Search Publications
Relationship between Distribution of Magnetic Decay Index and Filament Eruptions
Liu, Y.; Li, H.; Elmhamdi, A. +1 more
The decay index n of a horizontal magnetic field is considered to be an important parameter in judging the stability of a flux rope. However, the spatial distribution of this parameter has not been extensively explored so far. In this paper, we present a delineative study of the three-dimensional maps of n for two eruptive events, in which filamen…
The Intermediate-mass Star-forming Region Lynds 1340. An Optical View
Moór, Attila; Kun, Mária; Reipurth, Bo +1 more
We have performed an optical spectroscopic and photometric search for young stellar objects associated with the molecular cloud Lynds 1340, and examined the structure of the cloud by constructing an extinction map, based on SDSS data. The new extinction map suggests a shallow, strongly fragmented cloud, having a mass of some 3700 M ⊙. L…
X-Ray Afterglow of Swift J1644+57: A Compton Echo?
Cheng, K. S.; Kong, Albert K. H.; Chernyshov, D. O. +2 more
Swift, Chandra, and XMM have found a weak but nearly constant X-ray component from Swift J1644+57 that appeared at ∼500 days and was visible at least until ∼1400 days after the stellar capture, which cannot be explained by standard tidal disruption theories. We suggest that this X-ray afterglow component may result from the Thomson scattering betw…
Galaxy Infall by Interacting with Its Environment: A Comprehensive Study of 340 Galaxy Clusters
Gandhi, Poshak; Makishima, Kazuo; Nakazawa, Kazuhiro +7 more
To study systematically the evolution of the angular extents of the galaxy, intracluster medium (ICM), and dark matter components in galaxy clusters, we compiled the optical and X-ray properties of a sample of 340 clusters with redshifts <0.5, based on all the available data from the Sloan Digital Sky Survey and Chandra/XMM-Newton. For each clu…
On the Absence of EUV Emission from Comet C/2012 S1 (ISON)
Pesnell, W. Dean; Bryans, Paul
When the sungrazing comet C/2012 S1 (ISON) made its perihelion passage within two solar radii of the Sun’s surface, it was expected to be a bright emitter at extreme ultraviolet (EUV) wavelengths. However, despite solar EUV telescopes repointing to track the orbit of the comet, no emission was detected. This “null result” is interesting in its own…
Hard X-Ray Emission from Sh 2-104: A NuSTAR Search for Gamma-Ray Counterparts
Harrison, F. A.; Stern, D.; Zhang, W. W. +11 more
We present NuSTAR hard X-ray observations of Sh 2-104, a compact H II region containing several young massive stellar clusters (YMSCs). We have detected distinct hard X-ray sources coincident with localized VERITAS TeV emission recently resolved from the giant gamma-ray complex MGRO J2019+37 in the Cygnus region. Fainter, diffuse X-rays coincident…
On the Bright Loop Top Emission in Post-eruption Arcades
Isobe, Hiroaki; Tripathi, Durgesh; Ghosh, Avyarthana +1 more
Observations of post-eruption arcades (PEAs) in X-rays and EUV reveal strong localized brightenings at the loop top regions. The origins of these brightenings and their dynamics are not well understood to date. Here, we study the dynamics of PEAs using one-dimensional hydrodynamic modeling, focusing on understanding the formation of localized brig…
Coeval Intermediate-mass Star Formation in N4W
Chen, Zhiwei; Kwon, Jungmi; Tamura, Motohide +3 more
Protostars are mostly found in star-forming regions, where the natal molecular gas still remains. At about 5\prime west of the molecular bubble N4, N4W is identified as a star-forming clump hosting three Class II (IRS 1-3), and one Class I (IRS 4) young stellar objects (YSOs), as well as a submillimeter source SMM1. The near-IR polariza…
What Is the Source of Quiet Sun Transition Region Emission?
De Pontieu, Bart; Schmit, D. J.
Dating back to the first observations of the on-disk corona, there has been a qualitative link between the photosphere’s magnetic network and enhanced transition-temperature plasma emission. These observations led to the development of a general model that describes emission structures through the partitioning of the atmospheric volume with differ…
Calibration of the Voyager Ultraviolet Spectrometers and the Composition of the Heliosphere Neutrals: Reassessment
Holberg, J. B.; Ben-Jaffel, Lotfi
The data harvest from the Voyagers’ (V 1 and V 2) Ultraviolet Spectrometers (UVS) covers encounters with the outer planets, measurements of the heliosphere sky-background, and stellar spectrophotometry. Because their period of operation overlaps with many ultraviolet missions, the calibration of V1 and V2 UVS with other spectrometers is invaluable…