Perihelion advance and Yarkovsky drift of near-Earth asteroids: asteroid physical properties, solar oblateness, and general relativity

Funding

This 5-year investigation is supported by the Division of Astronomical Sciences of the National Science Foundation.

Abstract

Drs. Jean-Luc Margot and Jon Giorgini will obtain and interpret high-precision radar range measurements of twelve near-Earth asteroids (NEAs) that have trajectories strongly affected by the light of the Sun, the shape of the Sun, and general relativistic effects. Asteroid orbits are influenced by the absorption and reemission of solar energy, the so-called Yarkovsky effect. These changes to the motion will be quantified with the radar measurements in order to constrain the densities, compositions, and thermal properties of NEAs. Other perturbations to NEA orbits arise as a result of the non-uniformity of the gravitational field of the oblate Sun. The ranging data to the twelve NEAs will provide a direct probe of the mass distribution in the Suns interior by measuring changes to the asteroid trajectories. Radar tests of general relativity (GR) will also be improved by quantifying the perihelion advance of NEAs that reach deep inside the gravitational well of the Sun. The GR effects can be separated from the effects of oblateness as they have a different dependence on the size, eccentricity, and inclination of the NEA orbits. Both GR and oblateness effects can be separated from the distinct signature of the Yarkovsky drift. Most of the measurements will be performed with the planetary radar on the Arecibo telescope. Analysis of the results will make use of orbital determination software at JPL. High precision measurements in this extreme dynamical regime will provide unique observational constraints and will test current models of asteroid physics, solar physics, and fundamental physics.

Objects observed so far

Object	Date	Comments
1999 MN	2004 Jul 22-23
1999 MN	2005 May 30-31
2000 BD19	2006 Feb 26-27
2000 BD19	2007 Dec 22-23
2000 EE14	2007 Mar 04-06
2000 EE14	2008 Feb 28-29

Potential targets (partial list)

Object            Rate ("/cy)  H          Apparitions			a      e      i
     2000 BD19      26.85      16.7       6 7 11 15 20			0.876  0.895  25.7
     2006 CJ        23.72      20.1       12 17 22
     1999 KW4       22.07      16.6       3 4 15 16 17 18 19		0.642  0.688  38.9
     1999 MN        18.44      21.6       4 5 9 10			0.674  0.665   2.0
     1999 FK21      16.19      18.4       (9) 11 (16) 18 
     2000 EE14      15.04      16.9       7 8 14 15			0.662  0.533  26.5
     2000 NL10      14.44      15.5       (8) 9 (12) 16
     1994 XL1       14.40      20.8       11 16 22   
     1989 VA        13.10      17.8       7 12 17     
     2002 QY6       12.44      19.3       10 (11) (13)
     2000 WO107     12.39      19.1       11 (13) 20
     2002 AJ129     10.70      18.4       (8) 10 18
3200 Phaethon       10.13      14.6       7 (13) 16 17
1566 Icarus         10.06      16.9       (6) 15
5786 Talos           9.97      17.0       10 11 19 20
     1991 VE         9.18      18.2       10 12 15 20

References

J.L. Margot, Candidate Asteroids for Discerning General Relativity and Solar Oblateness, American Astronomical Society, DDA meeting #34, #06.13, 2003.

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jlm@astro.cornell.edu