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Metallicity estimates of young clusters in the Magellanic Clouds from Strömgren photometry of supergiant stars
Piatti, Andrés E.; Pietrzyński, Grzegorz; Graczyk, Dariusz +2 more
We present results obtained from Strömgren photometry of 13 young (∼30-220 Myr) Magellanic Cloud (MC) clusters, most of them lacking in the literature from direct metallicity measurements. We derived for them [Fe/H] values from a high-dispersion spectroscopy-based empirical calibration of the Strömgren metallicity sensitive index m1 for…
The Rocky-Like Behavior of Cometary Landslides on 67P/Churyumov-Gerasimenko
Bertaux, Jean-Loup; Da Deppo, Vania; Naletto, Giampiero +36 more
Landslides have been identified on several solar system bodies, and different mechanisms have been proposed to explain their runout length. We analyze images from the Rosetta mission and report the global characterization of such features on comet 67P/Churyumov-Gerasimenko's surface. By assuming the height to runout length as an approximation for …
Hubble Space Telescope photometry of multiple stellar populations in the inner parts of NGC 2419
Hernandez, Svea; Brodie, Jean; Larsen, Søren S. +2 more
We present new deep imaging of the central regions of the remote globular cluster NGC 2419, obtained with the F343N and F336W filters of the Wide Field Camera 3 on board the Hubble Space Telescope. The new data are combined with archival imaging to constrain nitrogen and helium abundance variations within the cluster. We find a clearly bimodal dis…
Chandra, MDM, Swift, and NuSTAR Observations Confirming the SFXT Nature of AX J1949.8+2534
Halpern, Jules P.; Hare, Jeremy; Rahoui, Farid +3 more
AX J1949.8+2534 is a candidate supergiant fast X-ray transient (SFXT) observed in outburst by the International Gamma-ray Astrophysics Laboratory (IGR J19498+2534). We report on the results of six Neil Gehrels Swift-XRT, one Chandra, and one Nuclear Spectroscopic Telescope Array observation of the source. We find evidence of rapid X-ray variabilit…
Impact of Data Assimilation on Thermal Tides in the Case of Venus Express Wind Observation
Sugimoto, Norihiko; Takagi, Masahiro; Kouyama, Toru
Impacts of horizontal winds assimilation on thermal tides are investigated by using the Venus atmospheric general circulation model for the Earth Simulator local ensemble transform Kalman filter data assimilation system. The assimilated data are horizontal winds derived from Venus ultraviolet images taken by the Venus Monitoring Camera onboard the…
Lyα Observations of High Radial Velocity Low-mass Stars Ross 1044 and Ross 825
Shkolnik, Evgenya L.; Schneider, Adam C.; Barman, Travis S. +1 more
The discovery of habitable zone (HZ) planets around low-mass stars has highlighted the need for a comprehensive understanding of the radiation environments in which such planets reside. Of particular importance is knowledge of the far-ultraviolet (FUV) radiation, as low-mass stars are typically much more active than solar-type stars and the proxim…
Gaia GraL: Gaia DR2 gravitational lens systems. IV. Keck/LRIS spectroscopic confirmation of GRAL 113100-441959 and model prediction of time delays
Djorgovski, S. G.; Stern, D.; Surdej, J. +17 more
We report the spectroscopic confirmation and modeling of the quadruply imaged quasar GRAL 113100-441959, the first gravitational lens (GL) to be discovered from a machine learning technique that only relies on the relative positions and fluxes of the observed images without considering colour informations. Follow-up spectra obtained with Keck/LRIS…
Kinematics of the Galaxy from a Sample of Young Open Star Clusters with Data from the Gaia DR2 Catalogue
Bobylev, V. V.; Bajkova, A. T.
We have selected a sample of 326 young (log t < 8) open star clusters with the proper motions and distances calculated by various authors from Gaia DR2 data. The mean values of their line-of-sight velocities have also been taken from various publications. As a result of our kinematic analysis, we have found the following parameters of the angul…
Probing the unidentified Fermi blazar-like population using optical polarization and machine learning
Blinov, D.; Liodakis, I.
The Fermi γ-ray space telescope has revolutionized our view of the γ-ray sky and the high-energy processes in the Universe. While the number of known γ-ray emitters has increased by orders of magnitude since the launch of Fermi, there is an ever increasing number of, now more than a thousand, detected point sources whose low-energy counterpart is …
Detection of metal-rich, cool-warm gas in the outskirts of galaxy clusters
Charlton, Jane C.; Nagai, Daisuke; Pradeep, Jayadev +3 more
We present an ultraviolet quasar absorption line analysis of metal lines associated with three strong intervening H I absorbers (with N(H I) > 1016.5 cm-2) detected in the outskirts of Sunyaev-Zel'dovich (SZ) effect-selected galaxy clusters (zcl ∼ 0.4-0.5), within clustocentric impact parameters of ρcl