Asteroid 2016 BS30 = 2010 HD50 - Cometary origin?

Horizon Web data
(2016 BS30)

Classification: Outer Main-belt Asteroid          SPK-ID: 3743356

[ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Close-Approach Data ]

[ show orbit diagram ]

Orbital Elements at Epoch 2458200.5 (2018-Mar-23.0) TDB Reference: JPL 9 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .3478863638049197 7.7899e-07 a 3.820502999526835 7.8608e-07 au q 2.491402103115656 3.4304e-06 au i 11.67728524676726 7.6434e-05 deg node 326.2245320214484 9.1269e-05 deg peri 245.4466373090264 0.00026973 deg M 60.18000341810182 0.00025871 deg tp 2457744.537683238532 (2016-Dec-22.03768324) 0.0018283 JED period 2727.590972265617 7.47 0.00084182 2.305e-06 d yr n .1319845987395147 4.0734e-08 deg/d Q 5.149603895938015 1.0596e-06 au

Orbit Determination Parameters    # obs. used (total)      54      data-arc span      4641 days (12.71 yr)      first obs. used      2003-08-26      last obs. used      2016-05-10      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      1      fit RMS      .55107      data source      ORB      producer      Otto Matic      solution date      2018-Jul-09 06:23:30   Additional Information  Earth MOID = 1.51491 au   Jupiter MOID = .65024 au   T_jup = 2.935

Clones generation

I generated 100 clones trying to achieve the same orbital parameter distribution as shown above (mean and sigma).

This is a table comparing what has been achieved versus the target:

	clones_mean	clones_sd	target_mean	target_sd
q	2.4914019	0.0000034	2.4914021	0.0000034
e	0.3478864	0.0000008	0.3478864	0.0000008
i	11.6772762	0.0000767	11.6772853	0.0000764
peri	245.4466251	0.0002691	245.4466373	0.0002697
node	326.2245392	0.0000916	326.2245320	0.0000913
tp	2457744.5376278	0.0018291	2457744.5376832	0.0018283

Backward simulation
I used the Bulirsch-Stoer algorithm implemented by the Mercury software by 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 (general)

   Integration start epoch:         2458200.5000000 days
   Integration stop  epoch:      -100000000.0000000
   Output interval:                     100.000
   Output precision:                 medium

   Initial timestep:                 .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

   Includes collisions:                 no
   Includes fragmentation:              no
   Includes relativity:                 no

The arbitrary threshold to consider an asteroid to be ejected from the solar system (or to enter it in case of backward simulation) is 100 au.

All planets from Mercury to Pluto plus asteroids Ceres, Pallas and Vesta have been taken into account.

Simulation results
76 out of 100 initial clones have entered the solar system from a distance greater than 100 au.

The graph below has to be read from right to left (the number of clones decreases as you go in the past - the simulation time has been divided into 10 intervals).

The arrival time into the solar system has the following density distribution:

In the following graphs, the simulation time has been divided into 10 intervals: in every interval and for every clone we find the maximum value for the relevant orbital parameter.

Orbit Specific Energy

Some clones were on a hyperbolic orbit with the following v-infinity:

Orbit eccentricity

Orbit Inclination

Analysis of Close Approaches

Kind Regards,
Alessandro Odasso

Asteroid 2018 LF5

Asteroids 2018 LF5 is an Amor (PHA) that had a relative close approach with earth yesterday July 7th, 2018.

Its orbit is still uncertain (condition code 6).

At the time of writing, it seems that this Amor has some potential to have a cometary origin. More details below.


Clones Generation

I generated 100 clones trying to achieve an orbital parameter distribution (mean and 1-sigma) that matches as far as possible the target nominal data read from Horizons Web a few hours ago on July 6th.

This is a comparison table that shows the clones distribution versus the target one:

	clones_mean	clones_sd	target_mean	target_sd
q	1.06373506	3.2E-06	1.06373514	3.21E-06
e	0.61855794	7.847E-05	0.61856034	7.85E-05
i	41.04180418	0.001757	41.04185685	0.0017567
peri	181.03405996	0.00019308	181.03405317	0.00019281
node	100.75809149	0.00030458	100.75808179	0.00030512
tp	2458309.05107042	0.00017576	2458309.05106226	0.0001761

Backward simulation
I used the Mercury Integrator by John E. Chambers (with some subroutines supplied by Hal Levison and Martin Duncan).

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

   Algorithm: Bulirsch-Stoer (general)

   Integration start epoch:         2458200.5000000 days
   Integration stop  epoch:      -100000000.0000000
   Output interval:                     100.000
   Output precision:                 medium

   Initial timestep:                 .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
LF_91    ejected at     -60075  9 16.03454
sun was hit by LF_54    at    -112260  1 30.7
sun was hit by LF_38    at    -115727  5 28.2
sun was hit by LF_72    at    -117581  3  8.3
sun was hit by LF_17    at    -133748  2 27.5
sun was hit by LF_46    at    -136245  9  8.1
 LF_63    ejected at    -144164  7  8.61087
sun was hit by LF_61    at    -149555 10 11.3
sun was hit by LF_69    at    -174783  1 21.9
 LF_48    ejected at    -193993 10  9.15850
sun was hit by LF_71    at    -194558  6 14.5
 LF_84    ejected at    -218748  7 12.96343
sun was hit by LF_81    at    -222146  6  1.6
sun was hit by LF_43    at    -225535  3 27.2
 LF_39    ejected at    -235862 11  1.20080
sun was hit by LF_28    at    -240288  5 16.1
 LF_20    ejected at    -244214  1  9.02367
 LF_95    ejected at    -245994  9 18.71844
 LF_100   ejected at    -262161  2 11.44480
sun was hit by LF_65    at    -265855  6  9.3
 LF_77    ejected at    -269187  3 12.79012
 LF_11    ejected at    -277829 10 18.10824

The same information can be displayed in a graphical form, where we can see that the number of clones (initial number 100) is decreasing as you go in the past:

Simulation Graphs

In the following graphs, the simulation period was divided into 10 intervals.

In every interval, the maximum value of the relevant orbital parameter was found for every clone and all clones values are finally displayed in a boxplot.

Orbit Specific energy

In the picture below:
energy = 0  parabolic orbit
energy > 0 hyperbolic orbit
energy <0 elliptical orbit

Just for curiosity, the distribution of V-infinity for the 7 hyperbolic clones is as follows:

Inclination

Eccentricity

Kind Regards,
Alessandro Odasso

174P/Echeclus

60558 Echeclus (2000 EC98) also known as 174P/Echeclus is a centaur that occasionally shows a cometary activity.

Outbursts happened in 2005, 2011 and in the first days of December 2017 (see MPML message from Brian Skiff) and confirmation from Richard Miles and Jean-François Soulier.

The 2017 outburst is the strongest ever witnessed.

I simulated 100 clones of this centaur in the past 10^8 days trying to confirm its possible cometary origin: note that I am not taking into account the non gravitational forces associated to its outburst, not clear to me if they have a considerable effect.

The first step was to generate clones having orbital parameters distributed around the nominal ones with 1-sigma uncertainty as follows:

JPL Small-Body Database Browser

60558 Echeclus (2000 EC98)

Classification: Centaur          SPK-ID: 2060558

[ 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 85 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .4556668817376728 1.2005e-07 a 10.68172886788859 2.2774e-06 au q 5.814418783090517 4.1275e-07 au i 4.344445692331014 6.4394e-06 deg node 173.3332131350017 5.505e-05 deg peri 162.8042218299513 5.7268e-05 deg M 24.47205469604485 6.4974e-06 deg tp 2457133.680473384613 (2015-Apr-21.18047338) 0.00022632 JED period 12751.48464064088 34.91 0.004078 1.116e-05 d yr n .02823200671493785 9.0289e-09 deg/d Q 15.54903895268667 3.3152e-06 au

Orbit Determination Parameters    # obs. used (total)      2888      data-arc span      13948 days (38.19 yr)      first obs. used      1979-09-23      last obs. used      2017-11-30      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      0      fit RMS      .44363      data source      ORB      producer      Otto Matic      solution date      2017-Dec-07 16:00:47   Additional Information  Earth MOID = 4.80483 au   Jupiter MOID = .838614 au   T_jup = 3.031

Simulation approach

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 (general)

   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


Simulation Results

• 77 out of 100 clones have a cometary orbit (i.e. they came from a distance greater than 100 AU).

• of which: 3 came on a hyperbolic orbit. The one that had the highest speed had a Vinfinity about 3.7 km/s (Vinfinity = 42.1219*sqrt(-0.5/a) --> the semi-major axis being about -63.6 AU

The time (Year) when they entered the solar system was distributed as follows:

   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.
-272080 -109330  -62183  -82802  -36357   -4980

In a graphical form:

A look at the nominal asteroid
The nominal asteroid itself has a cometary origin.

It entered into the solar system at about year -105000 B.C.

In the plot below, the dashed vertical lines correspond to a close approach with Jupiter.

Note that Jupiter was not immediately important. 

In its early history, 174P/Echeclus was much more influenced by Saturn as shown here:

Coming back to plots showing the role of Jupiter, we can see these other ones:

A look at the clones - "footprint" diagrams

At any given time in the past, a clone had a certain perihelium q and a certain aphelium Q (I disregard the clones when on an hyperbolic trajectory because Q would be infinite).

Let's imagine that we plot all possible q-Q points in a diagram: the highest density area is the one where the clones happened to be for most of the time.

This is shown here ( I have used the R function stat_density2d - color scale implemented by viridis library):

Analysis of close approaches
These plots show the distribution of close appproaches (number and Dmin distance) between the clones and the major planets.

Kind Regards,
Alessandro Odasso

Amor (Neo) 2017 BR93

This NEO is listed in the page of Asteroids with Comet-Like Orbits maintained by Y. Fernandez.

I simulated 100 clones of this asteroid in the past 10^8 days trying to confirm its possible cometary origin: the goal is to determine whether some clones might have arrived from the outskirt of the solar system - arbitrary threshold: 100 AU.

The first step was to generate clones having orbital parameters distributed around the nominal ones with 1-sigma uncertainty as follows:

JPL Small-Body Database Browser

 

(2017 BR93)

Classification: Amor [NEO]          SPK-ID: 3767926

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

[ show orbit diagram ]

Orbital Elements at Epoch 2458000.5 (2017-Sep-04.0) TDB Reference: JPL 5 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .7217412317070279 0.0001002 a 4.142675777273991 0.0015088 au q 1.152735859221392 3.3533e-05 au i 15.35366999553024 0.001219 deg node 97.57957971696266 0.0028893 deg peri 318.8120872155768 0.0036121 deg M 38.89039107061564 0.021706 deg tp 2457667.794750083124 (2016-Oct-06.29475008) 0.0066681 JED period 3079.781063466159 8.43 1.6825 0.004606 d yr n .1168914259102677 6.3858e-05 deg/d Q 7.13261569532659 0.0025977 au

Orbit Determination Parameters    # obs. used (total)      34      data-arc span      75 days      first obs. used      2016-11-23      last obs. used      2017-02-06      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      6      fit RMS      .44498      data source      ORB      producer      Otto Matic      solution date      2017-Nov-30 06:50:30   Additional Information  Earth MOID = .222957 au   Jupiter MOID = .227161 au   T_jup = 2.447

The orbit condition code is 6 so there is still a lot of uncertainty.

Simulation approach

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


Simulation Results

• 75 out of 100 clones have a cometary like orbit.
• of which: 16 came on a hyperbolic orbit. The one that had the highest speed had a Vinfinity about 15.2 km/s (Vinfinity = 42.1219*sqrt(-0.5/a) --> the semi-major axis being about -3.82 AU

The time (Year) when they entered the solar system was distributed as follows:

   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.
-276249 -148774  -75459  -98680  -33904    -709

In a graphical form:

A look at the nominal asteroid

The nominal asteroid itself does not have a cometary origin in the last 10^8 days. It appears to be nevertheless on a unstable orbit, there was a time in the past when its aphelion was at about 70 AU.

In the following plots (made with R package ggplot2), the vertical dashed lines show a close encounter with Jupiter.

A look at the clones - "footprint" diagrams

At any given time in the past, a clone had a certain perihelium q and a certain aphelium Q (I disregard the clones when on an hyperbolic trajectory because Q would be infinite).

Let's imagine that we plot all possible q-Q points in a diagram: the highest density area is the one where the clones happened to be for most of the time.

This is shown here ( I have used the R function stat_density2d):

In the diagram above, we can also see the current q-Q of the asteroid together with that of Jupiter and Saturn.
In a similar way, these are the footprints for w-om and e-i:

 

Analysis of close approaches
These plots show the distribution of close appproaches (number and Dmin distance) between the clones and the major planets.

Kind Regards,
Alessandro Odasso