Search Publications
Structure and Dynamics of Cool Flare Loops Observed by the Interface Region Imaging Spectrograph
Heinzel, P.; Berlicki, A.; Liu, W. +1 more
Flare loops were well observed with the Interface Region Imaging Spectrograph (IRIS) during the gradual phase of two solar flares on 2014 March 29 and 2015 June 22. Cool flare loops are visible in various spectral lines formed at chromospheric and transition-region temperatures and exhibit large downflows which correspond to the standard scenario.…
The Stochastic X-Ray Variability of the Accreting Millisecond Pulsar MAXI J0911-655
Bult, Peter
In this work, I report on the stochastic X-ray variability of the 340 Hz accreting millisecond pulsar MAXI J0911-655. Analyzing pointed observations of the XMM-Newton and NuSTAR observatories, I find that the source shows broad band-limited stochastic variability in the 0.01{--}10 {Hz} range with a total fractional variability of ∼ 24 % rms in the…
Near-infrared Spectroscopy of Five Ultra-massive Galaxies at 1.7 < z < 2.7
Muzzin, Adam; Labbé, Ivo; Quadri, Ryan +13 more
We present the results of a pilot near-infrared spectroscopic campaign of five very massive galaxies ({log}({M}\star /{M}⊙ )> 11.45) in the range of 1.7< z< 2.7. We measure an absorption feature redshift for one galaxy at {z}{spec}=2.000+/- 0.006. For the remaining galaxies, we combine the photometry with …
Propagation and Interaction Properties of Successive Coronal Mass Ejections in Relation to a Complex Type II Radio Burst
Liu, Ying D.; Zhao, Xiaowei; Zhu, Bei
We examine the propagation and interaction properties of three successive coronal mass ejections (CMEs) from 2001 November 21-22, with a focus on their connection with the behaviors of the associated long-duration complex type II radio burst. In combination with coronagraph and multi-point in situ observations, the long-duration type II burst prov…
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…