Search Publications
Cool Transition Region Loops Observed by the Interface Region Imaging Spectrograph
Madjarska, Maria S.; Li, Bo; Xia, Lidong +1 more
We report on the first Interface Region Imaging Spectrograph (IRIS) study of cool transition region loops, a class of loops that has received little attention in the literature. A cluster of such loops was observed on the solar disk in active region NOAA11934, in the Si iv 1402.8 Å spectral raster and 1400 Å slit-jaw images. We divide the loops in…
Peculiar Velocities of Galaxies in the Leo Spur
Tully, R. Brent; Karachentsev, Igor D.; Makarov, Dmitry I. +2 more
The Hubble Space Telescope Advanced Camera for Surveys has been used to determine accurate distances for the spiral galaxy NGC 2683 and 12 other galaxies in a zone of the “local velocity anomaly” from luminosity measurements of the brightest red giant branch stars. These galaxies lie in the Leo Spur, the nearest filament beyond our Local Sheet. Th…
A Global Star-forming Episode in M31 2-4 Gyr Ago
Bell, Eric F.; Monachesi, Antonela; Dolphin, Andrew E. +9 more
We have identified a major global enhancement of star formation in the inner M31 disk that occurred between 2-4 Gyr ago, producing ∼60% of the stellar mass formed in the past 5 Gyr. The presence of this episode in the inner disk was discovered by modeling the optical resolved star color-magnitude diagrams of low extinction regions in the main disk…
Understanding the Mg II and Hα Spectra in a Highly Dynamical Solar Prominence
Heinzel, P.; Schmieder, B.; Gunár, S. +1 more
Mg ii h and k and Hα spectra in a dynamical prominence have been obtained along the slit of the Interface Region Imaging Spectrograph (IRIS) and with the Meudon Multi-channel Subtractive Double Pass spectrograph on 2013 September 24, respectively. Single Mg ii line profiles are not much reversed, while at some positions along the IRIS slit the pro…
Properties of a Coronal Shock Wave as a Driver of Early SEP Acceleration
Raymond, J. C.; Lobzin, V. V.; Kozarev, K. A. +1 more
Coronal mass ejectmons (CMEs) are thought to drive collisionless shocks in the solar corona, which in turn have been shown to be capable of accelerating solar energetic particles (SEPs) in minutes. It has been notoriously difficult to extract information about energetic particle spectra in the corona, owing to a lack of in situ measurements. It is…
A Deep Search For Faint Galaxies Associated With Very Low-redshift C IV Absorbers. II. Program Design, Absorption-line Measurements, and Absorber Statistics
Tripp, Todd M.; Prochaska, J. Xavier; Tumlinson, Jason +6 more
To investigate the evolution of metal-enriched gas over recent cosmic epochs as well as to characterize the diffuse, ionized, metal-enriched circumgalactic medium, we have conducted a blind survey for C iv absorption systems in 89 QSO sightlines observed with the Hubble Space Telescope Cosmic Origins Spectrograph. We have identified 42 absorbers a…
Kinematic Classifications of Local Interacting Galaxies: Implications for the Merger/Disk Classifications at High-z
Casey, Caitlin M.; Kewley, Lisa J.; Sanders, D. B. +6 more
The classification of galaxy mergers and isolated disks is key for understanding the relative importance of galaxy interactions and secular evolution during the assembly of galaxies. Galaxy kinematics as traced by emission lines have been used to suggest the existence of a significant population of high-z star-forming galaxies consistent with isol…
On the Progenitor System of the Type Iax Supernova 2014dt in M61
Van Dyk, Schuyler D.; Filippenko, Alexei V.; Foley, Ryan J. +5 more
We present pre-explosion and post-explosion Hubble Space Telescope images of the Type Iax supernova (SN Iax) 2014dt in M61. After astrometrically aligning these images, we do not detect any stellar sources at the position of the SN in the pre-explosion images to relatively deep limits (3σ limits of M F438W > -5.0 mag and M F814W…
Three-dimensional Dust Mapping Reveals that Orion Forms Part of a Large Ring of Dust
Price, P. A.; Rix, H. -W.; Chambers, K. C. +12 more
The Orion Molecular Complex is the nearest site of ongoing high-mass star formation, making it one of the most extensively studied molecular complexes in the Galaxy. We have developed a new technique for mapping the three-dimensional distribution of dust in the Galaxy using Pan-STARRS1 photometry. We isolate the dust at the distance to Orion using…
A SMACK Model of Colliding Planetesimals in the β Pictoris Debris Disk
Nesvold, Erika R.; Kuchner, Marc J.
We present a new model of the β Pictoris disk-and-planet system that simulates both the planetesimal collisions and the dynamics of the resulting dust grains, allowing us to model features and asymmetries in both thermal and scattered light images of the disk. Our two-part model first simulates the collisional and dynamical evolution of the planet…