Search Publications
A Systematic Study of Hale and Anti-Hale Sunspot Physical Parameters
Li, Jing
We present a systematic study of sunspot physical parameters using full-disk magnetograms from the Michelson Doppler Imager/Solar and Heliospheric Observatory and the Helioseismic and Magnetic Imager/Solar Dynamic Observatory. Our aim is to use uniform data sets and analysis procedures to characterize the sunspots, paying particular attention to t…
Extinction Maps and Dust-to-gas Ratios in Nearby Galaxies with LEGUS
Schaerer, D.; Herrero, A.; Cignoni, M. +44 more
We present a study of the dust-to-gas ratios in five nearby galaxies: NGC 628 (M74), NGC 6503, NGC 7793, UGC 5139 (Holmberg I), and UGC 4305 (Holmberg II). Using Hubble Space Telescope broadband WFC3/UVIS UV and optical images from the Treasury program Legacy ExtraGalactic UV Survey (LEGUS) combined with archival HST/Advanced Camera for Surveys da…
The First Year of S-CUBED: The Swift Small Magellanic Cloud Survey
Coe, M. J.; Kennea, J. A.; Evans, P. A. +2 more
The Swift Small Magellanic Cloud (SMC) Survey, S-CUBED, is a high-cadence shallow X-ray survey of the SMC. The survey consists of 142 tiled pointings covering the optical extent of the SMC, which is performed weekly by NASA’s Neil Gehrels Swift Observatory, with an exposure per tile of 60 s. The survey is focused on discovery and monitoring of X-r…
RELICS: Strong-lensing Analysis of the Massive Clusters MACS J0308.9+2645 and PLCK G171.9-40.7
Ouchi, Masami; Mahler, Guillaume; Bradač, Maruša +37 more
Strong gravitational lensing by galaxy clusters has become a powerful tool for probing the high-redshift universe, magnifying distant and faint background galaxies. Reliable strong-lensing (SL) models are crucial for determining the intrinsic properties of distant, magnified sources and for constructing their luminosity function. We present here t…
Star Formation Histories of the LEGUS Dwarf Galaxies. I. Recent History of NGC 1705, NGC 4449, and Holmberg II
Cignoni, M.; Tosi, M.; Sabbi, E. +19 more
We use Hubble Space Telescope observations from the Legacy Extragalactic UV Survey to reconstruct the recent star formation histories (SFHs) of three actively star-forming dwarf galaxies, NGC 4449, Holmberg II, and NGC 1705, from their UV color-magnitude diagrams (CMDs). We apply a CMD fitting technique using two independent sets of stellar isochr…
Ruprecht 106: A Riddle, Wrapped in a Mystery, inside an Enigma
Milone, Antonino P.; Conroy, Charlie; Dotter, Aaron +2 more
Galactic globular clusters (GCs) show overwhelming photometric and spectroscopic evidence for the existence of multiple stellar populations. The question of whether or not there exists a GC that represents a true “simple stellar population” remains open. Here we focus on Ruprecht 106 (R106), a halo GC with [Fe/H] = -1.5 and [α/Fe] ≃0. A previous s…
A Young Ultramassive White Dwarf in the AB Doradus Moving Group
Faherty, Jacqueline K.; Gagné, Jonathan; Fontaine, Gilles +1 more
We use Gaia Data Release 2 (DR2) kinematic data and white dwarf evolutionary models to determine that the young and ultramassive 1.28 ± 0.08 M ⊙ white dwarf GD 50 is a likely member of the AB Doradus moving group (ABDMG). Comparison with the Montréal white dwarf evolutionary models and the MESA Isochrones and Stellar Tracks (MIST) main-…
Coronal Elemental Abundances in Solar Emerging Flux Regions
Long, David M.; Warren, Harry P.; Brooks, David H. +5 more
The chemical composition of solar and stellar atmospheres differs from the composition of their photospheres. Abundances of elements with low first ionization potential (FIP) are enhanced in the corona relative to high-FIP elements with respect to the photosphere. This is known as the FIP effect and it is important for understanding the flow of ma…
V1369 Cen High-resolution Panchromatic Late Nebular Spectra in the Context of a Unified Picture for Nova Ejecta
Izzo, Luca; Shore, Steven N.; Schwarz, Greg J. +3 more
Nova Cen 2013 (V1369 Cen) is the fourth bright nova observed panchromatically through high-resolution UV+optical multiepoch spectroscopy. It is also the nova with the richest set of spectra (in terms of both data quality and number of epochs) thanks to its exceptional brightness. Here, we use the late nebular spectra taken between day ∼250 and day…
Extended Structures of Planetary Nebulae Detected in H2 Emission
Zhang, Yong; Kwok, Sun; Guerrero, Martín A. +4 more
We present narrowband near-infrared images of a sample of 11 Galactic planetary nebulae (PNe) obtained in the H2 2.122 µm and Brγ 2.166 µm emission lines and the K c 2.218 µm continuum. These images were collected with the Wide-field Infrared Camera on the 3.6 m Canada-France-Hawaii Telescope (CFHT); their u…