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
Filter
  • ASTROPHYSICS  (15)
  • ASTRONOMY  (1)
Collection
Keywords
Years
  • 1
    facet.materialart.
    Unknown
    High resolution CO images of Seyfert Galaxies (1990)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The CO (J = 1-0) emission of three Seyfert galaxies, NGC 3227, NGC 7469, and NGC 5033 was imaged. The CO emission in NGC 3227 and NGC 7469 appears as compact structures centered on the active nuclei, containing substantial fractions of the single-dish flux. In NGC 3227, 10 percent of the CO flux detected by the interferometer is contained within the ionized narrow-line region. The unresolved molecular gas concentrations in the nucleus of NGC 3227 imply a CO mass of 65 million solar masses concentrated within a diameter less than 50 pc. The CO emission in NGC 5033 is not detected at this resolution, implying a CO structure size of 20 to 60 arcsec. Continuum emission at 2.7 mm is not detected in any of the three galaxies. In the center of NGC 7469, the H2 mass is comparable to the dynamical mass. Kinematic studies of the detected gas reveal a rotational motion of the gas in NGC 3227 and NGC 7469, allowing identification of the gas in NGC 7469 with a nuclear starburst. These data are consistent with the idea that interactions between galaxies cause gas to concentrate in their nuclei thereby feeding starburst and Seyfert activity.
    Keywords: ASTROPHYSICS
    Type: NASA, Ames Research Center, The Interstellar Medium in External Galaxies: Summaries of Contributed Papers; p 59-61
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    Does CO trace H2 at high galactic latitude (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A CO survey of 342 Infrared Excess Clouds (IRECs) distributed uniformly across the sky is presented. Following comparison of the integrated CO brightness with the 100 micron infrared brightness B(sub 4) obtained from the IRAS data, evidence was found for a threshold in B(sub 4) of 4-5 MJy sr(exp -1) below which CO does not form. Evidence is also presented that the threshold effect can be seen within an individual cloud, providing evidence for a phase transition between atomic and molecular gas. While the main thrust was to examine the CO content of the IRECs, it was also attempted to detect CO toward a number of UV stars so that CO brightness could be correlated with direct measurements of H2 column density and E(B-V). Of the 26 observed stars CO was detected toward 6. It is consistent with the results obtained using infrared data.
    Keywords: ASTROPHYSICS
    Type: NASA, Ames Research Center, Interstellar Dust: Contributed Papers; p 297-298
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    Molecular Clouds Within 100 Pc (1984)
    In:  CASI
    Details
    Publication Date: 2014-09-16
    Description: Observations at the 2.6 mm line of CO reveal the presence of a large number of molecular clouds at high galactic latitude. If the velocity dispersion of the clouds is a measure of their scale height, the mean distance of the ensemble detected is 100 pc. The clouds are unusual in that either they are not gravitationally bound or they are very deficient in CO relative to molecular hydrogen. These clouds represent a heretofore unrecognized component of the local interstellar medium. If they are pervasive in the Milky Way, they probably represent the small molecular cloud component of the interstellar medium.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center Local Interstellar Medium, No. 81; p 231-234
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    Giant molecular complexes and OB associations. I - The Rosette molecular complex (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: CO observations of the Rosette molecular complex associated with Mon OB2 are presented. The complex is extended along the galactic plane, has a maximum extent of about 100 pc, and shows a striking interaction with the Rosette Nebula. The molecular gas appears to be embedded in a H I cloud with a mass comparable to the molecular mass. The molecular mass is estimated to be 130,000 solar masses, and the inferred volume density is about 30 per cu cm. The complex has an overall velocity gradient of 0.20 km/s pc. At high resolution the CO appears to be very clumpy.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 241
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    Tidal stability of gas clouds in the Large Magellanic Cloud and M101 (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The tidal stability of the giant atomic gas clouds in the Large Magellanic Cloud (LMC) and in M101 is examined. The giant atomic clouds in the Large Magellanic Cloud are found to be unstable against tidal disruption by the gravity of the LMC, but the clouds in M101 are in approximate tidal balance. It is unlikely that there is sufficient unobserved molecular gas to stabilize the LMC clouds, although they may have substantial molecular cores which are tidally stable. The time scale for tidal disruption of the LMC clouds is of the order of 20-30 million years. Because most of the clouds have associated H II regions, the onset of star formation in these clouds must occur rapidly. In order to balance the loss due to tidal disruption, the clouds would have to be forming at a rate of approximately 0.09 solar masses/year per sq kpc, a value comparable to that derived for the Milky Way.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 252
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unknown
    The largest H II regions in M101 (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Coordinated millimeter, infrared, and ultraviolet observations of the five brightest H II regions in M101 are presented. A CO complex has been found to be associated with NGC 5461 which is much more massive than any Milky Way counterpart. A narrow line width has been observed which suggests that the molecular complex may consist of numerous fragments with a volume filling fraction approximately 0.01. NGC 5461 also shows a 10 micron and 20 micron excess which is similar to that of galactic H II regions. The ultraviolet observations show that the 2200 A dust feature is greatly attenuated in all of the H II regions but least of all in NGC 5461. The near-infrared flux densities and B-gamma line strengths are consistent with the hypothesis that a significant fraction of the infrared emission is free-free.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 249
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unknown
    Carbon monoxide isotope ratios in galactic centers and disks (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: For each of the six galaxies whose mm-wavelength emission of CO and C-13O were observed from both the center and the disk, and the ratio of integrated intensities P(CO)/P(C-13O) is noted to vary markedly from galactic center to galactic center, from galactic disk to galactic disk, and from point to point within a given galaxy. The observed integrated intensity ratios vary from 3 to 16, indicating that the use of a constant P(CO) to sigma(H2) conversion to derive H2 surface densities from extragalactic CO observations can produce major errors.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 292; L57-L60
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unknown
    H2O masers near OB associations (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Four new water masers have been found in the vicinity of three OB associations. One of these, in Cep OB3, is among the most intense sources yet discovered and may be related to the most recent epoch of star formation in the OB association. Two others, one in CMa OB1, the other in M16, have large radial velocities relative to their associated molecular clouds. These results are discussed in the context of star formation and CO line self-reversal within the individual sources.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 227
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unknown
    On the masses of giant molecular cloud complexes (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: A method of mass estimation for molecular clouds is presented which is based on approximate balance in the outer cloud layers between the cloud's gravitation, the galactic tide, and internal pressure. The largest observed clouds, which have greatest linear extents of 100 pc, are found to have masses of at least 200,000 solar masses. The cloud masses cannot exceed this lower limit by more than a factor of 3, or the velocity distributions of disk stars would be more relaxed than is actually observed. This implied upper limit to cloud masses combined with the galactic tide may be related to the absence of clouds at galactocentric radii less than 4 kpc. If Sagittarius B2 is bound, its mass must be more than 50 million solar masses.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 225
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 10
    facet.materialart.
    Unknown
    A millimeter-wave survey of CO emission in Seyfert galaxies (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Emission in the 115 GHz 1-0 line of CO has been detected in 18 Seyfert galaxies in a sample of 43. The CO properties of 29 Seyferts in the Revised Shapley Ames Catalog (RSA) are compared with the CO properties of normal galaxies of the same Hubble type. These RSA type 2 Seyferts have an average ratio of CO-to-blue luminosity that is about twice as large as that of the normal galaxies, but the RSA type 1 Seyferts have normal CO luminosities. The RSA type 2 Seyfert galaxies have an unusually large average ratio of CO luminosity-to-H I mass compared to normal disk galaxies. The RSA type 2 Seyferts have an average far-IR luminosity that is about four times larger than a non-Seyfert comparison sample, while the RSA type 1 Seyferts are not significantly more luminous than the non-Seyferts. The result imply that the two classes of Seyferts are intrinsically different from one another and that one class cannot evolve into another in less than a few million years.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 342; 735-758
    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...