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  • 1
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    Facular line profiles and facular models (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Profiles for lines near 5250 A have been calculated from facular models and compared with observed profiles. The observations are from photographic and photoelectric spectra. The atomic parameters are determined by comparison of calculated profiles with those observed for the quiet sun. The effects of finite spatial resolution and a magnetic field are required to obtain agreement with observed facular line profiles. The empirical magnetic field deduced by matching observed and calculated profiles is reasonably consistent with that in the facular models. The main purpose of this paper is to show that by including the effects of scattered photospheric light and a strong magnetic field, reasonable agreement can be achieved between observed and calculated facular line profiles. Results are also presented for the wing of the Ca II K line, showing line profiles and effective filtergram contrasts for several facular models. It is concluded that observations made with weak Fraunhofer lines are not very useful for discrimination among facular models, particularly without simultaneous magnetic-field measurements. The K line may offer a better discriminator. The facular model presently favored has a magnetic field strength of about 1500 gauss at the surface of the photosphere.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal Supplement Series; 33; Jan. 197
    Format: text
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  • 2
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    The shock tube as a device for testing transonic airfoils at high Reynolds numbers (1978)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A performance analysis of gas-driven shock tubes shows that transonic airfoil flows with chord Reynolds numbers in the range of 100 million can be generated behind the primary shock in a large shock tube. A study of flow over simple airfoils has been carried out at low and intermediate Reynolds numbers to assess the testing technique. Results obtained from schlieren photos and airfoil pressure measurements show that steady transonic flows similar to those observed for the airfoils in wind tunnels can be generated within the available testing time in a shock tube with either properly-contoured test section walls or a properly-designed slotted-wall test section. The study indicates that the shock tube is a useful facility for studying two-dimensional high Reynolds number transonic airfoil flows.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: AIAA PAPER 78-769 , Aerodynamic Testing Conference; Apr 19, 1978 - Apr 21, 1978; San Diego, CA
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  • 3
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    Use of shock tubes in high Reynolds number transonic testing (1975)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The shock tube as a device to fulfill current needs for testing of transonic airfoils at high Reynolds numbers is considered. Performance analysis of a gas-driven shock tube shows that transonic airfoil flows with chord Reynolds numbers in the range of 100 million can be produced. A study of flow development over a simple airfoil has been carried out in a shock tube at low and intermediate Reynolds numbers to assess the testing technique. Results obtained from schlieren photography and airfoil pressure measurements show that steady transonic flows similar to those produced for the same airfoil in a wind tunnel can be generated within the available testing time in a shock tube with properly contoured test section walls. The study indicates that the shock tube is a viable alternative as a facility for studying high Reynolds number transonic airfoil flows.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: Modern developments in shock tube research; Jul 14, 1975 - Jul 16, 1975; Kyoto; Japan
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  • 4
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    Linear clusters of galaxies - A999 and A1016 (1987)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: Redshifts have been measured for galaxies in two of the 'linear' clusters of the sample of Adams, Strom, and Strom (1980), including 44 redshifts in A999 and 40 in A1016. From the data, it is concluded that the galaxies in A999 are probably drawn from a spherically symmetric distribution, while those in A1016 probably are not. Both A999 and A1016 have mass-to-light ratios lower than typical of other clusters. The effect of anisotropy on the determination of cluster masses from the virial theorem is examined, and it is found that if the shortest axes of these clusters are close to the line of sight, the mass-to-light ratio may be underestimated by about 50 percent. No significant evidence is found for alignments of individual cluster members with the cluster axis in the convincing linear cluster A1016. There is similarly no evidence of segregation by luminosity morphological type in A1016.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 94; 571-586
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  • 5
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    Linear clusters of galaxies - A194 (1988)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: New measurements for 160 redshifts and previous measurements for 108 other redshifts are presented for galaxies within 5 deg of A194. The galaxy distribution in A194 is shown to be inconsistent with a spherically symmetric King model. A mass-to-light ratio is derived using the virial theorem which is lower than the mean for the groups in the CfA redshift survey (Huchra and Geller, 1982; Geller, 1984). A nonparametric test for galaxy-cluster alignment and a Chi-squared test are used to search for alignment of galaxy major axes with the axis of A194. Evidence for neither luminosity segregation nor significant differences in the velocity or surface distributions of galaxies as a function of morphological type is found.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 95; 999-1022
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