Search Publications
Possible effects of organelle charge and density on cell metabolism
Keenan, F. P.; Bates, B.; Catney, M. G.
To respond to gravity a biological system must: First, perceive the stimulus; and, second transduce the stimulus into an appropriate response. This laboratory has studied a system of perception and transduction involving the gravity-induced asymmetric distribution of a plant growth hormone. From these studies we have developed a working theory whi…
Distribution and kinematics of MgII in the LISM
Molaro, P.; Beckman, J. E.; Vladilo, G. +1 more
We have analyzed MgII emissions in the IUE spectra of 91 cool stars in a systematic search for interstellar components. 60% of the stars show evidence of interstellar contamination. The radial velocities of the IS features show that even at short distances (d < 30 pc) the motion of the LISM agrees with that derived from the analysis of optical …
Evolution of the chromospheric and coronal activity of intermediate mass stars
Brown, Alexander
Recent ultraviolet and X-ray observations pertaining to the outer atmospheric structure of intermediate mass (4-6 M0) stars and the evolution of their structure are presented. A distance-limited (d <= 200 pc) IUE ultraviolet survey of early K bright giants shows that C IV emission commonly is present. These stars are almost evenly sp…
Ultraviolet interstellar lines towards nearby fast rotators: ZnII distribution and MgII/MgI ratios
Molaro, P.; Beckman, J. E.; Centurion, M. +1 more
We present the column density distribution of the LISM towards a sample of 15 fast rotators observed with IUE at high resolution. The targets are closer than 200 pc and most of them have lines of sight not previously investigated. Hydrogen column densities are inferred using zinc, known to be little depleted. The results are in general agreement w…
A rapid planetary phase observed on the IUE spectral region of the carbon star, HD 59643
Querci, M.; Querci, F.; Johnson, H. R. +1 more
The IUE satellite has been used to obtain low-and high resolution LWP and SWP spectra of the unusual cool carbon star HD 59643 (R9; C6,2), which appears to suffer a planetary nebula phase. These spectra enable us to understand the nature of this fascinating object, which may be in a stage of rapid evolution. High resolution line profiles are exami…
Lyman-alpha emission from low dispersion IUE spectra
Catalano, S.; Bruno, M.; Marilli, E.
In spite of its importance as cooling mechanism of the chromosphere of late type stars, the hydrogen Lyman-alpha line has been neglected in most IUE programmes The high geocoronal background and the saturation often seen in the stellar emission peak are the major problems that prevent accurate determination of the Lyman alpha flux.
We have de…X-ray, UV, optical and radio observations of the visual binary 53 AQR
Pasquini, L.; Monsignori-Fossi, B. C.; Pallavicini, R. +1 more
The authors present optical (ESO), ultraviolet (IUE), X-ray (EXOSAT) and radio (VLA) observations of the visual binary 53 Aquarii. They show that the two components of the system can be used to infer the properties of the Sun at a much earlier epoch.
Coronal models of late-type stars observed with EXOSAT
Monsignori-Fossi, B. C.; Landini, M.; Pallavicini, R. +1 more
Differential emission measure distributions for transition region and corona able to reproduce X-ray and UV emission are investigated. The EXOSAT, EINSTEIN and IUE data for the solar type star K Cet are analyzed. A multitemperature differential emission measure distribution gives a satisfactory fit of the data.
IUE observations of neutral hydrogen and deuterium in the local interstellar medium.
Moos, H. W.; Murthy, J.; Linsky, J. L. +4 more
Small-aperture, high-dispersion IUE spectra have been obtained of seven late-type stars that, in general, confirm previous Copernicus results concerning the distribution of hydrogen and deuterium in the local interstellar medium. In addition, the IUE Ly α spectra of Altair, and of the α Cen components, suggest that multiple velocity components exi…
Upper limits to ultraviolet line emission in fully convective M-dwarfs
Moreno, H.; Ambruster, C. W.; Kunkel, W. E. +1 more
Theoretical stellar structure models find that stars later than ~dM3 are fully convective. It is widely believed that this should result in reduced non-radiative heating and activity levels, however, the observational evidence is sparse and somewhat contradictory. In order to expand the number of atmospheric diagnostics for these stars, we have ob…