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On the Correlation between L Dwarf Optical and Infrared Variability and Radio Aurorae
Richey-Yowell, Tyler; Kao, Melodie M.; Pineda, J. Sebastian +2 more
Photometric variability attributed to cloud phenomena is common in L/T transition brown dwarfs. Recent studies show that such variability may also trace aurorae, suggesting that localized magnetic heating may contribute to observed brown dwarf photometric variability. We assess this potential correlation with a survey of 17 photometrically variabl…
Observation and Modeling of High-temperature Solar Active Region Emission during the High-resolution Coronal Imager Flight of 2018 May 29
Golub, Leon; Winebarger, Amy R.; Warren, Harry P. +15 more
Excellent coordinated observations of NOAA active region 12712 were obtained during the flight of the High-resolution Coronal Imager (Hi-C) sounding rocket on 2018 May 29. This region displayed a typical active region core structure with relatively short, high-temperature loops crossing the polarity inversion line and bright "moss" located at the …
Evidence of Particle Acceleration in the Superbubble 30 Doradus C with NuSTAR
Auchettl, Katie; Madsen, Kristin K.; Grefenstette, Brian W. +2 more
We present evidence of diffuse, non-thermal X-ray emission from the superbubble 30 Doradus C (30 Dor C) using hard X-ray images and spectra from NuSTAR observations. For this analysis, we utilize data from a 200 ks targeted observation of 30 Dor C as well as 2.8 Ms of serendipitous off-axis observations from the monitoring of nearby SN 1987A. The …
The observational impact of dust trapping in self-gravitating discs
Cadman, James; Hall, Cassandra; Rice, Ken +2 more
We present a 3D semi-analytical model of self-gravitating discs, and include a prescription for dust trapping in the disc spiral arms. Using Monte Carlo radiative transfer, we produce synthetic ALMA (Atacama Large Millimeter/submillimeter Array) observations of these discs. In doing so, we demonstrate that our model is capable of producing observa…
Resonant capture in quadruple stellar systems
Tremaine, Scott
Some quadruple star systems in the hierarchical 2 + 2 configuration exhibit orbit-orbit resonances between the two compact binaries. We show that the most important resonances occur at period ratios of 1:1, 3:2, and 2:1. We describe the conditions required for capture and show that they can be satisfied at the 3:2 and 2:1 resonances in binaries th…
Predictions of Gaia's prize microlensing events are flawed
McGill, Peter; Everall, Andrew; Boubert, Douglas +1 more
Precision astrometry from the second Gaia data release has allowed astronomers to predict 5787 microlensing events, with 528 of these having maximums within the extended Gaia mission (J2014.5-J2026.5). Future analysis of the Gaiatime-series astrometry of these events will, in some cases, lead to precise gravitational mass measurements of the lens.…
The small inner satellites of Saturn: Shapes, structures and some implications
Thomas, P.; Helfenstein, P.
Properties of the small inner satellites of Saturn are updated using final Cassini image data. The equatorial ridges on Pan and Atlas are morphologically, structurally, and gravitationally distinct from their cores and represent distinct additions to, rather than modifications of, the precursor bodies. Exposures of lineated substrates on Pandora a…
HST/COS Observations of Quasar Outflows in the 500-1050 Å Rest Frame. VI. Wide, Energetic Outflows in SDSS J0755+2306
Xu, Xinfeng; Kriss, Gerard A.; Arav, Nahum +2 more
We present the analysis of two outflows (S1 at -5500 km s-1 and S2 at -9700 km s-1) seen in recent Hubble Space Telescope/Cosmic Origins Spectrograph observations of quasar SDSS J0755+2306 (z = 0.854). The outflows are detected as absorption troughs from both high-ionization species, including N III, O III, and S IV, and very…
Properties of Streamer Wave Events Observed during the STEREO Era
Van Doorsselaere, Tom; Zhukov, Andrei N.; Decraemer, Bieke
Transverse waves are sometimes observed in solar helmet streamers, typically after the passage of a coronal mass ejection (CME). The CME-driven shock wave moves the streamer sideways, and a decaying oscillation of the streamer is observed after the CME passage. Previous works generally reported observations of streamer oscillations taken from a si…
Periodic Eruptive Variability of the Isolated Pre-main-sequence Star V347 Aurigae
Hillenbrand, L. A.; Dahm, S. E.
V347 Aurigae is associated with the small dark cloud L1438 and appears to be an isolated pre-main-sequence star located at distance d ≈ 200 pc. Multi-epoch, archival photometry reveals periodic brightness variations with amplitude V ≈ 2.0 mag occurring on timescales of ∼160 days that have persisted for decades. Regular-cadence, optical imaging of …