Search Publications
Time Evolution of the Reverse Shock in SN 1006
Long, Knox S.; Fesen, Robert A.; Winkler, P. Frank +1 more
The Schweizer-Middleditch star, located behind the SN 1006 remnant and near its center in projection, provides the opportunity to study cold, expanding ejecta within the SN 1006 shell through UV absorption. Especially notable is an extremely sharp red edge to the Si II 1260 Å feature, which stems from the fastest moving ejecta on the far side of t…
Sub-THz and Hα Activity during the Preflare and Main Phases of a GOES Class M2 Event
White, Stephen M.; Kaufmann, Pierre; Marcon, Rogério +8 more
Radio and optical observations of the evolution of flare-associated phenomena have shown an initial and rapid burst at 0.4 THz only followed subsequently by a localized chromospheric heating producing an Hα brightening with later heating of the whole active region. A major instability occurred several minutes later producing one impulsive burst at…
Deriving the Physical Parameters of a Solar Ejection with an Isotropic Magnetohydrodynamic Evolutionary Model
Vourlidas, Angelos; Stenborg, Guillermo; Berdichevsky, Daniel B.
The time-space evolution of a ~50° wide coronal mass ejection (CME) on 2007 May 21 is followed remotely with the Solar Terrestrial Relations Observatory heliospheric imager HI-1, and measured in situ near Venus by the MESSENGER and Venus-Express spacecraft. The paper compares the observations of the CME structure with a simple, analytical magnetoh…
An Analytical Model for the Coronal Component of Major Solar Energetic Particle Events
Valtonen, Eino; Cho, Kyung-Suk; Kocharov, Leon
We formulate an analytical model of the coronal-phase acceleration observed in the beginning of major solar energetic particle (SEP) events, before the main-phase acceleration associated with coronal mass ejections (CMEs) in solar wind. The model is driven and constrained by the broadband observations of SEPs and CMEs, in particular SEP data from …
Evidence for Solar Frequency Dependence on Sunspot Type
Basu, Sarbani; Baldner, Charles S.; Bogart, Richard S.
High-degree solar mode frequencies as measured by ring diagrams are known to change in the presence of the strong magnetic fields found in active regions. We examine these changes in frequency for a large sample of active regions analyzed with data from the Michelson Doppler Imager on board the Solar and Heliospheric Observatory spacecraft, spanni…
Co-analysis of Solar Microwave and Hard X-Ray Spectral Evolutions. II. In Three Sources of a Flaring Loop
Huang, Guangli; Li, Jianping
Based on the spatially resolvable data of the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and Nobeyama Radio Heliograph (NoRH), co-analysis of solar hard X-ray and microwave spectral evolution is performed in three separate sources located in one looptop (LT) and two footpoints (FPs) of a huge flaring loop in the 2003 October 24 …
An Envelope Disrupted by a Quadrupolar Outflow in the Pre-planetary Nebula IRAS 19475+3119
Lee, Chin-Fei; Hsu, Ming-Chien
IRAS 19475+3119 is a quadrupolar pre-planetary nebula (PPN), with two bipolar lobes, one in the east-west (E-W) direction and one in the southeast-northwest (SE-NW) direction. We have observed it in CO J = 2-1 with the Submillimeter Array at ~1'' resolution. The E-W bipolar lobe is known to trace a bipolar outflow and it is detected at high veloci…
Is the Young Star Cluster NGC 376 Dissolving in the Field of the Small Magellanic Cloud?
Cignoni, M.; Tosi, M.; Sabbi, E. +3 more
We use deep images acquired with the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope in the filters F555W and F814W to characterize the properties of NGC 376, a young star cluster located in the wing of the Small Magellanic Cloud. Using isochrone fitting we derive for NGC 376 an age of 28 ± 7 Myr, in good agreement with previ…
High-resolution Observations of Siphon Flows in a Solar Magnetic Pore
Guglielmino, Salvo L.; Zuccarello, Francesca
We investigate signatures of siphon flows in a region around a solar magnetic pore, observed in the photosphere at µ = 0.6, during its decay phase. We analyze high-resolution Stokes spectra acquired by Hinode/Solar Optical Telescope along the Fe I pair at 630.2 nm. We determine the vector magnetic field and the line-of-sight velocity by an i…
Far-infrared Emission from the Intergalactic Medium in Stephan's Quintet Revealed by AKARI
Onaka, Takashi; Kaneda, Hidehiro; Kitayama, Tetsu +1 more
Stephan's Quintet (SQ, HCG92) was observed with the Far-Infrared Surveyor on board AKARI in four far-infrared (IR) bands at 65, 90, 140, and 160 µm. The AKARI four-band images show far-IR emission in the intergalactic medium of SQ. In particular, the 160 µm band image shows single peak emission in addition to the structure extending in…