VS: Re[2]: (meteorobs) e-Eridanids

Lyytinen Esko Esko.Lyytinen at MINEDU.FI
Tue Aug 24 02:10:36 EDT 2004


Hi,

I copy the 'reservations' from the paper here for those that did not
retrieve it or did not look carefully enough to see this chapter.
"
Of particular interest is the epsilon Eridanids shower (Figure 9),
tentatively associated with parent
comet C/1854 L1 (Klinkerfuess). This comet has only known parabolic
elements and may, or may
not, be long period. Furthermore, the initial account of the shower
implies that the e-Eridanids are
unusually broad (Jenniskens 1995). There is also a difference of more
than one degree in the node
between shower and comet orbit. We find that the one-revolution trail
calculated from the comet
elements does not cross the Earth orbit. It is possible that a
2-revolution old trail was observed that
could account for the broadness. However, we can not check this
possibility with the current
modelling.
"

According to this, the prediction is highly uncertain (also the
'miss-distance'would be considerable big even according to this
prediction). The prediction would be about valid only IF the observed
outburst was from 1-rev trail of a long period comet. If it was from
2-rev. trail, we do not have enough information for future predictions,
in lack of reliable comet orbit. It is also worth to know that outbursts
from long period comet trails, from other than 1-revoultion trail hardly
happen. To some degree these are possible around the lower limit of long
period orbits (around 200 to 300 (maybe 400) year orbital period). With
longer orbital period, even the 2-revolution trail will be formed from
multiple loops ('back and forth' in time, if we follow the timing of
successive model particles accordting to da0), that in a graph appear
almost as random points (Figure 3. in the paper). 

I think it more probable that no outburst will occur now. This shower
and the once observed outburst are quite interesting, however and more
or less problematic and it would be fine to get this meteor shower more
studied. Quite probably it is capable of producing oubursts, since
apparently one has been observed.

Esko

>>>

Lew,
This paper address is
http://aio.arc.nasa.gov/~leonid/ICARUSLP-final.pdf
The full name is epsilon-Eridanids. The stream is also known as
pi-Eridanids and gamma-Eridanids. In "Unusual meteor streams of 2004"
Sergey Shanov notes, that in the night of September 10/11 an enhanced
activity of small stream epsilon-Eridanids was seen. After 13.00 UT
Marry Gaisky [translation is from Russian, name may be incorrectly
written] observed step by step hourly rates of 0, 3, 11, 34 meteors
belonging to the stream. Lm was at 5.6 mag, till 13.00 UT radiant was
below horizon. Later director of WAMS Jeff Wood estimated maximum ZHR at
170+/-50. Esko Lyytinen and Peter Jenniskens suggested that an outburst
can be caused by trail of unknown long-period comet.

The rest is in the first message. In addition, stream radiant on
September 11 is at RA=56 deg, Dec=-14 deg. Velocity is 57 km/sec, so
meteors would be fast. The paper contains a large list of possible
outbursts from long-period comets till 2050.

Best regards, Mikhail Maslov



LJG> Mikhail, thanks for raising this topic on the list! I was not aware

LJG> of the particular prediction you mention. Does the "e-"
LJG> in your "e-Eridanids" refer to "epsilon", or "eta"? Also, does the 
LJG> paper you mention provide any further information on this predicted

LJG> activity - velocity of the meteors relative to earth, exact 
LJG> position (and drift) of the predicted radiant, predicted period of 
LJG> activity (and length of any outburst), etc.?

LJG> It would certainly be nice to have some additional activity to be 
LJG> "on the lookout for" in September! Even if it didn't appear, it 
LJG> would indeed be a good reason just to observe... :)

LJG> Clear skies,
LJG> Lew


>> -----Original Message-----
>> From: meteorobs-bounces at meteorobs.org 
>> [mailto:meteorobs-bounces at meteorobs.org] On Behalf Of Mikhail Maslov
>> Sent: Sunday, August 22, 2004 12:18 PM
>> To: meteorobs at meteorobs.org
>> Subject: (meteorobs) e-Eridanids
>>
>>
>> Hi, all.
>>
>> Now after Perseids people starts talking about future highlights - 
>> Orionids, Leonids and even Geminids. I'd like to remind, that there 
>> is a prediction of a possible outburst in the several week. I mean 
>> the paper "Meteor Outbursts From Long Period Comets" by Esko Lyytinen

>> and Peter Jenniskens, in which among other they suggested, that if 
>> e-Eridanids are formed by long-period comet, there is a possibility 
>> thet Earth will pass at 0.00127 a.u. from dust trail causing the 
>> outburst. Predicted time is 11 september 18:01 UT. It is noted that 
>> Earth could face only the edge of trail.
>> This forecast is much less confident than of Leonids and Perseids 
>> activity, but if it was not revised (I have no such information), it 
>> is at least the reason to observe. The Moon will not interfere.
>> Any comments?
>>
>> Best regards, Mikhail Maslov.



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