Search Publications
A Rapid Sequence of Solar Energetic Particle Events Associated with a Series of Extreme-ultraviolet Jets: Solar Orbiter, STEREO-A, and Near-Earth Spacecraft Observations
Lario, D.; Zhukov, A. N.; Jebaraj, I. C. +28 more
A series of solar energetic electron (SEE) events was observed from 2022 November 9 to November 15 by Solar Orbiter, STEREO-A, and near-Earth spacecraft. At least 32 SEE intensity enhancements at energies >10 keV were clearly distinguishable in Solar Orbiter particle data, with 13 of them occurring on November 11. Several of these events were a…
Infrared Spectroscopic and Physical Properties of Methanol Ices—Reconciling the Conflicting Published Band Strengths of an Important Interstellar Solid
Gerakines, Perry A.; Yarnall, Yukiko Y.; Hudson, Reggie L.
Infrared spectroscopic observations have established the presence of solid methanol (CH3OH) in the interstellar medium and in solar system ices, but the abundance of frozen CH3OH cannot be deduced without accurate band strengths, optical constants, and reference spectra. In this paper we identify disagreements, omissions, and…
Ly Halo Properties and Dust in the Circumgalactic Medium of z ∼ 2 Star-forming Galaxies
Shapley, Alice E.; Steidel, Charles C.; Reddy, Naveen A. +7 more
We present Keck Cosmic Web Imager integral-field unit observations around extended Lyα halos of 27 typical star-forming galaxies with redshifts 2.0 < z < 3.2 drawn from the MOSFIRE Deep Evolution Field survey. We examine the average Lyα surface brightness profiles in bins of star formation rate (SFR), stellar mass (M *), age, stel…
Stellar Cycle and Evolution of Polar Spots in an M+WD Binary
Liu, Jifeng; Wang, Song; Zhao, Xinlin +5 more
Stellar activity cycles reveal continuous relaxation and induction of magnetic fields. The activity cycle is typically traced through the observation of cyclic variations in total brightness or Ca H&K emission flux of stars, as well as cyclic variations in the orbital periods of binary systems. In this work, we report the identification of a s…
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…