1. Disintegrating Asteroid
P/2013 R3
Akinsanmi A. Babatunde
Department of Astronomy
University of Porto
Paper by Jewitt et al (2014)
AST 4007, October 2015
Akinsanmi A. Babatunde (University of Porto) Disintegrating Asteroid AST 4007, October 2015 1 / 17
2. Outline
1 INTRODUCTION
2 PROPERTIES
3 OBSERVATION
4 MORPHOLOGY AND DYNAMICS
5 DISCUSSION
6 SUMMARY AND CONCLUSION
7 REFERENCES
Akinsanmi A. Babatunde (University of Porto) Disintegrating Asteroid AST 4007, October 2015 2 / 17
3. INTRODUCTION
Introduction
Splitting of the nuclei of comets into multiple components has been
frequently observed but, to date, no main-belt asteroid has been
observed to break-up.
Using the Hubble Space Telescope, we find that main-belt asteroid
P/2013 R3 consists of 10 or more distinct components, the largest up
to 200 m in radius
It was discovered on 2013 September 15
Akinsanmi A. Babatunde (University of Porto) Disintegrating Asteroid AST 4007, October 2015 3 / 17
4. PROPERTIES
Properties
Combination of asteroid-like orbit and comet-like appearance
Orbital semimajor axis: 3.033 AU (mars at 1.67 and Jupiter at 5AU)
Eccentricity: 0.273
Inclination: 0.90o
The components velocity of dispersion, (0.2 to 0.5 m/s)
Tisserand parameter relative to Jupiter: 3.18
Akinsanmi A. Babatunde (University of Porto) Disintegrating Asteroid AST 4007, October 2015 4 / 17
6. OBSERVATION
Observation
At the time of observation, R3 had just passed perihelion (R= 2.20
AU) on 2013 August 05
Keck data on 2013 October 01 and 02 revealed three distinct,
co-moving components embedded in a dust envelope extending > 30
in the projected anti-solar direction
WFC3 camera on HST whose 0.04 pixels each correspond to about
41 km at the distance of R3 was used to obtain five exposures of 348s
duration
Akinsanmi A. Babatunde (University of Porto) Disintegrating Asteroid AST 4007, October 2015 6 / 17
7. OBSERVATION
Figure: 2. Four epochs of R3 imaging from 2013
Akinsanmi A. Babatunde (University of Porto) Disintegrating Asteroid AST 4007, October 2015 7 / 17
8. MORPHOLOGY AND DYNAMICS
Morphology and dynamics
The image shows three groups of objects (A, B and C) initially
distributed along a line corresponding neither to the projected orbit
nor to the antisolar direction
The number of components, the sky-plane separations between them,
L and their brightnesses all change with time
We measured L and dL/dt for the components taken pair-wise, and
calculated nominal ages, τ = L/(dL/dt). The separations projected
to zero over dates in the range 140 ≤ DOY ≤ 270 (May to
September 2013)
Akinsanmi A. Babatunde (University of Porto) Disintegrating Asteroid AST 4007, October 2015 8 / 17
9. MORPHOLOGY AND DYNAMICS
Morphology and dynamics
By December 13 we detect ten (10) distinct components, most
formed by the disintegration of A and B.
Each discrete component appears embedded in a dust coma having
steep surface brightness gradients at the center.
The largest components, A1, A2, B1 and B2, all have re ∼ 0.2 km.
Akinsanmi A. Babatunde (University of Porto) Disintegrating Asteroid AST 4007, October 2015 9 / 17
10. MORPHOLOGY AND DYNAMICS
Morphology and dynamics
Because of dust contamination we only know that the nucleus radii
rn ≤ re
However, the photometric limits to rn are sufficient to show that
mutual gravitational interactions are negligible by calculating the Hill
sphere of a body having radius 200m.
So they can be assumed to move independently.
All images of R3 taken after October 01 show both a tail of particles
in the west of the nuclei, and tails of new material east.
Akinsanmi A. Babatunde (University of Porto) Disintegrating Asteroid AST 4007, October 2015 10 / 17
11. DISCUSSION
Possible Causes for Disintegration
Tidal stresses (R3 orbits too far)
internal pressure forces from gases generated by sublimation. (R3 too
cold)
Impact at origin (separation to slow)
Rotational bursting (most probable)- YORP effect
Akinsanmi A. Babatunde (University of Porto) Disintegrating Asteroid AST 4007, October 2015 11 / 17
12. DISCUSSION
Evidence for YORP
Absence of fast ejecta
Low velocity of dispersion
initially linear arrangement of similarly-sized fragments
Geometry of R3
Akinsanmi A. Babatunde (University of Porto) Disintegrating Asteroid AST 4007, October 2015 12 / 17
13. SUMMARY AND CONCLUSION
Summary
Asteroid P/2013 R3 is split into at least 10 fragments, the largest of
which have effective radii of 200 m
The fragments exhibit a velocity dispersion 0.2 to 0.5 m/s and their
motions indicate break-up dates in the range 2013 February to
September
The small velocity dispersion and staggered separation dates lead us
to suspect that P/2013 R3 is undergoing a rotationally triggered
disruption.
Akinsanmi A. Babatunde (University of Porto) Disintegrating Asteroid AST 4007, October 2015 13 / 17
14. SUMMARY AND CONCLUSION
Conclusion
Fresh observational effort is warranted to secure additional
high-resolution measurements of the motions of the fragments in
order to better constrain the dynamics of R3
Continued physical observations are also needed to isolate the
embedded nuclei, and so to determine their sizes, shapes and
rotational states.
Akinsanmi A. Babatunde (University of Porto) Disintegrating Asteroid AST 4007, October 2015 14 / 17
15. REFERENCES
Reference
Dressel, L. 2012, Wide Field Camera 3, HST Instrument Handbook,
Finson, M. J., Probstein, R. F. 1968, ApJ, 154, 327
Hill, R. E., Armstrong, J. D., Molina, M., Sato, H. 2013, Central
Bureau Electronic Telegrams, 3658, 1
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