J/A+A/646/A182 Non-gravitational effects in retrograde orbits (Kankiewicz+ 2021)
Impact of non-gravitational effects on chaotic properties of retrograde orbits.
Kankiewicz P., Wlodarczyk I.
<Astron. Astrophys. 646, A182 (2021)>
=2021A&A...646A.182K 2021A&A...646A.182K (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Minor planets
Keywords: minor planets, asteroids: general - comets: general -
methods: numerical
Abstract:
Dynamical studies of asteroid populations in retrograde orbits, i.e.
with orbital inclinations greater than 90 degrees, are interesting
because the origin of such orbits is still unexplained. Generally, the
retrograde asteroids population includes mostly Centaurs and
transneptunian objects (TNOs). A special case is the Near Earth Object
(343158) 2009 HC82 from the Apollo group. Another interesting object
is the comet 333P/LINEAR, which for several years was considered as
the second retrograde object approaching Earth. One more comet in
retrograde orbit, 161P Hartley/IRAS appears to be an object of similar
type. Thanks to the large amount of observational data for these two
comets, we tested various models of cometary non-gravitational forces
applied to their dynamics.
The goal was to estimate which of non-gravitational perturbations
could affect the stability of retrograde bodies. In principle, we
study the local stability by measuring the divergence of nearby
orbits.
We have numerically determined Lyapunov chaotic indicators (LCI) and
the associated Lyapunov times (LT). This time, our calculations of
these parameters were extended by more advanced models of
non-gravitational perturbations (i.e. Yarkovsky drift and in selected
cases cometary forces). This allowed estimating the chaos in the
Lyapunov sense.
We found that the Yarkovsky effect for obliquities of gamma=0° and
gamma=180° can change LT substantially. In most cases, for the
prograde rotation, we received more stable solutions. Moreover, we
confirmed the role of retrograde resonances in this process.
Additionally, the studied cometary effects also significantly
influence the long-term behaviour of the selected comets. LT can reach
values from 100 to over 1000 years.
All results indicate that the use of models with non-gravitational
effects for retrograde bodies is clearly justified.
Description:
The file contains the table of estimated Lyapunov Times (LT) of of 31
numbered and multi-opposition retrograde asteroids.
LT were obtained by three models: gravitational, with Yarkovsky
effect, assuming prograde rotation and with Yarkovsky effect, assuming
retrograde rotation. In specific cases, due to the lack of convergence
in the numerical estimation procedure, some results are preceded by a
≥ sign, which can be interpreted as a time longer than or equal to
the obtained value.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 111 31 Lyapunov Times of retrograde asteroids
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 27 A27 --- Name Asteroid name
28- 32 F5.1 deg i Inclination of orbit
34- 40 F7.2 au a Semimajor axis
43- 47 F5.3 --- e Eccentricity
50- 54 F5.2 mag H Absolute magnitude
56- 61 F6.2 km D Diameter
64 A1 --- n_D [J] note on diameter (1)
67- 68 A2 --- n_LT [≥] remark on convergency of the
Lyapunov Time (gravitational model) (2)
69- 74 E6.2 yr LT Lyapunov Time (gravitational model)
76- 77 A2 --- n_LT0 [≥] remark on convergency of the
Lyapunov Time (Yarkovsky forces model,
obliquity = 0 deg.) (3)
78- 83 E6.2 yr LT0 Lyapunov Time (Yarkovsky forces model,
obliquity = 0 deg.)
85- 86 A2 --- n_LT180 [≥] remark on convergency of the
Lyapunov Time (Yarkovsky forces model,
obliquity = 180 deg.) (4)
87- 92 E6.2 yr LT180 Lyapunov Time (Yarkovsky forces model,
obliquity = 180 deg.)
95-101 E7.2 yr dLT0 Difference in Lyapunov Time values: LT0-LT
105-111 E7.2 yr dLT180 Difference in Lyapunov Time values: LT180-LT
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Note (1): Note on diameter as follows:
J = Diameter values taken from JPL Small Body Database.
If blank, approximate diameters were estimated with H and average albedo.
Note (2): If this field is filled by a '≥' sign, LT value can be interpreted
as longer than or equal to the obtained value.
Note (3): If this field is filled by a '≥' sign, LT0 value can be interpreted
as longer than or equal to the obtained value.
Note (4): If this field is filled by a '≥' sign, LT180 value can be interpreted
as longer than or equal to the obtained value.
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Acknowledgements:
Pawel Kankiewicz, pawel.kankiewicz(at)ujk.edu.pl
(End) Patricia Vannier [CDS] 25-Dec-2020