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The time evolution of the spectral index and the non-thermal flux in 24 impulsive solar hard X-ray flares of GOES class M was studied in RHESSI observations. The high spectral resolution allows for a clean separation of thermal and…

Astrophysics · Physics 2007-05-23 Paolo C. Grigis , Arnold O. Benz

A deep understanding of molecular photo-transformations is challenging because of the complex interaction between the configurations of electrons and nuclei. An initial optical excitation dissipates energy into electronic and structural…

Spectroscopic studies of Planetary Nebulae (PNe) and H {\sc ii} regions have driven much development in atomic physics. In the last few years the combination of a generation of powerful observatories, the development of ever more…

Astrophysics · Physics 2009-06-23 Manuel A. Bautista

The gravitational redshift measured by Cottam, Paerels and Mendez for the neutron star (NS) in the low-mass X-ray binary EXO 0748-676 depends on the identification of an absorption line during a type I burst as the H$\alpha$ line from…

Astrophysics · Physics 2009-11-07 L. Bildsten , P. Chang , F. Paerels

Resonant inelastic x-ray scattering (RIXS) is a widely used spectroscopic technique, providing access to the electronic structure and dynamics of atoms, molecules, and solids. However, RIXS requires a narrow bandwidth x-ray probe to achieve…

The characterization of exoplanet requires reliable determination of the fundamental parameters of their host stars. Spectral fitting plays an important role in this process. For the majority of stellar parameters matching synthetic spectra…

Solar and Stellar Astrophysics · Physics 2023-03-29 Ansgar Wehrhahn , Nikolai Piskunov , Tanja Ryabchikova

Our aims are to determine flux densities and their photometric accuracy for a set of seventeen stars that range in flux from intermediately bright (<2.5 Jy) to faint (>5 mJy) in the far-infrared (FIR). We also aim to derive signal-to-noise…

Solar and Stellar Astrophysics · Physics 2018-05-30 Ulrich Klaas , Zoltan Balog , Markus Nielbock , Thomas Muller , Hendrik Linz , Csaba Kiss

Relevant uncertainties on theoretical atomic data are vital to determine the accuracy of plasma diagnostics in a number of areas including in particular the astrophysical study. We present a new calculation of the uncertainties on the…

High Energy Astrophysical Phenomena · Physics 2022-01-19 Liyi Gu , Chintan Shah , Ruitian Zhang

We present model spectra of stellar populations with variable chemical composition. We derived the [alpha/Fe] abundance ratio of the stars of the most important libraries (ELODIE, CFLIB and MILES) using full spectrum fitting and we…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Philippe Prugniel , Mina Koleva

We analyze the ASCA spectra accumulated within ~100 kpc radii of 12 of the brightest groups of galaxies. Upon fitting isothermal models (1T) jointly to the ASCA SIS and GIS spectra we obtain fits for most groups that are of poor or at best…

Astrophysics · Physics 2016-08-30 David A. Buote

High precision atomic data is indispensable for experiments involving studies of fundamental interactions, astrophysics, atomic clocks, plasma science, and others. We develop new parallel atomic structure codes and explore the difficulties…

Atomic Physics · Physics 2021-03-11 C. Cheung , M. S. Safronova , S. G. Porsev

The ESA Herschel Spectral and Photometric Imaging Receiver (SPIRE) Fourier Transform Spectrometer (FTS) Spectral Feature Finder (FF) project is an automated spectral feature fitting routine developed within the SPIRE instrument team to…

Instrumentation and Methods for Astrophysics · Physics 2020-09-29 Chris S. Benson , N. Hladczuk , Locke D. Spencer , A. Robb , J. P. Scott , I. Valtchanov , R. Hopwood , David A. Naylor

We present cross-correlation studies of gamma-ray (0.1-300 GeV), X-ray (0.2-10 keV) and optical (R-band) variability of a sample of 26 blazars during 2008-2016. The light curves are from Fermi-LAT, Swift-XRT, and the Yale-SMARTS blazar…

High Energy Astrophysical Phenomena · Physics 2020-04-08 Anwesh Majumder , Kaustav Mitra , Ritaban Chatterjee , C. M. Urry , C. D. Bailyn , Prantik Nandi

The single-pulse spectrum of self-amplified spontaneous emission (SASE) free electron lasers (FELs) is characterized by random fluctuations in frequency. The typical spectrum bandwidth for a hard x-ray FEL is in the range of 10-20 eV and is…

Accelerator Physics · Physics 2016-12-08 Gennady Stupakov , Max Zolotorev

Continuum normalization of echelle spectra is an important data analysis step that is difficult to automate. Polynomial fitting requires a reasonably high order model to follow the steep slope of the blaze function. However, in the presence…

Instrumentation and Methods for Astrophysics · Physics 2019-06-05 Xin Xu , Jessi Cisewski-Kehe , Allen B. Davis , Debra A. Fischer , John M. Brewer

Recent radiative lifetime measurements accurate to +/- 5% using laser-induced fluorescence (LIF) on 43 even-parity and 15 odd-parity levels of Ce II have been combined with new branching fractions measured using a Fourier transform…

Solar and Stellar Astrophysics · Physics 2009-11-13 J. E. Lawler , C. Sneden , J. J. Cowan , I. I. Ivans , E. A. Den Hartog

We present a new and complete library of synthetic spectra for modeling the component of emission that is reflected from an illuminated accretion disk. The spectra were computed using an updated version of our code XILLVER that incorporates…

High Energy Astrophysical Phenomena · Physics 2015-06-15 J. Garcia , T. Dauser , C. S. Reynolds , T. R. Kallman , J. E. McClintock , J. Wilms , W. Eikmann

Utilizing new Voyager measurements at lower energies and higher energy spacecraft measurements near the Earth, the interstellar spectra of primary cosmic ray nuclei from H to Fe have now been determined from ~10 MeV/nuc to > 100 GeV/nuc.…

Space Physics · Physics 2015-08-10 W. R. Webber

This paper presents the set of plane-parallel model atmosphere equations for a very hot neutron star (X-ray burst source). The model equations assume both hydrostatic and radiative equilibrium, and the equation of state of an ideal gas in…

Astrophysics · Physics 2009-11-10 A. Majczyna , J. Madej , P. C. Joss , A. Rozanska

Coherent diffraction imaging (CDI) of single molecules at atomic resolution is a major goal for the x-ray free electron lasers (XFELs). However, during an imaging pulse, the fast laser-induced ionization may strongly affect the recorded…

Mesoscale and Nanoscale Physics · Physics 2015-06-05 Zoltan Jurek , Robert Thiele , Beata Ziaja , Robin Santra
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