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Oke, J. B.

Publications and source records attributed to Oke, J. B..

At least 91 records · Page 5
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NASA NTRS1975

Supernova 1972 e in NGC 5253

New absolute energy distributions of the Type 1 supernova 1972e in NGC 5253 extending to about 700 days after maximum light were obtained. A physical model of the expanding envelope, based on the identification of the feature at 6550 A with H-alpha, is proposed. It is described as a differentially expanding atmosphere, with electron density ranging from 10 to the 10th power near maximum light to about 10 to the 7th power, 340 days later, illuminated by a photosphere with temperature in the range 10,000 K to 7,000 K. More than 200 days after maximum, the spectrum was dominated by four features between 4200 A and 5500 A. Three of these four features matched the blended emissions from over 100 lines of Fe II. Possible identifications of the fourth feature with Mg I lambda 4571 or permitted lines of Fe II are also discussed.

Kirshner, R. P.↗
NASA NTRS1975

The spectral energy distribution of NGC 1275

An analysis of absolute spectral energy distributions of interstellar gas for a galaxy (NGC 1275) is presented. Infrared spectra data shows heavy reddening. It is proposed that the interstellar gas may be ionized by shock waves or by nonthermal or stellar radiation. It is suggested, that high velocity, emission-line knots are H2 regions in a Perseus cluster galaxy or intergalactic gas cloud seen in projection against NGC 1275.

Shields, G. A.↗
NASA NTRS1975

Optical and infrared spectrophotometry of 18 Markarian galaxies

Slit spectra, spectrophotometric scans and infrared broad band observations are presented. Eight of the program galaxies can be classified as Seyfert galaxies. Arguments are given that thermal, nonthermal and stellar radiation components were present. One group of Seyfert galaxies was characterized both by the presence of a high density region of gas and by a continuum dominated by nonthermal radiation. The continua of the remaining program Seyferts, which did not have a high density region of gas, were dominated by thermal radiation from dust and a stellar continuum. Ten of the galaxies, which are not Seyfert galaxies, are shown to be examples of extragalactic H 2 regions.

Becklin, E. E.↗
NASA NTRS1974

Photoelectric spectrophotometry of OQ 172 and OH 471

Absolute spectral energy distributions for the large-redshift quasars OQ 172 and OH 471 are discussed along with similar data for two other quasars: 4C 05.34 and PHL 957. If the redshift are assumed to be cosmological, OQ 172 and OH 471 are not as luminous as PHL 957. If these quasars are basically similar and if radiative processes dominate, the strength of alpha and the behavior of the continuum at the Lyman limit strongly suggest that these objects consist of a central ionizing source surrounded by discrete clouds, filaments, or a gaseous structure such as a disk. This gaseous matter does not cover the whole solid angle surrounding the source.

Oke, J. B.↗
NASA NTRS1974

The distance of BL Lacertae

Spectrophotometric observations of the extended object around BL Lacertae have been conducted from August 1969 to October 1973 using circular apertures of various diameters as well as an annular aperture with an outer diameter of 10-in. and an inner obscuring disk of 5 in. All observations were carried out with a multichannel spectrometer attached to the 200-in. Hale telescope. The annular-aperture spectrum shows the absorption lines normally seen in spectra of ordinary giant galaxies; these lines yield a redshift (z) equal to 0.07. The central source shows a power law spectrum with the exponent (alpha) equal to -1.55. The underlying galaxy energy distribution is consistent with that of a normal giant elliptical galaxy. If a Hubble constant of 60 km/sec per Mpc is used, the absolute visual magnitude of the galaxy is -22.9, and the distance is 350 Mpc.

Oke, J. B.↗
NASA NTRS1974

Photoelectric spectrophotometry of OQ 172 and OH 471

Absolute spectral energy distributions for the large redshift quasars OQ 172 and OH 471 are discussed along with similar data for two other quasars 4C05.34 and PHL 957. Assuming cosmological redshifts, OQ 172 and OH 471 are not as luminous as PHL 957. If these quasars are basically similar and if radiative processes dominate, the strength of Ly alpha and the behavior of the continuum at the Lyman limit strongly suggest that these objects consist of a central ionizing source surrounded by discrete clouds, filaments or a gaseous structure such as a disk. This gaseous matter does not cover the whole solid angle surrounding the source.

Oke, J. B.↗
NASA NTRS1974

Absolute spectrophotometry in M31 and M32

For a number of places in the bulge of M31 and for two places in M32 photometric scans from 3300 A to 10,600 A have been obtained with the multichannel spectrometer on the 5-meter Hale telescope. The scans show that in both objects the color temperature (particularly shortwards of 5000 A) decreases towards the center and that the strength of the CN bands increases towards the center in both objects in agreement with earlier observations. The new data can all be interpreted in terms of an increase of heavy element abundance towards the center in both objects by a factor probably less than 2 and by an excess of heavy elements in M31 compared to M32 by a factor probably greater than 2, in qualitative agreement with earlier conclusions.

Oke, J. B.↗
NASA NTRS1973

The spectra of supernovae.

Progress report on a continuing program of investigation into the nature of the spectra of supernovae. A description of these spectra is presented that is more quantitative and covers a wider wavelength range than heretofore published descriptions. Some preliminary conclusions are suggested in the light of the new data presented.

Kirshner, R. P.↗
NASA NTRS1972

3C 323.1 - A QSO in a rich cluster of galaxies.

The redshift and structural data on the compact cluster Zw Cl 1545.1+2104 have been determined from deep plates of the cluster region and from spectral scans of the central galaxy in the cluster. The cluster is of richness 1 on Abell's (1958) scale, and the redshift of its central galaxy agrees well with that of the quasar 3C 323.1 which lies at a projected distance of 6.5 sec from the center of the cluster. The data indicate that the quasar is a member of the cluster as opposed to the observed trend.

Oemler, A., Jr.↗
NASA NTRS1972

The spectrum of the quasi-stellar object PHL 957.

Spectra of the radio-quiet quasar PHL 957 were obtained at a 200-in. telescope with a Cassegrain image tube, a Cassegrain multichannel spectrometer, and an integrating television camera on the spectrograph. The image-tube spectra revealed 64 absorption lines between 3200 and 6800 A. The absolute energy distribution indicates that this quasar is one of the most luminous known. The absorption line redshifts and line profiles observed are discussed.

Lowrance, J. L.↗
NASA NTRS1972

The spectral dependence of circular polarization in Grw + 70 deg 8247.

Observation of sharp changes in circular polarization with wavelength in new observations of Grw + 70 deg 8247 made with 80 A resolution. Some of the structure is associated with the Minkowski bands. Continued broadband measurements show that while the polarization below 6000 A appears to remain constant, above this wavelength there have been significant changes in the past year.

Angel, J. R. P.↗
NASA NTRS1972

Spectral energy distributions of nuclei of peculiar galaxies.

Consideration of galaxies of the types described by Seyfert, Zwicky, Markarian and others. Quasars are discussed in terms of their similarities to the nuclei of peculiar galaxies. The data discussed were obtained almost exclusively with photoelectric spectrometers. Peculiar galaxies have a wide range of properties insofar as their spectra are concerned. Many have very strong emission lines. Sources of continuous radiation, and distance scale problems and selection effects are discussed. Data are presented which are representative of spectrophotometric observational results for 12 Markarian galaxies, 14 Zwicky compact objects, and 16 radio galaxies. The general properties of spectral energy distributions of peculiar galaxies and quasars are discussed.

Oke, J. B.↗
NASA NTRS1971

Redshifts and absolute spectral energy distributions of galaxies in distant clusters.

Absolute spectral energy distributions were measured in galaxies of three distant clusters. Redshifts and information on evolutionary effects are inferred by a comparison of the results with the integrated light energy distribution for nearby giant elliptical galaxies. Evidence for evolution over the last 3 to 6 billion years could not be established for these galaxies.

Oke, J. B.↗