Search Publications
Luminous and Variable Stars in M31 and M33. I. The Warm Hypergiants and Post-red Supergiant Evolution
Humphreys, Roberta M.; Davidson, Kris; Martin, John C. +4 more
The progenitors of Type IIP supernovae (SNe) have an apparent upper limit to their initial masses of about 20 M ⊙, suggesting that the most massive red supergiants evolve to warmer temperatures before their terminal explosion. But very few post-red supergiants are known. We have identified a small group of luminous stars in M31 and M33 …
Measuring Galaxy Star Formation Rates from Integrated Photometry: Insights from Color-Magnitude Diagrams of Resolved Stars
Dolphin, Andrew E.; Skillman, Evan D.; Williams, Benjamin F. +9 more
We use empirical star formation histories (SFHs), measured from Hubble-Space-Telescope-based resolved star color-magnitude diagrams, as input into population synthesis codes to model the broadband spectral energy distributions (SEDs) of 50 nearby dwarf galaxies (6.5 < log M */M ⊙ < 8.5, with metallicities ~10% solar). I…
Polarimetry and the High-energy Emission Mechanisms in Quasar Jets: The Case of PKS 1136-135
Baum, Stefi A.; O'Dea, Christopher P.; Perlman, Eric S. +11 more
Since the discovery of kiloparsec-scale X-ray emission from quasar jets, the physical processes responsible for their high-energy emission have been poorly defined. A number of mechanisms are under active debate, including synchrotron radiation, inverse-Comptonized cosmic microwave background (IC/CMB) emission, and other Comptonization processes. …
A Highly Elongated Prominent Lens at z = 0.87: First Strong-lensing Analysis of El Gordo
Hughes, John P.; Barrientos, L. Felipe; Mandelbaum, Rachel +4 more
We present the first strong-lensing (SL) analysis of the galaxy cluster ACT-CL J0102-4915 (El Gordo), in recent HST/ACS images, revealing a prominent strong lens at a redshift of z = 0.87. This finding adds to the already-established unique properties of El Gordo: it is the most massive, hot, X-ray luminous, and bright Sunyaev-Zeldovich effect clu…
Pathways of Large-scale Magnetic Couplings between Solar Coronal Events
DeRosa, Marc L.; Title, Alan M.; Schrijver, Carolus J. +1 more
The high-cadence, comprehensive view of the solar corona by SDO/AIA shows many events that are widely separated in space while occurring close together in time. In some cases, sets of coronal events are evidently causally related, while in many other instances indirect evidence can be found. We present case studies to highlight a variety of coupli…
The Role of Galaxy Interaction in the SFR-M * Relation: Characterizing Morphological Properties of Herschel-selected Galaxies at 0.2 < z < 1.5
Le Floc'h, E.; Riguccini, L.; Sanders, D. B. +13 more
Galaxy interactions/mergers have been shown to dominate the population of IR-luminous galaxies (L IR >~ 1011.6 L ⊙) in the local universe (z <~ 0.25). Recent studies based on the relation between galaxies' star formation rates and stellar mass (the SFR-M * relation or the "galaxy main sequence") ha…
Optical Proper Motion Measurements of the M87 Jet: New Results from the Hubble Space Telescope
Anderson, Jay; van der Marel, Roeland P.; Sparks, W. B. +5 more
We report new results from a Hubble Space Telescope archival program to study proper motions in the optical jet of the nearby radio galaxy M87. Using over 13 yr of archival imaging, we reach accuracies below 0.1c in measuring the apparent velocities of individual knots in the jet. We confirm previous findings of speeds up to 4.5c in the inner 6'' …
The Atacama Cosmology Telescope: Physical Properties of Sunyaev-Zel'dovich Effect Clusters on the Celestial Equator
Hilton, Matt; Hasselfield, Matthew; Sifón, Cristóbal +29 more
We present the optical and X-ray properties of 68 galaxy clusters selected via the Sunyaev-Zel'dovich (SZ) effect at 148 GHz by the Atacama Cosmology Telescope (ACT). Our sample, from an area of 504 deg2 centered on the celestial equator, is divided into two regions. The main region uses 270 deg2 of the ACT survey that overla…
The Kelvin-Helmholtz Instability at Coronal Mass Ejection Boundaries in the Solar Corona: Observations and 2.5D MHD Simulations
Temmer, M.; Veronig, A. M.; Möstl, U. V.
The Atmospheric Imaging Assembly on board the Solar Dynamics Observatory observed a coronal mass ejection with an embedded filament on 2011 February 24, revealing quasi-periodic vortex-like structures at the northern side of the filament boundary with a wavelength of approximately 14.4 Mm and a propagation speed of about 310 ± 20 km s-1…
Physical Parameters of Standard and Blowout Jets
Romoli, Marco; Sterling, Alphonse C.; Pucci, Stefano +1 more
The X-ray Telescope on board the Hinode mission revealed the occurrence, in polar coronal holes, of much more numerous jets than previously indicated by the Yohkoh/Soft X-ray Telescope. These plasma ejections can be of two types, depending on whether they fit the standard reconnection scenario for coronal jets or if they include a blowout-like eru…