Search Publications
Observation of a Reversal of Breakout Reconnection Preceding a Jet: Evidence of Oscillatory Magnetic Reconnection?
Yang, Bo; Yang, Jiayan; Bi, Yi +3 more
Recent studies have revealed that solar jets involving minifilament eruptions may be initiated under the well-known magnetic-breakout mechanism. Before or just at the onset of those jets, there should be a current sheet, where breakout magnetic reconnection takes place, between open fields and the outside of the jet-base arcade carrying a minifila…
Cloud Atlas: High-contrast Time-resolved Observations of Planetary-mass Companions
Schneider, Glenn; Metchev, Stanimir; Apai, Dániel +11 more
Directly imaged planetary-mass companions offer unique opportunities in atmospheric studies of exoplanets. They share characteristics of both brown dwarfs and transiting exoplanets, and therefore are critical for connecting atmospheric characterizations for these objects. Rotational phase mapping is a powerful technique to constrain the condensate…
The JCMT Transient Survey: An Extraordinary Submillimeter Flare in the T Tauri Binary System JW 566
Herczeg, Gregory J.; Johnstone, Doug; Lee, Jeong-Eun +7 more
The binary T Tauri system JW 566 in the Orion Molecular Cloud underwent an energetic, short-lived flare observed at submillimeter wavelengths by the SCUBA-2 instrument on 2016 November 26 (UT). The emission faded by nearly 50% during the 31 minute integration. The simultaneous source fluxes averaged over the observation are 500+/- 107 {mJy} {beam}…
Stellar Properties of Active G and K Stars: Exploring the Connection between Starspots and Chromospheric Activity
Hawley, Suzanne L.; Agol, Eric; Curtis, Jason L. +2 more
We gathered high resolution spectra for an ensemble of 55 bright active and inactive stars using the ARC 3.5 m Telescope Echelle Spectrograph at Apache Point Observatory (R ≈ 31,500). We measured spectroscopic effective temperatures, surface gravities, and metallicities for most stars in the sample with SME and MOOG. Our stellar property results a…
Two Types of Confined Solar Flares
Hou, Yijun; Li, Ting; Zhang, Jun +1 more
With the aim of understanding the physical mechanisms of confined flares, we selected 18 confined flares during 2011-2017, and first classified them into two types based on their different dynamic properties and magnetic configurations. “Type I” confined flares are characterized by slipping reconnection, strong shear, and a stable filament. “Type …
Evolving optical polarisation of the black hole X-ray binary MAXI J1820+070
Piirola, Vilppu; Tsygankov, Sergey S.; Poutanen, Juri +8 more
Aims: The optical emission of black hole transients increases by several magnitudes during the X-ray outbursts. Whether the extra light arises from the X-ray heated outer disc, from the inner hot accretion flow, or from the jet is currently debated. Optical polarisation measurements are able to distinguish the relative contributions of these …
The O star hinterland of the Galactic starburst, NGC 3603
Monguió, M.; Wright, N. J.; Drew, J. E.
The very bright and compact massive young cluster, NGC 3603, has been cited as an example of a starburst in the Milky Way and compared with the much-studied R136/30 Doradus region in the Large Magellanic Cloud. Here we build on the discovery by Mohr-Smith et al. of a large number of reddened O stars around this cluster. We construct a list of 288 …
A joint XMM-NuSTAR observation of the galaxy cluster Abell 523: Constraints on inverse Compton emission
Brunetti, G.; Rossetti, M.; Wik, D. R. +17 more
Aims: We present the results of a joint XMM-Newton and NuSTAR observation (200 ks) of the galaxy cluster Abell 523 at z = 0.104. The peculiar morphology of the cluster radio halo and its outlier position in the radio power P(1.4 GHz) - X-ray luminosity plane make it an ideal candidate for the study of radio and X-ray correlations and for the …
Active Galactic Nuclei with Ultrafast Outflows Monitoring Project: The Broad-line Region of Mrk 79 as a Disk Wind
Ho, Luis C.; Bian, Wei-Hao; Kim, Minjin +23 more
We developed a spectroscopic monitoring project to investigate the kinematics of the broad-line region (BLR) in active galactic nuclei (AGNs) with ultrafast outflows (UFOs). Mrk 79 is a radio-quiet AGN with UFOs and warm absorbers and has been monitored by three reverberation mapping (RM) campaigns, but its BLR kinematics are not yet understood. I…
Observations of a Footpoint Drift of an Erupting Flux Rope
Aulanier, Guillaume; Dudík, Jaroslav; Gömöry, Peter +2 more
We analyze the imaging observations of an M-class eruptive flare of 2015 November 4. The pre-eruptive Hα filament was modeled by the nonlinear force-free field model, which showed that it consisted of two helical systems. Tether-cutting reconnection involving these two systems led to the formation of a hot sigmoidal loop structure rooted in a smal…