2018 BE7 - an old comet?

Sam Deen has identified another  "imposter trojoan": 2018 BE7 

Andrew Walker has also analyzed its orbital characteristics.

I describe here the result of a backward simulation that shows that this object (as well as 2015 OL106) has 

the potential to be an old comet...not clear to me if this is just due to the high orbit uncertainty.

(2018 BE7)

Classification: Jupiter Trojan          SPK-ID: 3799005

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

Orbital Elements at Epoch 2459000.5 (2020-May-31.0) TDB Reference: JPL 2 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .2517145998227567 0.00044326   a 5.27745894489277 0.0010489 au q 3.949045478498058 0.0015619 au i 31.00080732455304 0.005232 deg node 359.9407079502051 0.015479 deg peri 92.1666975695555 0.20747 deg M 84.22380191004567 0.089188 deg tp 2457964.480181911063 (2017-Jul-29.98018191) 1.3392 TDB period 4428.286613211319 12.12 1.3202 0.003615 d yr n .08129555095326904 2.4237e-05 deg/d Q 6.605872411287481 0.0013129 au

Orbit Determination Parameters    # obs. used (total)      24      data-arc span      38 days      first obs. used      2017-12-30      last obs. used      2018-02-06      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      5      norm. resid. RMS      .47737      source      ORB      producer      Otto Matic      solution date      2018-Mar-12 02:55:18   Additional Information  Earth MOID = 3.14677 au   Jupiter MOID = .0750553 au   T_jup = 2.657

Clones generation

	Clones			Target
	mean	sd		mean	sd
q	3.94904546224	0.00156467669		3.9490454785	0.0015619
e	0.25172016357	0.00044422146		0.25171459982	0.00044326
i	31.00103111513	0.00522676417		31.00080732455	0.005232
peri	92.15222161758	0.20728675619		92.16669756956	0.20747
node	359.94053458161	0.01544262868		359.9407079502	0.015479
tp	2457964.37314359	1.33721191964		2457964.48018191	1.3392

100 clones were generated as above

Simulation parameters

Simulator Mercury6 by J. E. Chambers.

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

) 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

64 out of 100 clones entered the solar system from a distance greater than 100 AU

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

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	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