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Burbidge, E. M.

Publications and source records attributed to Burbidge, E. M..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

A study of the absorption-line spectra of six high-redshift quasi-stellar objects

High-resolution spectrograms of six QSOs with apparent visual magnitudes of 17.0 to 18.5 and redshifts greater than 2 are studied for absorption lines. Accurate wavelengths are measured for all the absorption lines that could be detected, attempts are made to identify redshift systems, and the redshifts in each object are examined. Analysis of the absorption-line spectra shows that: (1) a large number of redshifts covering a wide range of values are present in five of the QSOs; (2) about two-thirds of the absorption lines remain unidentified, cannot be of Galactic origin, and are not associated with existing redshift systems; (3) many comparatively small absorption redshifts exist which, if they are due to intervening galaxies, must be produced by very large halos; and (4) in one QSO there is a possible redshift system containing five lines with an absorption redshift that is significantly greater than the emission redshift.

Roberts, D. H.↗
NASA NTRS1978

Absorption in the spectra of quasi-stellar objects

A review of the key discoveries concerning absorption lines in QSOs is given. A number of recent studies bearing on the nature and origin of the absorption are discussed. It is concluded that it is most likely that the bulk of the absorption is intrinsic to the QSOs.

Burbidge, E. M.↗
NASA NTRS1978

Future prospects for spectroscopic and direct work - Optical and UV

A description of the main features and proposed instrumentation of the 2.4 m Space Telescope is given. Highlights of work that can be planned on active nuclei of galaxies, QSOs, and BL Lac objects are briefly outlined, involving spectroscopy over wavelengths from 1200 A to 1 mm, direct imaging with 0.1 sec resolution, and the capability for 0.1 sec resolution along the spectrograph slit. The resolution, the much reduced sky background, and the full wavelength coverage also make possible important observations relevant to cosmology.

Burbidge, E. M.↗
NASA NTRS1978

High-velocity gas in the jet in the radio galaxy DA 240

Spectrograms of the radio galaxy identified with the source DA 240, obtained with the Kitt Peak 4-m telescope and Ritchey-Chretien spectrograph, reveal the presence of ionized gas in the jet discovered earlier. This gas has a large negative velocity displacement of 3400 km/s relative to the center of the galaxy. This is further evidence for the ejection of gas in a violent event in the nucleus of a radio galaxy. The velocity gradient in this gas is less than about 50 km/s over 14 kpc.

Burbidge, E. M.↗
NASA NTRS1977

Spectrophotometric observations of Molonglo radio source identifications

The paper presents spectrophotometric observations of 76 optical objects identified with radio sources from the MC2 and MC3 catalogs. Line intensities, equivalent widths, line widths, and optical spectral indices are presented for 44 objects confirmed as quasi-stellar objects. The statistical and physical properties of the Molonglo sample are briefly discussed.

Smith, H. E.↗
NASA NTRS1975

Empirical evidence concerning absorption lines and radiation pressure in quasi-stellar objects

Empirical spectroscopic evidence is examined for the hypothesis that radiation pressure having large gradients with wavelength plays a crucial role in maintaining patterns of redshift differences in quasars. Seventy-four absorption-line redshift systems in 32 quasars and two Seyfert galaxies are analyzed and discussed in terms of the radiation-pressure line-locking hypothesis. Redshift line ratios greater than unity are computed for each quasar and plotted as histograms. Ratios which may indicate line and edge locking are identified, including those of the C IV and Mg II doublets and those of the N III/C III, He II/O III, C II/He I, Ly-beta/H I, and H I/He I ionization edges.

Burbidge, E. M.↗
NASA NTRS1975

The nebulosity around 3C 48

Results are reported for spectrophotometric measurements of the nebulosity around the quasar 3C 48 which were made with an image-tube scanner on a 3-m telescope. The forbidden emission lines of O III (5007 and 4959 A), Ne III (3869 A), and O II (3727 A) are detected in the nebulosity north of the quasar nucleus and are found to be narrower than those present in the nucleus, but with larger equivalent widths and a slightly larger redshift. No emission lines are detected south of the nucleus, and the continuum on the north is shown to be dominated by scattered continuum radiation from the central quasar. It is suggested that the hot gas responsible for the emission lines may be either part of a shell or disk rotating about the quasar or gas ejected from it.

Wampler, E. J.↗
NASA NTRS1975

Emission-line strengths and the chemical compositions of quasi-stellar objects

Estimates of emission-line strengths in 160 QSOs are listed. They are used, together with those for 60 objects published earlier, to compile a table of rest-frame equivalent widths for a composite QSO containing 28 lines seen in objects with z from 0.06 to 3.53. Models are computed for matter partially filling a spherical volume, ionized by ultraviolet flux from a central object and optically thick with absorption from heavy elements taken into account. Constant temperature and density are taken for the He II region, where most of the important lines are emitted. Allowance is made for lower and higher temperatures in the H I and He III regions. Emergent emission-line equivalent widths are computed and compared with the observations. An abnormally low helium abundance is not needed to achieve a fit, since the only anomalously weak line is He II 4686 A whose upper level may be depopulated by stimulated emission of He II 1215 A caused by very strong L-alpha 1216 A flux.

Chan, Y.-W. T.↗
NASA NTRS1975

The nature of BL Lacertae

Spectrophotometric measurements of the nebula around BL Lacertae have been made with the Lick image-tube scanner on the 3-m telescope. No absorption features were seen, and, although the nebular spectrum is curved and steeper than that of BL Lac itself, it is not a good match to the energy distribution of a normal elliptical galaxy. Thus we do not confirm the observations by Oke and Gunn in which absorption features were seen corresponding to those in the redshifted spectrum of an elliptical galaxy. We have found no evidence that the nebula around BL Lac is a normal galaxy of stars.

Baldwin, J. A.↗
NASA NTRS1974

Statistical analysis of close pairs of QSOs

The observation of close pairs of QSOs with very different redshifts has been suggested by some as evidence in support of the noncosmological redshift hypothesis. A method is described for determining the statistical significance of such pairs. As an example, it is shown that the statistical significance of the pair 1548+115a,b is not well defined and ranges from approximately 99% confidence to about 60%. If statistical methods are to be used in such cases, they must not be argued a posteriori.

Burbidge, E. M.↗
NASA NTRS1974

Observing quasars with the LST

The quasi-stellar objects (QSOs) are still a mystery as far as their energy source and physical nature are concerned. An understanding of them might throw light on basic problems such as the behavior and interaction of matter and radiation in very strong gravitational fields, and the cosmogony of galaxies. The LST will open up exciting new ways to study QSOs, e.g., observation of the UV in the crucial region 912-1550 A in QSOs with small redshifts. Searches for and studies of QSOs fainter than 20 magnitude and the removal of observational limits that restrict complete samples may help us to understand the nature of the redshifts.

Burbidge, E. M.↗
NASA NTRS1974

Recent observations of quasi-stellar objects

Some observational results are discussed which have a bearing on the problem of QSO redshifts. A general description of QSO absorption-line spectra is presented, and the spectra of four objects are reviewed. The hypothesis is advanced that production of absorption lines at many different redshifts is due to line-locking. Two QSOs with redshifts greater than 3 are described, and questions raised by the discovery of a double QSO with two different redshifts are discussed. Efforts to determine associations between QSOs and galaxies are outlined, and some questions are posed concerning physical models, effects of strong gravitational fields, and different types of QSOs.

Burbidge, E. M.↗
NASA NTRS1973

A spectroscopic survey of 92 QSO candidates

Spectra obtained for 92 QSO candidates selected mostly on the basis of their proximity to radio-source positions are presented. Thirty-two were classified as QSOs on the basis of broad emission lines and stellar appearance, whereas redshifts were determined in 14 instances.

Baldwin, J. A.↗
NASA NTRS1973

The absorption line spectrum of 1331 + 170.

The absorption-rich optical and near-infrared spectrum of the quasi-stellar object 1331 + 170 is analyzed. The emission-line redshift is about 2.08, and at least three absorption systems are shown to be present; the absorption redshifts are 1.7755, 1.7851, and 1.9637. We conclude that the absorbing material giving rise to the three systems is intrinsic to the QSO despite the high velocity difference between emission and absorption systems and the low velocity dispersion within each absorption system.

Strittmatter, P. A.↗
NASA NTRS1973

Redshift of OQ172.

Comments on a recently discovered second QSO with a redshift greater than 3. From a study of a composite spectrum of OQ172 formed by adding data from spectra obtained on different nights two strong emission features near 5540 and 7015 A are noted and are identified with Lyman alpha 1216 A and CIV 1549 A. The measured wavelength of the emission peaks corresponds to a redshift of 3.56 for Lyman alpha and 3.53 for CIV. It is concluded that the emission line redshift of OQ172 is near 3.53.

Wampler, E. J.↗