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Spatial and Kinematic Clustering of Stars in the Galactic Disk
Conroy, Charlie; Ting, Yuan-Sen; El-Badry, Kareem +1 more
The Galactic disk is expected to be spatially and kinematically clustered on many scales due to both star formation and the Galactic potential. In this work we calculate the spatial and kinematic two-point correlation functions (TPCF) using a sample of 1.7 × 106 stars with radial velocities from Gaia DR2. Clustering is detected on spati…
Eight more low luminosity globular clusters in the Sagittarius dwarf galaxy
Minniti, D.; Saito, R. K.; Alonso-García, J. +2 more
Context. The Sagittarius (Sgr) dwarf galaxy is merging with the Milky Way, and the study of its globular clusters (GCs) is important to understand the history and outcome of this ongoing process.
Aims: Our main goal is to characterize the GC system of the Sgr dwarf galaxy. This task is hampered by high foreground stellar contamination, mostly…
Multiwavelength detectability of isolated black holes in the Milky Way
Bertone, Gianfranco; Connors, Riley; Ricotti, Massimo +3 more
Isolated black holes in our Galaxy have eluded detection so far. We present here a comprehensive study on the detectability of isolated stellar-mass astrophysical black holes that accrete interstellar gas from molecular clouds in both the local region and the Central Molecular Zone. We adopt a state-of-the-art model for the accretion physics backe…
Blocks Size Frequency Distribution in the Enceladus Tiger Stripes Area: Implications on Their Formative Processes
Lucchetti, Alice; Pajola, Maurizio; Cremonese, Gabriele +1 more
We study the size frequency distribution of the blocks located in the deeply fractured, geologically active Enceladus South Polar Terrain with the aim to suggest their formative mechanisms. Through the Cassini ISS images, we identify ~17,000 blocks with sizes ranging from ~25 m to 366 m, and located at different distances from the Damascus, Baghda…
Magnetofrictional Modeling of an Erupting Pseudostreamer
Reeves, Katharine K.; DeLuca, Edward E.; Savcheva, Antonia +4 more
In this study, we present the magnetic configuration of an erupting pseudostreamer observed on 2015 April 19, on the southwest limb of the Sun, with a prominence cavity embedded inside. The eruption resulted in a partial halo coronal mass ejection. The prominence eruption begins with a slow rise and then evolves to a fast-rise phase. We analyze th…
The Weizmann Fast Astronomical Survey Telescope (W-FAST): System Overview
Gal-Yam, Avishay; Ofek, Eran O.; Yaron, Ofer +8 more
A relatively unexplored phase space of transients and stellar variability is that of second and sub-second timescales. We describe a new optical observatory operating in the Negev desert in Israel, with a 55 cm aperture, a field of view of 2°6 × 2°6 (≈7 deg2) equipped with a high frame rate, low read noise, CMOS camera. The system can o…
LASCO-C3 Observations of the K- and F-Coronae over 24 Years (1996 - 2019): Photopolarimetry and Electron Density Distribution
Lamy, Philippe; Quémerais, Eric; Gilardy, Hugo +2 more
We present the polarimetric analysis of the white-light images of the corona obtained with the Large-Angle Spectrometric COronagraph LASCO-C3 onboard the Solar and Heliospheric Observatory (SOHO) from 1996 to 2019, leading to the separation of the K- and F-components and the derivation of the electron-density distribution. The analysis makes use o…
Vertical Structure of Galactic Disk Kinematics from LAMOST K Giants
Zhao, Gang; Zhu, Zi; Yang, Chengqun +3 more
We examine the vertical structure of Galactic disk kinematics over a Galactocentric radial distance range of R = 5-15 kpc and up to 3 kpc away from the Galactic plane, using the K-type giants surveyed by LAMOST. Based on robust measurements of three-dimensional velocity moments, a wobbly disk is detected in a phenomenological sense. An outflow dom…
INTEGRAL reloaded: Spacecraft, instruments and ground system
Mereghetti, Sandro; Kretschmar, Peter; Götz, Diego +85 more
The European Space Agency's INTErnational Gamma-Ray Astrophysics Laboratory (ESA/INTEGRAL) was launched aboard a Proton-DM2 rocket on 17 October 2002 at 06:41 CEST, from Baikonur in Kazakhstan. Since then, INTEGRAL has been providing long, uninterrupted observations (up to about 47 h, or 170 ksec, per satellite orbit of 2.7 days) with a large fiel…
A possible planet candidate in an external galaxy detected through X-ray transit
Soria, Roberto; Urquhart, Ryan; Kashyap, Vinay L. +4 more
Many lines of reasoning suggest that external galaxies should host planetary systems, but detecting them by methods typically used in our own Galaxy is not possible. An alternative approach is to study the temporal behaviour of X-rays emitted by bright extragalactic X-ray sources, where an orbiting planet would temporarily block the X-rays and cau…