Engineering Papers⌕ Search

Engineering topics

Strittmatter, P. A.

Publications and source records attributed to Strittmatter, P. A..

31 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Radiation-pressure-driven mass loss from quasi-stellar objects.

It is shown that radiation pressure acting on the material in the outer envelopes of QSOs will cause mass outflow unless the mass M of the QSO exceeds a critical value Ms. If the QSOs are at cosmological distances, Ms is on the order of 10 to 100 billion solar masses, and otherwise scales according to intrinsic luminosity. Radiation-pressure-driven mass loss could be responsible for the absorption-line spectra observed in many QSOs. If so, the presence of blueshifted absorption lines in some but not all QSOs indicates that typically M is of the same order as Ms. It is also suggested that under radiative acceleration certain ratios of emission-line to absorption-line redshifts may be preferred as a result of a line-locking mechanism. Inferences are made concerning the magnitude of the gravitational component of the redshift. Possible tests of various aspects of the model are discussed.

Mushotzky, R. F.↗
NASA NTRS1972

X-ray emission from white dwarfs.

It is suggested that both the 250-eV background radiation and the recently observed variations in the optical emission from certain white dwarfs may be due to thermal bremsstrahlung from hot coronae surrounding such stars. The X-ray flux from the variable white dwarfs is predicted and in the most favorable case, R548, is sufficiently large to allow an observational test of the model. The possibility that the variations observed in strong X-ray sources are due to pulsations in the coronae surrounding degenerate stars, rather than in stars themselves, is also discussed. For the white dwarfs, both pulsation and rotation of the central star are found to be adequate sources of coronal energy, with pulsation being subject to relatively easy observational test. The energy requirements for the strong X-ray sources are briefly discussed.

Strittmatter, P. A.↗
NASA NTRS1972

Redshifts of twenty radio galaxies.

Spectroscopic observations and redshifts of 20 radio galaxies obtained with the Lick 120-inch telescope are presented. Ten of the radio galaxies are from the 3C R catalog, and the remainder are from the 4C, 5C, Ohio, and Parkes catalogs. The reported results represent a continuation of Burbidge's (1970) previously published data.

Burbidge, E. M.↗
NASA NTRS1972

The optical object identified with 3C 455.

It is shown that the optical object identified with 3C 455 is a quasi-stellar object with a redshift z = 0.543. The QSO is situated 23 sec northeast of the S0 galaxy NGC 7413, which has a redshift of 0.0332. It is pointed out that the discovery of the present object in a position so close to a galaxy is further evidence in favor of the existence of a physical association between 3C QSOs and bright galaxies.

Arp, H. C.↗
NASA NTRS1971

Apparent associations between bright galaxies and quasi-stellar objects.

A comparison of the spatial distribution of the 47 identified QSOs in the 3C and 3CR catalogs with the small-redshift galaxies contained in the Reference Catalog of Bright Galaxies shows that four QSOs with redshift in the range 0.5-1.4 are much closer to bright galaxies than would be expected if the 47 QSOs were distributed randomly. An extensive analysis of the distributions shows that the probability that this is a chance occurrence is less than 0.005. It is also shows that the radio-quiet QSO PHL 1226 lies very close to IC 1746 to which it appears to have a physical connection.

Burbidge, E. M.↗
NASA NTRS1971

G61-29, a helium emission-line star.

G61-29 is the first star discovered in which helium alone has been observed in emission. Three spectrograms of the star were obtained at the Lick 120-inch telescope. The most prominent spectral features in the blue region are the He I triplet lines at 4471, 4026, and 3889 A. All He I lines are extremely broad. The high proper motion of the star limits its maximum distance to about 200 pc or less if the star is gravitationally bound to the Galaxy.

Burbidge, E. M.↗
NASA NTRS1971

Quantitative results of stellar evolution and pulsation theories.

The discrepancy between the masses of Cepheid variables deduced from evolution theory and pulsation theory is examined. The effect of input physics on evolutionary tracks is first discussed; in particular, changes in the opacity are considered. The sensitivity of pulsation masses to opacity changes and to the ascribed values of luminosity and effective temperature are then analyzed. The Cepheid mass discrepancy is discussed in the light of the results already obtained. Other astronomical evidence, including the mass-luminosity relation for main sequence stars, the solar neutrino flux, and cluster ages are also considered in an attempt to determine the most likely source of error in the event that substantial mass loss has not occurred.

Fricke, K.↗