scholarly journals X-rays from colliding winds in massive binaries

2016 ◽  
Vol 12 (S329) ◽  
pp. 359-360
Author(s):  
Yaël Nazé ◽  
Gregor Rauw
Keyword(s):  
High Resolution ◽  
Mass Loss ◽  
Strong Shock ◽  
Stellar Mass ◽  
Stellar Winds ◽  
X Rays ◽  
Current Generation ◽  
X Ray ◽  
Colliding Winds

AbstractIn a massive binary, the strong shock between the stellar winds may lead to the generation of bright X-ray emission. While this phenomenon was detected decades ago, the detailed study of this emission was only made possible by the current generation of X-ray observatories. Through dedicated monitoring and observations at high resolution, unprecedented information was revealed, putting strong constraints on the amount and structure of stellar mass-loss.

scholarly journals X-ray Emission from O Stars

2007 ◽  
Vol 3 (S250) ◽  
pp. 17-24
Author(s):  
David H. Cohen
Keyword(s):  
Numerical Modeling ◽  
High Resolution ◽  
Magnetic Fields ◽  
Mass Loss ◽  
Strong Evidence ◽  
Stellar Winds ◽  
X Rays ◽  
X Ray ◽  
Shock Heating ◽  
Mhd Modeling

AbstractYoung O stars are strong, hard, and variable X-ray sources; properties that strongly affect their circumstellar and galactic environments. After ≈ 1 Myr, these stars settle down to become steady sources of soft X-rays. I will use high-resolution X-ray spectroscopy and MHD modeling to show that young O stars like θ1 Ori C are well explained by the magnetically channeled wind shock scenario. After their magnetic fields dissipate, older O stars produce X-rays via shock heating in their unstable stellar winds. Here too I will use X-ray spectroscopy and numerical modeling to confirm this scenario. In addition to elucidating the nature and cause of the O star X-ray emission, modeling of the high-resolution X-ray spectra of O supergiants provides strong evidence that mass-loss rates of these O stars have been overestimated.

scholarly journals What Do We Really Know About the Winds of Massive Stars?

2007 ◽  
Vol 3 (S250) ◽  
pp. 89-96
Author(s):  
D. John Hillier
Keyword(s):  
Mass Loss ◽  
Massive Stars ◽  
Standard Theory ◽  
Stellar Winds ◽  
X Rays ◽  
X Ray ◽  
Stellar Photosphere ◽  
Weak Winds ◽  
Ionization Balance ◽  
Loss Rates

AbstractThe standard theory of radiation driven winds has provided a useful framework to understand stellar winds arising from massive stars (O stars, Wolf-Rayet stars, and luminous blue variables). However, with new diagnostics, and advances in spectral modeling, deficiencies in our understanding of stellar winds have been thrust to the forefront of our research efforts. Spectroscopic observations and analyses have shown the importance of inhomogeneities in stellar winds, and revealed that there are fundamental discrepancies between predicted and theoretical mass-loss rates. For late O stars, spectroscopic analyses derive mass-loss rates significantly lower than predicted. For all O stars, observed X-ray fluxes are difficult to reproduce using standard shock theory, while observed X-ray profiles indicate lower mass-loss rates, the potential importance of porosity effects, and an origin surprisingly close to the stellar photosphere. In O stars with weak winds, X-rays play a crucial role in determining the ionization balance, and must be taken into account.

scholarly journals Massive star mass-loss revealed by X-ray observations of young supernovae

2018 ◽  
Vol 14 (S346) ◽  
pp. 83-87
Author(s):  
Vikram V. Dwarkadas
Keyword(s):  
Mass Loss ◽  
Massive Stars ◽  
Ambient Medium ◽  
Mass Loss Rate ◽  
Stellar Mass ◽  
X Rays ◽  
X Ray ◽  
The Common ◽  
Almost All ◽  
Loss Rates

AbstractMassive stars lose a considerable amount of mass during their lifetime. When the star explodes as a supernova (SN), the resulting shock wave expands in the medium created by the stellar mass-loss. Thermal X-ray emission from the SN depends on the square of the density of the ambient medium, which in turn depends on the mass-loss rate (and velocity) of the progenitor wind. The emission can therefore be used to probe the stellar mass-loss in the decades or centuries before the star’s death.We have aggregated together data available in the literature, or analysed by us, to compute the X-ray lightcurves of almost all young supernovae detectable in X-rays. We use this database to explore the mass-loss rates of massive stars that collapse to form supernovae. Mass-loss rates are lowest for the common Type IIP supernovae, but increase by several orders of magnitude for the highest luminosity X-ray SNe.

scholarly journals X-ray diagnostics of massive star winds

2016 ◽  
Vol 12 (S329) ◽  
pp. 151-155
Author(s):  
L. M. Oskinova ◽  
R. Ignace ◽  
D. P. Huenemoerder
Keyword(s):  
High Resolution ◽  
Stellar Wind ◽  
Massive Star ◽  
Massive Stars ◽  
Stellar Winds ◽  
X Rays ◽  
Early Type ◽  
Stellar Rotation ◽  
X Ray ◽  
Early Type Stars

AbstractObservations with powerful X-ray telescopes, such as XMM-Newton and Chandra, significantly advance our understanding of massive stars. Nearly all early-type stars are X-ray sources. Studies of their X-ray emission provide important diagnostics of stellar winds. High-resolution X-ray spectra of O-type stars are well explained when stellar wind clumping is taking into account, providing further support to a modern picture of stellar winds as non-stationary, inhomogeneous outflows. X-ray variability is detected from such winds, on time scales likely associated with stellar rotation. High-resolution X-ray spectroscopy indicates that the winds of late O-type stars are predominantly in a hot phase. Consequently, X-rays provide the best observational window to study these winds. X-ray spectroscopy of evolved, Wolf-Rayet type, stars allows to probe their powerful metal enhanced winds, while the mechanisms responsible for the X-ray emission of these stars are not yet understood.

scholarly journals X-Rays from Elliptical Galaxies

1987 ◽  
Vol 127 ◽  
pp. 155-165
Author(s):  
A.C. Fabian ◽  
P.A. Thomas
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Mass Loss ◽  
Elliptical Galaxies ◽  
Stellar Mass ◽  
X Rays ◽  
Early Type ◽  
X Ray ◽  
Isolated Galaxies

X-ray observations have shown that early-type galaxies contain a hot interstellar medium. This implies that the galaxies have a) a low supernova rate; b) high total gravitational binding masses and c) continuous star formation. Much of the gas in isolated galaxies is probably due to stellar mass-loss. The details of its behaviour are complex.

scholarly journals Multiwavelength morphological study of active galaxies

2019 ◽  
Vol 15 (S356) ◽  
pp. 295-298
Author(s):  
Betelehem Bilata-Woldeyes ◽  
Mirjana Pović ◽  
Zeleke Beyoro-Amado ◽  
Tilahun Getachew-Woreta ◽  
Shimeles Terefe
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Formation Rate ◽  
Stellar Mass ◽  
Active Galaxies ◽  
Morphological Properties ◽  
X Rays ◽  
Host Galaxies ◽  
X Ray ◽  
Public Data

AbstractStudying the morphology of a large sample of active galaxies at different wavelengths and comparing it with active galactic nuclei (AGN) properties, such as black hole mass (MBH) and Eddington ratio (λEdd), can help us in understanding better the connection between AGN and their host galaxies and the role of nuclear activity in galaxy formation and evolution. By using the BAT-SWIFT hard X-ray public data and by extracting those parameters measured for AGN and by using other public catalogues for parameters such as stellar mass (M*), star formation rate (SFR), bolometric luminosity (Lbol), etc., we studied the multiwavelength morphological properties of host galaxies of ultra-hard X-ray detected AGN and their correlation with other AGN properties. We found that ultra hard X-ray detected AGN can be hosted by all morphological types, but in larger fractions (42%) they seem to be hosted by spirals in optical, to be quiet in radio, and to have compact morphologies in X-rays. When comparing morphologies with other galaxy properties, we found that ultra hard X-ray detected AGN follow previously obtained relations. On the SFR vs. stellar mass diagram, we found that although the majority of sources are located below the main sequence (MS) of star formation (SF), still non-negligible number of sources, with diverse morphologies, is located on and/or above the MS, suggesting that AGN feedback might have more complex influence on the SF in galaxies than simply quenching it, as it was suggested in some of previous studies.

Cryogenic high-resolution X-ray spectrometers for SR-XRF and microanalysis

1998 ◽  
Vol 5 (3) ◽  
pp. 515-517 ◽  
Author(s):  
M. Frank ◽  
C. A. Mears ◽  
S. E. Labov ◽  
L. J. Hiller ◽  
J. B. le Grand ◽  
...  
Keyword(s):  
High Resolution ◽  
Energy Resolution ◽  
Superconducting Tunnel Junction ◽  
Semiconductor Detectors ◽  
X Rays ◽  
X Ray ◽  
Sr Xrf ◽  
Demonstration Experiment ◽  
Near Future ◽  
Stj Detector

Experimental results are presented obtained with a cryogenically cooled high-resolution X-ray spectrometer based on a 141 × 141 µm Nb-Al-Al2O3-Al-Nb superconducting tunnel junction (STJ) detector in an SR-XRF demonstration experiment. STJ detectors can operate at count rates approaching those of semiconductor detectors while still providing a significantly better energy resolution for soft X-rays. By measuring fluorescence X-rays from samples containing transition metals and low-Z elements, an FWHM energy resolution of 6–15 eV for X-rays in the energy range 180–1100 eV has been obtained. The results show that, in the near future, STJ detectors may prove very useful in XRF and microanalysis applications.

Applications of High-Resolution Powder X-Ray Diffraction

2007 ◽  
Vol 130 ◽  
pp. 7-14 ◽  
Author(s):  
Andrew N. Fitch
Keyword(s):  
High Resolution ◽  
Synchrotron Radiation ◽  
Powder Diffraction ◽  
X Rays ◽  
X Ray Diffraction ◽  
Crystalline Materials ◽  
X Ray ◽  
Structural Characterisation ◽  
Pdf Analysis

The highly-collimated, intense X-rays produced by a synchrotron radiation source can be harnessed to build high-resolution powder diffraction instruments with a wide variety of applications. The general advantages of using synchrotron radiation for powder diffraction are discussed and illustrated with reference to the structural characterisation of crystalline materials, atomic PDF analysis, in-situ and high-throughput studies where the structure is evolving between successive scans, and the measurement of residual strain in engineering components.

HIGH-RESOLUTION PIXE USING BRAGG’S SPECTROMETER

1991 ◽  
Vol 01 (03) ◽  
pp. 251-258 ◽  
Author(s):  
M. TERASAWA
Keyword(s):  
High Resolution ◽  
Heavy Ions ◽  
X Rays ◽  
Light Elements ◽  
Element Analysis ◽  
X Ray ◽  
Peak Intensity ◽  
Moderate Energy ◽  
Practical Analysis ◽  
Wavelength Selectivity

K, L, and M X-rays in the wavelengths between 6Å and 130Å generated by the bombardment of 200 keV protons and other heavy ions were measured by means of a wavelength dispersive Bragg’s spectrometer. The X-ray peak intensity was fairly high in general, while the background was very low. The technique was favorably applied to a practical analysis of several light elements (Be, B, C, N, O, and F). Use of moderate-energy heavy ions considering the wavelength selectivity in X-ray generation was effective for the element analysis. The high-resolution spectrometry in the analytical application of ion-induced X-ray generation was found to be useful for the study of fine electronic structure, e.g. satellite and hypersatellite X-ray study, and of the chemical state of materials.

scholarly journals Micrometer-resolution imaging using MÖNCH: towards G2-less grating interferometry

2016 ◽  
Vol 23 (6) ◽  
pp. 1462-1473 ◽  
Author(s):  
Sebastian Cartier ◽  
Matias Kagias ◽  
Anna Bergamaschi ◽  
Zhentian Wang ◽  
Roberto Dinapoli ◽  
...  
Keyword(s):  
High Resolution ◽  
Silicon Detector ◽  
Limiting Factor ◽  
X Rays ◽  
X Ray ◽  
Charge Cloud ◽  
High Resolution Images ◽  
Resolution Imaging ◽  
Hybrid Silicon ◽  
Small Pixel

MÖNCH is a 25 µm-pitch charge-integrating detector aimed at exploring the limits of current hybrid silicon detector technology. The small pixel size makes it ideal for high-resolution imaging. With an electronic noise of about 110 eV r.m.s., it opens new perspectives for many synchrotron applications where currently the detector is the limiting factor,e.g.inelastic X-ray scattering, Laue diffraction and soft X-ray or high-resolution color imaging. Due to the small pixel pitch, the charge cloud generated by absorbed X-rays is shared between neighboring pixels for most of the photons. Therefore, at low photon fluxes, interpolation algorithms can be applied to determine the absorption position of each photon with a resolution of the order of 1 µm. In this work, the characterization results of one of the MÖNCH prototypes are presented under low-flux conditions. A custom interpolation algorithm is described and applied to the data to obtain high-resolution images. Images obtained in grating interferometry experiments without the use of the absorption grating G2are shown and discussed. Perspectives for the future developments of the MÖNCH detector are also presented.

Sign in / Sign up

Export Citation Format

Share Document