Search Publications
Evidence for a Rotational Component in the Circumgalactic Medium of Nearby Galaxies
Wakker, Bart P.; French, David M.
We present results of a study comparing the relative velocity of Lyα absorbers to the rotation velocity of nearby galaxy disks in the local universe (z ≤ 0.03). We have obtained rotation curves via long-slit spectroscopy of eight galaxies with the Southern African Large Telescope, and combine this data set with an additional 16 galaxies with data …
Chemically Peculiar A and F Stars with Enhanced s-process and Iron-peak Elements: Stellar Radiative Acceleration at Work
Ting, Yuan-Sen; Rix, Hans-Walter; Zhang, Meng +6 more
We present ≳15,000 metal-rich ([Fe/H] > -0.2 dex) A and F stars whose surface abundances deviate strongly from solar abundance ratios and cannot plausibly reflect their birth material composition. These stars are identified by their high [Ba/Fe] abundance ratios ([Ba/Fe] > 1.0 dex) in the LAMOST DR5 spectra analyzed by Xiang et al. They are …
Chandra Monitoring of the J1809-1917 Pulsar Wind Nebula and Its Field
Pavlov, George G.; Kargaltsev, Oleg; Klingler, Noel +3 more
PSR J1809-1917 is a young (τ = 51 kyr) and energetic ( $\dot{E}=1.8\times {10}^{36}$ erg s-1) radio pulsar powering an X-ray pulsar wind nebula (PWN) that exhibits morphological variability. We report on the results of a new monitoring campaign by the Chandra X-ray Observatory (Chandra), carried out across six epochs with a ∼7 week cade…
A Rapidly Varying Red Supergiant X-Ray Binary in the Galactic Center
Gottlieb, Amy M.; Ackley, Kendall; DeWitt, Curtis +2 more
We analyzed multiwavelength observations of the previously identified Galactic center X-ray binary CXO 174528.79-290942.8 (XID 6592) and determine that the near-infrared counterpart is a red supergiant based on its spectrum and luminosity. Scutum X-1 is the only previously known X-ray binary with a red supergiant donor star and closely resembles X…
The Detection of Dust Gap-ring Structure in the Outer Region of the CR Cha Protoplanetary Disk
Dong, Ruobing; Kataoka, Akimasa; Sitko, Michael +13 more
We observe the dust continuum at 225 GHz and CO isotopologue (12CO, 13CO, and C18O) J = 2-1 emission lines toward the CR Cha protoplanetary disk using the Atacama Large Millimeter/submillimeter Array. The dust continuum image shows a dust gap-ring structure in the outer region of the dust disk. A faint dust ring is…
A Model-insensitive Baryon Acoustic Oscillation Feature in the 21 cm Signal from Reionization
Trac, Hy; Cain, Christopher; D'Aloisio, Anson +2 more
We examine the impact of baryon-dark matter relative velocities on intergalactic small-scale structure and the 21 cm signal during reionization. Streaming velocities reduced clumping in the intergalactic medium on mass scales of ∼104-108 M⊙. This effect produced a distinct baryon acoustic oscillation (BAO) feature …
Magnetohydrodynamic Turbulent Evolution of a Magnetic Cloud in the Outer Heliosphere
Telloni, Daniele; Zank, Gary P.; Adhikari, Laxman +8 more
This Letter exploits joint observations of the same interplanetary coronal mass ejection by widely separated spacecraft to study, for the first time, the turbulent evolution of the magnetohydrodynamic (MHD) properties of the embedded magnetic cloud, during its propagation throughout interplanetary space. Specifically, the event was observed by Win…
On the Correlation between L Dwarf Optical and Infrared Variability and Radio Aurorae
Richey-Yowell, Tyler; Kao, Melodie M.; Pineda, J. Sebastian +2 more
Photometric variability attributed to cloud phenomena is common in L/T transition brown dwarfs. Recent studies show that such variability may also trace aurorae, suggesting that localized magnetic heating may contribute to observed brown dwarf photometric variability. We assess this potential correlation with a survey of 17 photometrically variabl…
Observation and Modeling of High-temperature Solar Active Region Emission during the High-resolution Coronal Imager Flight of 2018 May 29
Golub, Leon; Winebarger, Amy R.; Warren, Harry P. +15 more
Excellent coordinated observations of NOAA active region 12712 were obtained during the flight of the High-resolution Coronal Imager (Hi-C) sounding rocket on 2018 May 29. This region displayed a typical active region core structure with relatively short, high-temperature loops crossing the polarity inversion line and bright "moss" located at the …
Evidence of Particle Acceleration in the Superbubble 30 Doradus C with NuSTAR
Auchettl, Katie; Madsen, Kristin K.; Grefenstette, Brian W. +2 more
We present evidence of diffuse, non-thermal X-ray emission from the superbubble 30 Doradus C (30 Dor C) using hard X-ray images and spectra from NuSTAR observations. For this analysis, we utilize data from a 200 ks targeted observation of 30 Dor C as well as 2.8 Ms of serendipitous off-axis observations from the monitoring of nearby SN 1987A. The …