Search Publications
No Evidence of Chemical Anomalies in the Bimodal Turnoff Cluster NGC 1806 in the Large Magellanic Cloud
Dalessandro, E.; Mucciarelli, A.; Origlia, L. +2 more
We have studied the chemical composition of NGC 1806, a massive, intermediate-age globular cluster that shows a double main sequence turnoff. We analyzed a sample of high-resolution spectra (secured with FLAMES at the Very Large Telescope) for eight giant stars, members of the cluster, finding an average iron content of [Fe/H] = -0.60 ± 0.01 dex a…
Observational Evidence of Torus Instability as Trigger Mechanism for Coronal Mass Ejections: The 2011 August 4 Filament Eruption
Mierla, M.; Seaton, D. B.; Poedts, S. +4 more
Solar filaments are magnetic structures often observed in the solar atmosphere and consist of plasma that is cooler and denser than their surroundings. They are visible for days—even weeks—which suggests that they are often in equilibrium with their environment before disappearing or erupting. Several eruption models have been proposed that aim to…
HerMES: The Rest-frame UV Emission and a Lensing Model for the z = 6.34 Luminous Dusty Starburst Galaxy HFLS3
Pérez-Fournon, I.; Ivison, R. J.; Burgarella, D. +23 more
We discuss the rest-frame ultraviolet emission from the starbursting galaxy HFLS3 at a redshift of 6.34. The galaxy was discovered in Herschel/SPIRE data due to its red color in the submillimeter wavelengths from 250 to 500 µm. Keck/NIRC2 K s -band adaptive optics imaging data showed two potential near-IR counterparts near HFLS3. …
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…