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Wampler, E. J.

Publications and source records attributed to Wampler, E. J..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Star trapping and metallicity enrichment in quasars and active galactic nuclei

Recent observational evidence suggests that the metallicity in quasars within a wide range of redshifts, in particular in gas flowing out of the nuclear regions, may be approximately redshift-independent and comparable with or larger than solar. It is plausible that the nuclear metallicity can be internally generated and maintained at approximately time-stationary values in quasars. We identify and estimate efficiency of a mechanism for rapid metallicity enrichment of quasar nuclear gas (in general, in active galactic nuclei) based on star-gas interactions and equivalent to an unusual mode of massive star formation. The mechanism involves capture of low-mass stars from the host galaxy's nucleus by the assemblages of clouds or by accretion disks orbiting the central massive objects (e.g., black holes). Trapping of stars within gaseous disks/clouds occurs through resonant density and bending wave excitation, as well as by hydrodynamical drag. The time scale for trapping stars with total mass equal to that of disk fragment/cloud is of order Hubble time and is remarkably model-independent. Our results show that the described mechanism can produce features suggested by observations, for example, the (super) solar gas metallicity in the nucleus. Thus the observed metallicities in high-redshift quasars do not necessarily imply that global star formation and efficient chemical changes have occurred in their host galaxies at very early cosmological epochs.

Artymowicz, Pawel↗
NASA NTRS1984

Spectrophotometry of two complete samples of flat radio spectrum quasars

Spectrophotometry of two complete samples of flat-spectrum radio quasars show that for these objects there is a strong correlation between the equivalent width of the C IV 1550 A emission line and the luminosity of the underlying continuum. Assuming Friedmann cosmologies, the scatter in this correlation is a minimum for Q(O) approximately unity. Alternatively, luminosity evolution can be invoked to give compact distributions for Q(O) approximately zero models. A sample of Seyfert galaxies observed with IUE shows that despite some dispersion the average equivalent width of C IV 1550 A in Seyfert galaxies is independent of the underlying continuum luminosity. New redshifts are given for four quasars.

Gaskell, C. M.↗
NASA NTRS1983

Luminosity calibration of low redshift quasars

European (SERC) were combined with U.S. shifts on the IUE in order to obtain the long integration times required to record spectra of faint quasars. LWR spectra of the nearby giant radio galaxy Centarus A(NGC 5548) was attempted in an effort to determine the chemical composition and stellar populations in this unusual galaxy. The IUE results from the low redshift quasar study, combined with the data from an extensive ground based survey, are described.

Wampler, E. J.↗
NASA NTRS1983

Spectrophotometry of 2 complete samples of flat radio spectrum quasars

Spectrophotometry of two complete samples of flat-spectrum radio quasars show that for these objects there is a strong correlation between the equivalent width of the CIV wavelength 1550 emission line and the luminosity of the underlying continuum. Assuming Friedmann cosmologies, the scatter in this correlation is a minimum for q (sub o) is approximately 1. Alternatively, luminosity evolution can be invoked to give compact distributions for q (sub o) is approximately 0 models. A sample of Seyfert galaxies observed with IUE shows that despite some dispersion the average equivalent width of CIV wavelength 1550 in Seyfert galaxies is independent of the underlying continuum luminosity. New redshifts for 4 quasars are given.

Wampler, E. J.↗
NASA NTRS1981

Abundances of refractory elements in quasars

A comparison of previous and new observations of iron, silicon, aluminum, magnesium and carbon lines in quasars with theoretical models shows that the gas-phase abundances of these refractory elements cannot be much less than solar, and that they do not show the order-of-magnitude depletions that are found in planetary nebulae and the interstellar medium. In light of this lack of refractory element depletions, it is suggested that the broad emission-line clouds must be devoid of dust.

Gaskell, C. M.↗
NASA NTRS1981

Spectroscopy of neutral-colored QSO candidates

Spectroscopic observations of 21 QSO candidates are discussed; the candidates were taken mainly from sets of objects described as neutral colored that have been listed as possible identifications of radio sources. Candidate identifications are accepted for study without color discrimination (that is, neutral-colored and even reddish objects are examined) in the hope of removing possible bias against finding QSOs with z greater than approximately 3.5. The largest redshift among the objects described here, however, is z = 2.43. The observations therefore support the tentative conclusion that the decline in numbers of objects with z greater than approximately 3 among these samples is real.

Baldwin, J. A.↗
NASA NTRS1980

The nebulosity associated with 3C 120

Spectrophotometric observations have been made of the nebulosity surrounding the Seyfert (or N) galaxy 3C 120, as well as of the nucleus. Observations of the nebulosity reveal an extensive network of H II regions characterized by a high ionization level, which, it is argued, is due to photoionizations by the nucleus. The O/H and N/O abundance ratios in this gas, at least as far out as 8 kpc from the nucleus, must be within a factor of 20 of the solar values. The velocity field of this gas is very chaotic, but the systematic gas velocities, relative to the nucleus, are mostly positive to one side of an axis passing through the nucleus at P.A. 72 deg and mostly negative on the other side. The position angle of this axis is consistent with the direction (P.A. 65 deg) along which the compact radio source in the nucleus is expanding, but it is about 45 deg away from the major or minor axes of the fainter elliptical structure visible on previously published broad-band direct plates.

Baldwin, J. A.↗
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

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

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 NTRS1973

A double quasistellar object

It is reported that 1548+115a is also a QSO. Spectral information is provided for 1548+115b and 1548+115a, giving attention to the very different redshifts of the objects. The observations reported are believed to add support to noncosmological theories of redshifts. Such theories will receive additional support if an interaction between the two components of a close pair can be shown.

Wampler, E. J.↗
NASA NTRS1973

Discrepant redshifts of QSOs in clusters of galaxies and a close QSO pair

The question is investigated whether QSO redshifts are cosmological in origin, taking into account the possibility that QSOs may be more local objects. A search is made for situations in which more than one blue stellar object (BSO) lay close to a radio position selected from the 4C catalog. It is found that in all four examples studied the radio emission arises in the QSO and not the galaxies or cluster of galaxies.

Hazard, C.↗
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.↗
NASA NTRS1973

Shakhbazian I - A distant cluster of compact galaxies.

Shakhbazian (1957) reported a cluster of red objects which he interpreted to be a cluster of stars in Ursa Major at a distance of 130 kpc. Spectra obtained with an image-tube scanner for 5 members of this cluster show that they are all galaxies with a redshift corresponding to a radial velocity 29.700 km/sec. The remaining 12 members of the group appear to be diffuse, and are probably also galaxies.

Robinson, L. B.↗
NASA NTRS1973

Spectrophotometry of Ton 524a, b.

Spectra of Ton 524a, b show that these two compact emission-line galaxies have nearly identical redshifts. This is the first pair of Seyfert-like galaxies that appear to form a physical pair.

Robinson, L. B.↗