Search Publications
X-MAS2: Study Systematics on the ICM Metallicity Measurements
Rasia, E.; Bourdin, H.; Mazzotta, P. +5 more
X-ray measurements of the intracluster medium metallicity are becoming more and more frequent due to the availability of powerful X-ray telescopes with excellent spatial and spectral resolutions. The information that can be extracted from measurements of the α-elements, such as oxygen, magnesium, and silicon, with respect to the iron abundance is …
The End of Amnesia: A New Method for Measuring the Metallicity of Type Ia Supernova Progenitors Using Manganese Lines in Supernova Remnants
Hughes, John P.; Badenes, Carles; Bravo, Eduardo
We propose a new method to measure the metallicity of Type Ia supernova progenitors using Mn and Cr lines in the X-ray spectra of young supernova remnants. We show that the Mn-to-Cr mass ratio in Type Ia supernova ejecta is tightly correlated with the initial metallicity of the progenitor, as determined by the neutron excess of the white dwarf mat…
Spectroscopic Detection of Turbulence in Post-CME Current Sheets
Bemporad, A.
Plasma in post-CME current sheets (CSs) is expected to be highly turbulent because of the tearing and coalescence instability and/or local microscopic instabilities. For this reason, in the last decade the inconsistency between the observed (~104-105 km) and the expected (~1-10 m) CS thickness has been tentatively explained i…
Comparison of Distances from RR Lyrae Stars, the Tip of the Red Giant Branch, and Classical Cepheids
Sandage, Allan; Tammann, G. A.; Reindl, B.
The extragalactic distance scale relies heavily on Cepheids. However, it has become clear from observations and pulsation models that the slope and zero point of their P-L relations differ from galaxy to galaxy. This makes the determination of Cepheid distances complex and calls for an independent test of their differences. The test is provided by…
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…