Far-Ultraviolet Observations of NGC 4151 during the [ITAL]ORFEUS-SPAS II[/ITAL] Mission

1998 ◽  
Vol 500 (1) ◽  
pp. L13-L16 ◽  
Author(s):  
B. R. Espey ◽  
G. A. Kriss ◽  
J. H. Krolik ◽  
W. Zheng ◽  
Z. Tsvetanov ◽  
...  
Keyword(s):  
Ngc 4151 ◽  
Far Ultraviolet ◽  
Ultraviolet Observations

scholarly journals Ultraviolet Observations of Some Close Binary Systems by the Astronomical Netherlands Satellite-Ans

1976 ◽  
Vol 73 ◽  
pp. 213-223
Author(s):  
Chi-Chao Wu
Keyword(s):  
Binary Systems ◽  
Hot Spot ◽  
Close Binary ◽  
Spectral Energy ◽  
Dwarf Novae ◽  
Energy Distributions ◽  
Primary Star ◽  
Higher Temperature ◽  
Far Ultraviolet ◽  
Ultraviolet Observations

Observations of δ Pic, a β Lyr type of eclipsing binary and seven dwarf novae are reported. The ultraviolet light curves of δ Pic indicate the accumulation of matter at the triangular Lagrangian points L4 and L5, the presence of a hot spot and a higher temperature for the primary star. The implication is that the cooler secondary fills its Roche lobe and is transfering mass to the primary; mass loss to the circumstellar space and possibly to the system may also be appreciable. The temperatures of dwarf novae are derived by comparing their ultraviolet spectral energy distributions with those for normal stars of luminosity classes IV and V. Piecing together observations for different objects, the SSCyg systems have temperatures of 28 500 K, 10 000 K and 9500 K, respectively, when they are at minimum, immediately before outburst and at the beginning of rise to maximum. At maximum, the temperature is 22 500 K or 17 300 K depending on the interstellar reddening correction for AR And. Immediately before outburst, there is a large excess of flux in the far ultraviolet as indicated by the large value of the ratio of flux at 1550 Å to that at 1800 Å. The observations of Z Cam during standstill gives a temperature of 14 900 K. No excess of flux in the far ultraviolet was observed during the maximum of AR And and the standstill of Z Cam.

scholarly journals Discovery of an Extremely Short Duration Flare from Proxima Centauri Using Millimeter through Far-ultraviolet Observations

2021 ◽  
Vol 911 (2) ◽  
pp. L25
Author(s):  
Meredith A. MacGregor ◽  
Alycia J. Weinberger ◽  
R. O. Parke Loyd ◽  
Evgenya Shkolnik ◽  
Thomas Barclay ◽  
...  
Keyword(s):  
Short Duration ◽  
Far Ultraviolet ◽  
Ultraviolet Observations

Extreme and Far Ultraviolet Observations from EURD after Three Years of Mission

2001 ◽  
pp. 345-348 ◽  
Author(s):  
C. Morales ◽  
J. F. Gómez ◽  
J. Trapero ◽  
V. Orozco ◽  
S. Bowyer ◽  
...  
Keyword(s):  
Far Ultraviolet ◽  
Ultraviolet Observations

A Discussion on astronomy in the ultraviolet - Observations of the interstellar gas with the Copernicus satellite

1975 ◽  
Vol 279 (1289) ◽  
pp. 299-302
Keyword(s):  
Absorption Lines ◽  
Heavy Elements ◽  
Interstellar Gas ◽  
Far Ultraviolet ◽  
Ultraviolet Observations

Recent results are summarized on interstellar H I, D I, H 2 , HD, and heavy elements whose absorption lines have been measured in the far ultraviolet.

scholarly journals The Role of Flare Stars in Cosmic-ray Origin

1995 ◽  
Vol 151 ◽  
pp. 185-192
Author(s):  
Maurice M. Shapiro
Keyword(s):  
Alternative Hypothesis ◽  
Cosmic Ray ◽  
Optical Data ◽  
Seed Particles ◽  
Cosmic Ray Acceleration ◽  
The Galaxy ◽  
Flare Stars ◽  
Far Ultraviolet ◽  
Ultraviolet Observations

AbstractSupernovae and their expanding shock fronts are evidently the main agents of cosmic-ray acceleration. The thermal gas in the interstellar medium has been regarded as the reservoir of seed particles destined to become cosmic-ray nuclei. This assumption is, however, at variance with the source composition of galactic cosmic iays. In an alternative hypothesis, the seed particles are injected into the interstellar material as suprathermal seed ions, and it has been surmised that flare stars provide the initial boost. We find that the dMe and dKe stars are probably the principal sources of cosmic-ray seed particles. Most stars in the Galaxy are red dwarfs and many of these flares much more powerfully and frequently than solar flares. Augmenting the optical data, recent X-ray and far-ultraviolet observations now permit a better estimate of the energy budget. Altogether, dMe and dKe stars seem to be the most promising class of cosmic-ray injectors.

Far-ultraviolet observations of the variable radio star LSI plus 61 deg 303

1981 ◽  
Vol 248 ◽  
pp. 1010 ◽  
Author(s):  
L. Maraschi ◽  
A. Treves ◽  
E. G. Tanzi
Keyword(s):  
Far Ultraviolet ◽  
Ultraviolet Observations ◽  
Variable Radio

Hopkins ultraviolet telescope observations of the far-ultraviolet spectrum of NGC 4151

1992 ◽  
Vol 392 ◽  
pp. 485 ◽  
Author(s):  
G. A. Kriss ◽  
A. F. Davidsen ◽  
William P. Blair ◽  
C. W. Bowers ◽  
W. V. Dixon ◽  
...  
Keyword(s):  
Ultraviolet Spectrum ◽  
Ngc 4151 ◽  
Far Ultraviolet

Far-ultraviolet observations of the Crab Nebula using the Hopkins Ultraviolet Telescope

1992 ◽  
Vol 399 ◽  
pp. 611 ◽  
Author(s):  
William P. Blair ◽  
Knox S. Long ◽  
Olaf Vancura ◽  
Charles W. Bowers ◽  
Sarah Conger ◽  
...  
Keyword(s):  
Crab Nebula ◽  
Far Ultraviolet ◽  
Ultraviolet Observations ◽  
The Crab Nebula

scholarly journals Far-ultraviolet observations of the neutral comae of comet Hale-Bopp (C/1995 01) near perihelion

2001 ◽  
Vol 28 (13) ◽  
pp. 2561-2564 ◽  
Author(s):  
M. Brittnacher ◽  
J. Kang ◽  
G. Parks ◽  
R. Elsen ◽  
G. Germany ◽  
...  
Keyword(s):  
Far Ultraviolet ◽  
Ultraviolet Observations

Far-Ultraviolet Observations of the North Ecliptic Pole with SPEAR

2006 ◽  
Vol 644 (2) ◽  
pp. L163-L166 ◽  
Author(s):  
Eric J. Korpela ◽  
Jerry Edelstein ◽  
Julia Kregenow ◽  
Kaori Nishikida ◽  
Kyoung-Wook Min ◽  
...  
Keyword(s):  
The North ◽  
Far Ultraviolet ◽  
Ultraviolet Observations
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