Preparing for the 1998/99 Leonid Storms

Jenniskens, Peter; Lignie, Marc de; Betlem, Hans; Borovička, J.; Laux, Christophe O.; Packan, Denis; Kruger, C.H.

doi:10.1007/978-94-011-4728-6_16

Cited by 14 publications

(7 citation statements)

References 16 publications

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“…This is shown in the graphs in Jenniskens et al (1999). However, as already noted in the pioneering work by Clifton (1973), the meteors close to the radiant are not well detected by a visual observer.…”

Section: Video Datamentioning

confidence: 82%

Activity of the 1998 Leonid shower from video records

Jenniskens

1999

Meteorit & Planetary Scien

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Abstract-Video observations of the Leonid shower aboard two aircraft in the 1998 L,eonid multi-instrument aircraft campaign and from ground locations in China are presented. Observ ng at altitude proved particularly effective, with four times higher rates due to low extinction and low angular velocity at the horizon. The rates, derived from a total of 2500 Leonid meteors, trace at least two distinct dust components.

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Section: Video Datamentioning

confidence: 82%

Activity of the 1998 Leonid shower from video records

Jenniskens

1999

Meteorit & Planetary Scien

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“…Figure 2 shows our best result, a Leonid with a brief terminal flare, which appeared in a westnorthwestern direction while flying over Little Rock, AR, at 09:05:58 UT, November 18 (92.97W, 134.80N, 37,000 ft). No meteor trajectory information is available from a stereoscopic perspective, because this was a single-plane mission, but the typical altitude at which such meteors end is 93 6 5 km (Jenniskens et al, 1998;Betlem et al, 2000). While most of the spectrum consists of second order lines of sodium, third order lines of ionized calcium are readily identified and very strong.…”

Section: Resultsmentioning

confidence: 98%

Meteors Do Not Break Exogenous Organic Molecules into High Yields of Diatomics

et al. 2004

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Meteoroids that dominate the Earth's extraterrestrial mass influx (50-300 microm size range) may have contributed a unique blend of exogenous organic molecules at the time of the origin of life. Such meteoroids are so large that most of their mass is ablated in the Earth's atmosphere. In the process, organic molecules are decomposed and chemically altered to molecules differently from those delivered to the Earth's surface by smaller (<50 microm) micrometeorites and larger (>10 cm) meteorites. The question addressed here is whether the organic matter in these meteoroids is fully decomposed into atoms or diatomic compounds during ablation. If not, then the ablation products made available for prebiotic organic chemistry, and perhaps early biology, might have retained some memory of their astrophysical nature. To test this hypothesis we searched for CN emission in meteor spectra in an airborne experiment during the 2001 Leonid meteor storm. We found that the meteor's light-emitting air plasma, which included products of meteor ablation, contained less than 1 CN molecule for every 30 meteoric iron atoms. This contrasts sharply with the nitrogen/iron ratio of 1:1.2 in the solid matter of comet 1P/Halley. Unless the nitrogen content or the abundance of complex organic matter in the Leonid parent body, comet 55P/Tempel-Tuttle, differs from that in comet 1P/Halley, it appears that very little of that organic nitrogen decomposes into CN molecules during meteor ablation in the rarefied flow conditions that characterize the atmospheric entry of meteoroids approximately 50 microm-10 cm in size. We propose that the organics of such meteoroids survive instead as larger compounds.

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“…If we allow for the weak positive trend with increasing mass, the temperature would be T 5 4,500 K for a typical 150 mm Leonid meteoroid (at 112 magnitude). Sporadic meteors with V 5 25 km/s of similar size would have a magnitude of about 116 (Jenniskens et al, 1998). Hence, temperatures measured for visual meteors are representative for conditions in the meteors associated with ,150 mm grains responsible for the peak of the mass influx.…”

Section: Discussionmentioning

confidence: 99%

The Mass and Speed Dependence of Meteor Air Plasma Temperatures

et al. 2004

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The speed and mass dependence of meteor air plasma temperatures is perhaps the most important data needed to understand how small meteoroids chemically change the ambient atmosphere in their path and enrich the ablated meteoric organic matter with oxygen. Such chemistry can play an important role in creating prebiotic compounds. The excitation conditions in various air plasma emissions were measured from high-resolution optical spectra of Leonid storm meteors during NASA's Leonid Multi-Instrument Aircraft Campaign. This was the first time a sufficient number and range of temperature measurements were obtained to search for meteoroid mass and speed dependencies. We found slight increases in temperature with decreasing altitude, but otherwise nearly constant values for meteoroids with speeds between 35 and 72 km/s and masses between 10(-5) g and 1 g. We conclude that faster and more massive meteoroids produce a larger emission volume, but not a higher air plasma temperature. We speculate that the meteoric plasma may be in multiphase equilibrium with the ambient atmosphere, which could mean lower plasma temperatures in a CO(2)-rich early Earth atmosphere.

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Preparing for the 1998/99 Leonid Storms

Cited by 14 publications

References 16 publications

Activity of the 1998 Leonid shower from video records

Activity of the 1998 Leonid shower from video records

Meteors Do Not Break Exogenous Organic Molecules into High Yields of Diatomics

The Mass and Speed Dependence of Meteor Air Plasma Temperatures

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