scholarly journals Soft X-ray and ultraviolet observations of MRK 841: implications for the blue bump

1995 ◽  
Vol 273 (1) ◽  
pp. 85-92 ◽  
Author(s):  
K. Nandra ◽  
T. J. Turner ◽  
I. M. George ◽  
A. C. Fabian ◽  
C. Shrader ◽  
...  
Keyword(s):  
X Ray ◽  
Ultraviolet Observations

scholarly journals X-ray and ultraviolet observations of the dwarf nova VW Hyi in quiescence

2003 ◽  
Vol 346 (4) ◽  
pp. 1231-1241 ◽  
Author(s):  
Dirk Pandel ◽  
France A. Córdova ◽  
Steve B. Howell
Keyword(s):  
X Ray ◽  
Dwarf Nova ◽  
Ultraviolet Observations

scholarly journals Regulation of accretion by its outflow in a symbiotic star: the 2016 outflow fast state of MWC 560

2020 ◽  
Vol 492 (3) ◽  
pp. 3107-3127 ◽  
Author(s):  
Adrian B Lucy ◽  
J L Sokoloski ◽  
U Munari ◽  
Nirupam Roy ◽  
N Paul M Kuin ◽  
...  
Keyword(s):  
Symbiotic Star ◽  
Fast State ◽  
Low Velocity ◽  
X Ray ◽  
Broad Absorption Line ◽  
Multi Wavelength ◽  
Order Of Magnitude ◽  
The Stability ◽  
Ultraviolet Observations ◽  
Optical Flux

ABSTRACT How are accretion discs affected by their outflows? To address this question for white dwarfs accreting from cool giants, we performed optical, radio, X-ray, and ultraviolet observations of the outflow-driving symbiotic star MWC 560 (≡V694 Mon) during its 2016 optical high state. We tracked multi-wavelength changes that signalled an abrupt increase in outflow power at the initiation of a months-long outflow fast state, just as the optical flux peaked: (1) an abrupt doubling of Balmer absorption velocities; (2) the onset of a 20 μJy per month increase in radio flux; and (3) an order-of-magnitude increase in soft X-ray flux. Juxtaposing to prior X-ray observations and their coeval optical spectra, we infer that both high-velocity and low-velocity optical outflow components must be simultaneously present to yield a large soft X-ray flux, which may originate in shocks where these fast and slow absorbers collide. Our optical and ultraviolet spectra indicate that the broad absorption-line gas was fast, stable, and dense (≳106.5  cm−3) throughout the 2016 outflow fast state, steadily feeding a lower density (≲105.5 cm−3) region of radio-emitting gas. Persistent optical and ultraviolet flickering indicate that the accretion disc remained intact. The stability of these properties in 2016 contrasts to their instability during MWC 560’s 1990 outburst, even though the disc reached a similar accretion rate. We propose that the self-regulatory effect of a steady fast outflow from the disc in 2016 prevented a catastrophic ejection of the inner disc. This behaviour in a symbiotic binary resembles disc/outflow relationships governing accretion state changes in X-ray binaries.

X-ray and ultraviolet observations of the Seyfert galaxy MCG 8-11-11

1990 ◽  
Vol 359 ◽  
pp. 98 ◽  
Author(s):  
A. Treves ◽  
G. Bonelli ◽  
L. Chiappetti ◽  
R. Falomo ◽  
L. Maraschi ◽  
...  
Keyword(s):  
Seyfert Galaxy ◽  
X Ray ◽  
Ultraviolet Observations

scholarly journals A Review of Recent Ultraviolet Observations of Close Binaries from Space

1980 ◽  
Vol 5 ◽  
pp. 849-851
Author(s):  
Yoji Kondo
Keyword(s):  
Joint Meeting ◽  
Close Binaries ◽  
First Year ◽  
Research Projects ◽  
X Ray ◽  
Cataclysmic Binaries ◽  
Second Year ◽  
Ultraviolet Observations ◽  
X Ray Binaries

The reason for presenting this review at this Joint Meeting, in spite of the fact that there was, a few days ago, a special Joint Discussion on recent UV observations is partially that somehow the general subject of close binaries was overlooked at the Joint Discussion, although unique close binaries, such as cataclysmic binaries and X-ray binaries, were included. There exist a large number of vigorous research projects being carried out with UV telescopes in the field of close binaries. I shall concentrate on IUE results, although other satellite and balloon-borne telescopes have continued to produce interesting UV observations of close binaries.There are a number of active IUE programs on this theme. In the time allocated to this review I shall only be able to present highlights of selected programs in the hope of giving a glimpse of what is going on. The programs on close binaries from the first year of IUE operations include those by P. Conti, M. Hack, J.B. Hutchings, R.H. Koch, Y. Kondo and G.E. McCluskey, M. Plavec, and J. Sahade. In the second year, additional astronomers are also observing close binaries with the IUE.

scholarly journals X-ray and ultraviolet observations of Markarian 421

1988 ◽  
Vol 232 (4) ◽  
pp. 793-808 ◽  
Author(s):  
I. M. George ◽  
R. S. Warwick ◽  
G. E. Bromage
Keyword(s):  
Markarian 421 ◽  
X Ray ◽  
Ultraviolet Observations

scholarly journals X-Ray and Ultraviolet Observations of AG Draconis during Quiescence and Outburst

1987 ◽  
Vol 93 ◽  
pp. 763-763
Author(s):  
A. Cassatella ◽  
F.A. Córdova ◽  
M. Friedjung ◽  
J. Kenyom ◽  
L. Piro ◽  
...  
Keyword(s):  
Orbital Motion ◽  
Uv Light ◽  
Low Energy ◽  
Emission Lines ◽  
Symbiotic Star ◽  
Symbiotic Stars ◽  
Uv Spectrum ◽  
X Ray ◽  
High Ionization ◽  
Ultraviolet Observations

AbstractWe describe the first X-ray monitoring of a symbiotic star during phases of enhanced activity. AG Dra is a Pop II object with a composite spectrum, characterized by a cool K-type component, prominent high ionization emission lines and a strong UV continuum which is attributed to a hot dwarf companion. Periodic variability of the UV radiation during minimum could be attributed to the orbital motion of the system. In April 1980 HEAO-2 detected an intense, soft X-ray flux from AG Dra, stronger than in other symbiotic stars. After one major outburst of November 1980, which continued until 1983, two more outbursts occurred in February 1985 and January 1986, and coordinated X-ray (EXOSAT) and ultraviolet (IUE) observations were organized to study the behaviour of AG Dra during different activity phases. EXOSAT observations made during decline after the 1985 outburst, revealed a weak X-ray flux in the Thin Lexan filter of the Low Energy dedtector. Observations made during minimum, in June and November 1985, at phases 0.22 and 0.50 of the UV light curve, disclosed the presence of an intense X-ray flux, which was not occulted in November. AG Dra was again observed with EXOSAT in February 1986 when the stellar luminosity was still at maximum. No X-ray flux was detected, in spite of the prominent, high ionization UV spectrum observed with IUE.A detailed discussion of the X-ray and ultraviolet results on AG Dra in the light of possible models is in progress.

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