ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    A ROSAT observation of NGC 5548 (1993)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: We present a detailed spectral and temporal analysis of a long ROSAT PSPC pointing centered on the bright Seyfert 1 galaxy NGC 5548. The spectrum is particularly complex, with a two-component model favored, confirming the existence of the soft excess in this source. In addition, an absorption feature arising from highly ionized oxygen in the line of sight has been detected, consistent with an origin in the 'warm absorber' which has been found to be a common feature in Seyfert galaxies observed by Ginga. The energy and depth of the feature should allow us to constrain the density and geometry of the absorbing gas, which may lie close to the central continuum source. NGC 5548 was in a low X-ray state during the observation, brightening by a factor of about 2 on a time-scale of about 2 d. Time-resolved spectral analysis shows a change in the ratio of the hard and soft fluxes, consistent with reprocessing models.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 260; 3; p. 504-512.
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    Broad Band X-Ray Telescope observations of NGC 4151 - Iron line diagnostics (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: The Fe K-alpha emission line is a potentially powerful diagnostic tool in the X-ray spectra of AGNs, however, this feature has previously been observed with relatively poor spectral resolution. The Broad Band X-Ray Telescope has provided us with the first high-quality, medium-resolution X-ray spectral data. We are able to constrain the width of the 6.4 keV Fe K-alpha line in NGC 4151 to be less than 160 eV FWHM (7,500 km/s), in contrast with former measurements of the line width. Also, we have limited information on the shape of the line profile. In addition to the strong narrow Fe K-alpha feature, we detect weaker broad residuals between 5-8 keV.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 401; 1; p. L11-L14.
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    Temperature and iron abundance variation of the gas in the Perseus cluster (1994)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: We present the first two-dimensional map of the temperature and iron abundance in the Perseus cluster. Analysis of spectra obtained using the Gas Imaging Spectrometer on ASCA shows nonaxisymmetric variations in both the temperature and iron abundance. Traveling west from the cluster center, the temperature increases to 9 keV at 20 min and then decreases rapidly to 5 keV at 40 min. There is a hot (greater than 10 keV) region to the northwest of the cluster center. The abundance is approximately constant over much of the surveyed region, but there is evidence for an increased abundance in the northwest hot area and a gradual decrease in a westerly direction.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 436; 1; p. L67-L70
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    Composition of comet Halley dust particles from Giotto observations (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Mass spectra of cometary dust particles measured by the PIA dust particle analyzer aboard the Giotto spacecraft show some unexpected and striking features. First, small particles below 10 to the -14th g are much more abundant than anticipated by models. Second, most of the particles are rich in light elements such as H, C, N, and O, suggesting the validity of models that describe the cometary dust as including organic material. Third, the light elements specifically seem to have a low ratio of mass to volume. Three examples of original mass spectra showing typical compositions are given; these have been measured, and are compared with a computer-simulated mass spectrum.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 321; 336
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    A disturbance of the ion tail of Comet Halley and the heliospheric structure as observed by Sakigake (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: In order to study the interaction between the solar wind measured by Sakigake and ion tail disturbances of comet Halley, more than 500 photographs of the comet taken on the ground during this apparition are surveyed. The focus of the present study is the December 31, 1985, event, when various types of disturbances occurred, including an outstanding disconnection event (DE)-like knot. Analysis of the Sakigake/IMF data reveals that comet Halley did not encounter the heliospheric neutral sheet on that day, demanding a new explanation for the DE-like event, different from the Niedner-Brandt model. During this event the comet encountered a high-speed solar wind stream from a coronal hole tongue of the sun. The event can be explained by a dynamic pressure model, according to which the DE-like plasmoid was caused by a sudden increase in the dynamic pressure of the solar wind. A result of the simulation work by Ogino is found to support this interpretation.
    Keywords: ASTROPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 13; 821-824
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unknown
    Structure and dynamics of the plasma tail of comet P/Halley. I - Knot event on December 31, 1985 (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: On the basis of about 500 photographs of comet Halley taken by many observers, Saito et al. (1986) classified the detected disturbances of the plasma tail as outstanding rays, streamer, helix, kink, arcade, and disconnection event (DE). In this paper, the interaction of the solar wind with the plasma tail of Comet P/Halley is examined by using results of observations by the Sakigake spacecraft of the December 31, 1985 event, which included various disturbances and one DE-like knot. On the basis of twenty photographs taken on December 31 by Japanese astronomers, the dynamic pressure model proposed by Saito et al. (1986) is examined, and the mechnism of the knot event that appeared in the plasma tail of the comet on December 31, is explained.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 187; 1-2,
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unknown
    Far-infrared observations of Circinus and NGC 4945 galaxies (1990)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Circinus and NGC 4945 are two galaxies luminous in the infrared and are characterized by compact non thermal radio nuclei, deep silicate absorption features and unusually strong water vapor maser luminosities. Moorwood and Glass (1984) have observed these galaxies extensively in the 1 to 20 micron range. In the far-infrared, observations up to 100 microns are available from the Infrared Astronomy Satellite (IRAS). In order to study the cool dust component of these galaxies, researchers observed them at 150 microns using the Tata Institute of Fundamental Research (TIFR) 100 cm balloon-borne telescope. Here, they report observations along with deconvolved maps at 50 and 100 microns obtained from the Chopped Photometric Channel (CPC) on board IRAS.
    Keywords: ASTROPHYSICS
    Type: NASA, Ames Research Center, The Interstellar Medium in External Galaxies: Summaries of Contributed Papers; p 86-88
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unknown
    Anisotropy of the neutral gas distribution of Comet Halley deduced from NGE/Vega 1 measurements (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The neutral gas density profile of comet Halley measured by the Neutral Gas Experiment on Vega 1 showed an asymmetry between the inbound and the outbound legs during the fly-by on 6 March 1986. The implications of this asymmetry are discussed, and it is shown how the asymmetry detected by NGE on Vega 1 can be traced back to regions on or near the nucleus to obtain their relative gas production activities at specific times of emission.
    Keywords: ASTROPHYSICS
    Type: ESA Proceedings of the 20th ESLAB Symposium on the Exploration of Halley's Comet. Volume 1: Plasma and Gas; p 417-421
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unknown
    The correlated X-ray and optical time variability of TT Arietis (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The results of Einstein X-ray observation and simultaneous optical observations of the cataclysmic variable TT Arietis extending over several binary orbits are reported. Evidence is found for correlations between the X-ray and optical variability of TT Ari on three distinct time scales: the 3.3 hour variability that has been associated with the orbital period of the star, the about 1000 s time scale of the irregular flickering activity, and the time scale of quasi-coherent oscillations which have periods of order 10 s. There is a modulation of the X-ray flux with a period consistent with the orbital period of approximately 200 minutes, but there is no apparent modulation of the X-ray spectrum. The optical flux is modulated with a similar period and may lag the X-ray modulation by about 0.1 in phase. The X-ray spectrum is well fitted by a thermal bremsstrahlung plus Gaunt factor model. The results suggest that the hard X-ray emission may be produced in a corona above and below the inner accretion disk.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 270; July 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 10
    facet.materialart.
    Unknown
    Quasi-simultaneous observations of BL Lac object Mrk 501 in X-ray, UV, visible, IR, and radio frequencies (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Observations in the X-ray, UV, visible, IR and radio regions of the BL Lac object Mrk 501 made over the course of two months are reported. The measurements were made with the A2 experiment on HEAO 1 (X-ray), the SWP and LWR cameras on IUE (UV), the 5-m Hale telescope (visible), the 2.5-m telescope at Mount Wilson (IR), the NRAO 92-m radio telescope at Green Bank (4750 MHz) and the 46-m radio telescope at the Algonquin Observatory (10275 and 10650 MHz). The quasi-simultaneously observed spectral slope is found to be positive and continuous from the X-ray to the UV, but to gradually flatten and possibly turn down from the mid-UV to the visible; the optical-radio emission cannot be accounted for by a single power law. The total spectrum is shown to be compatible with a synchrotron self-Compton emission mechanism, while the spectrum from the visible to the X-ray is consistent with synchrotron radiation or inverse-Compton scattering by a hot thermal electron cloud. The continuity of the spectrum from the UV to the X-ray is noted to imply a total luminosity greater than previous estimates by a factor of 3-4.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 243
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...