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  • 11
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    A molecular cloud in the local, hot interstellar medium (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Echelle spectra recorded at the D lines of Na I are reported for nine A or F stars. Lying at approximate distances ranging from 25 to 230 pc, the stars are projected on or near the high-latitude molecular cloud MBM 12 at l = 159 deg, b = -34 deg. Among a subgroup of five of these stars separated by no more than 1.2 deg on the sky, four which are located at distances d more than 70 pc show strong interstellar D line absorption near the radial velocity of the CO emission observed in this general direction. The fifth star, at roughly 60 pc, shows no detectable absorption. MBM 12 therefore probably lies at roughly 65 pc, within the local region filled primarily by very hot, low-density gas, a conclusion supported by the large internal velocity dispersion of the molecular cloud complex.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 306; L109-L11
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  • 12
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    Infrared cirrus and high-latitude molecular clouds (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: It is established that a close correlation exists between far-infrared cirrus emission observed with IRAS and the CO emission from high-latitude molecular clouds (HCLs). In all cases, the HLCs correspond to the central portions of 100-micron infrared cirrus features. This association firmly establishes at least some of the cirrus as features of the local interstellar medium with typical distances of 100 pc. The infrared energy distribution of the cirrus displays an excess of 12-micron and 25-micron emission over that expected from dust at equilibrium temperature, consistent with emission from very small (less than 10 A) transiently heated grains.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 306; L101-L10
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  • 13
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    A radio nebula associated with Circinus X-1 (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: An investigation of the variable source Circinus X-1 is reported that reveals that this eccentric double-star system is embedded in a nebula of steady radio emission extending over several parsecs, orders of magnitude larger than the binary stellar system responsible for the fluctuating component of emission. This is in marked constrast to most X-ray binaries, where an envelope of radio emission in conspicuously absent. There are difficulties in explaining the emission, but analogies with SS433 and the Crab nebula suggest possible models.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 324; 233-235
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  • 14
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    Brans-Dicke-type models with nonmetricity (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A scalar-tensor-nonmetric theory of gravity without matter fields is shown to be equivalent to the scalar-tensor-torsion theory proposed by German, the only difference being in the source of the Weyl vector or torsion vector (for equivalently the scalar field) which remains arbitrary in the theory. General extended conformal transformations, which leave the curvature tensor invariant, are presented and their implications for metric-affine theories and scalar-tensor theories are discussed.
    Keywords: ASTROPHYSICS
    Type: Physical Review D - Particles and Fields, 3rd Series (ISSN 0556-2821); 33; 3590-359
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  • 15
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    Time dependent chemistry in dense molecular clouds. III - Infrared band cross sections of molecules in the solid state at 10 K (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Thin film transmission infrared spectra and a list of integrated absorbance values (band strengths) of bands in the 2.5 to 20 micron range of various molecular solids deposited on a CsI window cooled to 10 K are presented. These solids include molecules known or suspected to be present on interstellar grains such as H2O, CO, NH3 and CH4 and mixtures of these molecules as well as various hydrocarbons. The method is described by which the absorbance values derived can be used to estimate column densities of species adsorbed on interstellar grains and other solids associated with celestial IR sources.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics Supplement Series (ISSN 0365-0138); 64; 3, Ju
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  • 16
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    SiO and H2O maser emission in OH/IR objects and late-type variable stars (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A four-year search for 86-GHz SiO and H2O maser emission towards about 20 unidentified OH/IR objects and about 35 optically identified variable stars has yielded information on the temporal variations of many of these sources. The SiO maser emission is noted to behave differently in OH/IR objects as compared with Mira variables. An attempt is made to explain the appearance of strong masers in both vibrational states solely at the 43 GHz transition, under the assumption that an intrinsically weak pump mechanism generates weak (v=1, J=2-1) emission.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 160; 2, Ma
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  • 17
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    Photometric light curves for seven rapidly-rotating K dwarfs in the Pleiades and Alpha Persei clusters (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Light curves and period estimates were obtained for several Pleiades and Alpha Persei cluster K dwarfs which were identified as rapid rotators in earlier spectroscopic studies. A few of the stars have previously-published light curves, making it possible to study the long-term variability of the light-curve shapes. The general cause of the photometric variability observed for these stars is an asymmetric distribution of photospheric inhomogeneities (starspots). The presence of these inhomogeneities combined with the rotation of the star lead to the light curves observed. The photometric periods derived are thus identified with the rotation period of the star, making it possible to estimate equatorial rotational velocities for these K dwarfs. These data are of particular importance because the clusters are sufficiently young that stars of this mass should have just arrived on the main sequence. These data could be used to estimate the temperatures and sizes of the spot groups necessary to produce the observed light curves for these stars.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 99; 471-481
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  • 18
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    Are the virial masses of clusters smaller than we think? (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The constraints that the available X-ray spectral and imaging data place on the mass distribution and mass to light ratio of rich clusters are considered. It was found for the best determined cases that the mass to light ratio is less than 125 h sub 50 at radii exceeding 1 h sub 50 Mpc. The mass to light ratio is approximately constant at radii exceeding 1 h sub 50 Mpc but may rise to values of roughly 200 h sub 50 in the central regions. The fraction of the total mass that is in baryons, primarily the hot X-ray emitting gas, is roughly 30 percent thus setting the mass to light ratio of the dark material to roughly 70. The model that fits the X-ray data for Coma is in good agreement with the observed optical velocity dispersion vs. radius data.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 317; 593-600
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  • 19
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    A multi-wavelength study of the long-period AM Her system E2003+225. I - The soft X-ray light curve and overall energy spectrum (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: X-ray, UV and optical data are presented of the longest period AM Her object, E2003+225, from October 12, 1983, together with a new linear polarization ephemeris. The optical and X-ray data were obtained simultaneously and the UV observations were carried out on the same day. A 6-hr observation with the Exosat 500 line/mm objective grating restricts soft X-ray blackbody temperatures to the range 18-29 eV. The blackbody luminosity exceeds the hard X-ray luminosity by at least a factor of 4.5, but is of the same order as the optical/UV component. Soft (0.1-0.25 keV) and hard X-ray (1-6 keV) light curves covering almost two orbital periods are presented and discussed.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 221; 823-838
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  • 20
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    Configurations of corotating shocks in the outer heliosphere (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Configurations of corotating shocks in the outer heliosphere are computed on the assumption that the shocks move at constant speeds between collisions. The basic physical process is the interaction of a forward shock with a reverse shock. The points at which this interaction takes place are determined algebraically in terms of the initial shock positions and speeds. Between the points at which the shocks interact, the shocks have the form of Archimedian spirals. Shock configurations are determined for the case of two corotating shock pairs originating at 2.5 AU and for a single shock pair at 2.5 AU. In both cases the heliosphere is divided into several distinct regions distinguished by the number of times the particles have passed through a shock. Since the shock strengths decrease when a forward shock interacts with a reverse shock, corotating shocks are expected to be weaker at larger distances from the sun.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 91; 8975-898
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