Blog Archive

Sunday, August 20, 2017

Hilda Asteroid 2017 OJ65 - an old TNO?

This object is currently an Hilda asteroid.

I run a simulation using the nominal orbital parameters read from JPL (Horizons Web Interface).

Uncertainty condition code: 0

Mercury6 simulator: configuration
More about the orbit simulator "A Hybrid Symplectic Integrator that Permits Close Encounters between Massive Bodies'' can be found here.

Main integration parameters:

   Algorithm: Bulirsch-Stoer (conservative systems)

   Integration start epoch:         2458000.5000000 days
   Integration stop  epoch:        -10^8 days
   Output interval:                     100.000 days
   Output precision:                   medium
   Initial timestep:                      0.100 days
   Accuracy parameter:             1.0000E-12
   Ejection distance:                  1.0000E+02 AU

Simulation results

This plot has been made using the R-package.



This seems to show that this asteroid was previously a TNO.

Kind Regards,
Alessandro Odasso

Friday, August 18, 2017

Asteroid 2017 DQ15

Asteroid 2017 DQ15 is a NEO (Apollo) displayed in the list of objects with a comet-like orbit maintained by Y. Fernandez.

Orbital Elements at Epoch 2458000.5 (2017-Sep-04.0) TDB
Reference: JPL 7 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .7272164269790051 1.279e-05
a 2.823784780342436 0.00011852 au
q .7702821018241148 3.8782e-06 au
i 20.18557131636563 0.00017551 deg
node 272.8777420846461 0.00046785 deg
peri 350.4179039106148 0.00040687 deg
M 22.44168793940112 0.0013623 deg
tp 2457892.456452631231
(2017-May-18.95645263)
0.00026204 JED
period 1733.18857109974
4.75
0.10912
0.0002988
d
yr
n .207709654911683 1.3077e-05 deg/d
Q 4.877287458860757 0.00020471 au

Orbit Determination Parameters
   # obs. used (total)      43  
   data-arc span      187 days  
   first obs. used      2017-02-10  
   last obs. used      2017-08-16  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      5  
   fit RMS      .50315  
   data source      ORB  
   producer      Otto Matic  
   solution date      2017-Aug-17 06:19:02  

Additional Information
 Earth MOID = .22774 au 
 Jupiter MOID = .339108 au 
 T_jup = 2.792 


Based on the nominal orbital parameters and uncertainty, I generated 100 clones with an R script and then I used the Mercury6 simulator by J.E. Chambers to investigate what happened in the last 10^8 days.

Mercury6 simulator: configuration
More about the program "A Hybrid Symplectic Integrator that Permits Close Encounters between Massive Bodies'' can be found here.

Main integration parameters:

   Algorithm: Bulirsch-Stoer (conservative systems)

   Integration start epoch:         2458000.5000000 days
   Integration stop  epoch:        -10^8 days
   Output interval:                     100.000 days
   Output precision:                   medium
   Initial timestep:                      0.100 days
   Accuracy parameter:             1.0000E-12
   Ejection distance:                  1.0000E+02 AU

Simulation results
As seen above, the "ejection distance" used to claim that an asteroid has arrived from the outskirts of the solar system is 100 AU.
The simulation shows that there is a good likelyhood that the asteroid has a cometary origin:
  • 47 out of 100 clones arrived from a distance greater than 100 AU in the last 10^8 days
  • 4 out of 100 clones would have "collided" with the sun 

The most recent arrival time was about 7906 B.C.
The mean arrival time was about 139274 B.C.
The less recent arrival time was about 268318 B.C.


The arrival time distribution of the 47 clones that were likely to be comets is shown below:




Kind Regards,
Alessandro Odasso

Asteroid (2017 OC9) - an extinct QHC?

I wonder whether Hilda asteroid (2017 OC9) was once a comet.

Almost two months ago, there was a nice example of a Hilda asteroid that showed a cometary activity:

Cometary behaviour of Hilda asteroid  (457175)  2008 GO98
As described here by GAMP's (Gruppo Astrofili Montagna Pistoiese, i.e. Pistoia Mountains Astronomical Observatory - MPC code 104) member Paolo Bacci, on the night of July 3rd, 2017, Mt. Lemmon Survey (G96) found that a Hilda asteroid (457175)  2008 GO98, at the time with a brightness of ~16.5 mag, showed a widespread 7/8" coma and a tail with a length of ~15" with PA 260°. 

Observations were subsequently confirmed by the observatory of the Steward Observatory, Mt. Lemmon Station (I52).

The Minor Planet Center on the same day published MPEC 2017-N50, announcing the asteroid cometary activity.

From the Pistoia Mountain Astronomical Observatory (code MPC 104), GAMP members Paolo Bacci and Martina Maestripieri  captured 50  images of the asteroids and they found that the asteroid showed a diffused ~ 16'' arc coma and a long tail ~ 15.3" .

This fact is not completely unexpected.

As described in the paper "Comet candidates among quasi-Hilda objects", there is a dynamical criteria to identify potential candidates in the unstable quasi-Hilda region, the so called Toth rule based on the calculation of horizontal and vertical components (k,h) of eccentricity in Lagrangian elements.

In that paper Asteroid (457175)  2008 GO98 was identified as a potential candidate.

More about the nature of this object can be found in this article  (thanks to David Rich for showing me his blog).


Hilda asteroid (2017 OC9)


It seems to me that this Hilda object satisfies the Toth rule so it might be a candidate to be an extinct comet .

I made a simulation using the Mercury6 simulator ("A Hybrid Symplectic Integrator that Permits Close Encounters between Massive Bodies''. Monthly Notices of the Royal Astronomical Society, vol 304, pp793-799.).

The object uncertainty is still extremely high (orbit condition code 9), so the simulation based only on the nominal parameters is far from being conclusive; anyway, just to have an idea of the possible behaviour, it seems that the object could have arrived from the outskirts of the solar system (100 AU) about 1,2 Millions years ago.

I would be interested to know from expert astromomers if this is a real possibility and if they think that this case deserves a deeper analysis when the orbit will be better known.

Kind Regards,
Alessandro Odasso


Monday, July 10, 2017

276353 (2002 UY20) vs 57202 (2001 QJ53)

276353 (2002 UY20) vs 57202 (2001 QJ53)

Same approach described in the previous posts.

276353 (2002 UY20)

Classification: Main-belt Asteroid          SPK-ID: 2276353
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 .1562105639420963 6.3914e-08
a 2.337601777404309 2.6617e-08 au
q 1.972443685483935 1.5861e-07 au
i 4.252343536114911 6.8871e-06 deg
node 23.41388838094758 0.0001045 deg
peri 35.95235952421835 0.00010784 deg
M 38.09017324814934 2.7256e-05 deg
tp 2457862.377424660816
(2017-Apr-18.87742466)
9.8187e-05 JED
period 1305.431897045054
3.57
2.2296e-05
6.104e-08
d
yr
n .2757708010773199 4.7101e-09 deg/d
Q 2.702759869324683 3.0775e-08 au
Orbit Determination Parameters
   # obs. used (total)      115  
   data-arc span      5111 days (13.99 yr)  
   first obs. used      2002-10-28  
   last obs. used      2016-10-25  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      0  
   fit RMS      .70803  
   data source      ORB  
   producer      Otto Matic  
   solution date      2017-Apr-10 16:21:05  

Additional Information
 Earth MOID = .986707 au 
 Jupiter MOID = 2.62843 au 
 T_jup = 3.546 

57202 (2001 QJ53)

Classification: Main-belt Asteroid          SPK-ID: 2057202
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 17 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .1557724906162496 4.4578e-08
a 2.338080038545681 1.0974e-08 au
q 1.973871487681283 1.03e-07 au
i 4.250626760813153 5.0566e-06 deg
node 23.42499161765863 6.5966e-05 deg
peri 36.16096420351912 6.8003e-05 deg
M 103.6361139081139 1.6156e-05 deg
tp 2457624.579415793553
(2016-Aug-24.07941579)
5.793e-05 JED
period 1305.832544380318
3.58
9.1935e-06
2.517e-08
d
yr
n .275686190813109 1.9409e-09 deg/d
Q 2.702288589410078 1.2683e-08 au
Orbit Determination Parameters
   # obs. used (total)      743  
   data-arc span      16797 days (45.99 yr)  
   first obs. used      1971-03-25  
   last obs. used      2017-03-20  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      0  
   fit RMS      .57656  
   data source      ORB  
   producer      Otto Matic  
   solution date      2017-Apr-11 18:07:27  

Additional Information
 Earth MOID = .988199 au 
 Jupiter MOID = 2.62768 au 
 T_jup = 3.546 

Simulation Results (note, Time 0 is JD 0 --> 4713 B.C.)



Kind Regards,
Alessandro Odasso

(2012 TQ236) vs 341874 (2008 GB53)

(2012 TQ236) vs 341874 (2008 GB53)

This is another interesting couple (same simulation approach described in the previous post).

(2012 TQ236)

Classification: Main-belt Asteroid          SPK-ID: 3612103
Ephemeris | Orbit Diagram | Orbital Elements | Physical Parameters ]

[ show orbit diagram ]

Orbital Elements at Epoch 2458000.5 (2017-Sep-04.0) TDB
Reference: JPL 6 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .1666400181863286 5.5861e-06
a 2.181322170293682 2.3565e-06 au
q 1.817826604165701 1.4148e-05 au
i 3.706000259833047 2.3889e-05 deg
node 130.8866173415038 0.00037736 deg
peri 225.066713022466 0.0031505 deg
M 207.0510430328395 0.0025163 deg
tp 2458500.444927002519
(2019-Jan-16.94492700)
0.0088584 JED
period 1176.73358020709
3.22
0.0019068
5.221e-06
d
yr
n .3059316110760132 4.9574e-07 deg/d
Q 2.544817736421663 2.7491e-06 au
Orbit Determination Parameters
   # obs. used (total)      25  
   data-arc span      1078 days (2.95 yr)  
   first obs. used      2012-09-23  
   last obs. used      2015-09-06  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      3  
   fit RMS      .65133  
   data source      ORB  
   producer      Otto Matic  
   solution date      2017-Apr-07 17:13:15  

Additional Information
 Earth MOID = .814749 au 
 Jupiter MOID = 2.88145 au 
 T_jup = 3.660 

341874 (2008 GB53)

Classification: Main-belt Asteroid          SPK-ID: 2341874
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 4 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .1669528069531998 1.1233e-07
a 2.180875946944555 3.0388e-08 au
q 1.816772585985444 2.5263e-07 au
i 3.706556681959036 1.2083e-05 deg
node 130.8943547687225 0.0001365 deg
peri 225.0440620302201 0.00014182 deg
M 182.8634290772902 3.7363e-05 deg
tp 2458579.329428649479
(2019-Apr-05.82942865)
0.00013018 JED
period 1176.372519962207
3.22
2.4587e-05
6.732e-08
d
yr
n .306025509684267 6.3962e-09 deg/d
Q 2.544979307903666 3.5462e-08 au
Orbit Determination Parameters
   # obs. used (total)      78  
   data-arc span      5842 days (15.99 yr)  
   first obs. used      2001-02-02  
   last obs. used      2017-01-31  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      0  
   fit RMS      .48759  
   data source      ORB  
   producer      Otto Matic  
   solution date      2017-Apr-10 08:47:34  

Additional Information
 Earth MOID = .813692 au 
 Jupiter MOID = 2.88132 au 
 T_jup = 3.660 

Simulation results ((note, Time 0 is JD 0 --> 4713 B.C.)

Kind Regards,
Alessandro Odasso