Formation of asteroid pairs by rotational fission
Petr Pravec
(1)
,
David Vokrouhlicky
(2)
,
David Polishook
(3)
,
Daniel J. Scheeres
(4)
,
Alan W. Harris
(5)
,
Adrian Galad
(1, 6)
,
Ovidiu Vaduvescu
(7, 8)
,
Francisco Pozo
(8)
,
Angie Barr
(8)
,
Penelope Longa
(8)
,
Frédéric Vachier
(9)
,
Francois Colas
(9)
,
Donald P. Pray
(10)
,
Joseph Pollock
(11)
,
Dan Reichart
(12)
,
Kevin Ivarsen
(12)
,
Josh Haislip
(12)
,
Aaron Lacluyze
(12)
,
Peter Kusnirak
(1)
,
Tomas Henych
(1)
,
Franck Marchis
(13, 14)
,
Betsy Macomber
(13, 14)
,
Seth A. Jacobson
(15)
,
Yuri N. Krugly
(16)
,
Andrei V. Sergeev
(16)
,
Arnaud Leroy
(17)
1
ASU / CAS -
Astronomical Institute of the Czech Academy of Sciences
2 Institute of Astronomy [Prague]
3 Wise Observatory and Department of geophysics and planetary sciences
4 Department of Aerospace Engineering Sciences, Colorado Center for Astrodynamics Research
5 SSI - Space Science Institute [Boulder]
6 Modra Observatory
7 Isaac Newton Group of Telescopes
8 Instituto de Astronomıa
9 IMCCE - Institut de Mécanique Céleste et de Calcul des Ephémérides
10 Carbuncle Hill Observatory
11 Department of Physics and Astronomy [Boone]
12 Physics and Astronomy Department
13 Department of Astronomy [Berkeley]
14 SETI Institute
15 Department of Astrophysical and Planetary Sciences [Boulder]
16 Institute of Astronomy [Kharkiv]
17 Association T60, Observatoire Midi-Pyrénées
2 Institute of Astronomy [Prague]
3 Wise Observatory and Department of geophysics and planetary sciences
4 Department of Aerospace Engineering Sciences, Colorado Center for Astrodynamics Research
5 SSI - Space Science Institute [Boulder]
6 Modra Observatory
7 Isaac Newton Group of Telescopes
8 Instituto de Astronomıa
9 IMCCE - Institut de Mécanique Céleste et de Calcul des Ephémérides
10 Carbuncle Hill Observatory
11 Department of Physics and Astronomy [Boone]
12 Physics and Astronomy Department
13 Department of Astronomy [Berkeley]
14 SETI Institute
15 Department of Astrophysical and Planetary Sciences [Boulder]
16 Institute of Astronomy [Kharkiv]
17 Association T60, Observatoire Midi-Pyrénées
Petr Pravec
- Fonction : Auteur
- PersonId : 764767
- ORCID : 0000-0001-8434-9776
Francois Colas
- Fonction : Auteur
- PersonId : 742285
- IdHAL : jean-francois-colas
- ORCID : 0000-0002-0764-5042
- IdRef : 05759872X
Franck Marchis
- Fonction : Auteur
- PersonId : 755708
- ORCID : 0000-0001-7016-7277
Résumé
Asteroid pairs sharing similar heliocentric orbits were found recently. Backward integrations of their orbits indicated that they separated gently with low relative velocities, but did not provide additional insight into their formation mechanism. A previously hypothesized rotational fission process4 may explain their formation - critical predictions are that the mass ratios are less than about 0.2 and, as the mass ratio approaches this upper limit, the spin period of the larger body becomes long. Here we report photometric observations of a sample of asteroid pairs revealing that primaries of pairs with mass ratios much less than 0.2 rotate rapidly, near their critical fission frequency. As the mass ratio approaches 0.2, the primary period grows long. This occurs as the total energy of the system approaches zero requiring the asteroid pair to extract an increasing fraction of energy from the primary's spin in order to escape. We do not find asteroid pairs with mass ratios larger than 0.2. Rotationally fissioned systems beyond this limit have insufficient energy to disrupt. We conclude that asteroid pairs are formed by the rotational fission of a parent asteroid into a proto-binary system which subsequently disrupts under its own internal system dynamics soon after formation.