Search Publications
Observations of Subarcsecond Bright Dots in the Transition Region above Sunspots with the Interface Region Imaging Spectrograph
Weber, M.; Peter, H.; Golub, L. +5 more
Observations with the Interface Region Imaging Spectrograph (IRIS) have revealed numerous sub-arcsecond bright dots in the transition region above sunspots. These bright dots are seen in the 1400 Å and 1330 Å slit-jaw images. They are clearly present in all sunspots we investigated, mostly in the penumbrae, but also occasionally in some umbrae and…
A Far-infrared Spectroscopic Survey of Intermediate Redshift (Ultra) Luminous Infrared Galaxies
Valtchanov, I.; Bock, J. J.; Scott, D. +16 more
We present Herschel far-IR photometry and spectroscopy as well as ground-based CO observations of an intermediate redshift (0.21 <= z <= 0.88) sample of Herschel-selected (ultra)-luminous infrared galaxies (L IR > 1011.5 L ⊙). With these measurements, we trace the dust continuum, far-IR atomic line emissio…
Probing the z > 6 Universe with the First Hubble Frontier Fields Cluster A2744
Richard, Johan; Kneib, Jean-Paul; Egami, Eiichi +8 more
The Hubble Frontier Fields program combines the capabilities of the Hubble Space Telescope (HST) with the gravitational lensing of massive galaxy clusters to probe the distant universe to an unprecedented depth. Here, we present the results of the first combined HST and Spitzer observations of the cluster A-2744. We combine the full near-infrared …
X-Ray Observations of XSS J12270-4859 in a New Low State: A Transformation to a Disk-free Rotation-powered Pulsar Binary
Bogdanov, Slavko; Hessels, Jason W. T.; Bassa, Cees +4 more
We present XMM-Newton and Chandra observations of the low-mass X-ray binary XSS J12270-4859, which experienced a dramatic decline in optical/X-ray brightness at the end of 2012, indicative of the disappearance of its accretion disk. In this new state, the system exhibits previously absent orbital-phase-dependent, large-amplitude X-ray modulations …
"Direct" Gas-phase Metallicities, Stellar Properties, and Local Environments of Emission-line Galaxies at Redshifts below 0.90
Shimasaku, Kazuhiro; Hayashi, Masao; Malkan, Matthew A. +3 more
Using deep narrow-band (NB) imaging and optical spectroscopy from the Keck telescope and MMT, we identify a sample of 20 emission-line galaxies at z = 0.065-0.90 where the weak auroral emission line, [O III] λ4363, is detected at >=3σ. These detections allow us to determine the gas-phase metallicity using the "direct" method. With electron temp…
High-resolution Ultraviolet Radiation Fields of Classical T Tauri Stars
France, Kevin; Bergin, Edwin A.; Roueff, Evelyne +2 more
The far-ultraviolet (FUV; 912-1700 Å) radiation field from accreting central stars in classical T Tauri systems influences the disk chemistry during the period of giant planet formation. The FUV field may also play a critical role in determining the evolution of the inner disk (r < 10 AU), from a gas- and dust-rich primordial disk to a transiti…
Delayed Star Formation in Isolated Dwarf galaxies: Hubble Space Telescope Star Formation History of the Aquarius Dwarf Irregular
Dolphin, Andrew E.; Skillman, Evan D.; Leaman, Ryan +4 more
We have obtained deep images of the highly isolated (d = 1 Mpc) Aquarius dwarf irregular galaxy (DDO 210) with the Hubble Space Telescope Advanced Camera for Surveys. The resulting color-magnitude diagram (CMD) reaches more than a magnitude below the oldest main-sequence turnoff, allowing us to derive the star formation history (SFH) over the enti…
Tracing the Cosmic Metal Evolution in the Low-redshift Intergalactic Medium
Shull, J. Michael; Danforth, Charles W.; Tilton, Evan M.
Using the Cosmic Origins Spectrograph aboard the Hubble Space Telescope, we measured the abundances of six ions (C III, C IV, Si III, Si IV, N V, and O VI) in the low-redshift (z <= 0.4) intergalactic medium (IGM). Both C IV and Si IV have increased in abundance by a factor of ~10 from z ≈ 5.5 to the present. We derive ion mass densities, ρ
Degree-scale Cosmic Microwave Background Polarization Measurements from Three Years of BICEP1 Data
Ade, P. A. R.; Bock, J. J.; Chiang, H. C. +31 more
BICEP1 is a millimeter-wavelength telescope designed specifically to measure the inflationary B-mode polarization of the cosmic microwave background at degree angular scales. We present results from an analysis of the data acquired during three seasons of observations at the South Pole (2006-2008). This work extends the two-year result published i…
Are X-Ray Emitting Coronae around Supermassive Black Holes Outflowing?
Wang, Jun-Xian; Zhu, Fei-Fan; Zhou, You-Yuan +2 more
Hard X-ray emission in radio-quiet active galactic nuclei (AGNs) is believed to be produced via inverse Compton scattering by hot and compact coronae near the supermassive black hole. However, the origin and physical properties of the coronae, including geometry, kinematics, and dynamics, remain poorly known. In this work, taking [O IV] 25.89 &mic…