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  (10)
  • 1980-1984  (10)
  • 1960-1964
  • 1945-1949
Collection
Keywords
Years
Year
  • 1
    facet.materialart.
    Unknown
    On C4H versus vibrationally excited CO in IRC + 10216 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The identification of the 114,221-MHz line in the spectrum of the evolved carbon star IRC +10216 with a blend of the rotational transition of C4H and the first rotational transition of vibrationally excited CO is investigated. A spectrum of the source was obtained using an 11-m telescope in the range covering the N = 12 to 11 and 11 to 10 spin-doublet rotational transitions of C4H. Two peaks of equal intensity and width are found in each band, suggesting a spin rotation constant of 1.06 for the 12 to 11 doublet and 1.09 for the 11 to 10 doublet, and excluding the possibility that vibrationally excited CO made any contribution to the 12 to 11 doublet. An additional survey of the regions from 103.8 to 107.5 and 113.3 to 117.0 GHz has revealed no new lines stronger than 0.1 K in the spectrum of IRC +10216.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 235
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    Model for the circumstellar gas around alpha Orionis (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Models are presented to explain the physical conditions in the circumstellar envelope surrounding the red supergiant Alpha Orionis. The models of the CO density and neutral atomic potassium density are calculated for the outer shell to reproduce simultaneously both the radio detection of CO and optical measurements of the amount of scattering by neutral potassium around Alpha Ori. CO and potassium loss rates of 7 x 10 to the 39th/sec and 8 x 10 to the 37th/sec are obtained, which imply a potassium to carbon ratio greater than that of the sun by about a factor of 25. The low carbon abundance may be attributed to extensive CNO processing, and, together with the potassium abundance, indicates a total mass loss rate of 0.000015 solar masses/year. The mass loss, mass and abundance properties of Alpha Ori suggest it to be the progenitor of a Type II supernova such as Cas A.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 251
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    Molecular self-shielding in the outflows from late-type stars (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: It is proposed that molecules, especially CO and H2, in the circumstellar outflows from late-type stars can be self-shielded from ambient interstellar UV radiation. The theory of self-shielding in spherical, expanding envelopes is developed for the case in which the photodestruction is dominated by absorption in the Doppler cores of the relevant UV lines, and it is shown that this theory can account for the observations of IRC plus 10216. Also considered is the case in which photodestruction takes place in the damping wings of the UV lines as is appropriate for H2. It is found that most of the hydrogen remains molecular, although the amount of atomic hydrogen is not completely negligible.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 264
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    The abundance and excitation of the carbon chains in interstellar molecular clouds (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Emission lines from the carbon chains HC3N, HC5N, HC7N and HC9N were observed at 3 mm, 7 mm, and 1.4 cm in a number of dark clouds, Orion A and IRC(plus)10216. Non-LTE models were constructed to describe excitation and column densities. Component models for the Taurus dark cloud TMC-1 suggested that relative molecular abundances do not vary substantially along the cloud ridge, whereas the H2 density does by a factor of three. Data available for other dark clouds showed that the decrease in abundance with length from one carbon chain to the next is nearly constant, being close to 2.3. The decline in carbon chain abundance with length is steeper in Orion KL than in dark clouds by a factor of approximately four. Abundance ratios derived for the carbon star IRC(plus)10216 are uncertain, due to difficulties in modeling excitation rates in this environment.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 99; 2, Ju; June 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    Hydrogen sulfide in a circumstellar envelope (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A search for hydrogen sulfide in the cool circumstellar envelopes of 25 stars was made using the 1(10)-1(01) rotational line at 1.8 mm. It was detected in the bipolar nebula/OH maser OH231.8+4.2, an object having a high rate of mass loss. An approximate analysis indicates that 1/60 of the sulfur in this outflowing envelope is in the form of H2S, a fraction which may be similar to that in the atmosphere of the central star. In addition, the shape of the observed line profile is discussed in terms of a possible variation of the outflow velocity with latitude above the system's equatorial plane.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 121; 1, Ma; May 1983
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unknown
    The nature of NML Cygnus (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Since the discovery of NML Cyg by Neugebauer et al. (1965), its nature has been uncertain because its distance and luminosity are not known. NML Cyg is partially surrounded by an H II region which is heavily obscured by intervening interstellar matter. This H II region has been mapped in the continuum at 21 cm, and it seems clearly associated with the star. In the present investigation it is proposed that the H II region has been created by ionizing radiation from the Cyg OB2 association. The close agreement between the observed structure of the H II region and that predicted by the considered model provides strong evidence that NML Cyg is indeed at the distance of the association, 2 kpc. At this distance it is among the most luminous red stars shown. Because of its high luminosity, NML Cygnus is probably a massive star of perhaps 50 solar masses.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 267
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unknown
    The three-dimensional structure of a circumstellar maser (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A 900-day observation of the line profile of the unusual 1667 MHz OH maser in the bipolar nebula OH 231.8+4.2 has indicated that it varies sinusoidally by a factor of about 3, with a period of 684 + or - 40 days. This is in agreement with recent IR observations. The phase of the variations varies strongly with velocity. By interpreting phase differences in terms of the line-of-sight light travel time, the emission at each of 15 velocity intervals was assigned a relative line-of-sight distance. The overall, 70-day phase lag across the profile implies that this is one of the largest circumstellar masers, with a radius of at least 6000 AU, and that the source is expanding, since the redshifted emission has the greatest phase lag and is thus on the far side of the source. This data, together with maps previously made of OH 231.8+4.2 with the VLA at a number of velocities within the 1667 MHz line profile, reveals the three-dimensional structure of the maser. This structure agrees with the qualitative model previously suggested on the basis of VLA data alone.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 276; 646-652
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unknown
    On the abundance of carbon monoxide in galaxies - A comparison of spiral and Magellanic irregular galaxies (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: CO emission has been sought in 52 directions toward six irregular, Magellanic-type galaxies, with null results at a typical detection limit of 0.04 K for a line width of 10 km/s. The positions searched correspond to those of bright OB star clusters, H II regions, H I peaks, and dark clouds. In two cases, one-third of the optical galaxy was covered by the observations. CO has been detected at 2.6 mm toward the nucleus of the low-mass SA(s)dm galaxy NGC 7793. The results imply that the mean surface brightness of CO emission in Magellanic irregulars is less than that of the Galaxy and other spirals which have been studied. Two categories of explanations for this are discussed, including (1) those based on a lower heating rate for interstellar clouds in irregulars, and thus a lower CO temperature, and (2) those based on a lower CO abundance.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 240
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unknown
    CN and C2H in IRC +10216 (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The effects of the production of the radicals CN and C2H from the dissociation of HCN and C2H2 by ambient UV photons in the outer envelope of IRC +10216 are investigated. The spatial distribution of the radicals and their observable millimeter emission-line characteristics are calculated from the inferred abundances of the progenitor species in the envelope of IRC +10216 using photochemical and radiative transfer models. These are compared with available observations to examine whether photoproduction is a possible explanation of the observed emission from these species. The results suggest that the variable abundances induced by photodestruction of their progenitors do affect the observed emission from the radicals.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 279; 284-290
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 10
    facet.materialart.
    Unknown
    Molecular clouds in Orion and Monoceros (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A 1.2-m millimeter-wave telescope has been used to survey CO in the constellations of Orion and Monoceros. Many new molecular clouds have been found. The distribution of molecular material shows two striking characteristics: (1) Most of the molecular clouds in this region appear to be connected by continuous extensions and filaments. To judge from continuity in radial velocity, most of these connections appear to be real, and are not merely the result of projection along the line of sight; (2) There are at least two slender filamentary features longer than 10 deg in angular extent. These filaments may connect the molecular clouds lying well out of the Galactic plane to clouds lying in the plane. Their shape and orientation suggest that magnetic fields may play a role in their evolution. The observed velocity gradients may be explained by accelerated gas flow along the filament.
    Keywords: ASTROPHYSICS
    Type: Symposium on Interstellar molecules; Aug 06, 1979 - Aug 10, 1979; Mont Tremblant, Quebec; Canada
    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...