Search Publications
Lyα Absorption in a "Croissant-like" Heliosphere
Wood, Brian E.; Tenishev, Valeriy; Toth, Gabor +6 more
Lyα absorption profiles have been used to detect astrospheres and heliospheric absorption from the hydrogen wall and heliotail. Using magnetohydrodynamic models of the heliosphere, we can compare simulated to observed Lyα profiles to probe the neutral hydrogen within and near the heliosphere. There is an ongoing controversy whether the heliosphere…
Fierce Feedback in an Obscured, Sub-Eddington State of the Seyfert 1.2 Markarian 817
Brandt, W. N.; Zoghbi, Abderahmen; Miller, Jon M. +7 more
Mrk 817 is a bright and variable Seyfert 1.2 active galactic nucleus (AGN). X-ray monitoring of Mrk 817 with the Neil Gehrels Swift Observatory in 2022 revealed that the source flux had declined to a lower level than recorded at any prior point in the then 19 yr mission. We present an analysis of deep XMM-Newton and NuSTAR observations obtained in…
Evidence for Dust Depletion in a Misaligned Protoplanetary Disk with JWST
Zhu, Z.; Reynolds, M.; Calvet, N. +12 more
Here we report the detection of dust depletion in a misaligned inner disk around UX Tau A using JWST MIRI spectra. Mid-infrared (MIR) continuum "seesaw" variability was detected in this disk by Spitzer and attributed to variable shadows cast on the outer disk by the inner disk. The JWST MIRI spectrum of UX Tau A also shows seesaw variability but w…
Constraints on the z ∼ 5 Star-forming Galaxy Luminosity Function From Hubble Space Telescope Imaging of an Unbiased and Complete Sample of Long Gamma-Ray Burst Host Galaxies
Strader, Jay; Perley, Daniel A.; Chornock, Ryan +4 more
We present rest-frame UV Hubble Space Telescope imaging of the largest and most complete sample of 23 long-duration gamma-ray burst (GRB) host galaxies between redshifts 4 and 6. Of these 23, we present new WFC3/F110W imaging for 19 of the hosts, which we combine with archival WFC3/F110W and WFC3/F140W imaging for the remaining four. We use the ph…
Cosmic-Ray Transport in the Presence of a Fisk-type Heliospheric Magnetic Field: Investigating the Influence of Drift
Engelbrecht, N. E.; Steyn, P. J.; Troskie, J. S.
Drifts due to the gradients in, and curvatures of, the heliospheric magnetic field (HMF) play a significant role in the transport of galactic cosmic rays (GCRs) in the heliosphere. Although this has been well studied for the Parker HMF, the influence of Fisk-type fields, with their unique geometry, has hitherto received less attention. Here, drift…
Retrieving Young Cloudy L Dwarfs: A Nearby Planetary-mass Companion BD+60 1417B and its Isolated Red Twin W0047
Gonzales, Eileen C.; Faherty, Jacqueline K.; Morley, Caroline V. +12 more
We present an atmospheric retrieval analysis on a set of young, cloudy, red L dwarfs—CWISER J124332.12+600126.2 (BD+60 1417B) and WISEP J004701.06+680352.1 (W0047)—using the Brewster retrieval framework. We also present the first elemental abundance measurements of the young K-dwarf (K0) host star, BD+60 1417, using high-resolution (R = 50,000) sp…
Resolving a Candidate Dual Active Galactic Nucleus with ∼100 pc Separation in MCG-03-34-64
Turner, T. J.; Kraemer, S. B.; Braito, V. +4 more
We report the serendipitous multiwavelength discovery of a candidate dual black hole system with a separation of ∼100 pc, in the gas-rich luminous infrared galaxy MCG-03-34-64 (z = 0.016). Hubble Space Telescope/Advanced Camera for Surveys observations show three distinct optical centroids in the [O III] narrow-band and F814W images. Subsequent an…
Combined JWST–MUSE Integral Field Spectroscopy of the Most Luminous Quasar in the Local Universe, PDS 456
Veilleux, Sylvain; Zakamska, Nadia L.; Liu, Weizhe +5 more
Fast accreting, extremely luminous quasars contribute heavily to the feedback process within galaxies. While these systems are most common at cosmic noon (z ∼ 2), here we choose to study PDS 456, an extremely luminous (L bol ∼ 1047 erg s‑1) but nearby (z ∼ 0.185) quasar where the physics of feedback can be studied …
Discovery of an Extremely r-process-enhanced Thin-disk Star with [Eu/H] = +0.78
Shi, Jianrong; Beers, Timothy C.; Allende Prieto, Carlos +9 more
Highly r-process-enhanced (RPE) stars are rare and usually metal poor ([Fe/H] < ‑1.0), and they mainly populate the Milky Way halo and dwarf galaxies. This study presents the discovery of a relatively bright (V = 12.72), highly RPE (r-II) star ([Eu/Fe] = +1.32, [Ba/Eu] = ‑0.95), LAMOST J020623.21+494127.9. This star was selected from the Large …
The Missing Symbiotic Stars: A Joint Analysis with Gaia, GALEX, and XMM-Newton Data
Shao, Yong; Li, Xiang-Dong; Xu, Xiao-jie
The existence of a population of low-accretion-rate symbiotic stars (SySts), consisting of a giant star and a compact companion (usually a white dwarf), has been proposed recently. However, their population has not been fully understood. In this work, we present an investigation on SySts candidates consisting of asymptotic giant branch stars (AGBs…