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Orbital Period Analysis of Four Eclipsing Binaries XY Boo, RW Com, MR Del and AK Her
Yılmaz, M.; Selam, S. O.; Özavcı, İ. +9 more
The orbital period variations of the eclipsing binaries XY Boo, RW Com, MR Del, and AK Her are investigated. This study includes the first orbital period analysis of the detached eclipsing binary MR Del and necessary updates for the remaining stars with addition of new mid-eclipse times calculated from our recent observations carried out at Ankara…
Extratidal Stars and Chemical Abundance Properties of Two Metal-poor Globular Clusters M53 (NGC 5024) and NGC 5053
Lee, Jae-Joon; Lim, Dongwook; Chun, Sang-Hyun
We search for extratidal stars around two metal-poor Galactic globular clusters, M53 and NGC 5053, using the near-infrared APOGEE spectra. Applying the t-distributed stochastic neighbor embedding (t-SNE) algorithm on the chemical abundances and radial velocities results in identification of two isolated stellar groups composed of cluster member st…
Dust in the Wolf-Rayet nebula M 1-67
Toalá, J. A.; Jiménez-Hernández, P.; Arthur, S. J.
The Wolf-Rayet nebula M 1-67 around WR 124 is located above the Galactic plane in a region mostly empty of interstellar medium, which makes it the perfect target to study the mass-loss episodes associated with the late stages of massive star evolution. Archive photometric observations from Wide-field Infrared Survey Explorer(WISE), Spitzer (MIPS),…
The rich lack close neighbours: the dependence of blue-straggler fraction on metallicity
Wyse, Rosemary F. G.; Kratter, Kaitlin M.; Moe, Maxwell
Blue-straggler stars (BSS) have been identified in star clusters and in field populations in our own Milky Way galaxy and in its satellite galaxies. They manifest as stars bluer and more luminous than the dominant old population, and usually have a spatial distribution that follows the old population. Their progenitors are likely to have been clos…
Machine learning applied to multifrequency data in astrophysics: blazar classification
Arsioli, B.; Dedin, P.
The study of machine learning (ML) techniques for the autonomous classification of astrophysical sources is of great interest, and we explore its applications in the context of a multifrequency data-frame. We test the use of supervised ML to classify blazars according to its synchrotron peak frequency, either lower or higher than 1015 H…
Extremely precise age and metallicity of the open cluster NGC 2506 using detached eclipsing binaries
Grundahl, F.; Knudstrup, E.; Lund, M. N. +10 more
Accurate stellar parameters of stars in open clusters can help constrain models of stellar structure and evolution. Here, we wish to determine the age and metallicity content of the open cluster NGC 2506. To this end, we investigated three detached eclipsing binaries (DEBs; V2032, V4, and V5) for which we determined their masses and radii, as well…
Kinematics of coronal mass ejections in the LASCO field of view
Yashiro, Seiji; Ravishankar, Anitha; Michałek, Grzegorz
In this paper we present a statistical study of the kinematics of 28894 coronal mass ejections (CMEs) recorded by the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory spacecraft from 1996 until mid-2017. The initial acceleration phase is characterized by a rapid increase in CME velocity just after e…
The Electron Proton Helium INstrument as an example for a Space Weather Radiation Instrument
Heber, Bernd; Malandraki, Olga; Posner, Arik +3 more
The near-Earth energetic particle environment has been monitored since the 1970's. With the increasing importance of quantifying the radiation risk for, e.g. for the human exploration of the Moon and Mars, it is essential to continue and further improve these measurements. The Electron Proton Helium INstrument (EPHIN) on-board SOHO continually pro…
Convection in the Magnetosphere-Ionosphere System: A Multimission Survey of Its Response to IMF <span type="mathematics">By Reversals
Fear, R. C.; Haaland, S.; Case, N. A. +2 more
Past studies have demonstrated that the interplanetary magnetic field (IMF) By component introduces asymmetries in the magnetosphere-ionosphere (M-I) system, though the exact timings involved are still unclear with two distinct mechanisms proposed. In this study, we statistically analyze convective flows from three regions of the M-I sy…
Compiling Magnetosheath Statistical Data Sets Under Specific Solar Wind Conditions: Lessons Learnt From the Dayside Kinetic Southward IMF GEM Challenge
Dimmock, A. P.; Hietala, H.; Zou, Y.
The Geospace Environmental Modelling (GEM) community offers a framework for collaborations between modelers, observers, and theoreticians in the form of regular challenges. In many cases, these challenges involve model-data comparisons to provide wider context to observations or validate model results. To perform meaningful comparisons, a statisti…