Search Publications
Confirmation of Hostless Type Ia Supernovae Using Hubble Space Telescope Imaging
Zaritsky, D.; Sand, D. J.; Graham, M. L. +1 more
We present deep Hubble Space Telescope imaging at the locations of four, potentially hostless, long-faded Type Ia supernovae (SNe Ia) in low-redshift, rich galaxy clusters that were identified in the Multi-Epoch Nearby Cluster Survey. Assuming a steep faint-end slope for the galaxy cluster luminosity function ({α }d=-1.5), our data incl…
Evolution of the Far-infrared Cloud at Titan’s South Pole
Teanby, N. A.; de Kok, R.; Flasar, F. M. +17 more
A condensate cloud on Titan identified by its 220 cm-1 far-infrared signature continues to undergo seasonal changes at both the north and south poles. In the north, the cloud, which extends from 55 N to the pole, has been gradually decreasing in emission intensity since the beginning of the Cassini mission with a half-life of 3.8 years.…
Nebular and Stellar Dust Extinction Across the Disk of Emission-line Galaxies on Kiloparsec Scales
Sobral, David; Mobasher, Bahram; Hemmati, Shoubaneh +3 more
We investigate the resolved kiloparsec-scale stellar and nebular dust distribution in eight star-forming galaxies at z ∼ 0.4 in the Great Observatories Origins Deep Survey fields. This is to get a better understanding of the effect of dust attenuation on measurements of physical properties and its variation with redshift. Constructing the observed…
Oxygen Abundance Measurements of SHIELD Galaxies
Cannon, John M.; Salzer, John J.; Marshall, Melissa V. +1 more
We have derived oxygen abundances for eight galaxies from the Survey for H I in Extremely Low-mass Dwarfs (SHIELD). The SHIELD survey is an ongoing study of very-low-mass galaxies, with MH \scriptsize{I} between 106.5 and 107.5 M ⊙, that were detected by the Arecibo Legacy Fast ALFA survey. Hα images fro…
Chromospheric Nanoflares as a Source of Coronal Plasma. II. Repeating Nanoflares
Klimchuk, J. A.; Bradshaw, S. J.
The million degree plasma of the solar corona must be supplied by the underlying layers of the atmosphere. The mechanism and location of energy release, and the precise source of coronal plasma, remain unresolved. In earlier work, we pursued the idea that warm plasma is supplied to the corona via direct heating of the chromosphere by nanoflares, c…
Characterizing the Atmospheres of the HR8799 Planets with HST/WFC3
Macintosh, Bruce; Pueyo, Laurent; Barman, Travis +7 more
We present results from a Hubble Space Telescope (HST) program characterizing the atmospheres of the outer two planets in the HR8799 system. The images were taken over 15 orbits in three near-infrared (near-IR) medium-band filters—F098M, F127M, and F139M—using the Wide Field Camera 3. One of the three filters is sensitive to a water absorption ban…
HST Images Reveal Dramatic Changes in the Core of IRC+10216
Lee, Ho-Gyu; Chu, You-Hua; Kim, Hyosun +1 more
IRC+10216 is the nearest carbon star with a very high mass-loss rate. The existence of a binary companion has been hinted at by indirect observational evidence, such as the bipolar morphology of its nebula and a spiral-like pattern in its circumstellar material; however, to date, no companion has been identified. We have examined archival Hubble S…
On Multiple Reconnection X-lines and Tripolar Perturbations of Strong Guide Magnetic Fields
Lavraud, B.; Khotyaintsev, Yu. V.; Carr, C. M. +7 more
We report new multi-spacecraft Cluster observations of tripolar guide magnetic field perturbations at a solar wind reconnection exhaust in the presence of a guide field BM which is almost four times as strong as the reversing field BL. The novel tripolar field consists of two narrow regions of depressed BM, with an…
Spectroscopic Signatures Related to a Sunquake
Green, L. M.; Harra, L. K.; Matthews, S. A. +1 more
The presence of flare-related acoustic emission (sunquakes (SQs)) in some flares, and only in specific locations within the flaring environment, represents a severe challenge to our current understanding of flare energy transport processes. In an attempt to contribute to understanding the origins of SQs we present a comparison of new spectral obse…
Spatial Distribution of X-Ray Emitting Ejecta in Tycho’s SNR: Indications of Shocked Titanium
Troja, E.; Miceli, M.; Orlando, S. +1 more
Young supernova remnants (SNRs) show characteristic ejecta-dominated X-ray emission that allows us to probe the products of explosive nucleosynthesis processes and to ascertain important information about the physics of supernova explosions. Hard X-ray observations have recently revealed the presence of the radioactive decay lines of 44…