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      Volume 33, Issue 2

      June 2012,   pages  201-278

    • Effect of Inhomogeneity of the Universe on a Gravitationally Bound Local System: A No-Go Result for Explaining the Secular Increase in the Astronomical Unit

      Hideyoshi Arakida

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      We will investigate the influence of the inhomogeneity of the Universe, especially that of the Lemaître–Tolman–Bondi (LTB) model, on a gravitationally bound local system such as the solar system.We concentrate on the dynamical perturbation to the planetary motion and derive the leading order effect generated from the LTB model. It will be shown that there appear not only a well-known cosmological effect arisen from the homogeneous and isotropic model, such as the Robertson–Walker (RW) model, but also the additional terms due to the radial inhomogeneity of the LTB model. We will also apply the obtained results to the problem of secular increase in the astronomical unit, reported by Krasinsky and Brumberg (2004), and imply that the inhomogeneity of the Universe cannot have a significant effect for explaining the observed dAU/d𝑡 = 15 ± 4 [m/century].

    • Star Formation Rate Indicators in Wide-Field Infrared Survey Preliminary Release

      Fei Shi Xu Kong James Wicker Yang Chen Zi-Qiang Gong Dong-Xin Fan

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      With the goal of investigating the degree at which the MIR luminosity in the Wide-field Infrared Survey Explorer (WISE) traces the SFR, we analyse 3.4, 4.6, 12 and 22 𝜇m data in a sample of ∼ 140,000 star-forming galaxies or star-forming regions covering a wide range in metallicity 7.66 < 12 + \log (O/H) < 9.46, with redshift 𝑧 < 0.4. These star-forming galaxies or star-forming regions are selected by matching the WISE Preliminary Release Catalog with the star-forming galaxy Catalog in SDSS DR8 provided by JHU/MPA. We study the relationship between the luminosity at 3.4, 4.6, 12 and 22 𝜇m from WISE and H𝛼 luminosity in SDSS DR8. From these comparisons, we derive reference SFR indicators for use in our analysis. Linear correlations between SFR and the 3.4, 4.6, 12 and 22 𝜇m luminosity are found, and calibrations of SFRs based on L(3.4), L(4.6), L(12) and L(22) are proposed. The calibrations hold for galaxies with verified spectral observations. The dispersion in the relation between 3.4, 4.6, 12 and 22 𝜇m luminosity and SFR relates to the galaxy’s properties, such as 4000 Å break and galaxy color.

    • The Hemispheric Asymmetry of Polar Faculae

      L. H. Deng Z. Q. Qu X. L. Yan T. Liu K. R. Wang

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      In this paper, the north–south (N–S) asymmetry of the polar faculae at relatively low (RLLs), relatively high (RHLs) as well as total latitudes (TLs) respectively, are investigated. It is found that

      1. the polar faculae behave in a different asymmetrical way at different latitudinal bands;

      2. the asymmetry of solar activity may be a function of latitudes, which is present not only in the low-latitude solar activity but also in the high-latitude solar activity;

      3. the N–S asymmetry of the polar faculae at TLs depends on that at RHLs, and the asymmetry of the polar faculae at RLLs only plays a modulatory role.

    • Photoelectric Radial Velocities, Paper XIX Additional Spectroscopic Binaries among the Redman K Stars

      R. F. Griffin

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      The `Redman K stars’ project, described more particularly in the paper immediately following this one, involved the repeated measurement on a quasi-annual basis of the radial velocities of a group of 86 seventh-magnitude late-type stars over an interval of 45 years. Certain of the stars proved to vary in velocity and were then transferred to a different observing programme, in which they were measured more frequently with a view to determining their orbits. Orbits have already been published for 18 of the stars. Presented here (and summarized in Table 9) are the results on six more; all are single-lined. One of them (HD 191046, a star which has a literature coverage about ten times as rich as that of any of the others, probably on account of its high space velocity which includes a 𝛾-velocity of nearly -100 km s-1) has a good orbit with a period of about 8000 days (22 years). Five others (HD 3345, 15728, 20509, 188058 and 191084) have orbits that are perfectly secure in principle, but their periods range between 40 and perhaps 70 years, and (particularly in some cases) their radial velocities have not been observed well enough for long enough to establish either the periods or the orbits very accurately. One star, HD 9354, has exhibited a monotonic variation of velocity throughout the duration of the observing programme; it is possible to draw a Keplerian velocity curve that does justice to the measurements, but it cannot be expected to have much predictive power.

    • Photoelectric Radial Velocities, Paper XX 45 Years’ Monitoring of the Radial Velocities of the Redman K Stars

      R. F. Griffin A. Stroe

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      The ‘Redman K stars’ are a group of 80-odd seventh-magnitude late-type stars, nearly all giants, distributed along the Galactic equator between approximate longitudes 50° and 150° (roughly Sagitta to Cassiopeia). Their radial velocities have been measured systematically once per season in 30 of the 45 seasons from 1966 to 2010/11. At least 26 of them (30%) have proved to vary in velocity. Orbits have been derived for all but one of the 26, many of them having longer periods than have normally been associated with spectroscopic binaries; several are comparable with, or longer than, the present duration of the observing campaign. Also reported here are radial-velocity measurements made casually of stars seen in the fields of some of the Redman stars. Two of the companions have proved to vary in velocity on long time-scales, and (somewhat preliminary) orbits are given for them.

  • Journal of Astrophysics and Astronomy | News

    • Continuous Article Publication

      Posted on January 27, 2016

      Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately. All these have helped shorten the publication time and have improved the visibility of the articles.

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