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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 238 (1972), S. 263-263 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Markarian 231 is such a Seyfert galaxy with a very luminous nucleus. Arakelian et al.6 find an emission redshift of z = 0.041. Using a Hubble constant of 50 km s?1 Mpc-?1 and the photographic magnitude 14.1 given by Zwicky and Herzog7, we find an intrinsic photographic magnitude Mp= ?22.9. (The ...
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2015-11-13
    Description: The elemental abundances of symbiotic giants are essential to address the role of chemical composition in the evolution of symbiotic binaries, to map their parent population, and to trace their mass transfer history. However, the number of symbiotic giants with fairly well determined photospheric composition is still insufficient for statistical analyses. This is the third in a series of papers on the chemical composition of symbiotic giants determined from high-resolution ( R  ~ 50 000), near-infrared spectra. Here we present results for 24 S-type systems. Spectrum synthesis methods employing standard local thermal equilibrium analysis and atmosphere models were used to obtain photospheric abundances of CNO and elements around the iron peak (Fe, Ti, Ni, and Sc). Our analysis reveals metallicities distributed in a wide range from slightly supersolar ([Fe/H] ~ +0.35 dex) to significantly subsolar ([Fe/H] ~ –0.8 dex) but principally with near-solar and slightly subsolar metallicity ([Fe/H] ~ –0.4 to –0.3 dex). The enrichment in 14 N isotope, found in all these objects, indicates that the giants have experienced the first dredge-up. This was confirmed in a number of objects by the low 12 C/ 13 C ratio (5–23). We found that the relative abundance of [Ti/Fe] is generally large in red symbiotic systems.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 4
    Publication Date: 2011-08-19
    Description: Continuum emission has been detected during 3.44-3.64 micron spectral region observations of Comets P/Brorsen-Metcalf, Okazaki-Levy-Rudenko, and Levy. The spatial brightness profile of the 3.52-micron emission feature was measured and found to be consistent with uniform outflow from a central, unresolved source; the molecule generating the emission is either directly sublimated from the cometary surface or is a short-lived parent specie's dissociation product. The modeled IR spectrum of CH3OH implies the consistency of the observed spectra with a methanol origin for the 3.52 emission.
    Keywords: ASTROPHYSICS
    Type: Icarus (ISSN 0019-1035); 93; 122-134
    Format: text
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  • 5
    Publication Date: 2011-08-19
    Description: Observations of the potential optical counterparts of the unusual source IRAS 18333-2357 are reported. There are three distinct optical objects located within roughly 2 arcsec of the IR source: a red star, a very blue star, and an extended emission line nebulosity. IRAS 18333-2357 indeed appears to be physically associated with the Galactic globular cluster M22, and while it probably should be considered a PN, its very small nebular mass and extreme abundance anomalies are very unusual among known PNe. IRAS 18333-2357 does not appear to be at an early stage of PN evolution, but instead may be in a late stage. The lack of an associated radio or H-alpha source is the result of abundance anomalies in the source.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 338; 862-874
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  • 6
    Publication Date: 2006-02-14
    Description: The initial testing performed on the Hughes Metal Oxide Semiconductor Direct Readout (MOS DRO) with a Si:In extrinsic infrared array is described. The testing to date was of a screening nature and the results are primarily qualitative rather than quantitative. At a later date the performance optimization phase will be initiated. An encouraging result is that this response is strongly dependent on the detector temperature, to the extent that thermal transients introduced during the chip readout will affect the performance. A responsivity of 1 A/W at 2.2 microns with a bias of 15 volts, which is well below what is optimum bias, was obtained.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Ames Research Center Proceedings of the Second Infrared Detector Technology Workshop; 12 p
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  • 7
    Publication Date: 2011-08-17
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 227
    Format: text
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  • 8
    Publication Date: 2019-07-12
    Description: The inefficiency of the stellar formation process leads rather generally to high residual dust densities, and so to the existence of infrared reflection nebulosity (IRN), in regions of star formation. Polarization images of several star-forming regions with mass outflows (GSS 30, S255, GL 5180, GL 2591, GGD 27, and NGC 7538) presented here: (1) establish the universality of bipolarity and of shell or cavity structure in the IRN consistent with that of CO outflow; (2) identify the source of the mass outflow in each case; (3) show that the opening angle near this central source is large; and (4) demonstrate several instances of multiple shells, probably arising from episodic mass loss. Astrometry of 2.2-micron sources with arcsecond accuracy identifies the illuminating source of each IRN uniquely with a compact H II region or a bright IR source. The polarization images provide strong evidence for large-scale dust toroids around each of these sources. The density and mass of these disks are estimated from the extinction through the disk.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 378; 611-627
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  • 9
    Publication Date: 2019-07-12
    Description: A K-band IR image of the z = 1.13 radio galaxy 3C 368, one of the brightest examples of the recently discovered phenomenon of alignment between the optical and radio axes of powerful distant radio galaxies, is presented. The observations show that the IR morphology is also elongated and aligned along the optical and radio axes, but is not coincident with the radio emission. Various mechanisms for producing the IR and optical flux and the resultant constraints on the origin of the alignment effect in high-redshift radio galaxies are discussed. The most likely explanation is that the emission is produced mainly by young stars formed by interaction of the radio source with the ISM. The IR flux is then interpreted as dominated by a population of red supergiants. Independent of the origin of the emission, the observed alignment implies that powerful radio galaxies at high redshifts are distant from giant ellipticals, even in the IR. Hence, attempts to derive a cosmological 'standard candle' using studies which combine these two types of galaxies are likely to be invalid.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 329; L75-L79
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  • 10
    Publication Date: 2019-07-12
    Description: Published observational data (including IRAS observations) for a flux-limited sample of 215 Galactic carbon stars (CSs) selected from the 2-micron sky survey of Neugebauer and Leighton (1969) are compiled in extensive tables and graphs and analyzed statistically. The sample is found to penetrate a volume of radius 1.5 kpc, and the local CS space density and surface density are calculated as log rho0 (per cu kpc) = 2.0 + or - 0.4 and log N (per sq kpc) = 1.6 + or - 0.2, respectively. The total Galactic mass-return rate from these CSs is estimated as 0.013 solar mass/yr, implying a time scale of 0.1-1 Myr for the CS evolutionary phase and a mass of 1.2-1.6 solar mass for the (probably F-type) main-seqence progenitors of CSs.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 65; 385-404
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