Search Publications
Missions
Journals
Publication Years
Similarity of the variability patterns in the EXOSAT and GINGA folded light curves of the Seyfert galaxy NGC 6814.
Karas, V.; Abramowicz, M. A.; Bao, G. +1 more
The Seyfert galaxy NGC 6814 is known to show periodic variation of its X-ray luminosity. We found that the sequences of peaks (variability patterns) in the folded X-ray light curves constructed from the Exosat and Ginga data are remarkably similar when one ignores amplitudes of the peaks and considers only their phases. The stable pattern consists…
ULF waves in other magnetospheres - observations and possible source mechanisms.
Khurana, K. K.
This paper presents an overview of the work done so far in the field of the ULF waves in the magnetospheres of Mercury, Jupiter, Saturn and Uranus. In the magnetosphere of Mercury, ULF waves were observed in the vicinity of the magnetopause and in the inner magnetosphere with frequencies in the range of 0.1 - 0.5 Hz. In the magnetosphere of Jupite…
IUE and HI observations of gas components towards HD 174632.
Davies, R. D.; Bates, B.; Kemp, S. N. +1 more
IUE spectra of gas components towards the nearby star HD 174632 are reported, together with 21-cm H I emission profiles obtained in the direction of the star and at several neighboring positions some 1 deg from the star. These new observations reveal a far more complex velocity structure of the interstellar gas than that reported through optical s…
Image Deconvolution of Extended Objects: A Comparison of the Inverse Fourier and the Lucy Techniques
Cunningham, C. C.; Anthony, D.
We have investigated the relative effectiveness of two deconvolution techniques in restoring spherically aberrated Hubble Space Telescope (HST) images. These images were restricted to extended objects (such as planets) of high signal-to-noise. Our reason for pursuing these studies was that one of the deconvolution methods, the Lucy iterative techn…
Hydrogen from Jupiter's atmosphere in the Jovian magnetosphere
Balsiger, H.; Geiss, J.; Galvin, A. B. +3 more
The passage of Ulysses through Jupiter's magnetosphere presents a new opportunity to investigate the contribution to the Jovian magnetosphere of ions of atmospheric origin. A determination of the magnetospheric H +/He 2+ flux ratio allows an estimate of the relative abundance of ionospheric material in the Jovian magnetospher…
The Ultraviolet Spectrum of the Planetary Nebula VY 2-2
Feibelman, Walter A.
New ultraviolet short-wavelength (SWP) IUE observations for the protoplanetary nebula Vy 2-2 were obtained in the low dispersion mode. An exposure of 400 minute duration reveals a weak stellar continuum and several definite emission lines as well as a number of absorption features. Emission features of C III], Si III], and [Ne III] are clearly obs…
An IUE Search for Star Formation in Ellipticals with Gaseous Disks
Renzini, Alvio; Burstein, David; Bertola, Francesco +1 more
New IUE observations are presented of NGC 5077, an elliptical galaxy known to have a Hα bright gaseous disk in its central region. The ultraviolet spectral energy distribution of NGC 5077 is compared to those of the bulges of two galaxies, M31 and NGC 3115, that are of similar Mg_2_ absorption-line strength and are known not to contain obvious gas…
Ultraviolet spectroscopy of nova MUSCAE 1991.
Panagia, N.; Horne, K.; Shrader, C. R. +4 more
We report on a series of ultraviolet spectroscopic observations made with the IUE satellite, which sampled critical outburst stages of the soft X-ray transient Nova Muscae 1991. Continuum light curves, and a multi-epoch line analysis are presented. In addition, a single epoch optical-UV spectra obtained with the HST/FOS is discussed. The optical-U…
The Companion of the 18d Classical Cepheid YZ CAR
Evans, Nancy R.; Butler, John
We have obtained a deep IUE spectrum of the 18d Cepheid YZ Car. Flux has been detected at the level of 1-2 X 10^-15 ergs cm^-2 A^-1 sec^-1 from 1200 to 200 A, which we identify as the companion in the binary system. Since this is at least partly a result of "camera artifacts" built up during a long exposure, this is an upper limit to the flux of t…
Deflection of Light by the Earth
Gould, Andrew
General relativity predicts that light rays are deflected by gravitational fields. This effect has been observed with various degrees of precision on distance scales from 10 exp 11 to 10 exp 23 cm and on mass scales from 10 exp -3 to 10 exp 13 solar masses. The Hipparcos satellite can detect deflection of light by the earth, and can thereby extend…