Search Publications
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 …
Properties of Streamer Wave Events Observed during the STEREO Era
Van Doorsselaere, Tom; Zhukov, Andrei N.; Decraemer, Bieke
Transverse waves are sometimes observed in solar helmet streamers, typically after the passage of a coronal mass ejection (CME). The CME-driven shock wave moves the streamer sideways, and a decaying oscillation of the streamer is observed after the CME passage. Previous works generally reported observations of streamer oscillations taken from a si…
Analysis of XMM-Newton Observations of Supernova Remnant W49B and Clues to the Progenitor
Frank, Kari A.; Burrows, David N.; Dwarkadas, Vikram V. +1 more
W49B is a supernova remnant (SNR) discovered over 60 yr ago in early radio surveys. It has since been observed over the entire wavelength range, with the X-ray morphology resembling a centrally filled SNR. The nature of its progenitor star is still debated. Applying Smoothed Particle Inference techniques to analyze the X-Ray emission from W49B, we…
Five Stellar Populations in M22 (NGC 6656)
Lee, Jae-Woo
We present the Ca-CN-CH photometry of the metal-complex globular cluster (GC) M22 (NGC 6656). Our photometry clearly shows the discrete double CN-CH anticorrelations in M22 red giant branch (RGB) stars, due to the difference in the mean metallicity. The populational number ratio between the two main groups is n(G1):n(G2) = 63:37(±3), with the G1 b…
Evidence of Dust Grain Evolution from Extinction Mapping in the IC 63 Photodissociation Region
Williams, Benjamin F.; Gordon, Karl D.; Baes, Maarten +5 more
Photodissociation regions (PDRs) are parts of the ISM consisting of predominantly neutral gas, located at the interface between H II regions and molecular clouds. The physical conditions within these regions show variations on very short spatial scales, and therefore PDRs constitute ideal laboratories for investigating the properties and evolution…
On the Granulation and Irregular Variation of Red Supergiants
Jiang, Bi-Wei; Ren, Yi
The mechanisms and characteristics of the irregular variations of red supergiants (RSGs) are studied based on the RSG samples in the Small Magellanic Cloud (SMC), Large Magellanic Cloud (LMC), and M31. With the time-series data from the All-Sky Automated Survey for SuperNovae and Intermediate Palomar Transient Factory survey, we use the continuous…
Unveiling Sizes of Compact AGN Hosts with ALMA
Juneau, Stéphanie; Marchesi, Stefano; Dekel, Avishai +7 more
We present rest-frame far-infrared (FIR) and optical size measurements of active galactic nucleus (AGN) hosts and star-forming galaxies (SFGs) in the COSMOS field, enabled by high-resolution Atacama Large Millimeter/submillimeter Array (ALMA)/1 mm (0.″1-0.″4) and Hubble Space Telescope (HST)/F814W imaging (∼0.″1). Our sample includes 27 galaxies a…
Rapid Rotation of Kepler Field Dwarfs and Subgiants: Spectroscopic v sin i from APOGEE
van Saders, Jennifer L.; Simonian, Gregory V. A.; Pinsonneault, Marc H. +1 more
We use 5337 spectroscopic $v\sin i$ measurements of Kepler dwarfs and subgiants from the APOGEE survey to study stellar rotation trends. We find a detection threshold of 10 km s-1, which allows us to explore the spindown of intermediate-mass stars leaving the main sequence, merger products, young stars, and tidally synchronized binaries…