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
    The photometric period of the recurrent Nova T Pyxidis (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: The paper presents 1713 photometric measurements of T Pyx from 1966 to 1990. The light curve of T Pyx shows roughly sinusoidal variations with a typical amplitude of 0.09 mag and a time scale of 2 hr. Discrete Fourier transforms of data from individual nights and runs reveal a highly significant periodic modulation. This modulation is proven to be coherent only on time scales shorter than from 6 d to under 1 d. The present period for the modulation is 0.07616 +/- 0.00017 d. Since other stars have variable photometric periods (possibly related to the superhump phenomenon) which are slightly different from the orbital period, an orbital period of about 0.073 d for T Pyx is suggested.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 81; 1, Ju; 321-333
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    Quasiperiodicity in cataclysmic variable stars caused by solar-type magnetic cycles (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Cyclical variations of orbital periods, quiescent magnitudes and outburst intervals in the activity of cataclysmic variable binary stars are inter-related and are ascribed to variations in radii of the secondaries, caused by solar-type (sunspot) magnetic cycles. In the nova remnant DQ Herculis the observed variations in orbital period and quiescent magnitude are consistent with this mechanism. But accretion onto the white dwarf, from an accretion disk acquired from its companion, cannot explain the observed variation of the 71-second oscillations.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 336; 129-134
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    Two young stars in L 43 (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Optical and infrared photometry has been obtained for the two stars (RNO 90 and RNO 91) illuminating reflection nebulae in the small, filamentary dust cloud L 43. Spectrograms of RNO 90 in the blue and red have also been obtained, which show that it is a T Tauri star. Both stars have strong infrared excesses, placing them firmly in the 'dust' position of the H - K, K - L diagram. The absorption reversals superimposed on the Balmer lines from H-alpha to H-delta in RNO 90 display an interesting effect. They appear to move progressively redward from a position near the blue edge of the emission line at H-alpha to a nearly central location at H-delta. L 43 is located near the star-forming end of the Sco OB2 association, but is relatively isolated from the major center of activity, the Rho Oph cloud. There are a large number of similar-looking small clouds in its vicinity, only one of which is known to have an associated T Tauri star (AS 209). The complexity of this, the nearest star-forming region in an OB association, is illustrated.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 86; June 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    Lunar highland rock types: Their implications for impact-induced fractionation (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Lunar rocks may be classified into three major groups: (1) coarse-grained igneous rocks, (2) fine-grained igneous rocks, and (3) breccias. Group 1 is interpreted as primitive lunar crustal rocks that display various degrees of crushing and/or annealing. Group 2 is interpreted as volcanic rocks. Group 3 is interpreted as resulting from impacts on the lunar surface and is subdivided on the basis of matrix textures into fragmental breccias, crystalline breccias that have been annealed, and crystalline breccias with igneous matrices. A synthesis of the data concerning lunar highlands polymict breccias compels the prediction that the breccias should have homogeneous matrices from rock to rock within regions of the highlands of limited size where impact mixing has been efficient and extensive. But the returned breccias, even from one landing site, display a wide range in composition. This incompatibility between prediction and observation is a paradox that may be resolved by a process that acts after impact mixing to cause a differentiation of the breccia compositions. Partial melting of the local average crustal composition (as modeled by the average soil composition for each site) and separation of melt and residue in ejecta and/or fall-back blankets are compatible with the reviewed data and may resolve the paradox.
    Keywords: ASTROPHYSICS
    Type: CONTRIB-230 , The Soviet-Am. Conf. on Cosmochem. of the Moon and Planets, pt. 1; p 91-126
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    Development of a spectral break in the nonthermal emission of AO 0235+164 (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Results are reported for braod-band photometry of the BL Lac object AO 0235+164 carried out over the spectral range from 0.36 to 3.5 microns in December 1975 and in October and November 1976. It is found that the continuum of this object steepened at visible wavelengths between December 1975 and October 1976, but maintained a relatively constant slope in the near-IR despite a factor-of-ten decrease in flux from the maximum level. Visible-wavelength data are cited which appear to suggest that the steepening of the visible spectrum occurred in less than 300 days, while the near-IR level may have been nearly constant. It is shown that the observed change in the spectral shape of the visible-wavelength continuum cannot be explained in terms of a 'composite' model consisting of an unchanging galaxy and a varying nonthermal source with constant spectral index. Two other general classes of models are considered: intrinsic variability and extrinsic modulation.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 214
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unknown
    Photometric and spectral properties of some T Tauri stars (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Photometric and spectroscopic data have been obtained for selected T Tauri members of the Taurus-Aurigae cloud and the Orion complex. A correlation between the intensity ratio of calcium and hydrogen emission lines and the infrared excess at 3.5 microns is found for these stars, which indicates a causal relationship between 'chromospheric activity' and emission processes in the circumstellar shells. It is argued that a comparison with properties of well-studied novae could lead to a better understanding of the physical structure of T Tauri stars.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 83; Dec. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unknown
    Synthesis of a new class of highly fluorinated aliphatic diisocyanates (1971)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Synthesis is basis for preparation of polyurethanes that are compatible with liquid oxygen. The two step process preparation from fluorocarbon diacid fluorides is explained in text.
    Keywords: MATERIALS
    Type: MFS-20883
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unknown
    Tidal disruptions by supermassive black holes - Hydrodynamic evolution of stars on a Schwarzschild background (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-08-14
    Description: We present a three-dimensional numerical study of tidal disruption of a main-sequence star by a supermassive black hole. The simulations include general relativistic effects which are important in this regime. We analyze stars in a marginally bound orbit around the black hole with pericentric separation of a few Schwarzschild radii. We show that during a close passage, as a result of relativistic effects analogous to the perihelion shift, the trajectories of the debris of the star fan out into a crescent-like shape centered on the black hole. We also discuss the increase of the central density of the star as it approaches pericentric distance, the fraction of the debris accreted by the hole, its accretion rate, the distribution of debris orbits bound to the hole, and the velocity of unbound ejected material. We compare these results with the disruption of the star by a Newtonian point mass.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 410; 2; p. L83-L86.
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unknown
    Superconducting Films On Microwave Dielectric Substrates (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Thin films of superconductor YBa(2)Cu(3)O(7-delta), formed on microwave dielectric substrates of SrTiO3, MgO, Al2O3 coated with ZrO2, and LaAlO3. Films formed by repeated sequential desposition of layers of Cu, BaF2, and Y in electro-beam evaporator, followed by annealing in oxygen. Technique employed gives layers uniformity and reproducibility required for fabrication of microwave circuits.
    Keywords: MATERIALS
    Type: LEW-15011 , NASA Tech Briefs (ISSN 0145-319X); 16; 10; P. 67
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 10
    facet.materialart.
    Unknown
    HD 38452 - J. R. Hind's star that changed colour (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: In 1851, John Russell Hind announced that a star previously observed by him to be very red had become bluish white in color. It is shown that this star, HD 38451, is a ninth magnitude shell star which presumably was ejecting a shell when Hind first observed it. From high dispersion coude spectra, low dispersion IUE spectra, and ground-based photometry, HD 38451 is found to be a normal A21V shell star. Its current values of E(B-V) of about 0.14 is probably caused by interstellar rather than circumstellar reddening. There remains a problem to reconcile the large amount of reddening present when Hind first observed the star with its evidently small diminution in visual brightness at that time.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 234; 269-279
    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...