Meteors from 209P/LINEAR

A Summary by Rob McNaught

TA meeting 2014 May 10

209P/LINEAR

• 2004 Feb 03 - NEA 2004 CB discovered by LINEAR (MPEC 2004-C16)

• 2004 Mar 30 - Found to be a comet by Rob McNaught (IAUC 8314)

We

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Animation of three 10sec expsTail 1 arcmin long2004 Mar 301.0-m reflectorSiding Spring ObservatoryR. H. McNaught

North

q = 0.969 AUe = 0.672i = 21.2 dega = 2.96 (P = 5.09 yrs)

Meteor Shower• Jenniskens (2006) 1st to note possibility• Lyytinen made dust trail calculations• Vaubaillon used supercomputer to calculate

millions of particle motions• Maslov made dust trail calculations• Ye and Wiegert (2013) modelled dust tail of

209P, used supercomputer for particles• Asher (2014) dust trail calculations• All indicate a shower over N America

Night tonautical twilight

Radiant 40o elevation

B. Berard, IMCCE

Max radiantElev = 58o

Radiant elevations corrected for zenithal attraction

Radianton horizon

For 07:00UTshift plot eastby 7.5 deg

209P meteor shower

Daylight tonautical twilight

Sh

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vis

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ind

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Fiji

New Caledonia

Hawaii

Samoa

Galapagos

True RADIANT

• RA 122 +/- 1d Dec +79 +/- 1d (Ye and Wiegert)

• 122.8 +79.1 19.6km/s (Maslov,Asher)

(Vaubaillon)

(J2000)Atmospheric velocity – very slow meteors

The observed (apparent) radiant will be higher in the sky due to the gravitational bending of the incoming meteors by the Earth (to a max. of 11 deg). This is called Zenithal Attraction.

Nearbydust trails

2014 EncounterVery consistent with the dust trails, but saturation of this plotallows no interpretation of the shower profile or peak time.

Vaubaillon

Asher’s dust trails

Note: profile through Ye’s plot has peak after the dust trails

20-rev21-rev

22-rev

23-rev

24-45-rev

46-rev

47-rev

48-52-rev

Asher’s dust trails

• Binning +/- 7 days will diffuse the reality of what is happening at the instant of the nodal encounter

• Dust trail calculations are much simpler to do and detail precisely where the centre of a dust trail is at the instant it crosses the node

• If the trail is wide enough, it will produce meteors at that instant

Asher’s dust trails

• Start with ejection at prior perihelion

• Alter orbital period to estimate particle arrival at node at same time as Earth in 2014

• Perturbations change this arrival time

• Iterate the starting period to produce arrival at node at exactly the instant the Earth is at that same solar longitude.

• Note the distance of the particle from the Earth (rE-rD)

Asher’s dust trails

Earth’s orbit

Particle orbit

Node

Initial P too short

Initial P too long

Initial P correct

To Sun

Simplified diagram

Earth at node, time = T

Assume initial orbital period(P) for particle and calculateits location in 2014 (time = T)

rE = distance of Earth from SunrD = distance of dust trail from Sun

rE-rD

Asher’s dust trails

• Dust trails <20-rev old have large rE-rD

i.e. too distant for meteors• The 22 and 47-rev trails have direct hits• Trails between 27 and 45-revs are almost

coincident, but rather offset from the Earth’s orbit

• Dust trails >52-rev old are still in the Earth’s vicinity, but strongly disrupted and not well suited for dust trail prediction

• The trails align across the Earth’s orbit almost perpendicularly, so peak at similar times (Leonid trails were more scattered).

• The first trails to be encountered are older, then younger and finally much older.

• Dust trail calculations are based on the centre of the Earth. A time adjustment is needed for when a specific location passes through the dust sheet.

Asher’s dust trails

Asher’s dust trailsYear Mo Da UT Revs a0 rE-rD fM

2014 5 24 07:58 20 0.002 0.00200 -0.2292014 5 24 07:22 21 0.001 0.00059 -0.1492014 5 24 07:06 22 0.001 0.00003 -0.1132014 5 24 06:59 23 0.001 -0.00027 -0.0952014 5 24 06:53 24 0.001 -0.00046 -0.0822014 5 24 06:50 25 0.000 -0.00059 -0.0742014 5 24 06:46 26 0.000 -0.00069 -0.0672014 5 24 06:43 27 0.000 -0.00081 -0.0502014 5 24 06:40 28 0.000 -0.00088 -0.0402014 5 24 06:37 29 0.000 -0.00092 -0.0332014 5 24 06:36 30 0.000 -0.00095 -0.0292014 5 24 06:35 31 0.000 -0.00097 -0.0262014 5 24 06:35 32 0.000 -0.00098 -0.0202014 5 24 06:33 33 0.000 -0.00099 -0.0212014 5 24 06:32 34 0.000 -0.00099 -0.0222014 5 24 06:32 35 0.000 -0.00101 -.---2014 5 24 06:32 36 0.000 -0.00102 -.---2014 5 24 06:32 37 0.000 -0.00103 -.---2014 5 24 06:32 38 0.000 -0.00104 -.---2014 5 24 06:32 39 0.000 -0.00104 -.---2014 5 24 06:32 40 0.000 -0.00103 -.---2014 5 24 06:32 41 0.000 -0.00103 -.---2014 5 24 06:36 42 0.000 -0.00101 -0.017

Revs – number of orbits of dust from ejection to 2014

a0 – difference betweensemi-major axis (a0) ofthe comet and the

particle at ejection. a0~0.0 => large particles

rE-rD – distance of the dust trail node from Earth’s orbit.(Earth radius=0.00004AU)

fM – estimate of dispersion of the trail since ejection(at ejection fM=1.000)

Asher’s dust trailsYear Mo Da UT Revs a0 rE-rD fM

2014 5 24 06:35 43 0.000 -0.00098 -0.0232014 5 24 06:37 44 0.000 -0.00093 -0.0312014 5 24 06:45 45 0.000 -0.00080 -0.0542014 5 24 07:12 46 0.001 -0.00045 -0.1162014 5 24 07:45 47 0.001 -0.00001 -0.0472014 5 24 08:00 48 0.001 0.00017 -.---2014 5 24 08:07 49 0.001 0.00028 -.---2014 5 24 08:12 50 0.001 0.00036 -.---2014 5 24 08:17 51 0.001 0.00044 -.---2014 5 24 08:20 52 0.001 0.00052 -.---

Revs – number of orbits of dust from ejection to 2014

a0 – difference betweensemi-major axis (a0) ofthe comet and the

particle at ejection. a0~0.0 => large particles

rE-rD – distance of the dust trail node from Earth’s orbit.(Earth radius=0.00004AU)

fM – estimate of dispersion of the trail since ejection(at ejection fM=1.000)

The 46-rev trail would combine with the main 22-rev peak.

The 47-rev trail will be a direct hit but this and older trails are encountered much later. This should give a second lower peak with a slow tail off.

Shower profile

Ye and Wiegert

(08:15UT)

(06:29UT)

For the reasonsgiven, I believethis is too broad &inconsistent withtheir other plot.

Asher’s dust trailsindicate a similarbut narrower spreadcomprising 2 peaks

Ap

pro

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ZH

R

What will happen?

• All studies suggest the encountered particles will be large – bright meteors

• Rates are very uncertain, as nothing is known of the comet’s historical activity. Rates will be ZHR=0 to storm! Estimated ZHR=200-400 from comet’s current activity

• Differences in peak (06:29-07:40UT) and duration (FWHM~0.4 day to rather less)

When is the peak?

• Ye and Wiegert - 06:29UT (modelling)

• Lyytinen - 07:00UT (dust trail)

• Asher (1st peak) - 07:06UT (dust trail)

• Maslov - 07:21UT (dust trail)

• Vaubaillon - 07:40UT (modelling)

• Asher (2nd peak) - 07:45UT (dust trail)

• Predictions are for the Earth’s centre. Peak will be 8 mins earlier from N America

Night tonautical twilight

B. Berard, IMCCE

Sh

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vis

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Correction to Peak times

Daylight tonautical twilight

Fiji

New Caledonia

Hawaii

Samoa

Galapagos +8 min

+4 min

+0 min

-4 min

-4 min

+4 min

+0 min

-8 min-8 min

-10 min

• Ye and Wiegert have probably too large a bin size which diffuses the reality

• I trust Asher’s dust trail calculations• Main peak centred around the 22-rev trail at

07:06UT (unadjusted), superimposed on a broader shower with slow rise and sharper fall off

• A lower peak from the 47-rev trail at 07:45UT (unadjusted) should have a sharp rise and slower decline

Conclusion

Finally• Staying in the UK? Don’t

let daylight ruin a good shower• Core of the 22-rev dust trail will intersect the

daylight side of the Earth, e.g. UK• Should fireballs occur, they will be visible if

the sky is clear• Peaks at 06:57UT & 07:36UT (adjusted) for

central UK, the apparent radiant will be at: Az=10 deg Alt=51 deg