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  • Other Sources  (9)
  • ASTROPHYSICS  (9)
  • 1990-1994  (9)
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  • Other Sources  (9)
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  • 1
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    Detection of a z=0.0515, 0.0522 absorption system in the QSO S4 0248+430 due to an intervening galaxy (1990)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: In some of the few cases where the line of sight to a Quasi-Stellar Object (QSO) passes near a galaxy, the galaxy redshift is almost identical to an absorption redshift in the spectrum of the QSO. Although these relatively low redshift QSO-galaxy pairs may not be typical of the majority of the narrow heavy-element QSO absorption systems, they provide a direct measure of column densities in the outer parts of galaxies and some limits on the relative abundances of the gas. Observations are presented here of the QSO S4 0248+430 and a nearby anonymous galaxy (Kuhr 1977). The 14 second separation of the line of sight to the QSO (z sub e = 1.316) and the z=0.052 spiral galaxy, (a projected separation of 20 kpc ((h sub o = 50, q sub o = 0)), makes this a particularly suitable pair for probing the extent and content of gas in the galaxy. Low resolution (6A full width half maximum), long slit charge coupled device (CCD) spectra show strong CA II H and K lines in absorption at the redshift of the galaxy (Junkkarinen 1987). Higher resolution spectra showing both Ca II H and K and Na I D1 and D2 in absorption and direct images are reported here.
    Keywords: ASTROPHYSICS
    Type: NASA, Ames Research Center, The Interstellar Medium in External Galaxies: Summaries of Contributed Papers; p 362-364
    Format: application/pdf
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  • 2
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    Conditions in the z = 0.692 absorber toward 3CR 286 (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: We present Hubble Space Telescope/Faint Object Spectrograph (HST/FOS) ultraviolet and ground-based optical spectra of the z = 0.692 21 cm absorption system in the quasi-stellar object (QSO) 3CR 286. The strength of the damped Lyman-alpha absorption implies an H I column density, N(H I) approximately 2 x 10(exp 21)/sq cm. We derive a high spin temperature for the H I gas, T(sub s) greater than or approximately equal to 10(exp 3) K, as has been found for other high-redshift 21 cm absorbing systems; at least 80% of the H I is hotter than 1200 K. Curve-of-growth analysis yields Mg(+) and Fe(+) abundances which are approximately 1-2 dex below solar values; the Ca(+) abundance is even lower implying some depletion onto dust grains. The H2 fraction is not high. We speculate that the high inferred T(sub s) for the gas may reflect continuing active star formation at the 5-8 Gyr look-back time to the absorbing galaxy.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 421; 2; p. 453-457
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  • 3
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    Narrow-line region kinematics in Seyfert nuclei (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: We present results of a study of narrow-line region (NLR) kinematics in Seyfert nuclei. We draw five important conclusions from this work. The scenario in agreement with the greatest number of observational considerations consists of clouds which are accelerated outward with v varies as r(exp 1/2) (i.e., constant force) and n(sub e) varies as 1/r(exp 2)). The clouds start out at the inner NLR radius with n(sub e) approximately = 10(exp 6)/cu cm and with a very large column density (10(exp 23) - 10(exp 24)/sq cm). These clouds are uniformly accelerated from a few tens of km/s to less than or approximately equal to 1000 km/s. When the clouds reach the outer NLR radius, they have n(sub e) approximately = 10(exp 2)/cu cm and a column density of 10(exp 21) - 10(exp 22)/sq cm. The clouds maintain an ionization parameter of about 0.3 throughout the NLR.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 433; 2; p. 602-624
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  • 4
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    Lick slit spectra of thirty-eight objective prism quasar candidates and low metallicity halo stars (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: Lick Observatory slit spectra of 38 objects which were claimed to have pronounced UV excess and emission lines are presented. Eleven QSOs, four galaxies at z of about 0.1, 22 stars, and one unidentified object with a low S/N spectrum were found. Of 11 objects which Zhan and Chen (1987, 1989) suggested were QSO with z(prism) not greater than 2.8; eight are QSOs. Six of the QSOs show absorption systems, including Q0000+027A with a relatively strong associated C IV absorption system, and Q0008+008 with a damped Ly-alpha system with an H I column density of 10 exp 21/sq cm. The equivalent widths of the Ca II K line, the G band, and the Balmer lines in 10 stars with the best spectra are measured, and metallicities are derived. Seven of them are in the range -2.5 to -1.7, while the others are less metal-poor.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 106; 2; p. 426-443.
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  • 5
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    Lyman-alpha emission from young galaxy disks (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: An imaging survey of Ly-alpha disk absorption systems for Ly-alpha emission from the absorbing objects, which are candidate young disk galaxies, has been conducted. Limits are set to the flux in Ly-alpha from these objects of approximately 10 exp -16 ergs/sq cm s (3 sigma), which corresponds to a limit on the star formation rate of 2-7 solar masses/yr, in the absence of dust. This suggests that although disk structures form early, rapid star formation does not occur immediately, or else occurs in episodic fashion.
    Keywords: ASTROPHYSICS
    Type: Edwin Hubble Centennial Symposium; Jun 21, 1989 - Jun 23, 1989; Berkeley, CA; United States
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  • 6
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    Far-ultraviolet spectroscopy of the quasar UM 675 with the faint object spectrograph on the Hubble Space Telescope (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: To investigate the far-UV spectral properties of a QSO and to look for evidence of He I 584 A emission and absorption the Faint Object Spectrograph aboard the HST was used to observed UM 675. Light is detected down to 520 A in the object in the rest frame and limits are set to He I emission, the He I Gunn-Peterson effect at z = 2.148, and Ly-alpha absorption at z roughly 0.5.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 377; L1-L4
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  • 7
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    Optical and infrared spectrophotometry of the symbiotic system V1016 Cygni (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Spectrophotometry from 0.46 to 1.3 micron of the peculiar emission-line object V1016 Cyg is presented. The optical region displays a weak continuum underlying the rich emission-line spectrum detailed in past studies. The infrared spectrum consists of prominent emission lines of H I, He I, He II, forbidden Ni, O I, and forbidden S III overlying a strong stellar continuum. The latter displays bands at 0.94 micron and 1.13 micron characteristic of a late-type, oxygen-rich giant as well as an absorption at 1.05 micron which is due to VO. The presence of these molecular features indicates a spectral class of M6 or later for the cool secondary. The reddening of the secondary does not appear to be much different from that of the emission lines. Among the infrared emission features is the rarely seen permitted transition of neutral oxygen at 1.1287 micron. Its presence at a strength comparable to O I 8446 A, together with the absence of O I 13164 A, confirms the result of Strafella that the strong O I lines arise primarily from fluorescent excitation by Ly-beta.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 362; 346-353
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  • 8
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    Ca II and Na I absorption in the QSO S4 0248 + 430 due to an intervening galaxy (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Observations of the QSO S4 0248 + 430 and a nearby anonymous galaxy are presented. Two absorption components are found in both Ca II H and K and Na I D1 and D2 at z(a) = 0.0515, 0.0523. Column densities of log N(Ca II) = 13.29, 13.50, and log N(Na I) = 13.79, 14.18 are found for z(a) = 0.0515, 0.0523 absorption systems, respectively. The column density ratios imply considerable calcium depletion and disk-type absorbing gas. At least one and possibly both absorption components are produced by high-velocity gas. A broadband image of the field shows an asymmetrical armlike feature or possible tidal tail covering and extending past the position of the QSO. The presence of this extended feature and the apparent difference between the absorption velocities and galaxy rotation velocity suggest that the absorbing gas is not ordinary disk gas, but rather is a result of tidal disruption.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 100; 1785-179
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  • 9
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    Strong Fe II forbidden line emission from NGC 1275 (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The detection of a bright Fe II 12567-A forbidden line from the central regions of NGC 1275 is reported. The intensity of the Fe II 12567-A forbidden line relative to that of the other emission lines indicates the presence of a high abundance of iron in the gas phase, while the narrow width of the feature implies an origin outside the active nucleus. While a power-law continuum from the nucleus or from the cooling flows could excite the Fe II forbidden line emission, neither offers a likely mechanism for processing the circumnuclear dust grains in NGC 1275. This is not the case for shocks, which can also produce the low-ionization features characteristic of many of the off-nucleus emission line regions of NGC 1275.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 414; 2; p. 527-534.
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