470785 (2008 UX299) vs 233771 (2008 TO124)

These two main belt asteroids have similar obit parameters.

Their orbit condition codes are 1 and 0 respectively

Using the JPL Small-Body Database Browser, we can see:

470785 (2008 UX299)

Classification: Main-belt Asteroid          SPK-ID: 2470785

[ Ephemeris | Orbit Diagram | Orbital Elements | Physical Parameters | Discovery Circumstances ]

[ show orbit diagram ]

Orbital Elements at Epoch 2458000.5 (2017-Sep-04.0) TDB Reference: JPL 8 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .1009684932114735 2.8551e-07   a 2.689930801283626 1.8626e-07 au q 2.418332541434887 9.1801e-07 au i 3.214698487892873 1.5513e-05 deg node 305.753597645791 0.00017107 deg peri 87.42148259454721 0.00027647 deg M 13.75396504670777 0.00023418 deg tp 2457938.934770288169 (2017-Jul-04.43477029) 0.0010426 JED period 1611.42496879941 4.41 0.00016737 4.582e-07 d yr n .2234047547793786 2.3204e-08 deg/d Q 2.961529061132366 2.0506e-07 au

Orbit Determination Parameters    # obs. used (total)      45      data-arc span      4277 days (11.71 yr)      first obs. used      2004-12-15      last obs. used      2016-08-31      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      1      fit RMS      .58441      data source      ORB      producer      Otto Matic      solution date      2017-Apr-09 07:28:47   Additional Information  Earth MOID = 1.42674 au   Jupiter MOID = 2.43518 au   T_jup = 3.363

233771 (2008 TO124)

Classification: Main-belt Asteroid          SPK-ID: 2233771

[ Ephemeris | Orbit Diagram | Orbital Elements | Physical Parameters | Discovery Circumstances | Close-Approach Data ]

[ show orbit diagram ]

Orbital Elements at Epoch 2458000.5 (2017-Sep-04.0) TDB Reference: JPL 8 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .1009140923237167 8.811e-08   a 2.690005559689887 3.9217e-08 au q 2.41854609028803 2.3857e-07 au i 3.214945766069064 1.0959e-05 deg node 305.7617498385058 0.00017798 deg peri 87.60982730687554 0.0001892 deg M 353.2000614611609 6.4573e-05 deg tp 2458030.939020972455 (2017-Oct-04.43902097) 0.00028938 JED period 1611.492146214952 4.41 3.5241e-05 9.648e-08 d yr n .2233954418242512 4.8853e-09 deg/d Q 2.961465029091743 4.3175e-08 au

Orbit Determination Parameters    # obs. used (total)      112      data-arc span      7084 days (19.39 yr)      first obs. used      1995-11-18      last obs. used      2015-04-11      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      0      fit RMS      .60277      data source      ORB      producer      Otto Matic      solution date      2017-Apr-10 21:12:24   Additional Information  Earth MOID = 1.42701 au   Jupiter MOID = 2.43425 au   T_jup = 3.363

I tried to simulate their behavior in the past to investigate whether they might be related.

Simulation set-up

Mercury6 Integrator

reference:

J.E.Chambers (1999) 

A Hybrid Symplectic Integrator that Permits Close Encounters between Massive Bodies''. Monthly Notices of the Royal Astronomical Society, vol 304, pp793-799.

           Integration parameters
           ----------------------

   Algorithm: Bulirsch-Stoer (conservative systems)

   Integration start epoch:         2458000.5000000 days
   Integration stop  epoch:      -100000000.0000000
   Output interval:                     100.000
   Output precision:                 medium

   Initial timestep:                0.050 days
   Accuracy parameter:              1.0000E-12
   Central mass:                    1.0000E+00 solar masses
   J_2:                              0.0000E+00
   J_4:                              0.0000E+00
   J_6:                              0.0000E+00
   Ejection distance:               1.0000E+02 AU
   Radius of central body:          5.0000E-03 AU

In order to perform the simulation I generated 30 clones for each asteroids (same average orbital parameters as the nominal ones and standard deviation almost about the one calculated by JPL).

Thus, I evaluated 900 couples to check whether there was a moment in the past when two clones were very near with a very low relative velocity.

In particular, I used two arbitrary thresholds to detect interesting couples:

• distance less than 1 Lunar Distance - about 0.0020 AU
• relative velocity less than 1 m/s

The clone generation and the couples evaluation have been done using scripts written in R.

Simulation Results
The results are interesting because 819 out of 900 couples satisfy the thresholds mentioned above.

Distance between clones (km):
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.   sd
    105    1200    2190    3270    3230  119000  9030
Relative velocity (m/s) when at minimum distance:
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.   sd
  0.034   0.092   0.120   0.140   0.150   0.940  0.09
Time of minimum distance (Years):
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.   sd
-272820  -75850  -62761  -74560  -56070  -18177  41444

In a graphical form:

same as above but with a little more  "zoom" ...:

The couple that went very near
Note that the time step is 100 days (this is consistent with a physical separation):

Conclusion
While this does not prove that the asteroids originated from a common body,  it seems that this is certainly a possibility.

Kind Regards,
Alessandro Odasso

304873 (2007 RD148) vs 95750 (2003 ED28)

These two main belt asteroids have similar obit parameters.

Their orbits are well known, in fact they are numbered objects and their orbit condition code is 0

Using the JPL Small-Body Database Browser, we can see:

304873 (2007 RD148)

Classification: Main-belt Asteroid          SPK-ID: 2304873

[ Ephemeris | Orbit Diagram | Orbital Elements | Physical Parameters | Discovery Circumstances | Close-Approach Data ]

[ show orbit diagram ]

Orbital Elements at Epoch 2458000.5 (2017-Sep-04.0) TDB Reference: JPL 8 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .112706956254304 8.1867e-08 a 2.356322451918862 3.2148e-08 au q 2.090748520409409 2.1203e-07 au i 7.649992278043358 1.0168e-05 deg node 27.84270465718106 5.3513e-05 deg peri 271.5923935241259 6.9656e-05 deg M 320.2483032081591 4.5862e-05 deg tp 2458146.382661936927 (2018-Jan-27.88266194) 0.00016876 JED period 1321.145071424301 3.62 2.7037e-05 7.402e-08 d yr n .2724908927767416 5.5765e-09 deg/d Q 2.621896383428315 3.5771e-08 au

Orbit Determination Parameters    # obs. used (total)      122      data-arc span      5996 days (16.42 yr)      first obs. used      2000-11-30      last obs. used      2017-05-01      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      0      fit RMS      .62685      data source      ORB      producer      Otto Matic      solution date      2017-May-15 18:17:37   Additional Information  Earth MOID = 1.09229 au   Jupiter MOID = 2.56959 au   T_jup = 3.534

95750 (2003 ED28)

Classification: Main-belt Asteroid          SPK-ID: 2095750

[ Ephemeris | Orbit Diagram | Orbital Elements | Physical Parameters | Discovery Circumstances ]

[ show orbit diagram ]

Orbital Elements at Epoch 2458000.5 (2017-Sep-04.0) TDB Reference: JPL 15 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .1131879964824657 5.3076e-08 a 2.356588129411903 1.9765e-08 au q 2.089850640509408 1.2124e-07 au i 7.650207304601344 7.0217e-06 deg node 27.83162309848563 3.2879e-05 deg peri 271.7844693300495 4.7721e-05 deg M 252.9376849706002 3.6597e-05 deg tp 2458393.468812675760 (2018-Oct-01.96881268) 0.00013583 JED period 1321.368518179582 3.62 1.6624e-05 4.551e-08 d yr n .2724448138782385 3.4276e-09 deg/d Q 2.623325618314398 2.2002e-08 au

Orbit Determination Parameters    # obs. used (total)      464      data-arc span      7627 days (20.88 yr)      first obs. used      1996-04-17      last obs. used      2017-03-05      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      0      fit RMS      .57403      data source      ORB      producer      Otto Matic      solution date      2017-Apr-11 13:52:05   Additional Information  Earth MOID = 1.09141 au   Jupiter MOID = 2.56949 au   T_jup = 3.533

I tried to simulate their behavior in the past to investigate whether they might be related.

Simulation set-up

Mercury6 Integrator

reference:

J.E.Chambers (1999) 

A Hybrid Symplectic Integrator that Permits Close Encounters between Massive Bodies''. Monthly Notices of the Royal Astronomical Society, vol 304, pp793-799.

           Integration parameters
           ----------------------

   Algorithm: Bulirsch-Stoer (conservative systems)

   Integration start epoch:         2458000.5000000 days
   Integration stop  epoch:      -100000000.0000000
   Output interval:                     100.000
   Output precision:                 medium

   Initial timestep:                0.050 days
   Accuracy parameter:              1.0000E-12
   Central mass:                    1.0000E+00 solar masses
   J_2:                              0.0000E+00
   J_4:                              0.0000E+00
   J_6:                              0.0000E+00
   Ejection distance:               1.0000E+02 AU
   Radius of central body:          5.0000E-03 AU

In order to perform the simulation I generated 30 clones for each asteroids (same average orbital parameters as the nominal ones and standard deviation almost about the one calculated by JPL).

Thus, I evaluated 900 couples to check whether there was a moment in the past when two clones were very near with a very low relative velocity.

In particular, I used two arbitrary thresholds to detect interesting couples:

• distance less than 1 Lunar Distance - about 0.0020 AU
• relative velocity less than 1 m/s

The clone generation and the couples evaluation have been done using scripts written in R.

Simulation Results
The results are interesting because 770 out of 900 couples satisfy the thresholds mentioned above.

Distance between clones (km):

   Min. 1st Qu.  Median    Mean  3rd Qu.   Max.     sd
    961    4540    6849   13342   21245  126502    11832


Relative velocity (m/s) when at minimum distance:

   Min. 1st Qu.  Median    Mean   3rd Qu.  Max.     sd
   0.33    0.57    0.77    0.74    0.92    1.00     0.18


Time of minimum distance (Years):
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.     sd
-276373 -115975 -114199 -130260 -113592 -109542    42281

In a graphical form:

The couple that went very near
Note that the time step is 100 days (this is consistent with a physical separation):

Conclusion
This does not prove that the asteroids originated from a common body but I think that this is certainly a possibility.

Kind Regards,
Alessandro Odasso

Asteroid 2017 FW17 - an extinct comet?

Asteroid 2017 FW17 was first observed at Pan-STARRS 1, Haleakala on 2017-03-18.
 

Orbital Elements at Epoch 2457831.5 (2017-Mar-19.0) TDB Reference: JPL 5 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .3756229227781228 0.020776 a 4.071577338499798 0.075338 au q 2.542199558295334 0.13088 au i 4.36476081532836 0.4957 deg node 353.1159388040458 0.37693 deg peri 206.4444762192174 1.1805 deg M 350.7475904922186 0.39597 deg tp 2457908.624933945908 (2017-Jun-04.12493395) 5.191 JED period 3000.837370760166 8.22 83.288 0.228 d yr n .1199665145161817 0.0033297 deg/d Q 5.600955118704262 0.10364 au

Orbit Determination Parameters    # obs. used (total)      15      data-arc span      8 days      first obs. used      2017-03-18      last obs. used      2017-03-26      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      8      fit RMS      .96317      data source      ORB      producer      Otto Matic      solution date      2017-Apr-06 09:58:49   Additional Information  Earth MOID = 1.54121 au   Jupiter MOID = .0287021 au   T_jup = 2.913   JPL covariance   MPC orbit ref: MPEC 2017-FF0

The orbit condition code is 8 so it is extremely uncertain.

The object is interesting because it might have a cometary origin although this is difficult to say given the uncertainty.

I generated 100 clones with orbit parameters average and 1-sigma as shown above and simulated what happened in the last 10^8 days.

Note 1:
thanks to Tony Dunn for a comment that he sent me: if its current nominal orbit is correct, this asteroid is a Hilda with a 3:2 resonance with Jupiter.
But as Tony run it forwards and backwards, it leaves the 3:2 resonance within a few hundred years.
Tony has a online simulator that shows the short term Hilda behaviour .

Note 2:
I used Tony Dunn's simulator to check what happens with asteroid using its nominal parameters.  The likely cometary origin seems confirmed

Simulation set-up

Mercury6 Integrator

reference:

J.E.Chambers (1999) 

A Hybrid Symplectic Integrator that Permits Close Encounters between Massive Bodies''. Monthly Notices of the Royal Astronomical Society, vol 304, pp793-799.

           Integration parameters
           ----------------------

   Algorithm: Bulirsch-Stoer (conservative systems)

   Integration start epoch:         2457831.5000000 days
   Integration stop  epoch:      -100000000.0000000
   Output interval:                     100.000
   Output precision:                 medium

   Initial timestep:                0.050 days
   Accuracy parameter:              1.0000E-12
   Central mass:                    1.0000E+00 solar masses
   J_2:                              0.0000E+00
   J_4:                              0.0000E+00
   J_6:                              0.0000E+00
   Ejection distance:               1.0000E+02 AU
   Radius of central body:          5.0000E-03 AU

Simulation results
The result of the simulation is that 47 out of 100 clones might have arrived in the solar system from a distance greater than 100 AU.
Their arrival time is very much uncertain.
Going back in the past, the first arrival was in year 2075 B.C. while the last arrival was in year 249000 B.C.
This is the distribution of arrival times showing a relative moderate peak about 40000 B.C:

Every clone has its own "orbital history" and different clones have completely different "histories".
While there is no reason to focus the attention on a specific clone, one might choose a clone just to have an idea of the general macroscopic behaviour.
One can also try to capture the effect of the close encounters with the major planets: the details are not necessarily true but the overall pattern might be reasonable.

Thus, let's see the history of a clone that arrived in the solar system about 45000 Years B.C.

The simulator calculated the following number close encounters (other clones had a greater number of encounters, I choose this because it is easier to be managed graphically...):

JUPITER  SATURN  URANUS
     72      20       1

These encounters occurred at a distance Dmin summarized here:

$JUPITER
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.
0.08149 0.52310 0.73397 0.68313 0.90392 1.03749

$SATURN
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.
 0.2115  0.7622  0.8714  0.8798  1.1167  1.2990

$URANUS
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.
 0.9797  0.9797  0.9797  0.9797  0.9797  0.9797


This is a plot (made with package ggplot of the programming environment R that was also used to calculate the above tables) showing semi-major axis, perhelium and aphelium distance as a function of time.
The close encounter with Uranus is shown as a vertical dotted line.
It occurred at a distance 0f 0.97 AU and its effect is not so clear:

This second plot below shows the same thing but this time the vertical dotted lines are associated to the Saturn close encounters.

Finally, the same plot this time for Jupiter close encounters:

I made similar plots (only for Jupiter) showing the other orbital parameters:

Eccentricity

Inclination

Ascending Node and argument of perihelion

Close encounters: summary views

As said above, there is no reason to focus on a specific clone besides the possibility to look in a graphical form to one of the possible asteroid "histories".

More in general, we can consider that any given clone had multiple encounters with any given planet, so we can make an average of the these encounters (we can focus first of all on number_of_encounters and encounter distance). Even better: we can make a box-plot  (showing min, max, median, 1st and 3rd percentile) to have an idea of the distribution.

In some special cases (like the case of encounters with planet Mercury that you see below), there is only one clone that contributes: thus, the boxplot of the numer of encounters is "flat" and equal to the number of encounters of this clone.

In the plots below, it is also possible to compare the clones suspected to be comets with the normal asteroid clones: look at "cometary-origin".

Neptune

Uranus

Saturn

Jupiter

Mars

Earth-Moon

Venus

Mercury

Kind Regards,
Alessandro Odasso