Search Publications
New Evidence for Extended He I> Reionization at z ≳ 3.5 from He II Lyman Alpha and Beta Transmission Spikes
Richter, Philipp; Hennawi, Joseph F.; Worseck, Gábor +3 more
We present new high-resolution (R = λ/Δλ ∼ 14,000) spectra of the two brightest He II-transparent quasars in the far-UV at zem > 3.5, HE2QS J2311-1417 (zem = 3.70) and HE2QS J1630+0435 (zem = 3.81), obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope. In the predominantly saturated He II …
Metallicity Estimation of RR Lyrae Stars From Their I-Band Light Curves
Grebel, Eva K.; Pojmański, Grzegorz; Dékány, István
We have revisited the problem of metallicity prediction of RR Lyrae stars from their near-infrared light curves in the Cousins I wave band. Our study is based on high-quality time series photometry and state-of-the-art high-resolution spectroscopic abundance measurements of 80 fundamental-mode (RRab) and 24 first-overtone (RRc) stars, spanning ~[-…
The Nature of the Milky Way's Stellar Halo Revealed by the Three Integrals of Motion
Carollo, Daniela; Chiba, Masashi
We developed a new selection method of halo stars in the phase-space distribution defined by the three integrals of motion in an axisymmetric Galactic potential (E, Lz, I3), where I3 is the third integral of motion. The method is used to explore the general chemodynamical structure of the halo based on stellar samp…
Exemplary Merging Clusters: Weak-lensing and X-Ray Analysis of the Double Radio Relic, Merging Galaxy Clusters MACS J1752.0+4440 and ZWCL 1856.8+6616
Dawson, William A.; Jones, Christine; Forman, William R. +8 more
The investigation of merging galaxy clusters that exhibit radio relics is strengthening our understanding of the formation and evolution of galaxy clusters, the nature of dark matter, the intracluster medium, and astrophysical particle acceleration. Each merging cluster provides only a single view of the cluster formation process, and the variety …
A Spatially Resolved Survey of Distant Quasar Host Galaxies. I. Dynamics of Galactic Outflows
Armus, Lee; Larkin, James E.; Wright, Shelley A. +6 more
We present observations of ionized gas outflows in 11 z = 1.39-2.59 radio-loud quasar host galaxies. Data were taken with the integral field spectrograph OSIRIS and the adaptive optics system at the W.M. Keck Observatory targeting nebular emission lines (Hβ, [O III], Hα, [N II], and [S II]) redshifted into the near-infrared (1-2.4 µm). Outfl…
Targeting Bright Metal-poor Stars in the Disk and Halo Systems of the Galaxy
Casey, Andrew R.; Beers, Timothy C.; Lee, Young Sun +7 more
We present the results of spectroscopic follow-up for 1897 low-metallicity star candidates, selected from the Best & Brightest (B&B) Survey, carried out with the GMOS-N/S (Gemini North/South telescopes) and Goodman (SOAR Telescope) spectrographs. From these low-resolution (R ∼ 2000) spectra, we estimate stellar atmospheric parameters, as w…
A Coplanar Circumbinary Protoplanetary Disk in the TWA 3 Triple M Dwarf System
Duchêne, Gaspard; Andrews, Sean M.; Czekala, Ian +5 more
We present sensitive ALMA observations of TWA 3, a nearby, young (∼10 Myr) hierarchical system composed of three pre-main-sequence M3-M4.5 stars. For the first time, we detected 12CO and 13CO J = 2-1 emissions from the circumbinary protoplanetary disk around TWA 3A. We jointly fit the protoplanetary disk velocity field, stell…
Luminous Late-time Radio Emission from Supernovae Detected by the Karl G. Jansky Very Large Array Sky Survey (VLASS)
Paterson, Kerry; Margutti, Raffaella; Terreran, Giacomo +10 more
We present a population of 19 radio-luminous supernovae (SNe) with emission reaching L ν ~ 1026-1029 erg s-1 Hz-1 in the first epoch of the Very Large Array Sky Survey (VLASS) at 2-4 GHz. Our sample includes one long gamma-ray burst, SN 2017iuk/GRB 171205A, and 18 core-collapse SNe detected …
A Catalog of Interplanetary Coronal Mass Ejections Observed by Juno between 1 and 5.4 au
Lugaz, Noé; Winslow, Réka M.; Möstl, Christian +2 more
We use magnetic field measurements by the Juno spacecraft to catalog and investigate interplanetary coronal mass ejections (ICMEs) beyond 1 au. During its cruise phase, Juno spent about 5 yr in the solar wind between 2011 September and 2016 June, providing measurements of the interplanetary magnetic field (IMF) between 1 and 5.4 au. Juno therefore…
Eclipsing the X-Ray Emitting Region in the Active Galaxy NGC 6814
Miller, Jon M.; Gallo, Luigi C.; Gonzalez, Adam G.
We report the detection of a rapid occultation event in the nearby Seyfert galaxy NGC 6814, simultaneously captured in a transient light curve and spectral variability. The intensity and hardness ratio curves capture distinct ingress and egress periods that are symmetric in duration. Independent of the selected continuum model, the changes can be …