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Lucy, L. B.

Publications and source records attributed to Lucy, L. B..

7 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Multiline Transfer and the Dynamics of Stellar Winds

A Monte Carlo technique for treating multiline transfer in stellar winds is described. With a line list containing many thousands of transitions and with fairly realistic treatments of ionization, excitation and line formation, the resulting code allows the dynamic effects of overlapping lines the investigation of and provides the means to directly synthesize the complete spectrum of a star and its wind. It is found that the computed mass loss rate for data Puppis agrees with the observed rate. The synthesized spectrum of zeta Puppis also agrees with observational data. This confirms that line driving is the dominant acceleration mechanism in this star's wind.

Abbott, D. C.↗
NASA NTRS1980

X-ray properties of quasars

The X-ray properties of 111 catalogued quasars have been examined with the imaging proportional counter on board the Einstein Observatory. Thirty-five of the objects, of redshift between 0.064 and 3.53, were detected as X-ray sources. The 0.5-4.5-keV X-ray properties of these quasars are correlated with their optical and radio continuum properties and with their redshifts and variability characteristics. The X-ray luminosity of quasars tends to be highest for those objects which are bright in the optical and radio regimes and which exhibit optically violent variability. These observations suggest that quasars should be divided into two classes on the basis of radio luminosities, spectra, evolution and underlying morphology and that quasars can make up a significant portion of the diffuse soft X-ray background only if the slope of the optical quasar log N-log S relation is steeper than 2 to m sub b of about 21.5.

Ku, W. H.-M.↗
NASA NTRS1980

X-ray emission from the winds of hot stars

A phenomenological theory is proposed for the structure of the unstable line-driven winds of early-type stars. These winds are conjectured to break up into a population of blobs that are being radiatively driven through, and confined by ram pressure of an ambient gas that is not itself being radiatively driven. Radiation from the bow shocks preceding the blobs can account for the X-ray luminosity of zeta Puppis. The theory breaks down when used to model the much lower density wind of tau Scorpii, for then the blobs are destroyed by heat conduction from shocked gas. This effect explains why the profiles of this star's UV resonance lines depart from classical P Cygni form.

Lucy, L. B.↗
NASA NTRS1972

Nature of the secondary component of beta Lyrae.

Development of a hypothesis concerning the nature of the secondary component of beta Lyrae which is regarded as more plausible than the suggestion that this component is a black hole. Adopting Huang's (1962) and Woolf's (1965) basic model for beta Lyrae, it is suggested that the secondary star may be a massive 'main-sequence' star in rapid, nonuniform motion. Certain findings regarding mu Sco and V356 Sgr, which have primaries that are very cool and underluminous for their masses, are cited as evidence for such an inference, since their underluminosity is probably due to high angular momentum and they are normal enough not to be suspected of harboring a black hole.

Stothers, R.↗
NASA NTRS1970

Mass loss by hot stars

Luminous hot stars mass loss attributed to negative effective gravities in outer parts of reversing layers from ionic UV resonance lines

Lucy, L. B.↗
NASA NTRS1968

Mass Loss by Hot Stars

Mechanism explaining mass loss for luminous hot stars using ultraviolet line spectra of some ions

Lucy, L. B.↗