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Showing posts with label centaur. Show all posts
Showing posts with label centaur. Show all posts

Saturday, January 9, 2021

Centaur 2020 OR5 - cometary origin?

JPL Small-Body Database Browser

The orbit condition code is U=1

The inclination is 166 degrees, retrograde orbit

(2020 OR5)
Classification: Centaur          SPK-ID: 54049832

Orbital Elements at Epoch 2459000.5 (2020-May-31.0) TDB
Reference: JPL 4 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .3759703157485813 5.2059e-07  
a 6.232512912510303 1.7807e-06 au
q 3.889273064886694 3.1967e-06 au
i 166.5660130248566 1.6785e-05 deg
node 329.7310790615828 3.6225e-05 deg
peri 18.7667110659504 0.00015733 deg
M 343.8074710007652 5.4893e-05 deg
tp 2459256.126215268748
(2021-Feb-10.62621527)
0.00084017 TDB
period 5683.203500892169
15.56
0.0024356
6.668e-06
d
yr
n .06334455557389172 2.7147e-08 deg/d
Q 8.575752760133911 2.4502e-06 au
  Orbit Determination Parameters
   # obs. used (total)      69  
   data-arc span      6200 days (16.97 yr)  
   first obs. used      2003-09-27  
   last obs. used      2020-09-17  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      1  
   norm. resid. RMS      .66567  
   source      ORB  
   producer      Otto Matic  
   solution date      2020-Sep-24 03:24:06  

Additional Information
 Earth MOID = 2.87882 au 
 Jupiter MOID = .764924 au 
 T_jup = -1.138 

 

Clones generation

I generated 100 clones trying to achieve the same nominal orbital parameters and uncertainty as shown by JPL:


Clones  Target

mean sd   mean sd
q 3.88927291677 3.11616e-06   3.88927306489 3.1967e-06
e 0.37597036055 5.1608e-07   0.37597031575 5.2059e-07
i 166.56601061164 1.70801e-05   166.56601302486 1.6785e-05
peri 18.76671785638 0.00015793153   18.76671106595 0.00015733
node 329.73107930577 3.599887e-05   329.73107906158 3.6225e-05
tp2459256.126247480.00084814629 2459256.126215270.00084017

Backward simulation

I used Mercury Integrator Package Version 6 by J.E. Chambers.

I simulated the 100 clones in the past 10^8 days running the Bulirsch-Stoer algorithm.

Initialization parameters:

)O+_06 Integration parameters  (WARNING: Do not delete this line!!)
) Lines beginning with `)' are ignored.
)---------------------------------------------------------------------
) Important integration parameters:
)---------------------------------------------------------------------
 algorithm (MVS, BS, BS2, RADAU, HYBRID etc) = BS
 start time (days)= 2459167.50000
 stop time (days) = -1d8
 output interval (days) = 100
 timestep (days) = 0.05
 accuracy parameter=1.d-12
 ejection distance (AU)= 100

Simulation results

11 clones ( (abbreviated OR_<xx>) entered the solar system from a distance grater that 100 AU, so they can be considered to have a cometary origin.

Time when they entered the solar system:

Clone    Year
1  OR_79  -94821
2  OR_38 -105224
3  OR_39 -147499
4  OR_51 -163252
5  OR_97 -175502
6  OR_75 -217757
7  OR_18 -222400
8   OR_5 -231305
9  OR_55 -256597
10 OR_54 -259051
11 OR_98 -260336

6 of these 11 clones (abbreviated OR_<xx>) entered the solar system on a hyperbolic trajectory with the following V-infinity:

   Clone     V-Inf (Km/s)
1: OR_18.aei 16.04
2: OR_55.aei 14.09
3: OR_54.aei 10.27
4: OR_51.aei  9.90
5: OR_97.aei  6.82
6: OR_38.aei  4.72

Not clear to me:

  • is the hyperbolic trajectory just a "simulation artifact" or is it a real possibility (...also considering the retrograde motion) ?

More details abut hyperbolic clone OR_18

Looking at the simulator output:

At JD -79500232.50000 the object was travelling on a hyperbolic trajectory:

a=-3.43644 AU

e=1.416468  

i=70.6839  deg

Arg of perihelium:76.6540 deg

Ascending Node:143.8652 deg

Galactic long: 220.5192 deg

At JD -79500132.50000 (i.e. 100 days later - following a close encouter with Jupyter), the object was captured in this orbit:

a=5.92628 AU

e=0.128047

i= 166.8601 deg

Arg of perihelium: 228.0687 deg

Ascending Node: 148.3240 deg

Galactic Long 16.3927 deg

Overall Clone Behaviour

The simulation period has been divided into time slots.

In every time slot and for every clone, we look at the minimum perihelium distance, then we look at the resulting distribution calculating the mean plus 25 and 75 percentile.

(similar approach for the other parameters)

 




Kind Regards,

Alessandro Odasso