Search Publications
The Milky Way's Shell Structure Reveals the Time of a Radial Collision
Widrow, Lawrence M.; Sanderson, Robyn; Newberg, Heidi Jo +1 more
We identify shell structures in the Milky Way for the first time. We find two shells in the Virgo Overdensity region and two shells in the Hercules Aquila Cloud region using Sloan Digital Sky Survey, Gaia, and LAMOST data. These shell stars are a subset of the substructure previously identified as the Virgo Radial Merger (VRM). Timing arguments fo…
Tidal Inflation Reconciles Low-density Sub-Saturns with Core Accretion
Batygin, Konstantin; Millholland, Sarah; Petigura, Erik
While the solar system contains no planets between the sizes of Uranus and Saturn, our current exoplanet census includes several dozen such planets with well-measured masses and radii. These sub-Saturns exhibit a diversity of bulk densities, ranging from ∼0.1 to 3 g cm-3. When modeled simply as hydrogen/helium envelopes atop rocky cores…
The µ Tau Association: A 60 Myr Old Coeval Group at 150 pc from the Sun
Mann, Andrew W.; Faherty, Jacqueline K.; Gagné, Jonathan +3 more
We present an analysis of the newly identified µ Tau Association (MUTA) of young stars at ≃150 pc from the Sun that is part of the large Cas-Tau structure, coeval and comoving with the α Persei cluster. This association is also located in the vicinity of the Taurus-Auriga star-forming region and the Pleiades association, although it is unrel…
Hinode/EIS Measurements of Active-region Magnetic Fields
Landi, E.; Li, W.; Hutton, R. +1 more
The present work illustrates the potential of a new diagnostic technique that allows the measurement of the coronal magnetic field strength in solar active regions by utilizing a handful of bright Fe X and Fe XI lines commonly observed by the high-resolution Hinode/EUV Imaging Spectrometer (EIS). The importance of this new diagnostic technique is …
SCUBA-2 Ultra Deep Imaging EAO Survey (Studies). III. Multiwavelength Properties, Luminosity Functions, and Preliminary Source Catalog of 450 µm Selected Galaxies
Goto, Tomotsugu; Smail, Ian; Ho, Luis C. +35 more
We construct a SCUBA-2 450 µm map in the COSMOS field that covers an area of 300 arcmin2 and reaches a 1σ noise level of 0.65 mJy in the deepest region. We extract 256 sources detected at 450 µm with signal-to-noise ratios >4.0 and analyze the physical properties of their multiwavelength counterparts. We find that most of…
New Insights into the H II Region G18.88-0.49: Hub-Filament System and Accreting Filaments
Dewangan, L. K.; Ojha, D. K.; Sharma, Saurabh +3 more
We present an analysis of multiwavelength observations of an area of 0°27 × 0°27 around the Galactic H II region G18.88-0.49, which is powered by an O-type star (age ∼ 105 yr). The Herschel column density map reveals a shell-like feature of extension ∼12 pc × 7 pc and mass ∼2.9 × 104 M⊙ around the H II region; its …
Multiband GPI Imaging of the HR 4796A Debris Disk
Weinberger, Alycia J.; Schneider, Glenn; Duchêne, Gaspard +36 more
We have obtained Gemini Planet Imager (GPI) J-, H-, K1-, and K2-Spec observations of the iconic debris ring around the young, main-sequence star HR 4796A. We applied several point-spread function (PSF) subtraction techniques to the observations (Mask-and-Interpolate, RDI-NMF, RDI-KLIP, and ADI-KLIP) to measure the geometric parameters and the scat…
A Gaia-based Catalog of Candidate Stripped Nuclei and Luminous Globular Clusters in the Halo of Centaurus A
Caldwell, Nelson; Strader, Jay; Seth, Anil C. +4 more
Tidally stripped galaxy nuclei and luminous globular clusters (GCs) are important tracers of the halos and assembly histories of nearby galaxies, but are difficult to reliably identify with typical ground-based imaging data. In this paper we present a new method to find these massive star clusters using Gaia DR2, focusing on the massive elliptical…
Super Star Clusters in the Central Starburst of NGC 4945
Meier, David S.; Ott, Jürgen; Bolatto, Alberto D. +12 more
The nearby (3.8 Mpc) galaxy NGC 4945 hosts a nuclear starburst and Seyfert type 2 active galactic nucleus (AGN). We use the Atacama Large Millimeter/submillimeter Array (ALMA) to image the 93 GHz (3.2 mm) free-free continuum and hydrogen recombination line emission (H40α and H42α) at 2.2 pc (0"12) resolution. Our observations reveal 27 bright, com…
A Catalog of AGN Host Galaxies Observed with HST/ACS: Correlations between Star Formation and AGN Activity
Griffith, Roger L.; Stern, Daniel; Stemo, Aaron +3 more
We present the Advanced Camera for Surveys Active Galactic Nuclei (ACS-AGN) Catalog, a catalog of 2585 active galactic nucleus (AGN) host galaxies that are at redshifts 0.2 < z < 2.5 and that were imaged with the Hubble Space Telescope’s Advanced Camera for Surveys (ACS). Using the ACS General Catalog (ACS-GC) as our initial sample, we selec…