Search Publications
Global Empirical Picture of Magnetospheric Substorms Inferred From Multimission Magnetometer Data
Sitnov, M. I.; Tsyganenko, N. A.; Stephens, G. K. +4 more
Magnetospheric substorms represent key explosive processes in the interaction of the Earth's magnetosphere with the solar wind, and their understanding and modeling are critical for space weather forecasting. During substorms, the magnetic field on the nightside is first stretched in the antisunward direction and then it rapidly contracts earthwar…
An Eccentric Massive Jupiter Orbiting a Subgiant on a 9.5-day Period Discovered in the Transiting Exoplanet Survey Satellite Full Frame Images
Henning, Thomas; Torres, Guillermo; Barclay, Thomas +71 more
We report the discovery of TOI-172 b from the Transiting Exoplanet Survey Satellite (TESS) mission, a massive hot Jupiter transiting a slightly evolved G star with a 9.48-day orbital period. This is the first planet to be confirmed from analysis of only the TESS full frame images, because the host star was not chosen as a two-minute cadence target…
Search for RR Lyrae stars in DES ultrafaint systems: Grus I, Kim 2, Phoenix II, and Grus II
Bechtol, K.; Smith, M.; Annis, J. +58 more
This work presents the first search for RR Lyrae stars (RRLs) in four of the ultrafaint systems imaged by the Dark Energy Survey using SOAR/Goodman and Blanco/DECam imagers. We have detected two RRLs in the field of Grus I, none in Kim 2, one in Phoenix II, and four in Grus II. With the detection of these stars, we accurately determine the distanc…
Why Do Torus-unstable Solar Filaments Experience Failed Eruptions?
Wang, Yuming; Zhuang, Bin; Liu, Lijuan +5 more
We study the magnetic field and 3D configuration of 16 filament eruptions during 2010 July-2013 February in order to investigate the factors that control the success and/or failure of solar eruptions. All of these events, i.e., eruptions that failed to be ejected and become coronal mass ejections, have filament maximum heights exceeding 100 Mm. Th…
Towards a complete understanding of the Magellanic Stream Formation
Hammer, Francois; Ripepi, Vincenzo; Cioni, Maria-Rosa L. +4 more
The Magellanic Clouds (MCs) have lost most of their gas during their passage by the Milky Way, a property that has never been successfully modelled. Here, we use accurate and mesh-free hydrodynamic simulations to reproduce the Magellanic Stream and the MCs in the frame of a `ram-pressure plus collision' model. This model reproduces many of the obs…
Reverberation reveals the truncated disc in the hard state of GX 339-4
Done, Chris; Mahmoud, Ra'ad D.; De Marco, Barbara
The nature and geometry of the hard state in black hole binaries is controversial. The broad-band continuum spectrum and fast variability properties can be explained in a model where the inner disc evaporates into a geometrically thick, hot flow. However, these models are challenged by the persistent detection of an extremely broad iron line, whic…
A Family Picture: Tracing the Dynamical Path of the Structural Properties of Multiple Populations in Globular Clusters
Dalessandro, Emanuele; Martocchia, S.; Bastian, N. +6 more
We studied the spatial distributions of multiple stellar populations (MPs) in a sample of 20 globular clusters (GCs) spanning a broad range of dynamical ages. The differences between first-population (FP) and second-population (SP) stars were measured by means of the parameter A +, defined as the area enclosed between their cumulative r…
A census of massive stars in NGC 346. Stellar parameters and rotational velocities
Dufton, P. L.; Lennon, D. J.; Evans, C. J. +2 more
Spectroscopy for 247 stars towards the young cluster NGC 346 in the Small Magellanic Cloud has been combined with that for 116 targets from the VLT-FLAMES Survey of Massive Stars. Spectral classification yields a sample of 47 O-type and 287 B-type spectra, while radial-velocity variations and/or spectral multiplicity have been used to identify 45 …
First Detection of Plasmoids from Breakout Reconnection on the Sun
Antiochos, Spiro K.; Kumar, Pankaj; DeVore, C. Richard +2 more
Transient collimated plasma ejections (jets) occur frequently throughout the solar corona, in active regions, quiet Sun, and coronal holes. Although magnetic reconnection is generally agreed to be the mechanism of energy release in jets, the factors that dictate the location and rate of reconnection remain unclear. Our previous studies demonstrate…
Systematic serendipity: a test of unsupervised machine learning as a method for anomaly detection
Giles, Daniel; Walkowicz, Lucianne
Advances in astronomy are often driven by serendipitous discoveries. As survey astronomy continues to grow, the size and complexity of astronomical data bases will increase, and the ability of astronomers to manually scour data and make such discoveries decreases. In this work, we introduce a machine learning-based method to identify anomalies in …