Abstract
The observationally complete sample of the main belt asteroids nowspans more than two orders of magnitude in size and numbers more than 64 000 (excluding collisional family members). We undertook an analysis of asteroids' eccentricities and their interpretation with simple physical models. We find that a century old conclusion that the asteroids' eccentricities follow a Rayleigh distribution holds for the osculating eccentricities of large asteroids, but the proper eccentricities deviate from a Rayleigh distribution; there is a deficit of eccentricities smaller than~0.1 and an excess of larger eccentricities. We further find that the proper eccentricities do not depend significantly on asteroid size but have strong dependence on heliocentric distance; the outer asteroid belt follows a Rayleigh distribution, but the inner belt is strikingly different. Eccentricities in the inner belt can be modelled as a vector sum of a primordial eccentricity vector of random orientation and magnitude drawn from a Rayleigh distribution of parameter ~0.06, and an excitation of random phase and magnitude ~0.13. These results imply that when a late dynamical excitation of the asteroids occurred, it was independent of asteroid size and was stronger in the inner belt than in the outer belt. We discuss implications for the primordial asteroid belt and suggest that the observationally complete sample size of main belt asteroids is large enough that more sophisticated model-fitting of the eccentricities is warranted and could serve to test alternative theoretical models of the dynamical excitation history of asteroids and its links to the migration history of the giant planets.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 4381-4389 |
| Number of pages | 9 |
| Journal | Monthly Notices of the Royal Astronomical Society |
| Volume | 465 |
| Issue number | 4 |
| DOIs | |
| State | Published - 2017 |
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Keywords
- Celestial mechanics
- Minor planets, asteroids: general
- Planets and satellites: dynamical evolution and stability
- Planets and satellites: formation
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science
Cite this
Eccentricity distribution in the main asteroid belt. / Malhotra, Renu; Wang, Xianyu.
In: Monthly Notices of the Royal Astronomical Society, Vol. 465, No. 4, 2017, p. 4381-4389.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Eccentricity distribution in the main asteroid belt
AU - Malhotra, Renu
AU - Wang, Xianyu
PY - 2017
Y1 - 2017
N2 - The observationally complete sample of the main belt asteroids nowspans more than two orders of magnitude in size and numbers more than 64 000 (excluding collisional family members). We undertook an analysis of asteroids' eccentricities and their interpretation with simple physical models. We find that a century old conclusion that the asteroids' eccentricities follow a Rayleigh distribution holds for the osculating eccentricities of large asteroids, but the proper eccentricities deviate from a Rayleigh distribution; there is a deficit of eccentricities smaller than~0.1 and an excess of larger eccentricities. We further find that the proper eccentricities do not depend significantly on asteroid size but have strong dependence on heliocentric distance; the outer asteroid belt follows a Rayleigh distribution, but the inner belt is strikingly different. Eccentricities in the inner belt can be modelled as a vector sum of a primordial eccentricity vector of random orientation and magnitude drawn from a Rayleigh distribution of parameter ~0.06, and an excitation of random phase and magnitude ~0.13. These results imply that when a late dynamical excitation of the asteroids occurred, it was independent of asteroid size and was stronger in the inner belt than in the outer belt. We discuss implications for the primordial asteroid belt and suggest that the observationally complete sample size of main belt asteroids is large enough that more sophisticated model-fitting of the eccentricities is warranted and could serve to test alternative theoretical models of the dynamical excitation history of asteroids and its links to the migration history of the giant planets.
AB - The observationally complete sample of the main belt asteroids nowspans more than two orders of magnitude in size and numbers more than 64 000 (excluding collisional family members). We undertook an analysis of asteroids' eccentricities and their interpretation with simple physical models. We find that a century old conclusion that the asteroids' eccentricities follow a Rayleigh distribution holds for the osculating eccentricities of large asteroids, but the proper eccentricities deviate from a Rayleigh distribution; there is a deficit of eccentricities smaller than~0.1 and an excess of larger eccentricities. We further find that the proper eccentricities do not depend significantly on asteroid size but have strong dependence on heliocentric distance; the outer asteroid belt follows a Rayleigh distribution, but the inner belt is strikingly different. Eccentricities in the inner belt can be modelled as a vector sum of a primordial eccentricity vector of random orientation and magnitude drawn from a Rayleigh distribution of parameter ~0.06, and an excitation of random phase and magnitude ~0.13. These results imply that when a late dynamical excitation of the asteroids occurred, it was independent of asteroid size and was stronger in the inner belt than in the outer belt. We discuss implications for the primordial asteroid belt and suggest that the observationally complete sample size of main belt asteroids is large enough that more sophisticated model-fitting of the eccentricities is warranted and could serve to test alternative theoretical models of the dynamical excitation history of asteroids and its links to the migration history of the giant planets.
KW - Celestial mechanics
KW - Minor planets, asteroids: general
KW - Planets and satellites: dynamical evolution and stability
KW - Planets and satellites: formation
UR - http://www.scopus.com/inward/record.url?scp=85014845494&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85014845494&partnerID=8YFLogxK
U2 - 10.1093/mnras/stw3009
DO - 10.1093/mnras/stw3009
M3 - Article
AN - SCOPUS:85014845494
VL - 465
SP - 4381
EP - 4389
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 4
ER -