Detection of O VI lambda 1033 Emission and Far-Ultraviolet Spectral Variability in the Gravitational Lens PG 1115+080

1996 ◽  
Vol 461 ◽  
pp. 593 ◽  
Author(s):  
A. G. Michalitsianos ◽  
R. J. Oliversen ◽  
J. Nichols
Keyword(s):  
Gravitational Lens ◽  
Spectral Variability ◽  
Far Ultraviolet

scholarly journals The search for magnetic fields in two Wolf–Rayet stars and the discovery of a variable magnetic field in WR 55

2020 ◽  
Vol 499 (1) ◽  
pp. L116-L120
Author(s):  
S Hubrig ◽  
M Schöller ◽  
A Cikota ◽  
S P Järvinen
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Rotation Period ◽  
Indirect Evidence ◽  
Variable Magnetic Field ◽  
Spectral Variability ◽  
Significance Level ◽  
Field Detection ◽  
Ring Nebula ◽  
Far Ultraviolet

ABSTRACT Magnetic fields in Wolf–Rayet (WR) stars are not well explored, although there is indirect evidence, e.g. from spectral variability and X-ray emission, that magnetic fields should be present in these stars. Being in an advanced stage of their evolution, WR stars have lost their hydrogen envelope, but their dense winds make the stellar core almost unobservable. To substantiate the expectations on the presence of magnetic fields in the most-evolved massive stars, we selected two WR stars, WR 46 and WR 55, for the search of the presence of magnetic fields using FORS 2 spectropolarimetric observations. We achieve a formally definite detection of a variable mean longitudinal magnetic field of the order of a few hundred gauss in WR 55. The field detection in this star, which is associated with the ring nebula RCW 78 and the molecular environment, is of exceptional importance for our understanding of star formation. No field detection at a significance level of 3σ was achieved for WR 46, but the variability of the measured field strengths can be rather well phased with the rotation period of 15.5 h previously suggested by FUSE(Far Ultraviolet Spectroscopic Explorer) observations.

Detection of Far-Ultraviolet High-Excitation Line Emission and Lyman- beta Absorption in the Gravitational Lens Q0957+561

1993 ◽  
Vol 417 ◽  
pp. L57 ◽  
Author(s):  
A. G. Michalitsianos ◽  
J. Nichols-Bohlin ◽  
F. C. Bruhweiler ◽  
D. Kazanas ◽  
Y. Kondo ◽  
...  
Keyword(s):  
Line Emission ◽  
Gravitational Lens ◽  
High Excitation ◽  
Excitation Line ◽  
Far Ultraviolet

Far-UV Spectral Variability in the Gravitational Lens Candidate UM 425

1996 ◽  
Vol 458 ◽  
pp. 67 ◽  
Author(s):  
A. G. Michalitsianos ◽  
R. J. Oliversen ◽  
S. P. Maran
Keyword(s):  
Gravitational Lens ◽  
Spectral Variability

scholarly journals 1146+111B,C: A Giant Gravitational Lens?

1987 ◽  
Vol 124 ◽  
pp. 755-760 ◽  
Author(s):  
E.L. Turner
Keyword(s):  
Ir Spectra ◽  
Time Delays ◽  
Gravitational Lens ◽  
Spectral Variability ◽  
Positive Evidence ◽  
Spectroscopic Observations ◽  
Uv And Ir Spectra ◽  
Observational Status

The history and current observational status of the giant gravitational lens candidate 1146+111B,C are reviewed. In the absence of any new positive evidence and in the presence of reported differences in the UV and IR spectra of B and C, the lens hypothesis is clearly much weaker than previously. Nevertheless, given the substantial similarity of the spectra over a broad range of wavelengths, discrepancies among various spectroscopic observations of C, and the possibility of spectral variability plus large differential time delays, the data do not yet support any definite conclusion as to the nature of 1146+111B,C.

Seti Space Missions

1997 ◽  
Vol 161 ◽  
pp. 761-776 ◽  
Author(s):  
Claudio Maccone
Keyword(s):  
Electromagnetic Waves ◽  
Space Missions ◽  
Gravitational Lens ◽  
The Sun ◽  
Space Antenna ◽  
Focal Distance ◽  
Large Space ◽  
The Earth ◽  
Space Antennas ◽  
New Space

AbstractSETI from space is currently envisaged in three ways: i) by large space antennas orbiting the Earth that could be used for both VLBI and SETI (VSOP and RadioAstron missions), ii) by a radiotelescope inside the Saha far side Moon crater and an Earth-link antenna on the Mare Smythii near side plain. Such SETIMOON mission would require no astronaut work since a Tether, deployed in Moon orbit until the two antennas landed softly, would also be the cable connecting them. Alternatively, a data relay satellite orbiting the Earth-Moon Lagrangian pointL2would avoid the Earthlink antenna, iii) by a large space antenna put at the foci of the Sun gravitational lens: 1) for electromagnetic waves, the minimal focal distance is 550 Astronomical Units (AU) or 14 times beyond Pluto. One could use the huge radio magnifications of sources aligned to the Sun and spacecraft; 2) for gravitational waves and neutrinos, the focus lies between 22.45 and 29.59 AU (Uranus and Neptune orbits), with a flight time of less than 30 years. Two new space missions, of SETI interest if ET’s use neutrinos for communications, are proposed.

A Spectroscopic Study of the Environments of Gravitational Lens Galaxies

2006 ◽  
Vol 20 ◽  
pp. 289-290
Author(s):  
I. Momcheva ◽  
K. Williams ◽  
C. Keeton ◽  
A. Zabludoff
Keyword(s):  
Spectroscopic Study ◽  
Gravitational Lens ◽  
Lens Galaxies

Simulation of a gravitational lens in a lecture demonstration

1982 ◽  
Vol 138 (9) ◽  
pp. 147 ◽  
Author(s):  
G.S. Egorov ◽  
Nikolai S. Stepanov
Keyword(s):  
Gravitational Lens ◽  
Lecture Demonstration

scholarly journals HST far-ultraviolet imaging of DG Tauri

2013 ◽  
Vol 557 ◽  
pp. A110 ◽  
Author(s):  
P. C. Schneider ◽  
J. Eislöffel ◽  
M. Güdel ◽  
H. M. Günther ◽  
G. Herczeg ◽  
...  
Keyword(s):  
Far Ultraviolet
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