Search Publications
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…
Toward Precision Photometry for the ELT Era: The Double Subgiant Branch of NGC 1851 Observed with the Gemini/GeMS MCAO System
Stetson, P. B.; Bono, G.; Fiorentino, G. +4 more
The Extremely Large Telescopes currently under construction have a collecting area that is an order of magnitude larger than the present largest optical telescopes. For seeing-limited observations the performance will scale as the collecting area, but with the successful use of adaptive optics (AO), for many applications it will scale as D4
A Measurement of Diffusion in 47 Tucanae
Richer, Harvey B.; Heyl, Jeremy; Kalirai, Jason +4 more
Using images from the Hubble Space Telescope Wide-Field Camera 3, we measure the rate of diffusion of stars through the core of the globular cluster 47 Tucanae (47 Tuc) using a sample of young white dwarfs that were identified in these observations. This is the first direct measurement of diffusion due to gravitational relaxation. We find that the…