H. H. Aumann

California Institute of Technology, Pasadena, California, United States

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Publications (36)199.26 Total impact

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    ABSTRACT: The primary aim of the IRAS mission is a survey of the entire sky at infrared wavelengths of 12, 25, 60 and 100 m. Some of the preliminary results of the IRAS mission relating to stars include: 1) a characterization of the properties of the infrared sky based on a careful survey of a 900 sq. dog. of sky; 2) the presence of young stars of roughly solar mass within the dense cores of dark clouds; 3) the existence of a cloud of large dust particles around the AO V star, Vega, implying, perhaps, the existence of a pre-planetary system around that star; and 4) the discovery of the infrared counterparts to a large number of stellar OH masers.
    No preview · Chapter · Jan 2006
  • J. W. Fowler · H. H. Aumann

    No preview · Article · Jan 1994
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    R. M. Melnyk · J. W. Fowler · W. L. Rice · H. H. Aumann

    Full-text · Article · Aug 1990
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    H. H. Aumann · John W. Fowler · Michael Melnyk
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    ABSTRACT: An algorithm is presented for the construction of images using linear array data with nonuniform scan coverage of object space and nonuniform detector responses. The algorithm achieves the maximum correlation between adjacent pixels, i.e., the smoothest image, consistent with the data and data uncertainties. For high spatial data density and signal-to-noise ratio, the achievable spatial resolution can exceed the diffraction limit of the optics. The capability of the algorithm is illustrated using 60-micron data from the region centered on the galaxy M101, obtained during the all-sky survey performed by the Infrared Astronomical Satellite. The 60-micron map produced has a resolution of about 36 arcsec and allows the identification of many H II regions by position and aperture photometry for the brighter ones. The achieved resolution is discussed in terms of the a priori estimate of the mean correlation length of the data, the directly measured FWHM in the final image, and the results of aperture photometry of M101 H II regions NGC 5447, 5455, 5461, 5462 and 5471.
    Full-text · Article · Jun 1990 · The Astronomical Journal
  • R.G. Walker · H.H. Aumann
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    ABSTRACT: IRAS observations of comets include photometry, spectroscopy, and multiple wavelength imagery. The large beam of the IRAS detector array, which was well suited to detect faint extended emissions of cometary origin, has produced a large data set that is complex to analyze. Although some preliminary results of the IRAS comet photometry have been published, definitive analysis must explicitly account for the convolution of the emission source with the non-uniform spatial response of the detector array. This paper reviews the progress made toward the production and subsequent analysis of instrument-free comet images, and presents the current state of the art IRAS images of comet Kopff.
    No preview · Article · Feb 1990 · Advances in Space Research
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    H. H. Aumann · R. G. Walker
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    ABSTRACT: High-signal-to-noise-ratio observations of the Pluto-Charon system at 25, 60, and 100 microns using IRAS are combined with visual-magnitude and mutual-eclipse constraints to evaluate thermal models of Pluto and Charon. These models are consistent with eclipse observation by Dunbar and Tedesco (1986) but not with Reinsch and Pakull (1987). The most likely model for Charon is the standard asteroid model, typical for the icy Galilean and Saturnian satellites. Charon models with a significant atmosphere can be ruled out. Based on currently available radius and albedo constraints, no significant numerical distinction is possible between Pluto models ranging from isothermal spheres with surface emissivity between 0.4 and 0.9. Concerns regarding the viability of an emissivity as low as 0.4 favor the higher-emissivity models. The globally uniform surface temperature of Pluto may thus at present be as low as 45 K, with a methane column abundance of 6.7 cm atm. The most likely models are centered on radii of 1180 and 747 km and albedos of 0.47 and 0.26 for Pluto and Charon, respectively.
    Preview · Article · Nov 1987 · The Astronomical Journal
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    Full-text · Article · May 1987
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    ABSTRACT: The authors present plots of all 5425 spectra in the IRAS catalogue of low-resolution spectra. The LRS catalogue contains the average spectra of most IRAS point sources with 12 μm flux densities above 10 Jy. More than 95 percent of the LRS sources are stars, most of them with circumstellar envelopes.
    No preview · Article · Aug 1986 · Astronomy and Astrophysics Supplement Series
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    J. F. Appleby · H. H. Aumann · D. J. Diner

    Preview · Article · May 1986
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    ABSTRACT: Three separate functions must be performed in order to reconstruct the flux of a source from the telescope data stream. The effects of the telescope transfer function must be removed from the data. The results must be transferred to relative photometric units. In the case of IRAS, this amounted to establishing the relationship between source amplitudes observed during the survey scans and outputs of flashes of the internal reference source. The relative photometry must be put on an absolute scale; i.e., the flashes of the internal reference source must be calibrated in an absolute sense. The processing by which the signal received at the ground station was converted to the effective detector current is described as well as the process by which the relative photometry was achieved.
    Preview · Article · Feb 1985
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    ABSTRACT: During the infrared astronomy satellite (IRAS) mission, a number of in-flight tests were conducted to verify or understand those aspects of the performance of the instrument which could not be estimated with sufficient accuracy before the flight. These tests are described herein. Detector/focal plane performance, spectral passband verification, optical performance, and internal reference source stability are addressed.
    No preview · Article · Feb 1985
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    ABSTRACT: The IR Astronomy Satellite (IRAS) mission has yielded an all-sky IR survey with a detailed pointing history. An analysis is being conducted which will allow an estimate to be made of the detectable population of comets and Apollo asteroids. On the basis of results obtained to date, it is expected that IRAS will detect comets having visual magnitudes lower than 17 if their motions are greater than about 1 arcmin/hour. The positional accuracy of such detections depends on the number of bands in which an object was observed, although the accuracy has so far proved unsuitable for orbit determination. There is no evidence of an undiscovered main belt asteroid population at high ecliptic latitudes.
    No preview · Article · Jun 1984 · Nature
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    ABSTRACT: For 10 months the Infrared Astronomical Satellite (IRAS) provided astronomers with what might be termed their first view of the infrared sky on a clear, dark night. Without IRAS, atmospheric absorption and the thermal emission from both the atmosphere and Earthbound telescopes make the task of the infrared astronomer comparable to what an optical astronomer would face if required to work only on cloudy afternoons. IRAS observations are serving astronomers in the same manner as the photographic plates of the Palomar Observatory Sky Survey; just as the optical survey has been used by all astronomers for over three decades, as a source of quantitative information about the sky and as a "roadmap" for future observations, the results of IRAS will be studied for years to come. IRAS has demonstrated the power of infrared astronomy from space. Already, from a brief look at a miniscule fraction of the data available, we have learned much about the solar system, about nearby stars, about the Galaxy as a whole and about distant extragalactic systems. Comets are much dustier than previously thought. Solid particles, presumably the remnants of the star-formation process, orbit around Vega and other stars and may provide the raw material for planetary systems. Emission from cool interstellar material has been traced throughout the Galaxy all the way to the galactic poles. Both the clumpiness and breadth of the distribution of this material were previously unsuspected. The far-infrared sky away from the galactic plane has been found to be dominated by spiral galaxies, some of which emit more than 50 percent and as much as 98 percent of their energy in the infrared-an exciting and surprising revelation. The IRAS mission is clearly the pathfinder for future missions that, to a large extent, will be devoted to the discoveries revealed by IRAS.
    No preview · Article · May 1984 · Science
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    ABSTRACT: A total of 86 galaxies have been detected at 60 microns in the high galactic latitude portion of the IRAS minisurvey. The surface density of detected galaxies with flux densities greater than 0.5 Jy is 0.25 sq deg. Virtually all the galaxies detected are spiral galaxies and have an infrared to blue luminosity ratio ranging from 50 to 0.5. For the infrared-selected sample, no obvious correlation exists between infrared excess and color temperature. The infrared flux from 10 to 100 microns contributes approximately 5 percent of the blue luminosity for galaxies in the magnitude range 14 less than m(pg) less than 18 mag. The fraction of interacting galaxies is between one-eighth and one-fourth of the sample.
    Full-text · Article · Apr 1984 · The Astrophysical Journal
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    ABSTRACT: A preliminary discussion of the infrared properties of a representative subsample of galaxies in the Revised Shapley-Ames Catalog (B less than about 13 mag) is presented. Of the 165 galaxies in the sample, 108 predominantly spiral galaxies, are detected in the infrared by IRAS. None of the elliptical galaxies and only about 25 percent of the lenticular galaxies scanned were detected. The range of infrared-to-blue luminosity ratios, a measure of the infrared excess of galaxies, is large, varying from roughly 0.1 to roughly 5. The data suggest that weakly infrared emitting galaxies are cool (100-60 micron color temperatures of about 25 K), while the more infrared luminous ones tend to be warmer (about 50 K). The rate of star formation in barred spiral galaxies is apparently higher than in normal spirals. About 1 solar mass/year of interstellar matter is converted into massive stars in the typical spiral galaxy.
    Full-text · Article · Apr 1984 · The Astrophysical Journal
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    ABSTRACT: Observations of comet IRAS-Araki-Alcock 1983d in the infrared region from 12 to 100 microns are reported. The dominant feature seen in the infrared is an extensive dust tail not reported in visual observations. A dust production rate of 200 kg/s is deduced. The far-infrared spectrum suggests that the radius of a mean grain decreases from 30 to 5 microns along the tail.
    No preview · Article · Apr 1984 · The Astrophysical Journal
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    ABSTRACT: Before the main Infrared Astronomical Satellite (IRAS) all-sky survey was started, a preliminary survey of 900 sq deg was carried out. Some results from this 'minisurvey' are given here. The completeness of the minisurvey at galactic latitudes from 20 to 40 deg drops sharply at flux densities below 0.4, 0.4, 0.5, and 2.5 Jy at 12, 25, 60, and 100 microns, respectively. The corresponding surface densities of point sources brighter than these flux levels are 1.1, 0.4, 0.65, and 1.25/sq deg, respectively. Outside the galactic plane, the majority of the sources at 12 and 25 microns are stars, while galaxies make up a significant proportion of 60 micron sources. The 100 micron band is dominated by emission from interstellar dust over much of the minisurvey area.
    Full-text · Article · Apr 1984 · The Astrophysical Journal
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    ABSTRACT: IRAS data reveal bright emission from interplanetary dust which dominates the celestial background at 12, 25, and 60 microns except near the galactic plane. At 100 microns, interplanetary dust emission is prominent only near the ecliptic plane; diffuse galactic emission is found over the rest of the sky. At the galactic poles, the observed brightness implies that A(v) is likely to be of order 0.1 mag. The angular variation of the zodiacal emission in the ecliptic plane and in the plane at elongation 90 deg, and an annual modulation of the ecliptic pole brightness, are generally consistent with previously determined interplanetary dust distributions.
    Full-text · Article · Apr 1984 · The Astrophysical Journal
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    ABSTRACT: Some preliminary IRAS results in the form of images at 12, 25, 60, and 100 microns of an 8 deg x 15 deg area around the galactic center are presented. These absolute intensity maps have unprecedented sensitivity combined with high angular resolution, wide field coverage, and large wavelength range. They give a broad view of the central galaxy revealing previously unseen details, especially in regions far from the central few arcmin. Well-defined infrared features in the nucleus correspond to the nuclear radio sources Sgr A, B2, C, and D. Extremely faint structures are detected, such as the cold molecular cloud associated with Sgr B2 which has never before been detected at wavelenths shorter than 40 microns.
    No preview · Article · Apr 1984 · The Astrophysical Journal
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    ABSTRACT: Extended sources of far-infrared emission superposed on the zodiacal and galactic backgrounds are found at high galactic latitudes and near the ecliptic plane. Clouds of interstellar dust at color temperatures as high as 35 K account for much of this complex structure, but the relationship to H I column density is not simple. Other features of the extended emission show the existence of warm structures within the solar system. Three bands of dust clouds at temperatures of 150-200 K appear within 10 deg on both sides of the ecliptic plane. Their ecliptic latitudes and derived distances suggest that they are associated with the main asteroid belt. A third component of the 100-micron cirrus, poorly correlated with H I, may represent cold material in the outer solar system or a new component of the interstellar medium.
    No preview · Article · Apr 1984 · The Astrophysical Journal

Publication Stats

2k Citations
199.26 Total Impact Points

Institutions

  • 1976-1990
    • California Institute of Technology
      • Jet Propulsion Laboratory
      Pasadena, California, United States
  • 1984
    • University of Leeds
      Leeds, England, United Kingdom
    • NASA
      • Goddard Space Flight Centre
      Вашингтон, West Virginia, United States
    • University of Amsterdam
      Amsterdamo, North Holland, Netherlands