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811.
Accelerometer measurements made by Spirit and Opportunity during their entries through the martian atmosphere are reported. Vertical profiles of atmospheric density, pressure, and temperature with sub-km vertical resolution were obtained using these data between 10 and 100 km. Spirit's temperature profile is ∼10 K warmer than Opportunity's between 20 and 80 km. Unlike all other martian entry profiles, Spirit's temperature profile does not contain any large amplitude, long wavelength oscillations and is nearly isothermal below 30 km. Opportunity's temperature profile contains a strong inversion between 8 and 12 km. A moderate dust storm, which occurred on Mars shortly before these two atmospheric entries, may account for some of the differences between the two profiles. The poorly known angle of attack and unknown wind velocity may cause the temperature profiles to contain errors of tens of Kelvin at 10 km, but these errors would be an order of magnitude smaller above 30 km. On broad scales, the two profiles are consistent with Mars Global Surveyor Thermal Emission Spectrometer (TES) pressure/temperature profiles. Differences exist on smaller scales, particularly associated with the near-isothermal portion of Spirit's profile and the temperature inversion in Opportunity's profile. 相似文献
812.
Zsolt Kővári Katalin Oláh János Bartus Klaus G. Strassmeier Michael Weber Albert Washuettl John B. Rice Szilárd Csizmadia 《Astrophysics and Space Science》2006,304(1-4):375-377
Doppler images are presented for the RS CVn-type binary ζ And. Our upgraded Doppler imaging code TempMapε takes into account the distorted geometry of the primary giant component. On the maps several low latitude spots are restored with a temperature contrast of about 1000 K. Some weak polar features are also found. Cross-correlation of the consecutive Doppler-maps suggests solar-like differential surface rotation. 相似文献
813.
Michael Friedjung Andrej Dobrotka Alon Retter Ladislav Hric Rudolf Novák 《Astrophysics and Space Science》2006,304(1-4):317-319
Our mainly R band photometry of V1493 Aql (1999) during its outburst, indicates periodic variations with a period of 0.156 days, seen only 5 days after the maximum in V. This period can be orbital. The light curve indicates in addition, the presence of a faint eclipse like feature. We try to explain its extremely low amlitude, as being due to the eclipse of an expanded white dwarf component of the binary below an optically thick wind. We discuss what conditions would be required for such an interpretation to work. 相似文献
814.
Jonathan A. Tedds Peter W. J. L. Brand Michael G. Burton Antonio Chrysostomou Amadeu J. L. Fernandes 《Astrophysics and Space Science》1995,224(1-2):139-142
Recent near-IR imaging of the Orion molecular cloud has revealed a complex of dense bullets, visible as [FeII] emitting HH-objects at the tips of H2 wakes, ejected explosively from the cloud core. Having resolved individual bow-shock structures for the first time in this bright source, we have observed [FeII] 1.644µm velocity profiles of selected bullets and H2 1-0 S(1), 2.122µm velocity profiles for a series of positions along and across the corresponding bow-shock wakes. We present observed profiles for the bullet M42 HH1 and its associated wake and compare with theoretical bow-shock models. 相似文献
815.
Michael S. Briggs 《Astrophysics and Space Science》1995,231(1-2):3-10
In four years BATSE has observed more than 1000 gamma-ray bursts, making unprecedented measurements of their spatial and brightness distributions. These measurements and their implications for the origin of gamma-ray bursts are reviewed. 相似文献
816.
817.
818.
Neil Dello Russo Michael J. Mumma Karen Magee-Sauer Boncho P. Bonev I.S. McLean 《Icarus》2006,184(1):255-276
We obtained high-resolution (λ/Δλ∼25,000) spectra of Comet C/1999 H1 (Lee) on UT 1999 August 19.6 and 21.6 using the cross-dispersed Near InfraRed SPECtrometer (NIRSPEC) at the Keck Observatory atop Mauna Kea, HI. Here we present spectra of Comet Lee between 2.874 and 3.701 μm (3479-2702 cm−1) representing the most complete high-resolution infrared survey of a comet to date in this wavelength region. Using published line lists and laboratory spectra we have identified 444 of the 545 distinct emission features present in these spectra. We have tabulated the rest frequencies, assignments, relative intensities, and signal-to-noise ratios of all detected emissions. In addition to gaining insights into the chemistry of Comet Lee, this survey provides a valuable tool for planning future high-resolution infrared observations of comets and other astronomical targets, and for retrospective comparison to existing high-resolution infrared datasets. 相似文献
819.
Catherine Heymans Ludovic Van Waerbeke David Bacon Joel Berge Gary Bernstein Emmanuel Bertin Sarah Bridle Michael L. Brown Douglas Clowe Håkon Dahle Thomas Erben Meghan Gray Marco Hetterscheidt Henk Hoekstra Patrick Hudelot Mike Jarvis Konrad Kuijken Vera Margoniner Richard Massey Yannick Mellier Reiko Nakajima Alexandre Refregier Jason Rhodes Tim Schrabback David Wittman 《Monthly notices of the Royal Astronomical Society》2006,368(3):1323-1339
820.
In light of recent reductions in sulphur (S) and nitrogen (N) emissions mandated by Title IV of the Clean Air Act Amendments of 1990, temporal trends and trend coherence in precipitation (1984–2001 and 1992–2001) and surface water chemistry (1992–2001) were determined in two of the most acid‐sensitive regions of North America, i.e. the Catskill and Adirondack Mountains of New York. Precipitation chemistry data from six sites located near these regions showed decreasing sulphate (SO42?), nitrate (NO3?), and base cation (CB) concentrations and increasing pH during 1984–2001, but few significant trends during 1992–2001. Data from five Catskill streams and 12 Adirondack lakes showed decreasing trends in SO42? concentrations at all sites, and decreasing trends in NO3?, CB, and H+ concentrations and increasing trends in dissolved organic carbon at most sites. In contrast, acid‐neutralizing capacity (ANC) increased significantly at only about half the Adirondack lakes and in one of the Catskill streams. Flow correction prior to trend analysis did not change any trend directions and had little effect on SO42? trends, but it caused several significant non‐flow‐corrected trends in NO3? and ANC to become non‐significant, suggesting that trend results for flow‐sensitive constituents are affected by flow‐related climate variation. SO42? concentrations showed high temporal coherence in precipitation, surface waters, and in precipitation–surface water comparisons, reflecting a strong link between S emissions, precipitation SO42? concentrations, and the processes that affect S cycling within these regions. NO3? and H+ concentrations and ANC generally showed weak coherence, especially in surface waters and in precipitation–surface water comparisons, indicating that variation in local‐scale processes driven by factors such as climate are affecting trends in acid–base chemistry in these two regions. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献