Search Publications
Plasma Flows Guided by Strong Magnetic Fields in the Solar Corona
Tian, Hui; Marsch, Eckart; Sun, Jian +2 more
In this study new results are presented regarding the relationships between the coronal magnetic field and the intensities and Doppler shifts of ultraviolet emission lines. This combination of magnetic field and spectroscopic data is used here to study material flows in association with the coronal field. We introduce the term "coronal circulation…
Persistent Horizontal Flows and Magnetic Support of Vertical Threads in a Quiescent Prominence
Chae, Jongchul; Choe, G. S.; Lim, Eun-Kyung +2 more
There has been some controversy as to whether the magnetic fields of vertical threads seen in quiescent prominences are predominantly vertical or horizontal. We report finding special patterns of flow in a quiescent prominence observed by the Solar Optical Telescope aboard Hinode. This prominence is a small hedgerow prominence composed of many ver…
Spectropolarimetric Observation of an Emerging Flux Region: Triggering Mechanisms of Ellerman Bombs
Shibata, K.; Ueno, S.; Kitai, R. +6 more
A high spatial resolution observation of an emerging flux region (EFR) was made using a vector magnetograph and a Hα Lyot filtergraph with the Domeless Solar Telescope at Hida Observatory on 2006 October 22. In Hα wing images, we could see many Ellerman bombs (EBs) in the EFR. Observations in two modes, slit scan and slit fixed, were performed wit…
Prevalence of High X-Ray Obscuring Columns among AGNs that Host H2O Masers
Tilak, Avanti; Greenhill, Lincoln J.; Madejski, Grzegorz
Of 104 AGNs known to exhibit H2O maser emission, X-ray data that enable estimation of column densities, or lower limits, are available for 42. Contributing to this, we report analysis of new and archival X-ray data for eight galaxies and collation of values for three more. Maser emission is indicative of large columns of cold gas, and i…
A New Comptonization Model for Weakly Magnetized, Accreting Neutron Stars in Low-Mass X-Ray Binaries
Titarchuk, Lev; Farinelli, Ruben; Paizis, Ada +1 more
We have developed a new model for the X-ray spectral fitting package XSPEC that takes into account the effects of both thermal and dynamical (i.e., bulk) Comptonization. The model consists of two components: one is the direct blackbody-like emission due to seed photons that are not subjected to effective Compton scattering, while the other is a co…
Variability of Disk Emission in Pre-Main-Sequence and Related Stars. I. HD 31648 and HD 163296: Isolated Herbig Ae Stars Driving Herbig-Haro Flows
Polomski, Elisha F.; Russell, Ray W.; Sitko, Michael L. +13 more
Infrared photometry and spectroscopy covering a time span of a quarter-century are presented for HD 31648 (MWC 480) and HD 163296 (MWC 275). Both are isolated Herbig Ae stars that exhibit signs of active accretion, including driving bipolar flows with embedded Herbig-Haro (HH) objects. HD 163296 was found to be relatively quiescent photometrically…
The Slow X-Ray Expansion of the Northwestern Rim of the Supernova Remnant RX J0852.0-4622
Mori, K.; Katsuda, S.; Tsunemi, H.
The detection of the radioactive decay line of 44Ti provides unique evidence that the γ-ray source is a young (<1000 yr) supernova remnant because of the short 44Ti lifetime of ~90 yr. Only two Galactic remnants, Cassiopeia A and RX J0852.0-4622, have hitherto been reported as 44Ti line emitters, although the de…
Evidence for Polar Jets as Precursors of Polar Plume Formation
Solanki, S. K.; Henney, C. J.; Raouafi, N. -E. +2 more
Observations from the Hinode/XRT telescope and STEREO/SECCHI/EUVI are utilized to study polar coronal jets and plumes. The study focuses on the temporal evolution of both structures and their relationship. The data sample, spanning 2007 April 7-8, shows that over 90% of the 28 observed jet events are associated with polar plumes. EUV images (STERE…
Identifying Stellar Streams in the First RAVE Public Data Release
Rix, H. -W.; Klement, R.; Fuchs, B.
We have searched for and detected stellar streams or moving groups in the solar neighborhood, using the data provided by the first RAVE public data release. This analysis is based on distances to RAVE stars estimated from a color-magnitude relation calibrated on Hipparcos stars. Our final sample consists of 7015 stars selected to be within 500 pc …
Improved Constraints on the Preferential Heating and Acceleration of Oxygen Ions in the Extended Solar Corona
Kohl, John L.; Cranmer, Steven R.; Panasyuk, Alexander V.
We present a detailed analysis of oxygen ion velocity distributions in the extended solar corona, based on observations made with the Ultraviolet Coronagraph Spectrometer (UVCS) on the SOHO spacecraft. Polar coronal holes exhibit broad line widths and unusual intensity ratios of the O VI λλ1032, 1037 emission-line doublet. A traditional interpreta…