Search Publications
Where do Galaxies End?
Shull, J. Michael
Our current view of galaxies considers them as systems of stars and gas embedded in extended halos of dark matter, much of it formed by the infall of smaller systems at earlier times. The true extent of a galaxy remains poorly determined, with the "virial radius" (R vir) providing a characteristic separation between collapsed structures…
Blue Straggler Masses from Pulsation Properties. I. The Case of NGC 6541
Dalessandro, E.; Marconi, M.; Bono, G. +3 more
We used high spatial resolution images acquired with the Wide Field Camera 3 on board Hubble Space Telescope to probe the population of variable blue straggler stars (BSSs) in the central region of the poorly studied Galactic globular cluster NGC 6541. The time sampling of the acquired multiwavelength (F390W, F555W, and F814W) data allowed us to d…
A Full-sky, High-resolution Atlas of Galactic 12 µm Dust Emission with WISE
Meisner, Aaron M.; Finkbeiner, Douglas P.
We describe our custom processing of the entire Wide-field Infrared Survey Explorer (WISE) 12 µm imaging data set, and present a high-resolution, full-sky map of diffuse Galactic dust emission that is free of compact sources and other contaminating artifacts. The principal distinctions between our resulting co-added images and the WISE Atlas…
New Perspective on Galaxy Outflows from the First Detection of Both Intrinsic and Traverse Metal-line Absorption
Martin, Crystal L.; Bouché, Nicolas; Kacprzak, Glenn G. +6 more
We present the first observation of a galaxy (z = 0.2) that exhibits metal-line absorption back-illuminated by the galaxy (down-the-barrel) and transversely by a background quasar at a projected distance of 58 kpc. Both absorption systems, traced by Mg II, are blueshifted relative to the galaxy systemic velocity. The quasar sight line, which resid…
Hydrogen Balmer Continuum in Solar Flares Detected by the Interface Region Imaging Spectrograph (IRIS)
Heinzel, P.; Kleint, L.
We present a novel observation of the white light flare (WLF) continuum, which was significantly enhanced during the X1 flare on 2014 March 29 (SOL2014-03-29T17:48). Data from the Interface Region Imaging Spectrograph (IRIS) in its near-UV channel show that at the peak of the continuum enhancement, the contrast at the quasi-continuum window above …
Parallax beyond a Kiloparsec from Spatially Scanning the Wide Field Camera 3 on the Hubble Space Telescope
Casertano, Stefano; Anderson, Jay; Filippenko, Alexei V. +2 more
We use a newly developed observing mode on the Hubble Space Telescope (HST) and Wide Field Camera 3, spatial scanning, to increase source sampling a thousand-fold and measure changes in source positions to a precision of 20-40 µas, more than an order of magnitude better than attainable in pointed observations. This observing mode can usefull…
The Broad-band X-Ray Spectrum of IC 4329A from a Joint NuSTAR/Suzaku Observation
Harrison, F. A.; Stern, D.; Zhang, W. W. +16 more
We have obtained a deep, simultaneous observation of the bright, nearby Seyfert galaxy IC 4329A with Suzaku and NuSTAR. Through a detailed spectral analysis, we are able to robustly separate the continuum, absorption, and distant reflection components in the spectrum. The absorbing column is found to be modest ({\sim }6 \times 10^{21} {\, cm^{-2}\…
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. …