Journal Article

Dynamical erosion of asteroid groups in the region of the Phocaea family

V. Carruba

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 403, issue 4, pages 1834-1848
Published in print April 2010 | ISSN: 0035-8711
Published online April 2010 | e-ISSN: 1365-2966 | DOI:
Dynamical erosion of asteroid groups in the region of the Phocaea family

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In a previous paper, the current state of knowledge of the region containing the Phocaea dynamical family was revised. Here, the dynamical evolution and possible origin of the Phocaea dynamical family and asteroid groups in the region are investigated. First, I study the case of asteroids at high eccentricity (e > 0.31). I find that these objects are unstable because of encounters with Mars on time-scales of up to 270 Myr. The minimum time needed by members of the Phocaea classical family to reach the orbital locations of these objects, 370 Myr, can be used to set a lower limit on the age of the Phocaea family.

Next, attention is focused on the chaotic layer previously identified near the ν6 secular resonance border. Using analytical and numerical tools, I find that the presence of the ν6 secular resonance forces asteroids with |gg6| < 2.55 arcsec yr−1 to reach eccentricities high enough to allow them to experience deep, close encounters with Mars. Results of the analytical model of Yoshikawa and of my numerical simulations fully explain the low-inclination chaotic region found by Carruba.

Finally, I investigate the long-term stability of the minor families and clumps identified in the previous paper, with particular emphasis on a clump only identifiable in the domain of proper frequencies (n, g, gs) around (6246) Komurotoru. I find that while the clumps identified in the space of proper elements quickly disperse when the Yarkovsky effect is considered, the family around (19536) is still observable for time-scales of more than 50 Myr. The (6246) clump, characterized by its interaction with the ν516 and 2ν6−ν16 secular resonances, is robust on time-scales of 50 Myr. I confirm that this group may be the first clump ever detected in the frequency domain that can be associated with a real collisional event.

Keywords: celestial mechanics; minor planets, asteroids

Journal Article.  9930 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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