hansen, C. J.; Hendrix, A. R.; Esposito, L. W.
Saturn's moon Enceladus is known to have a water vapor plume erupting from fissures across its south polar region. The plume was detectable in an observation of Enceladus transiting Saturn by Cassini's Ultraviolet Imaging Spectrograph (UVIS), but only at 1216 Å (Lyman alpha). Jupiter's moon Europa also may have multiple water vapor plumes, detecte…
Magnetic activity of the young solar analog V1358 Orinis
Granzer, T.; Carroll, T. A.; Kriskovics, L. +3 more
Context. Young, fast-rotating single stars can show dramatically different magnetic signatures and levels of magnetic activity as compared with the Sun. While losing angular momentum due to magnetic breaking and mass loss through stellar winds, the stars gradually spin down resulting in decreasing levels of activity. Studying magnetic activity on …
A Thermal Inertia Map of Titan
MacKenzie, Shannon M.; Lorenz, Ralph D.; Lora, Juan M.
Like Earth, the atmosphere of Titan, Saturn's largest moon, is affected by the ability of the surface to store and release heat. Modeling efforts have shown that global temperature distributions and wind profiles differ between simulations describing Titan's surface with a uniform thermal inertia. Cassini-Huygens demonstrated, however, that a vari…
Stellar masses from granulation and oscillations of 23 bright red giants observed by BRITE-Constellation
Handler, G.; Wade, G. A.; Hekker, S. +11 more
Context. The study of stellar structure and evolution depends crucially on accurate stellar parameters. The photometry from space telescopes has provided superb data that enabled the asteroseismic characterisation of thousands of stars. However, typical targets of space telescopes are rather faint and complementary measurements are difficult to ob…
APOGEE/Kepler Overlap Yields Orbital Solutions for a Variety of Eclipsing Binaries
Stassun, Keivan G.; Agol, Eric; Rawls, Meredith L. +4 more
Spectroscopic eclipsing binaries (SEBs) are fundamental benchmarks in stellar astrophysics and today are observed in breathtaking detail by missions like the Transiting Exoplanet Survey Satellite (TESS), Kepler, and Apache Point Observatory Galactic Evolution Experiment (APOGEE). We develop a methodology for simultaneous analysis of high-precision…