2015 OL106 - an old comet?

See Sam Deen's message thread in MPML about 2015 OL106  being an "imposter trojan". 

I performed a simulation with 100 clones trying to achieve the same nominal orbital parameters and uncertainty as below.

From Horizons web interface:

(2015 OL106) Classification: Jupiter Trojan          SPK-ID: 3928029 [ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Close-Approach Data ] [ show orbit diagram ] Orbital Elements at Epoch 2459000.5 (2020-May-31.0) TDB Reference: JPL 2 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .2863714556023872 9.3239e-06   a 5.270192122670955 0.0001095 au q 3.760959533197438 2.9098e-05 au i 21.4224769951995 5.1601e-05 deg node 359.8294629245777 4.4923e-05 deg peri 313.6982197132379 0.0021834 deg M 145.9574151264247 0.0056942 deg tp 2457208.814574639116 (2015-Jul-05.31457464) 0.014075 TDB period 4419.143436948574 12.10 0.13773 0.0003771 d yr n .0814637508685576 2.5389e-06 deg/d Q 6.779424712144472 0.00014086 au   Orbit Determination Parameters    # obs. used (total)      39      data-arc span      850 days (2.33 yr)      first obs. used      2015-07-26      last obs. used      2017-11-22      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      4      norm. resid. RMS      .68872      source      ORB      producer      Otto Matic      solution date      2020-Mar-16 17:29:21   Additional Information  Earth MOID = 2.79199 au   Jupiter MOID = .530935 au   T_jup = 2.783

PL Small-Body Database Browser

Search: [ help ]

	Clones			Target
	mean	sd		mean	sd
q	3.76096161305	2.919293e-05		3.7609595332	2.9098e-05
e	0.28637206423	9.3409e-06		0.2863714556	9.3239e-06
i	21.42247962456	5.175126e-05		21.4224769952	5.1601e-05
peri	313.69838452814	0.00218824566		313.69821971324	0.0021834
node	359.82946145114	4.488101e-05		359.82946292458	4.4923e-05
tp	2457208.81561007	0.01411030776		2457208.81457464	0.014075

Simulation done with Mercury6 software with these parameters:

)---------------------------------------------------------------------
) 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

The simultion resuls are as follows:

78 clones arrived into the solar system from a distance greater than 100 AU

So it seems that this asteroid has the potential to be an old comet!

Cheers,

Alessandro Odasso

C/2014 OG392 - about its cometary origin

A coma was recently detected as far as 400,000 km from centaur 2014 OG392 by NAU researchers (click here to access their paper).

Following this discovery, the centaur was given a comet designation: C/2014 OG392 

C/2014 OG392 (PANSTARRS)

Classification: Chiron-type Comet          SPK-ID: 1003735

[ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters ]

[ show orbit diagram ]

Orbital Elements at Epoch 2457785.5 (2017-Feb-01.0) TDB Reference: JPL 14 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .1804389828275273 7.4417e-06   a 12.150254615787 0.00018697 au q 9.957875031818922 6.704e-05 au i 9.046144236347711 4.6644e-05 deg node 145.8645384329216 0.00015579 deg peri 254.7881434680575 0.0027215 deg M 318.4435044274125 0.0027357 deg tp 2459571.218143409214 (2021-Dec-22.71814341) 0.076746 TDB period 15469.50778138701 42.35 0.35708 0.0009776 d yr n .0232715872468259 5.3717e-07 deg/d Q 14.34263419975507 0.00022071 au

Orbit Determination Parameters    # obs. used (total)      213      data-arc span      3371 days (9.23 yr)      first obs. used      2011-07-27      last obs. used      2020-10-18      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      3      norm. resid. RMS      .22122      source      ORB      producer      Otto Matic      solution date      2020-Oct-26 19:43:48   Additional Information  Earth MOID = 8.97742 au   Jupiter MOID = 5.06363 au   T_jup = 3.397

I tried to investigate the cometary nature running a backward integration using Mercury6 software by E. Chambers.

I generated 100 clones trying to achieve the same nominal orbital parameters and uncertainty as above.

	Clones			Target
	mean	sd		mean	sd
q	9.95787410878	6.694624e-05		9.95787503182	6.704e-05
e	0.18043892764	7.50991e-06		0.18043898283	7.4417e-06
i	9.04614599334	4.699782e-05		9.04614423635	4.6644e-05
peri	254.78819470552	0.00271470415		254.78814346806	0.0027215
node	145.86454031167	0.0001548109		145.86453843292	0.00015579
tp	2459571.21974672	0.07635106812		2459571.21814341	0.076746

Simulation parameters

integration algorithm: Bulirsch-Stoer

ejection distance from the solar system: 100 au

simulation start time: 2020 A.D.

simulation stop time: -1d8 (about -274K years BC)

Simulation results

A "true" cometary origin is confirmed for 29 clones, in fact, they entered the solar system from a distance greater than 100 au according to this arrival time distribution

In order to read the following plots, you need to know that:

the simulated time is divided into 50 intervals , in every interval and for every clone I have calculated the min perihelium and then I have plotted the interquantile distribution in that interval.

Similar approach for max aphelium, max eccentricity, ... etc.

Perihelium q

Aphelium Q

Eccentricity e

Inclination i

Peri w

Node om

Kind Regards,

Alessandro Odasso

Centaur 2020 MK4

 See Sam Deen's post on MPML

JPL Small-Body Database Browser

(2020 MK4)

Classification: Centaur          SPK-ID: 54028098

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

[ show orbit diagram ]

Orbital Elements at Epoch 2459000.5 (2020-May-31.0) TDB Reference: JPL 4 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .02195188337952747 0.00026496   a 6.158612875846196 0.00097828 au q 6.023419724215964 0.0020101 au i 6.667359451314571 0.00055296 deg node 2.340270538083764 0.0080184 deg peri 176.0179742158394 0.82761 deg M 112.9081690495819 0.85696 deg tp 2457249.663268073103 (2015-Aug-15.16326807) 12.903 TDB period 5582.423564205491 15.28 1.3301 0.003642 d yr n .06448811987472979 1.5366e-05 deg/d Q 6.293806027476427 0.00099976 au

Orbit Determination Parameters    # obs. used (total)      99      data-arc span      70 days      first obs. used      2020-06-15      last obs. used      2020-08-24      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      5      norm. resid. RMS      .42831      source      ORB      producer      Otto Matic      solution date      2020-Sep-07 09:41:28   Additional Information  Earth MOID = 5.02655 au   Jupiter MOID = .574557 au   T_jup = 3.006

Backward simulation 

100 clones generated:

	Clones			Target
	mean	sd		mean	sd
q	6.02351360763	0.00201082117		6.02341972422	0.0020101
e	0.02194045805	0.00026498393		0.02195188338	0.00026496
i	6.66737828519	0.00055323416		6.66735945131	0.00055296
peri	176.0244406455	0.82839257994		176.01797421584	0.82761
node	2.33984409116	0.00803481217		2.34027053808	0.0080184
tp	2457249.73101293	12.90996695426		2457249.66326807	12.903

The simulation was performed with Mercury6 simulator from J. E. Chambers.

The time interval from now back to 180K years ago was investigated.

The following clones appear yo have a cometary origin because they entered the solar system from a distance greater than 100 AU:

 MK87     ejected at      -3992 10 15.95739

 MK25     ejected at     -11386  5  6.63099

 MK69     ejected at     -11668  7 18.91268

 MK65     ejected at     -13267  1  2.82563

 MK66     ejected at     -13674  4 27.93527

 MK57     ejected at     -18216 12  4.27966

 MK16     ejected at     -22393 11 16.92234

 MK56     ejected at     -24538  5 23.00058

 MK100    ejected at     -24872 11  3.71037

 MK33     ejected at     -25672  8 29.33118

 MK14     ejected at     -26908 10 12.16609

 MK79     ejected at     -27042  1 10.47236

 MK59     ejected at     -27477  5 21.28744

 MK41     ejected at     -28193 12 31.77309

 MK50     ejected at     -28229  6 24.30764

 MK70     ejected at     -30832  2 18.82571

 MK86     ejected at     -33366 10  3.35722

 MK83     ejected at     -36505  4 22.99516

 MK11     ejected at     -42971  5 25.41050

 MK52     ejected at     -43914  6 24.36384

 MK15     ejected at     -45152 10 31.83684

 MK75     ejected at     -46261  3 18.78421

 MK20     ejected at     -46400  2 13.00000

 MK24     ejected at     -52981  8  4.81971

 MK39     ejected at     -54008  2  8.41040

 MK44     ejected at     -54032  5 23.55889

 MK36     ejected at     -56218  3  9.00000

 MK13     ejected at     -58238  6 27.08479

 MK58     ejected at     -61702  8 22.73425

 MK73     ejected at     -63075  1 20.75482

 MK63     ejected at     -65472  1 22.91155

 MK98     ejected at     -69333 10 24.33742

 MK19     ejected at     -70475  6 20.82479

 MK43     ejected at     -76905  9 26.09250

 MK78     ejected at     -81576  4 16.15310

 MK5      ejected at     -81766  3 24.20996

 MK27     ejected at     -81906  2 20.04496

 MK88     ejected at     -82300 11  9.76100

 MK84     ejected at     -82695  7 11.00000

 MK53     ejected at     -83313  4 14.51728

 MK64     ejected at     -85820  2 27.87065

 MK51     ejected at     -86401  8 29.32042

 MK7      ejected at     -90081  6 21.71342

 MK61     ejected at     -94034  3 26.84777

 MK10     ejected at     -95133 10 16.26793

 MK92     ejected at     -96254  6 24.13705

 MK68     ejected at     -97012  6 11.67088

 MK21     ejected at     -97348  9 22.80596

 MK34     ejected at     -97977  4  4.52762

 MK90     ejected at    -105289  3  9.80638

 MK32     ejected at    -107468  8 18.14496

 MK3      ejected at    -110733 12 20.80791

 MK40     ejected at    -113571 10  4.91780

 MK76     ejected at    -116794  4 30.66382

 MK38     ejected at    -122623  3 31.58393

 MK8      ejected at    -123524  2 13.51981

 MK80     ejected at    -124886  5  8.57397

 MK9      ejected at    -141230 12 15.21267

 MK91     ejected at    -142117  5 23.59862

 MK97     ejected at    -151011  6 25.85088

 MK82     ejected at    -158864 10 19.14006

 MK81     ejected at    -160420  4 20.25107

  was hit by MK17     at    -168177  7  5.2

 MK31     ejected at    -176722 11  5.97609

Cheers,

Alessandro Odasso

comet P/2019 LD2 (ATLAS)

In this mpml message, Sam Deen pointed out that this asteroid in not a Jupyter Troian  but probably a 4-8 km size long period comet that in February 2017 achieved a perihelium low enough to start outgassing .

In this simulation, Tony Dunn confirmed that 2019 LD2 is not a Troian, Greek or Hilda but a comet that regulary makes very close passed to Jupiter and Saturn.

In fact, the object has now been given a cometary designation P/2019 LD2 (ATLAS)

For what's worth due to the uncertainty, I also tried a couple of day ago  to see when the comet entered the solar system assuming a conventional distance greater than 100 au .

I simulated 100 clones in the past 280K years (Mercury6 software by John E. Chambers - Bulirsch-Stoer integration, intial timestep 0.05 days).

	Clones			Target
	mean	sd		mean	sd
q	4.57802477541	1.671146e-05		4.57801992309	1.6782e-05
e	0.13528015709	9.88572e-06		0.13527811197	9.8665e-06
i	11.55192320685	1.746557e-05		11.55192194572	1.7512e-05
peri	123.44833869054	0.00209362353		123.44893096687	0.0021043
node	179.74537221523	0.00017704315		179.74536895343	0.00017777
tp	2458949.96748775	0.01979864266		2458949.97292011	0.01993

**In the meantime, the nominal parameters have been updated but I hope that this does not radically change the macroscopic behaviour.

The nominal comet entered the solar system about 32K years ago, while the most recent date for a clone to enter the solar system was about 4K years ago.

This is the overall time distribution (being a backward simulation, the clones are "ejected" from the point of view of the simulator...):

At first glance, it seemed to me that some clones entered the solar system on a hyperbolic trajectory (total energy > 0) but this is not the case.

This would be quite strange if real, many thanks to Marshall Eubanks for noting this aspect.

Looking better, we see situations like this, where you can see that the simulation does not end with the clone on a hyperbolic trajectory even if that orbit was apparently achieved in a given moment:

Time	a	e	i	peri	node	long
311100.5	11.10955	0.56037	12.7835	207.0631	179.7592	26.8223
311000.5	12.17985	0.599077	13.1885	206.6135	180.4985	27.112
310900.5	-6.12701	1.813375	2.8379	213.9255	160.4411	14.3666
310800.5	126.90366	0.960378	4.4906	347.4277	20.2166	7.6443
310700.5	58.4381	0.913926	4.4251	347.0157	20.7539	7.7696
310600.5	48.95964	0.897233	4.3941	346.7163	21.1435	7.8598

The reason why this can happen was explained by Jean Meeus:

"When one calculates the HELIOCENTRIC orbit near the time the object is close to Jupiter, one obtains a hyperbolic orbit, that however is meaningless because at that instant the object is attracted more by Jupiter than by the Sun."

So in the following plots, it is safe to ignore the brief moments where the orbit has apparently a total energy > 0 

This is the v_infinity distribution:   plot not meaninfgful (it just "captures" a brief close encounter moment):

Mimimum perihelium distribution

Due to the wild uncertainty, the minimum perihelium could have been very low: in fact, about 10% of the clones could have had a close pass with Earth but not sooner than 4K years ago.

Max eccentricity distribution

(dis-regard the points with eccentricity > 1)

Kind Regards,

Alessandro Odasso