Sources and sinks for atmospheric H₂: A current analysis with projections for the influence of anthropogenic activity     

Joyce E. Penner  Michael B. McElroy  Steven C. Wofsy 《Planetary and Space Science》1977,25(6):521-540

Oxidation of CH₄ provides the major source for atmospheric H₂ which is removed mainly by reaction with OH. Biological activity at the Earth's surface appears to represent at most a minor sink for H₂. Anthropogenic activity is a significant source for both H₂ and CO in the present atmosphere and may be expected to exert a growing influence in the future. Models are presented which suggest a rise in the mixing ratio of H₂ from its present value of 5.6 × 10^?7 to about 1.8 × 10^?6 by the year 2100. The mixing ratio of CO should grow from 9.7 × 10^?8 to 2.3 × 10^?7 over the same time period and there should be a rise in CH₄ by about a factor of 1.5 associated with anthropogenically induced reductions in tropospheric OH.  相似文献   

Astrophysical consequences of neutron-antineutron oscillations     

V. Krishan  C. Sivaram 《Astrophysics and Space Science》1982,87(1-2):205-210

Grand unified theories predict baryon number violating interactions and one of the implications of this is the possible existence of neutron-antineutron oscillations. The neutron-antineutron oscillations have been considered in the neutron rich astrophysical sources such as solar flares, supernovae explosions, neutron stars and the nucleosynthetic phase of the early universe in order to partly account for the antiproton flux of the cosmic rays at low energies and the -ray emission, at GeV energies. Low magnetic fields and high neutron concentrations provide the right environment for the production of antineutrons and hence antiprotons and GeV rays.  相似文献   

Observation of MKN 501 at gamma-ray energies     

L. Bassani  R. C. Butler  A. J. Dean  G. Di Cocco  A. Della Ventura  F. Perotti  G. Villa 《Astrophysics and Space Science》1982,82(2):311-316

During a balloon flight in September 1979 of the MISO low-energy -ray telescope, the BL Lac-object MkN 501 was studied in the hard X-ray range above 30 keV and in the low energy -ray range up to 19 MeV. No statistically significant X- and -ray fluxes were detected. The implications of the upper limits obtained are discussed in the light of the relativistic jet theories recently proposed.  相似文献   

Massive configurations with constant densities     

M. C. Durgapal  A. K. Pande  K. Pandey 《Astrophysics and Space Science》1982,88(2):469-475

Two new classes of solutions with constant observed proper and rest mass densities are described. Unlike the well-known solution of constant coordinate mass density, these solutions pertain to realistic physical situations. For these solutions, the various relevant parameters, viz. the redshifts (dP/d)₀ and binding coefficients have been calculated.  相似文献   

Search for variability in hydrogen-poor stars     

C. Bartolini  A. Bonifazi  F. D'antona  F. Fusi Pecci  L. Oculi  A. Piccioni  R. Serra 《Astrophysics and Space Science》1982,83(1-2):287-310

The evolutionary status of hydrogen-poor stars is analyzed.Photoelectric observations of six objects are reported as a first step of a long-term project devoted to search for variability of a large sample of hydrogen-poor stars.The observed stars show phenomena of microvariability with an amplitude of the order of 0^m. 1 or less.Two extreme helium stars have been examined: a period in the range of 0^d.162-0^d.164 has been found for BD+ 10⁰2179, andP=0^d.1079962 for BD+13⁰3324.The mass-losing O subdwarf (sdO) BD+37⁰ 443 presents short-term fluctuations with a time-scale of several minutes and long-term variations on a scale of months. The standard sdO BD+75⁰325 is probably non-variable, although light variations of very small amplitude (m0.03) with a time-scale of about 1 hr might be present. The high gravity sdO BD+25⁰4655, which is very close to the white dwarf stage, also presents variability on a time-scale of about 13 minutes, and might be an analog of the recently discovered pulsating sdO, or hot white dwarf, PG 1159-035.The variability of the intermediate helium star HD 37776 is finally confirmed.  相似文献   

Unusual coronal activity following the flare of 6 November 1980     

Z. Švestka  B. R. Dennis  M. Pick  A. Raoult  C. G. Rapley  R. T. Stewart  B. E. Woodgate 《Solar physics》1982,80(1):143-159

For almost 30 hr after the major (gamma-ray) two-ribbon flare on 6 November 1980, 03:30 UT, the Hard X-Ray Imaging Spectrometer (HXIS) aboard the SMM satellite imaged in > 3.5 keV X-rays a gigantic arch extending above the active region over the limb. Like a similar configuration on 22 May 1980, this arch formed the lowest part of a stationary post-flare radio noise storm recorded at metric wavelengths at Nançay and Culgoora. 6.5 hr after the flare a coronal region below the arch started quasi-periodic pulsations in X-ray brightness, observed by several SMM instruments. These brightness variations had no response in the chromosphere (H), very little in the transition layer (O v), but they clearly correlated with similar variations in brightness at 169 MHz. There were 13 pulses of this kind, with apparent periodicity of about 20 min, until another flare occurred in the active region at 15:00 UT. All the brightenings appeared within a localized area of about 30000 km² in the northern part of the active region, but they definitely did not occur all at the same place.The top of the X-ray arch, at an altitude of 155 000 km, was continuously and smoothly decaying, taking no part in the striking variations below it. Therefore, the area variable in brightness does not seem to be the footpoint of the arch, as we supposed for similar variations on 22 May. More likely, it is a separate region connected directly with the source of the radio storm; particles accelerated in the storm may be dumped into the low corona and cause the X-ray enhancements. The X-ray arch was enhanced by two orders of magnitude in 3.5–5.5 keV X-ray counts and the temperature increased from 7.3 × 10⁶ to 9 × 10⁶ K when the new two-ribbon flare occurred at 15:00 UT. Thus, it is possible that energy is brought into the arch via the upper parts of the reconnecting flare loops - a process that can continue for hours.  相似文献   

Observations of the Orion Nebula in Hα, [NII] and Hβ lines     

C. T. Hua  R. Louise 《Astrophysics and Space Science》1982,88(2):477-485

Monochromatic photographs of the Orion Nebula taken through narrow bandpass interference filters (Δλ=10 Å) centred on Hα, Hβ and [NII] lines are presented. Ratio contours of Hα/[NII] and Hα/Hβ are derived. They enable a detailed study of the point-to-point variation in ionization structure and temperature throughout the nebula. Dust located within the ionized gas is studied from the Hα/Hβ ratio which varies from point to point over the nebula. Its strongest concentration, apart in the obvious ‘dark bay’, occurs in a shell surrounding the exciting stars, with about 2′ of diameter. Close to Θ¹ Ori the Hα/Hβ ratio, corrected for interstellar reddening, is about 3.0 in good agreement with the predicted value (Brocklehurst, 1971). To account for these measures, the following arguments are proposed:

1. Dust grains are completely or partially destroyed in region close to the exciting stars.
2. Radiation pressure and stellar wind push the remaining dust up to some equilibrium distance outwards. The consequence of this action is obviously the formation of a ‘dust mantle’ which is seen as a ring in projection.

  相似文献   

Tunneling and interference of Alfvén waves     

Y. D. Žugžda  V. Locāns 《Solar physics》1982,76(1):77-108

The propagation and interference of Alfvén waves in magnetic regions is studied. A multilayer approximation of the standard models of the solar atmosphere is used. In each layer, there is a linear law of temperature variation and a power law of Alfvén velocity variation. The analytical solutions of a wave equation are stitched at the layer boundaries. The low-frequency Alfvén waves (P > 1 s) are able to transfer the energy from sunspots into the corona by tunneling only. The chromosphere is not a resonance filter for the Alfvén waves. The interference and resonance of Alfvén waves are found to be important to wave propagation through the magnetic coronal arches. The transmission coefficient of Alfvén waves into the corona increases sharply on the resonance frequences. To take into account the wave absorption in the corona, a method of equivalent schemes is developed. The heating of a coronal arch by Alfvén waves is discussed.  相似文献   

Some factors influencing variations in the rate of natural increase of population in western Maharashtra     

Sawant SB  Khan YS 《Population geography : a journal of the Association of Population Geographers of India》1982,4(1-2):67-75

This paper analyzes the impact of various factors on variations in the rate of natural increase of population in Western Maharashtra, India. By using district level data, coefficients of correlation have been calculated between the rate of natural increase, the birth rate and the death rate on the 1 hand and different factors affecting them on the other. The analysis shows that in Western Maharashtra the birth rate is high in response to the high death rate and the high infant mortality rate. It is also revealed that the rate of natural increase of the population declines with an increase in the proportion of working females as well as the proportion of educated males. All this signifies that the region under study is in the 2nd stage of the "demographic transition."  相似文献   

Seasonal variations of atmospheric sulfur dioxide and dimethylsulfide concentrations at Amsterdam Island in the southern Indian Ocean     

J. P. Putaud  N. Mihalopoulos  B. C. Nguyen  J. M. Campin  S. Belviso 《Journal of Atmospheric Chemistry》1992,15(2):117-131

Daily measurements of atmospheric sulfur dioxide (SO₂) concentrations were performed from March 1989 to January 1991 at Amsterdam Island (37°50 S–77°30 E), a remote site located in the southern Indian Ocean. Long-range transport of continental air masses was studied using Radon (²²²Rn) as continental tracer. Average monthly SO₂ concentrations range from less than 0.2 to 3.9 nmol m^-3 (annual average = 0.7 nmol m^-3) and present a seasonal cycle with a minimum in winter and a maximum in summer, similar to that described for atmospheric DMS concentrations measured during the same period. Clear diel correlation between atmospheric DMS and SO₂ concentrations is also observed during summer. A photochemical box model using measured atmospheric DMS concentrations as input data reproduces the seasonal variations in the measured atmospheric SO₂ concentrations within ±30%. Comparing between computed and measured SO₂ concentrations allowed us to estimate a yield of SO₂ from DMS oxidation of about 70%.  相似文献