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Wade, R. A.

Publications and source records attributed to Wade, R. A..

7 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1997

Habitable moons around extrasolar giant planets

Possible planetary objects have now been discovered orbiting nine different main-sequence stars. These companion objects (some of which might actually be brown dwarfs) all have a mass at least half that of Jupiter, and are therefore unlikely to be hospitable to Earth-like life: jovian planets and brown dwarfs support neither a solid nor a liquid surface near which organisms might dwell. Here we argue that rocky moons orbiting these companions could be habitable if the planet-moon system orbits the parent star within the so-called 'habitable zone', where life-supporting liquid water could be present. The companions to the stars 16 Cygni B and 47 Ursae Majoris might satisfy this criterion. Such a moon would, however, need to be large enough (>0.12 Earth masses) to retain a substantial and long-lived atmosphere, and would also need to possess a strong magnetic field in order to prevent its atmosphere from being sputtered away by the constant bombardment of energetic ions from the planet's magnetosphere.

NASA Discipline Exobiology↗
NASA NTRS1986

IUE/Voyager observations of luminous accretion disk systems

The importance of simultaneous IUE and Voyager observations of luminous accretion disk systems is shown. The composite spectra of SS Cyg, VW Hyi, CPD-48 1577, and V3895 Sgr show the changes which occur in the continuum flux distributions from 3200 A down to the Lyman limit. Results imply that current disk ingredients (i.e., blackbodies and Kurucz atmospheres) cannot explain the IUE/Voyager observations.

Carone, T. E.↗
NASA NTRS1983

A nebula around Nova BT Monocerotis

H-alpha observations of Nova BT Mon obtained on December 15, 1981 using an 800x800-pixel CCD detector on the double spectrograph of the 5-m Hale telescope at Palomar Observatory are reported. The reciprocal dispersion at H-alpha was 6.04 A/pixel and the angular scale along the 1.0-arcsec-wide east-west slit was 0.58 arcsec/pixel; resolution of the combined, processed image is about 12 A. A ring-shaped nebular emission with a center displaced slightly from the stellar image and an expansion distance to BT Mon of about 1800 pc was detected. The velocity diameter is found to be about 1500 km/sec along the ridge line and 2100 km/sec along the 10-unit contour. The mass of the visible nebula is estimated as 0.00003 solar mass, similar to the BT Mon ejection mass determined by Schaefer and Patterson (1983).

Marsh, T. R.↗
NASA NTRS1982

A spectrophotometric survey of cataclysmic variable stars

A sample of dwarf novae and other cataclysmic variable stars were observed using the multichannel spectrophotometer on the 5-m Hale reflector. A preliminary qualitative description of the continuum distributions is given and a discussion of the Balmer emission-line fluxes is made. For the spectral energy distributions, the logarithm of the monochromatic flux density is plotted against the inverse of the wavelength. It is concluded that the presence or absence of evident flux from a late-type stellar component is consistent with the standard picture which has been developed for the structure of cataclysmic variable stars. The presence of the Balmer jump in emission or absorption can be understood in terms of the relative importance of an optically thick accreting disk characteristic of nova-like variables and dwarf novae in outburst and an optically thin outer accreting disk characteristic of quiescent dwarf novae.

Oke, J. B.↗
NASA NTRS1981

Z Camelopardalis at standstill

Coude spectra of the H alpha region in Z Cam are used to study line structure and velocity variations during the current extended standstill. Orbital elements and fine structure in the line profiles are consistent with results of Robinson (1973), which indicates that the standstill does not alter the velocity structure of the inner parts of the accretion disk and that of a possible circumstellar shell. Mass loss rates of about 6 x 10 to the -10th solar mass/yr are derived for both quiescence and standstill, while the disk light from Z Cam at 4200 A is found to be brighter by about 2.8 mag at standstill compared to quiescence. It is concluded that if the standstill is related to increased mass accretion relative to quiescence, the line emission areas are apparently unaffected.

Szkody, P.↗
NASA NTRS1977

Optical spectrum of HDE 245770 /A0535 + 26/

Narrow-band spectrophotometric observations of HDE 245770 with the multichannel spectrometer and slit spectra obtained with the SIT digital spectrograph at the Cassegrain focus of the 5-m Hale telescope indicate that this star is of spectral type B0 with emission at H-alpha, H-beta, and probably 5876 A of He I. There is some evidence that it is of luminosity class III. The reddening is estimated in various ways and corresponds to a B-V color excess of 0.80. If the star is really a giant, its distance is approximately 1.8 kpc. No variations larger than 1% at the reported 104-x X-ray pulse period are evident in the data in visual magnitude, color, or H-alpha emission intensity. This is not surprising, since the optical star is much more luminous than the X-ray object, and the heating effect of the X-ray source (which is assumed to be one component of a binary) on the B0 star's atmosphere can produce at most a few percent modulation in visual light.

Wade, R. A.↗