scholarly journals [ITAL]EXTREME ULTRAVIOLET EXPLORER[/ITAL][ITAL]Extreme Ultraviolet Explorer[/ITAL] Optical Identification Campaign. IV. A Northern Hemisphere Sample of Active Late-Type Stars and Typical EUV Sources

2001 ◽  
Vol 122 (1) ◽  
pp. 378-391 ◽  
Author(s):  
Damian J. Christian ◽  
Nahide Craig ◽  
Jean Dupuis ◽  
Bryce A. Roberts ◽  
Roger F. Malina
Keyword(s):  
Northern Hemisphere ◽  
Extreme Ultraviolet ◽  
Late Type ◽  
Optical Identification

Optical Identification of the ROSAT All-Sky Survey Sources in Two 2° × 2° Fields

1997 ◽  
Vol 159 ◽  
pp. 427-428
Author(s):  
Y. Zhao ◽  
J. Zhong ◽  
J. Wei ◽  
J. Hu ◽  
Q. Li
Keyword(s):  
Ccd Camera ◽  
Seyfert Galaxies ◽  
Astronomical Observatory ◽  
Active Galaxies ◽  
Clusters Of Galaxies ◽  
Late Type ◽  
Optical Identification ◽  
X Ray ◽  
Sky Survey

AbstractWe used the CCD camera and spectrograph of the 2.16-m telescope of Beijing Astronomical Observatory to identify the ROSAT All-Sky survey sources in two 2° Ü 2° fields. Of a total of 16 X-ray sources, we identified 13 of them as follows: two QSOs, two Seyfert galaxies, two active galaxies, two clusters of galaxies, and five late-type stars. Three X-ray sources remained unidentified.

scholarly journals Rosat WFC EUV Observations of Ab Dor (And other Local Group Stars)

1993 ◽  
Vol 137 ◽  
pp. 658-661
Author(s):  
Barry J. Kellett ◽  
Gordon E. Bromage
Keyword(s):  
Energy Range ◽  
Local Group ◽  
Extreme Ultraviolet ◽  
Broad Band ◽  
Full Description ◽  
Wide Field ◽  
Late Type ◽  
Rutherford Appleton Laboratory ◽  
Sky Survey ◽  
The Uk

The Rosat Observatory was launched on June 1st, 1990, and after a brief Performance Verification phase, performed an almost complete sky survey. One of the two main telescopes on the Observatory is the UK Wide Field Camera (WFC). The WFC is the first extreme ultraviolet (EUV) instrument to survey the whole sky, and during the survey detected several hundred active late-type stars.The WFC (Wells et al., 1990) was built by a consortium of five UK institutes, four Universities and the Rutherford Appleton Laboratory. During the all-sky survey, two filters were used. These allow broad-band photometry to be performed. The SIA filter (lexan/carbon/boron) and S2A filter (lexan/beryllium) were alternated on a one day basis. The SIA filter covers the energy range 0.085-0.180 KeV, centred on 0.124 KeV, while the softer S2A filter covers the range 0.070-0.110 KeV (centred on 0.090 KeV) (10% efficiency) [see Kent et al. (1990) for a full description of the WFC filters].

scholarly journals EUVE Spectra of Coronae and Flares

1996 ◽  
Vol 152 ◽  
pp. 81-88 ◽  
Author(s):  
Carole Jordan
Keyword(s):  
Short Wavelength ◽  
Extreme Ultraviolet ◽  
Emission Measure ◽  
Wavelength Region ◽  
Late Type ◽  
Short Wavelength Region ◽  
Plane Parallel ◽  
Parallel Geometry ◽  
Measure Distribution

Following a summary of early solar EUV spectroscopy the spectra of some late-type stars obtained with the Extreme Ultraviolet Explorer (EUVE) are briefly surveyed. Some transitions which are not included in current emissivity codes but could lead to numerous weak lines, and an apparent continuum in the EUVE short wavelength region, are discussed. The importance of the geometry adopted when interpreting the emission measure distribution is stressed, since radial factors can lead to an apparent emission measure distribution gradient that is steeper than the value of 3/2 expected in plane parallel geometry.

scholarly journals Extreme‐Ultraviolet Flare Activity in Late‐Type Stars

2000 ◽  
Vol 541 (1) ◽  
pp. 396-409 ◽  
Author(s):  
Marc Audard ◽  
Manuel Gudel ◽  
Jeremy J. Drake ◽  
Vinay L. Kashyap
Keyword(s):  
Extreme Ultraviolet ◽  
Flare Activity ◽  
Late Type

scholarly journals High-Resolution Optical Observations of Extreme-Ultraviolet–selected Active Late-Type Stars

2002 ◽  
Vol 123 (5) ◽  
pp. 2796-2805 ◽  
Author(s):  
Damian J. Christian ◽  
Mihalis Mathioudakis
Keyword(s):  
High Resolution ◽  
Extreme Ultraviolet ◽  
Optical Observations ◽  
Late Type

scholarly journals Temporal Behaviour of Sources in the ROSAT Extreme-Ultraviolet All-Sky Survey

1996 ◽  
Vol 152 ◽  
pp. 15-19
Author(s):  
Paul McGale ◽  
J.P. Pye ◽  
C.R. Barber ◽  
C.G. Page
Keyword(s):  
Extreme Ultraviolet ◽  
Cataclysmic Variables ◽  
Eclipsing Binaries ◽  
High Mass ◽  
Late Type ◽  
Temporal Behaviour ◽  
Source Type ◽  
Luminosity Functions ◽  
Sky Survey ◽  
M Stars

From a total catalogue of 479 2RE sources, 31 have been found to be variable. All the variable sources are optically identified, with a breakdown by source type as follows: cataclysmic variables 9, late-type (F-M) stars 18, the high-mass X-ray binary Her X-1, the eclipsing binaries Algol and V471 Tau, and the active galaxy Mkn 478. The most highly variable objects in the EUV band are cataclysmic variables. The survey was sensitive to timescales from ~ 1.5 h to ~ 5 d, and observed variability ranges from flare-like events lasting < 1.5 h to irregular and periodic flux changes over ~ 0.5–2 d. With the exception of the cataclysmic variables, and possibly a few late-type dK-dMe stars with large flares, the observed variability levels should not substantially affect EUV luminosity functions

Extreme ultraviolet emission from late-type stars - Initial results from Extreme Ultraviolet Explorer

1993 ◽  
Vol 414 ◽  
pp. L61 ◽  
Author(s):  
Peter W. Vedder ◽  
Robert J. Patterer ◽  
Patrick Jelinsky ◽  
Alex Brown ◽  
Stuart Bowyer
Keyword(s):  
Extreme Ultraviolet ◽  
Late Type ◽  
Ultraviolet Emission ◽  
Initial Results

The EUVE Optical Identification Campaign II: Late-Type and White Dwarf Stars

1995 ◽  
Vol 110 ◽  
pp. 1304 ◽  
Author(s):  
N. Craig ◽  
A. Fruscione ◽  
J. Dupuis ◽  
M. Mathioudakis ◽  
J. J. Drake ◽  
...  
Keyword(s):  
White Dwarf ◽  
Late Type ◽  
Optical Identification ◽  
Dwarf Stars ◽  
White Dwarf Stars

scholarly journals Ionospheric response to solar extreme ultraviolet radiation variations: comparison based on CTIPe model simulations and satellite measurements

2021 ◽  
Vol 39 (2) ◽  
pp. 341-355
Author(s):  
Rajesh Vaishnav ◽  
Erik Schmölter ◽  
Christoph Jacobi ◽  
Jens Berdermann ◽  
Mihail Codrescu
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Extreme Ultraviolet ◽  
Electron Content ◽  
Solar Dynamics Observatory ◽  
International Gnss Service ◽  
Average Delay ◽  
Total Electron ◽  
Ionospheric Response ◽  
Flux Model

Abstract. The ionospheric total electron content (TEC) provided by the International GNSS Service (IGS) and the TEC simulated by the Coupled Thermosphere Ionosphere Plasmasphere Electrodynamics (CTIPe) model have been used to investigate the delayed ionospheric response against solar flux and its trend during the years 2011 to 2013. The analysis of the distinct low-latitude and midlatitude TEC response over 15∘ E shows a better correlation of observed TEC and the solar radio flux index F10.7 in the Southern Hemisphere compared to the Northern Hemisphere. Thus, a significant hemispheric asymmetry is observed. The ionospheric delay estimated using model-simulated TEC is in good agreement with the delay estimated for observed TEC against the flux measured by the Solar Dynamics Observatory (SDO) extreme ultraviolet (EUV) Variability Experiment (EVE). The average delay for the observed (modeled) TEC is 17(16) h. The average delay calculated for observed and modeled TEC is 1 and 2 h longer in the Southern Hemisphere compared to the Northern Hemisphere. Furthermore, the observed TEC is compared with the modeled TEC simulated using the SOLAR2000 and EUVAC flux models within CTIPe over northern and southern hemispheric grid points. The analysis suggests that TEC simulated using the SOLAR2000 flux model overestimates the observed TEC, which is not the case when using the EUVAC flux model.

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