Search Publications
Brightening and Darkening of the Extended Solar Corona during the Superflares of September 2017
West, Matthew J.; Podladchikova, O.; D'Huys, Elke +3 more
On 2017 September 6 and 10, the strongest X9.3 and X8.2 flares of the decade occurred in the active region NOAA Active Region 12673. During these flares, the Sun Watcher with Active Pixels and Image Processing (SWAP) telescope on board the Project for Onboard Autonomy 2 (PROBA2) satellite registered the unusual alternate brightening and darkening …
Extraplanar H II Regions in Spiral Galaxies. II. In Situ Star Formation in the Interstellar Thick Disk of NGC 4013
Savage, Blair D.; Lehner, Nicolas; Howk, J. Christopher +3 more
We present observations of an Hα-emitting knot in the thick disk of NGC 4013, demonstrating it is an H II region surrounding a cluster of young hot stars z = 860 pc above the plane of this edge-on spiral galaxy. With LBT/MODS spectroscopy we show that this H II region has an Hα luminosity ∼4-7 times that of the Orion nebula, with an implied ionizi…
Resonant Scattering Effect on the Soft X-Ray Line Emission from the Hot Interstellar Medium. I. Galactic Bulges
Wang, Q. Daniel; Chen, Yang; Zhang, Shuinai +2 more
Diffuse soft X-ray line emission is commonly used to trace the thermal and chemical properties of the hot interstellar medium, as well as its content, in nearby galaxies. Although resonant-line scattering complicates the interpretation of the emission, it also offers an opportunity to measure the kinematics of the medium. We have implemented a dir…
The Influence of Stellar Spin on Ignition of Thermonuclear Runaways
Galloway, Duncan K.; Kuulkers, Erik; Chenevez, Jérôme +8 more
Runaway thermonuclear burning of a layer of accumulated fuel on the surface of a compact star provides a brief but intense display of stellar nuclear processes. For neutron stars accreting from a binary companion, these events manifest as thermonuclear (type-I) X-ray bursts, and recur on typical timescales of hours to days. We measured the burst r…
Transport of Internetwork Magnetic Flux Elements in the Solar Photosphere
Rempel, Matthias; Bellot Rubio, Luis R.; Gošić, Milan +2 more
The motions of small-scale magnetic flux elements in the solar photosphere can provide some measure of the Lagrangian properties of the convective flow. Measurements of these motions have been critical in estimating the turbulent diffusion coefficient in flux-transport dynamo models and in determining the Alfvén wave excitation spectrum for corona…
Motions in Prominence Barbs Observed on the Solar Limb
Tarbell, T. D.; Kucera, T. A.; Ofman, L.
We analyze and discuss an example of prominence barbs observed on the limb on 2016 January 7 by the Hinode/Solar Optical Telescope in Ca II and Hα, the Interface Region Imaging Spectrograph, with slit jaw images and Mg II spectral data, and the Solar Dynamics Observatory’s Atmospheric Imaging Assembly. In the recent literature there has been a deb…
A Deep X-Ray View of the Synchrotron-dominated Supernova Remnant G330.2+1.0
Temim, Tea; Petre, Robert; Williams, Brian J. +1 more
We present moderately deep (125 ks) XMM-Newton observations of supernova remnant G330.2+1.0. This remnant is one of only a few known that fall into the “synchrotron-dominated” category, with the emission almost entirely dominated by a nonthermal continuum. Previous X-ray observations could only characterize the spectra of a few regions. Here, we e…
Banyan. X. Discovery of a Wide, Low-gravity L-type Companion to a Fast-rotating M3 Dwarf
Faherty, Jacqueline K.; Gagné, Jonathan; Doyon, René +4 more
We report the discovery of a substellar-mass co-moving companion to 2MASS J22501512+2325342, an M3 candidate member of the young (130-200 Myr) AB Doradus Moving Group (ABDMG). This L3 β companion was discovered in a 2MASS search for companions at separations of 3″-18″ from a list of 2812 stars suspected to be young (≲500 Myr) in the literature, an…
Aliasing in the Radial Velocities of YZ Ceti: An Ultra-short Period for YZ Ceti c?
Robertson, Paul
Mid-to-late M stars are opportunistic targets for the study of low-mass exoplanets in transit because of the high planet-to-star radius ratios of their planets. Recent studies of such stars have shown that, like their early-M counterparts, they often host multi-resonant networks of small planets. Here, I reanalyze radial velocity measurements of Y…
Chandra X-Ray Observatory and Hubble Space Telescope Observations of the Intermediate-age Cluster GLIMPSE-C01
Kargaltsev, Oleg; Hare, Jeremy; Rangelov, Blagoy
We report the results of Hubble Space Telescope and Chandra X-Ray Observatory observations of the GLIMPSE-C01 (hereafter GC01) star cluster. Color-magnitude and color-color diagrams suggest a cluster age of ≳2 Gyr up to ∼10 Gyr (dependent on GC01's metallicity), a distance of 3.3-3.5 kpc, and strong differential reddening with A V = 1…