Search Publications
Modeling a Propagating Sawtooth Flare Ribbon Structure as a Tearing Mode in the Presence of Velocity Shear
Longcope, Dana; Parker, Jacob
On 2014 April 18 (SOL2014-04-18T13:03), an M-class flare was observed by IRIS. The associated flare ribbon contained a quasi-periodic sawtooth pattern that was observed to propagate along the ribbon, perpendicular to the IRIS spectral slit, with a phase velocity of ∼15 km s-1. This motion resulted in periodicities in both intensity and …
Testing for Shock-heated X-Ray Gas around Compact Steep Spectrum Radio Galaxies
Worrall, D. M.; O'Dea, C. P.; Clarke, T. E. +7 more
We present Chandra and XMM-Newton X-ray, Very Large Array (VLA) radio, and optical observations of three candidate compact steep spectrum (CSS) radio galaxies. CSS sources are of a galactic scale and are presumably driving a shock through the interstellar medium (ISM) of their host galaxy. B3 1445+410 is a low-excitation emission line CSS radio ga…
Spectral Evidence for an Inner Carbon-rich Circumstellar Belt in the Young HD 36546 A-star System
Melis, C.; Sitko, M. L.; Marengo, M. +5 more
Using the NASA/IRTF SpeX and BASS spectrometers we have obtained 0.7-13 µm observations of the newly imaged 3-10 Myr old HD 36546 disk system. The SpeX spectrum is most consistent with the photospheric emission expected from an L * ∼ 20 L ⊙, solar abundance A1.5V star with little to no extinction, and excess emission fr…
X Marks the Spot: Nexus of Filaments, Cores, and Outflows in a Young Star-forming Region
Bieging, John H.; Lombardi, Marco; Kong, Shuo +4 more
We present a multiwavelength investigation of a region of a nearby giant molecular cloud that is distinguished by a minimal level of star formation activity. With our new {}12{CO}(J = 2-1) and {}13{CO}(J = 2-1) observations of a remote region within the middle of the California molecular cloud, we aim to investigate the relat…
Which Bow Shock Theory, Gasdynamic or Magnetohydrodynamic, Better Explains CME Stand-off Distance Ratios from LASCO-C2 Observations ?
Cho, K. -S.; Moon, Y. -J.; Kim, R. -S. +2 more
It is generally believed that fast coronal mass ejections (CMEs) can generate their associated shocks, which are characterized by faint structures ahead of CMEs in white-light coronagraph images. In this study, we examine whether the observational stand-off distance ratio, defined as the CME stand-off distance divided by its radius, can be explain…
Comparison of Solar Fine Structure Observed Simultaneously in Lyα and Mg II h
Auchère, F.; De Pontieu, B.; Schmit, D. +10 more
The Chromospheric Lyman Alpha Spectropolarimeter (CLASP) observed the Sun in H I Lyα during a suborbital rocket flight on 2015 September 3. The Interface Region Imaging Telescope (IRIS) coordinated with the CLASP observations and recorded nearly simultaneous and co-spatial observations in the Mg II h and k lines. The Mg II h and Lyα lines are impo…
Polarization Characteristics of Zebra Patterns in Type IV Solar Radio Bursts
Misawa, H.; Masuda, S.; Tsuchiya, F. +4 more
The polarization characteristics of zebra patterns (ZPs) in type IV solar bursts were studied. We analyzed 21 ZP events observed by the Assembly of Metric-band Aperture Telescope and Real-time Analysis System between 2010 and 2015 and identified the following characteristics: a degree of circular polarization (DCP) in the range of 0%-70%, a tempor…
Observation of a Large-scale Quasi-circular Secondary Ribbon Associated with Successive Flares and a Halo CME
Yurchyshyn, Vasyl; Chae, Jongchul; Cho, Kyuhyoun +7 more
Solar flare ribbons provide an important clue to the magnetic reconnection process and associated magnetic field topology in the solar corona. We detected a large-scale secondary flare ribbon of a circular shape that developed in association with two successive M-class flares and one coronal mass ejection. The ribbon revealed interesting propertie…
A New 3D Multi-fluid Dust Model: A Study of the Effects of Activity and Nucleus Rotation on Dust Grain Behavior at Comet 67P/Churyumov-Gerasimenko
Huang, Z.; Jia, X.; Fougere, N. +7 more
Improving our capability to interpret observations of cometary dust is necessary to deepen our understanding of the role of dust in the formation of comets and in altering the cometary environments. Models including dust grains are in demand to interpret observations and test hypotheses. Several existing models have taken into account the gas-dust…
Photospheric Velocity Structures during the Emergence of Small Active Regions on the Sun
Toriumi, Shin; Khlystova, Anna
We study the plasma flows in the solar photosphere during the emergence of two small active regions, NOAA 9021 and 10768. Using Solar and Heliospheric Observatory/Michelson Doppler Imager data, we find that the strong plasma upflows appear at the initial stage of active region formation, with maximum upflow velocities of -1650 and -1320 m s-1…