view Abstract Citations (135) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The existence of Ca II absorption lines in the spectrum of the quasar 3C 232 due to the galaxy NGC 3067. Boksenberg, A. ; Sargent, W. L. W. Abstract We have discovered Ca ii H and K absorption lines in the spectrum of the quasar 3C 232 (Zem = 0.5303) at the same redshift as that of the galaxy NGC 3067, which lies 1 `.9 away on the plane of the sky. The H and K lines have a velocity of(1406 1 11) km s in excellent agreement with the 21 cm neutral hydrogen absorption line found in the system by Haschick and Burke. The 21 cm line is much narrower than are the Ca ii lines. We present arguments that the H and K lines and the 21 cm line are produced in the outer halo rather than the outer disk of NGC 3067. The implications of our discovery concerning the nature of QSO absorption lines in general are discussed. Subject headings: galaxies: redshifts - galaxies: structure - quasars Publication: The Astrophysical Journal Pub Date: February 1978 DOI: 10.1086/155880 Bibcode: 1978ApJ...220...42B Keywords: Absorption Spectra; Calcium; Galactic Structure; Milky Way Galaxy; Quasars; H Lines; Interstellar Matter; K Lines; Metal Ions; Red Shift; Astronomy; Galaxies:Quasars; Quasars:Spectra full text sources ADS | data products NED (4) SIMBAD (2)
view Abstract Citations (106) References (74) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS High-Resolution Spectra of 24 Low-Redshift QSOs: The Properties of MG II Absorption Systems Tytler, David ; Boksenberg, A. ; Sargent, Wallace L. W. ; Young, Peter ; Kunth, Daniel Abstract High-resolution spectra of 245 low-redshift QSOs are presented, and Mg II emission-line equivalent widths and velocity widths are measured and briefly discussed. Improved statistical methods are presented for the extraction of significant absorption features from spectra. These techniques provide a simple and accurate estimate of the minimum equivalent widths which could be detected in any region of a spectrum. A search for Galactic Ca II in 13 lines of sight reveals five detections. Equivalent widths are in the range 0.2-0.3 A. Only three redshifted absorption systems were found, all dominated by Mg II 2796 A, 2803 A doublets. Mg(+)/Mg(0) and Mg(+)/Fe(+) values cannot be accounted for by collisional ionization alone. Factors determining the frequency of occurrence of Mg II systems are investigated using a composite sample of 14 systems from the spectra of 90 QSOs. Ten out of the 14 systems occur in five pairs of two systems each per QSO. The probability of these pairs being chance occurrences is only 0.0007. Publication: The Astrophysical Journal Supplement Series Pub Date: August 1987 DOI: 10.1086/191213 Bibcode: 1987ApJS...64..667T Keywords: Absorption Spectra; Magnesium; Quasars; Red Shift; Spectral Resolution; Abundance; Astronomical Spectroscopy; Atomic Interactions; Cosmology; Astrophysics; ATOMIC PROCESSES; COSMOLOGY; GALAXIES: INTERGALACTIC MEDIUM; INTERSTELLAR: ABUNDANCES; LINE IDENTIFICATIONS; QUASARS full text sources ADS | data products SIMBAD (90) NED (83)
view Abstract Citations (54) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Study of the close environment of the active nucleus in NGC 1068 by decomposition of and H beta emission-line profiles. Alloin, D. ; Pelat, D. ; Boksenberg, A. ; Sargent, W. L. W. Abstract We analyze and discuss in this paper the [O III] λλ4959, 5007 and Hβ emission-line profiles observed in various positions over the central region in NGC 1068. The profiles change drastically over a spacing of 1".2. We have performed a quantitative decomposition of these profiles using Gaussian individual components and find a clear separation of the following systems: i) A narrow feature (FWHM ∼100 km s-1) seen both along position angle PA = 55° and 145°. This component follows the stellar rotation observed in PA = 55°, while it appears to have large radial motions in PA =145°. It shows up more strongly along PA = 55°, which is also the position of the major axis corresponding to the inner spiral arm structure observed in this galaxy. The value of its line intensity ratio I([O III] λλ4959 + 5007)/I(Hβ) = 8 is compatible with a classical ionization by hot stars, although not uniquely. We interpret this feature as the line emission from ionized regions in the inner disk of the galaxy. Along the minor axis, the overall emission from this component is weaker and corresponds to gas in a lower stage of ionization. ii) A narrow feature (FWHM ∼100 km s-1) detected in the NE quadrant. Dynamically this is clearly separated from the disk narrow feature along PA = 55°, while the value here found for the line intensity ratio, I([O III])/I(Hβ) = 17, implies ionization by nonstellar radiation. We attribute this feature to a nebulosity seen in projection in the NE quadrant, but most probably situated out of the plane of the disk and directly photoionized by the synchrotron emission from the active nucleus in NGC 1068. iii) A broad (FWHM = 1670 km s-1), blueshifted component (Vɛ - Vsystemic = -210 km s-1) is found in both the [O III] and the Hβ line profiles. From the present results this feature seems to be slightly extended (about 240 pc in radius) rather than being confined to the center, suggesting that the broadening is due to a widely distributed collection of cloudlets or filaments and not to an organized motion such as that of a rotating disk, which could not be so large. iv) A characteristic of the individual clouds detected in the central region of NGC 1068 is that the blueshifted ones are also the more central, as is seen in other objects. Publication: The Astrophysical Journal Pub Date: December 1983 DOI: 10.1086/161550 Bibcode: 1983ApJ...275..493A Keywords: Galactic Nuclei; H Beta Line; Oxygen Spectra; Emission Spectra; Forbidden Transitions; Galactic Radiation; Astrophysics full text sources ADS | data products SIMBAD (1) NED (1)
Repeated observations of the Seyfert 1 galaxies I Zw 1 and II Zw 136, which have very strong Fe II emission lines in the optical region, were made at low resolution with the IUE Satellite. The ultraviolet spectra are very similar: both are variable and show broad emission features of Fe II (especially the UV multiplets 1, 33, 60, 62, and 63) as well as the emission lines usually strong in Seyferts and quasars. The data strongly support the hypothesis that the optical Fe II emission lines are primarily due to collisional excitation and that resonance fluorescence makes only a minor contribution to the excitation of these lines.
view Abstract Citations (38) References (11) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Discovery of nebulosity associated with the quasar 3C 273. Wyckoff, S. ; Gehren, T. ; Morton, D. C. ; Albrecht, R. ; Wehinger, P. A. ; Boksenberg, A. Abstract The discovery of a diffuse nebulosity physically associated with the quasar 3C 273 (excluding its optical jet) is reported. The nebulosity was detected as a diffuse asymmetrical extension in the isophotes of a photographic image of the quasar obtained at the prime focus of a 3.6-m telescope which is resolved with a radial size scale of approximately 15 arcsec at a surface brightness level of 25 mag/sq arcsec. Spectra of the extended structure exhibit narrow emission lines at the redshifted positions of the forbidden O II line at 3727 A and Ne III line at 3869 A, indicating the presence of low-density hot gas at a projected distance of approximately 4.5 arcsec from the quasar. Comparison of photometric and spectroscopic data indicates the dominant emission to be continuum radiation, which may originate from an underlying galaxy associated with 3C 273. Publication: The Astrophysical Journal Pub Date: December 1980 DOI: 10.1086/183403 Bibcode: 1980ApJ...242L..59W Keywords: Nebulae; Quasars; Stellar Spectra; Stellar Spectrophotometry; Astronomical Photography; Galactic Structure; Image Resolution; Line Spectra; Red Shift; Astronomy full text sources ADS | data products SIMBAD (3)
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