2000 BD19
2000 BD19
Background
2000 BD19 is interesting because among all the numbered near-Earth
asteroids (NEAs), it comes closest to the Sun. This extreme
trajectory puts 2000 BD19 in an unusual dynamical class where various
perturbations strongly affect the orientation of the orbit. With a
change in orbit orientation ('perihelion shift rate') of 27 arcseconds
per century, this near-Earth object (NEO) is one of our best
candidates for measuring the perihelion shift due to general
relativity (GR) and the oblate Sun
[Margot, 2003].
These observations represent one component of a larger program in
which the orbits of a dozen NEOs are monitored over several years to
reduce uncertainties on GR parameters and to provide a dynamical
measurement or upper bound on the gravitational quadrupole moment of
the Sun (J2). Considerable improvements over previous studies
involving Mercury and Icarus are expected because 1) several
newly-discovered asteroids have orbits offering a better sensitivity
to the solar J2, 2) our sample incorporates a range of heliocentric
distances and inclinations that can unambiguously separate GR and J2
effects, 3) the center of mass locations of small bodies is more
accurately determined than that of Mercury.
By obtaining precise radar astrometry for a number of objects at
several apparitions, we can disentangle Yarkovsky, GR, and solar J2
perturbations on the orbit.
2000 BD19 (a = 0.876, e = 0.895, i = 25.7 deg) has an orbital period
of 0.82 years, perihelion at 0.092 AU (only 20 solar radii) and
aphelion at 1.66 AU. The object was detected during the 2006 and 2007
approaches. The 2011 approaches provides another good opportunity for
astrometry (SNR/run in excess of 5) while the 2020 approach represents
the best opportunity for physical characterization (SNR/run in excess
of 100).
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Figure 1: Predicted rates of perihelion shift due to GR alone for a
number of newly discovered NEOs, compared to that of 1566 Icarus.
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Figure 2: Trajectories of 2000 BD19 (solid) and Earth (dashed) looking
down on the ecliptic plane. The Sun is at the origin and the vernal
equinox is in the positive X-direction. |
Return to the Dynamics of asteroids in Icarus-like orbits page.
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jlm@ess.ucla.edu
