Search Publications
Constraints on the Surface Magnetic Fields and Age of a Cool Hypergiant: XMM-Newton X-Ray Observations of VY CMa
Humphreys, Roberta M.; Davidson, Kris; Kastner, Joel H. +2 more
The complex circumstellar ejecta of highly evolved, cool hypergiants are indicative of multiple, asymmetric mass-loss events. To explore whether such episodic, non-isotropic mass loss may be driven by surface magnetic activity, we have observed the archetypical cool hypergiant VY CMa with the XMM-Newton X-ray satellite observatory. The hypergiant …
A Tale of Three Mysterious Spectral Features in Carbon-rich Evolved Stars: The 21 µm, 30 µm, and “Unidentified Infrared” Emission Features
Li, Aigen; Jiang, B. W.; Mishra, Ajay
The mysterious “21 µm” emission feature seen almost exclusively in the short-lived protoplanetary nebula (PPN) phase of stellar evolution remains unidentified since its discovery two decades ago. This feature is always accompanied by the equally mysterious, unidentified “30 µm” feature and the so-called “unidentified infrared” (UIR) fe…
Re-evaluation of the Neutron Emission from the Solar Flare of 2005 September 7, Detected by the Solar Neutron Telescope at Sierra Negra
Watanabe, K.; Matsubara, Y.; Muraki, Y. +9 more
The X17.0 solar flare of 2005 September 7 released high-energy neutrons that were detected by the Solar Neutron Telescope (SNT) at Sierra Negra, Mexico. In three separate and independent studies of this solar neutron event, several of its unique characteristics were studied; in particular, a power-law energy spectra was estimated. In this paper, w…
Plasma Physical Parameters along CME-driven Shocks. II. Observation-Simulation Comparison
Bemporad, A.; Susino, R.; Lapenta, G. +1 more
In this work, we compare the spatial distribution of the plasma parameters along the 1999 June 11 coronal mass ejection (CME)-driven shock front with the results obtained from a CME-like event simulated with the FLIPMHD3D code, based on the FLIP-MHD particle-in-cell method. The observational data are retrieved from the combination of white-light c…
Herschel Dust Emission as a Probe of Starless Cores Mass: MCLD 123.5+24.9 of the Polaris Flare
Ferland, Gary J.; Abel, Nicholas P.; Wagle, Gururaj A. +1 more
We present newly processed archival Herschel images of molecular cloud MCLD 123.5+24.9 in the Polaris Flare. This cloud contains five starless cores. Using the spectral synthesis code Cloudy, we explore uncertainties in the derivation of column densities, and hence masses of molecular cores from Herschel data. We first consider several detailed gr…
X-Ray Perspective of the Twisted Magnetospheres of Magnetars
Göğüş, Ersin; Weng, Shan-Shan; Lin, Lin +1 more
Anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs) are recognized as the most promising magnetar candidates, as indicated by their energetic bursts and rapid spin-downs. It is expected that the strong magnetic field leaves distinctive imprints on the emergent radiation both by affecting the radiative processes in atmospheres of mag…
Far-ultraviolet Study of the ζ-Ophiuchi H II Region
Choi, Yeon-Ju; Min, Kyoung-Wook; Seon, Kwang-Il
We report the results of our analysis of the H II region around ζ Oph based on far-ultraviolet (FUV) spectral imaging observations, together with data made in other wavelengths. We found that scattering by dust grains of the FUV photons, which originate mostly from ζ Oph, dominates the FUV emission in this region, while contributions from the two-…
Detection of a Compact Nuclear Radio Source in the Local Group Elliptical Galaxy M32
Wang, Q. Daniel; Kraft, Ralph P.; Li, Zhiyuan +4 more
The Local Group compact elliptical galaxy M32 hosts one of the nearest candidate supermassive black holes (SMBHs), which has a previously suggested X-ray counterpart. Based on sensitive observations taken with the Karl G. Jansky Very Large Array (VLA), we detect for the first time a compact radio source coincident with the nucleus of M32, which ex…
High Energy Polarization of Blazars: Detection Prospects
Chakraborty, N.; Pavlidou, V.; Fields, B. D.
Emission from blazar jets in the ultraviolet, optical, and infrared is polarized. If these low-energy photons were inverse-Compton scattered, the upscattered high-energy photons retain a fraction of the polarization. Current and future X-ray and gamma-ray polarimeters such as INTEGRAL-SPI, PoGOLITE, X-Calibur, Gamma-Ray Burst Polarimeter, GEMS-lik…
Multiwavelength Observations of a Slow-rise, Multistep X1.6 Flare and the Associated Eruption
Cho, K. -S.; Yurchyshyn, V.; Abramenko, V. I. +2 more
Using multiwavelength observations, we studied a slow-rise, multistep X1.6 flare that began on 2014 November 7 as a localized eruption of core fields inside a δ-sunspot and later engulfed the entire active region (AR). This flare event was associated with formation of two systems of post-eruption arcades (PEAs) and several J-shaped flare ribbons s…