scholarly journals The Cycles of Alpha Centauri

2009 ◽  
Vol 5 (S264) ◽  
pp. 146-149
Author(s):  
Thomas R. Ayres
Keyword(s):  
High Resolution ◽  
Triple System ◽  
The Sun ◽  
X Ray ◽  
Spatially Resolved ◽  
Common Basis ◽  
Cosmic Object

AbstractThe main AB pair of the nearby Alpha Centauri triple system has one of the most extensive X-ray records of any cosmic object, stretching over three decades. The primary, α Cen A (G2V), is a near twin of the Sun, with a similarly soft (1–2 MK) corona. The secondary, α Cen B (K1V), is more active than the Sun, with a generally harder coronal spectrum. Here, spatially resolved measurements of the pair by Chandra's High Resolution Camera are compared, on a common basis, with previous pointings from ROSAT and XMM-Newton.

scholarly journals Hydrodynamic Models of Solar and Stellar Flares

1989 ◽  
Vol 104 (1) ◽  
pp. 289-298
Author(s):  
Giovanni Peres
Keyword(s):  
High Resolution ◽  
Light Curve ◽  
Solar Flares ◽  
Impulsive Phase ◽  
Light Curves ◽  
Physical Parameters ◽  
The Sun ◽  
Hydrodynamic Models ◽  
X Ray ◽  
Stellar Flares

AbstractThis paper discusses the hydrodynamic modeling of flaring plasma confined in magnetic loops and its objectives within the broader scope of flare physics. In particular, the Palermo-Harvard model is discussed along with its applications to the detailed fitting of X-ray light curves of solar flares and to the simulation of high-resolution Caxix spectra in the impulsive phase. These two approaches provide complementary constraints on the relevant features of solar flares. The extension to the stellar case, with the fitting of the light curve of an X-ray flare which occurred on Proxima Centauri, demonstrates the feasibility of using this kind of model for stars too. Although the stellar observations do not provide the wealth of details available for the Sun, and, therefore, constrain the model more loosely, there are strong motivations to pursue this line of research: the wider range of physical parameters in stellar flares and the possibility of studying further the solar-stellar connection.

scholarly journals Detailed X-ray Observations of the Cygnus Loop

1983 ◽  
Vol 101 ◽  
pp. 253-260
Author(s):  
W. H.-M. Ku ◽  
K. Long ◽  
R. Pisarski ◽  
M. Vartanian
Keyword(s):  
High Resolution ◽  
Proportional Counter ◽  
Supernova Remnant ◽  
Sounding Rocket ◽  
Loop Structure ◽  
High Quality ◽  
Radio Structure ◽  
X Ray ◽  
Cygnus Loop ◽  
Spatially Resolved

High quality X-ray spectral and imaging observations of the Cygnus Loop have been obtained with three different instruments. The High Resolution Imager (HRI) on the Einstein Observatory was used to obtain arcsecond resolution images of select bright regions in the Cygnus Loop which permit detailed comparisons between the X-ray, optical, and radio structure of the Loop. The Imaging Proportional Counter (IPC) on the Einstein Observatory was used to obtain an arcminute resolution map of essentially the full Loop structure. Finally, an Imaging Gas Scintillation Proportional Counter (IGSPC), carried aloft by a sounding rocket last fall, obtained modest resolution, spatially resolved spectrophotometry of the Cygnus Loop. An X-ray map of the Loop in the energy of the 0 VIII line was obtained. These data combine to yield a very powerful probe of the abundance, temperature, and density distribution of material in the supernova remnant, and in the interstellar medium.

scholarly journals Characterization of spatially resolved high resolution x-ray spectrometers for high energy density physics and light source experiments

2014 ◽  
Vol 85 (11) ◽  
pp. 11D612 ◽  
Author(s):  
K. W. Hill ◽  
M. Bitter ◽  
L. Delgado-Aparacio ◽  
P. Efthimion ◽  
N. A. Pablant ◽  
...  
Keyword(s):  
High Resolution ◽  
Energy Density ◽  
Light Source ◽  
High Energy ◽  
High Energy Density ◽  
X Ray ◽  
High Energy Density Physics ◽  
Spatially Resolved

THE 2008 MULTIWAVELENGTH CAMPAIGN OF THE TeV RADIO-GALAXY M 87

2009 ◽  
Vol 18 (10) ◽  
pp. 1493-1498
Author(s):  
◽  
PIERRE COLIN ◽  
MATTHIAS BEILICKE ◽  
FREDERICK DAVIES ◽  
D. E. HARRIS ◽  
...  
Keyword(s):  
High Resolution ◽  
Radio Galaxy ◽  
Time Correlation ◽  
Line Of Sight ◽  
Emission Process ◽  
X Ray ◽  
Cherenkov Telescopes ◽  
Extragalactic Object ◽  
Spatially Resolved ◽  
Radio Band

M 87 is the first and brightest radio galaxy detected in the TeV regime. It is the closest extragalactic object showing variability and the only one that does not have its jet pointing toward the line of sight. The structure of the M 87 jet is spatially resolved in X-ray, optical and radio observations. Time correlation between the TeV flux and emission at other wavelengths provides a unique opportunity to localize the VHE emission process occurring in active galaxy nuclei. For 10 years, M87 has been monitored in the TeV band by imaging air Cherenkov telescopes (IACT) as well as in X-ray, optical and radio bands. In 2008, the three main IACTs, H.E.S.S./MAGIC/VERITAS, coordinated their observations in a joint campaign. In February, high TeV activities with rapid flares have been detected. Contemporaneously, M 87 was observed with high resolution instruments in the X-ray (Chandra) and Radio band (VLBA).

Spatially resolved high resolution x-ray spectroscopy for magnetically confined fusion plasmas (invited)

2008 ◽  
Vol 79 (10) ◽  
pp. 10E302 ◽  
Author(s):  
A. Ince-Cushman ◽  
J. E. Rice ◽  
M. Bitter ◽  
M. L. Reinke ◽  
K. W. Hill ◽  
...  
Keyword(s):  
High Resolution ◽  
Fusion Plasmas ◽  
X Ray ◽  
Spatially Resolved ◽  
Magnetically Confined

VI. The Sun as a Star

1988 ◽  
Vol 20 (1) ◽  
pp. 102-106
Author(s):  
L.E. Cram
Keyword(s):  
Time Scales ◽  
Spatial Extent ◽  
The Sun ◽  
Distinguishing Characteristic ◽  
X Ray ◽  
Spatially Resolved ◽  
Solar Observations ◽  
The Earth ◽  
The Subject

Studies of the global (spatially unresolved) output from the sun are important for two main reasons: (1) the global solar output directed towards the earth plays a central role in solar-terrestrial relations, and (2) global solar observations form a link between (neccessarily) global observations of stars and the more refined spatially resolved observations which are available for the sun. This report covers both aspects (insofar as they concern the sun), using the time-scales of various phenomena as a basic distinguishing characteristic. Note that certain studies of spatially unresolved solar output have not been discussed, since they are actually directed toward the investigation of phenomena of strictly limited spatial extent [e.g. radiospectrograph observations (e.g. Wiehl et al. 1985) and studies of X-ray bursts (e.g. Thomas et al. 1985)]. Collections of relevant papers may be found in De Jager and Svestka (1985) and Labonte et al. (1984), while a review of germane stellar work is available in Baliunas and Vaughan (1985) and solar-terrestrial work in Donnelly and Heath (1985). A comprehensive summary of the subject by Hudson will appear soon in Review of Geophysics and Planetary Physics.

Spatially resolved high-resolution x-ray spectroscopy of high-current plasma-focus discharges

2010 ◽  
Vol 81 (10) ◽  
pp. 10E312 ◽  
Author(s):  
S. Zając ◽  
J. Rzadkiewicz ◽  
O. Rosmej ◽  
M. Scholz ◽  
Zhao Yongtao ◽  
...  
Keyword(s):  
High Resolution ◽  
Plasma Focus ◽  
High Current ◽  
X Ray ◽  
Spatially Resolved

scholarly journals Ultraviolet Observations of Stellar Coronae: Early Results from HST

1992 ◽  
Vol 9 ◽  
pp. 657-658
Author(s):  
J.L. Linsky
Keyword(s):  
High Resolution ◽  
Spectral Resolution ◽  
Solar Flares ◽  
Extreme Ultraviolet ◽  
The Sun ◽  
X Ray ◽  
Spectroscopic Diagnostics ◽  
Early Results ◽  
Active Stars ◽  
Ultraviolet Observations

Although coronae for stars other than the Sun have previously been detected only in the X-ray and radio portions of the spectrum, the HST and future spacecraft sensitive to ultraviolet (UV) and extreme ultraviolet (ETIV) light will have the spectral resolution to study the dynamics and spectroscopic diagnostics of hot coronal plasmas. In the UV region accessible to HST, forbidden lines of FeXII at 1242 and 1349Å, of FeXXI at 1354Å, and other species seen in solar flares, are predicted to be present in the spectra of active stars. Upcoming observations with the Goddard High Resolution Spectrograph (GHRS) by S. Maran will search for these lines in the dM2e star AU Mic and other stars.

scholarly journals The Photospheric Abundances of Active Binaries: First Results

2004 ◽  
Vol 219 ◽  
pp. 259-263 ◽  
Author(s):  
T. Morel ◽  
G. Micela ◽  
F. Favata ◽  
D. Katz ◽  
I. Pillitteri
Keyword(s):  
High Resolution ◽  
Chemical Species ◽  
The Sun ◽  
X Ray ◽  
First Results

Photospheric parameters and abundances of 13 chemical species are presented for a sample of single-lined chromospherically active binaries from a differential LTE analysis of high-resolution spectra. Our results indicate that the X-ray active binaries studied are not as metal poor as previously claimed, but are at most mildly iron-depleted relative to the Sun (—0.41 ≲ [Fe/H] ≲ +0.11). A significant overabundance of several elements (e.g., Na, Mg, Al, Ca) is observed. The temperatures derived from the (V — R) and (V — I) colours are found to be significantly affected by activity processes.

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