Variation of Meteor Heights and Solar-Cycle Activity
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Abstract:
Photographic meteor observations of the Perseid meteoroid stream compiled from the IAU Meteor Data Center catalogue are analyzed from the viewpoint of possible long-term variation of meteor heights with the solar-cycle activity, which was previously reported from radio observations. The observed beginning and end-point heights of the Perseids, normalized for the geocentric velocity and the absolute photographic magnitude, do not show a variation consistent with the solar-cycle activity. This result is valid for the mass range of larger meteoroids observed by photographic techniques, and must be still verified also for the range of smaller meteoroids observed by TV and radio methods.Keywords:
Variation (astronomy)
We report results of the first search specifically targeting short-timescale X-ray flares from low-mass X-ray binaries in an early-type galaxy. A new method for flare detection is presented. In NGC 4697, the nearest, optically luminous, X-ray faint elliptical galaxy, 3 out of 157 sources are found to display flares at >99.95% probability, and all show more than one flare. Two sources are coincident with globular clusters and show flare durations and luminosities similar to (but larger than) Type-I X-ray superbursts found in Galactic neutron star (NS) X-ray binaries (XRBs). The third source shows more extreme flares. Its flare luminosity (~6E39 erg/s) is very super-Eddington for an NS and is similar to the peak luminosities of the brightest Galactic black hole (BH) XRBs. However, the flare duration (~70 s) is much shorter than are typically seen for outbursts reaching those luminosities in Galactic BH sources. Alternative models for the flares are considered.
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Flare star
Black hole (networking)
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Jupiter (rocket family)
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Abstract The radio observations of meteor echoes using FM broadcasting were carried out from January, 1981 to June, 1985. The annual variation of meteor rates in the 5 years was obtained from the observations made from 25h through 29h in local time (16h-20h UT). Some features in this annual variation can be explained by the occurrence of the major meteor showers. After the effects of these major showers are removed there remains a significant annual variation which shows higher rates in the winter half of the year (October to March). This seems to be caused by the annual variation of non-shower meteors radiating from the apex region.
Variation (astronomy)
Meteor shower
Shower
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<p>Meteors ablation is a source of dust particles in the upper atmosphere. The remnants of meteor ablation that prevail in the mesosphere condense to nm-sized particles, denoted as Meteoric Smoke Particles (MSPs). Theory suggest that MSPs act as condensation nuclei for ice particles in the summer mesosphere, which form during summer months around the mesopause at high and mid latitudes. They are related to mesospheric phenomena such as the Noctilucent Clouds, Polar Mesospheric Summer and Winter Echoes (PMSE/PMWE). However, due to their altitude location, the only means of in situ measurement is with rocket experiments. There have been several attempts to collect these MSP particles with probes on rockets over the years, but no conclusive results have been reported so far.</p><p>UiT have proposed a new sample collector, the MEteoric Smoke Sampler (MESS). We report on the progress of the work that has focused on the design of the detector and simulation of the entry and impact of dust onto the detector. The focus of the planned measurements is on collecting ice particles, since the airflow affect them less than smaller MSPs. Estimations of the collection surface properties and impact energy are presented. An estimate of the expected mass in the traversed volume of one collecting plate, diameter of 3 mm diameter over 1 km, suggest that the volume contains ~1e8 particles. This corresponds to a mass of 7e16 amu. These estimates are made assuming spherical particles with average density 2.8 g per m<sup>3</sup> and radius 1 nm, and an MSP density of 1e10 per m<sup>3.</sup>&#160;</p>
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Orbital elements
Jupiter (rocket family)
Planetary science
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A calculation of the rate of separation of gases of different density in the earth's atmosphere leads us to expect a uniform mixture of all gases below 100 km and densities of hydrogen and helium roughly a hundred thousandth of those previously calculated, for greater heights. Known absorption and radiation coefficients for gases of the upper atmosphere indicate that we should expect a daily temperature variation of about 140° during the summer and 30° during the winter for all heights greater than 80 km. Carbon dioxide is found to be more effective than water vapor in determining the final escape of radiation from the earth and the conclusion is drawn that variations in the carbon dioxide content of the air may explain the variation in climatic conditions of the earth indicated by the ice ages of the past. Frictional resistance offered by the upper atmosphere to the passage of meteors through it is not sufficient to account for the energy radiated by meteors and the conclusion is reached that the energy of the meteor is probably dissipated into the air by the escape of atoms and molecules driven from the meteor by the energies of impacts with molecules of the air.
Atmosphere of Earth
Atmospheric escape
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Diurnal temperature variation
Seasonality
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