Cyt, po angielsku:
P.Jenniskens pisze:
ALPHA MONOCEROTIDS 2019
P. Jenniskens, SETI Institute and NASA Ames Research Center, and E.
Lyytinen, Helsinki, Finland, report that a significant return of the alpha
Monocerotid meteor shower (IAU shower 246, AMO) is expected on Nov. 22,
centered at 4h50m UTC. Past dust-trail calculations (cf. Lyytinen and
Jenniskens 2003, Icarus 162, 443) were re-evaluated assuming now that past
outbursts were caused by the one-revolution dust trail of a long-period
comet with a shorter orbital period of about 500 years. From this, the 2019
encounter is expected at solar longitude 239.308 degrees (equinox J2000.0),
and the earth is expected to cross the dust trail slightly further out from
the sun. If the trail was crossed through its center in 1925 and 1935, then
the earth passed 0.0002 AU from the trail center (inside the trail) in 1985
and 1995. The heliocentric-distance difference of dust trail minus earth
orbit will be -0.00016 AU in 2019. Because the uncertainty of where the
trail center is, the distance could range between -0.00036 and +0.0000 AU.
Depending on that distance, peak rates in 2019 could be about similar to, or
in excess of, those observed in 1995, when the zenith hourly rate was 400
meteors/hr in the minute centered on the peak (cf. Jenniskens et al. 1997,
Ap.J. 479, 441). Past dust-trail encounters were very brief, with a
full-width-at-half-maximum of only 0.29 hr.
ALPHA MONOCEROTIDS 2019
P. Jenniskens, SETI Institute and NASA Ames Research Center, and E.
Lyytinen, Helsinki, Finland, report that a significant return of the alpha
Monocerotid meteor shower (IAU shower 246, AMO) is expected on Nov. 22,
centered at 4h50m UTC. Past dust-trail calculations (cf. Lyytinen and
Jenniskens 2003, Icarus 162, 443) were re-evaluated assuming now that past
outbursts were caused by the one-revolution dust trail of a long-period
comet with a shorter orbital period of about 500 years. From this, the 2019
encounter is expected at solar longitude 239.308 degrees (equinox J2000.0),
and the earth is expected to cross the dust trail slightly further out from
the sun. If the trail was crossed through its center in 1925 and 1935, then
the earth passed 0.0002 AU from the trail center (inside the trail) in 1985
and 1995. The heliocentric-distance difference of dust trail minus earth
orbit will be -0.00016 AU in 2019. Because the uncertainty of where the
trail center is, the distance could range between -0.00036 and +0.0000 AU.
Depending on that distance, peak rates in 2019 could be about similar to, or
in excess of, those observed in 1995, when the zenith hourly rate was 400
meteors/hr in the minute centered on the peak (cf. Jenniskens et al. 1997,
Ap.J. 479, 441). Past dust-trail encounters were very brief, with a
full-width-at-half-maximum of only 0.29 hr.
Karol SQ5KVS