Radar Observations of Asteroid 2063 Bacchus

Details Radar Observations of Asteroid 2063 Bacchus Radar Observations of Asteroid 2063 Bacchus

Jun 1999

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1999icar..139..309b&link_type=abstract

Icarus, Volume 139, Issue Icarus, pp. 309-327.

Other

16

Scientific paper

We report Doppler-only (cw) and delay-Doppler radar observations of Bacchus obtained at Goldstone at a transmitter frequency of 8510 MHz (3.5 cm) on 1996 March 22, 24, and 29. Weighted, optimally filtered sums of cw and delay-Doppler echoes achieve signal-to-noise ratios of ~80 and ~25, respectively, and cover about 180 deg of rotation phase (period=14.90 h; Pravec et al. 1998). Our cw observations place up to four 2-Hz-resolution cells on Bacchus at echo powers greater than two standard deviations of the noise. Delay-Doppler observations typically place about ten 0.5-mus (75-m)x1-Hz cells on Bacchus above the same threshold. A weighted sum of all cw spectra gives an OC radar cross section of 0.12^+0.06_-0.02 km^2 and a circular polarization ratio of 0.21+/-0.01. The dispersion of the echoes in time delay indicates a lower bound on Bacchus' maximum pole-on breadth of 0.6 km that is consistent with the echo bandwidth (6+/-2 Hz) and rotation period. Echo spectra on March 22 and delay-Doppler images on all three days show a central deficit of echo power that provides strong evidence for a bifurcation in the shape. Inversion of delay-Doppler images, cw spectra, and optical lightcurves obtained at Ondr̆ejov Observatory yields single-lobe and two-lobe models that define lower and upper bounds on the degree of bifurcation. Both shape models have a prominent central concavity, modestly asymmetric shapes, and similar physical dimensions, spin vectors, and radar and optical geometric albedos. We adopt the more conservative single-lobe shape model as our working model and explore its implications. It has a radar-derived sidereal rotation period P_sid=15.0+/-0.2 h and a north pole within a few tens of degrees of ecliptic longitude lambda=24 deg and ecliptic latitude beta=-26 deg; retrograde rotation is likely. It has dimensions of 1.11x0.53x0.50 km, an effective diameter (the diameter of a sphere with the same volume as the model) D_eff=0.63^+0.13_-0.06 km, and radar and optical geometric albedos sigma=0.33^+0.25_-0.11 and p_v=0.56^+0.12_-0.18, respectively, that are larger than most estimated for other asteroids. Bacchus' low circular polarization ratio and high radar albedo are consistent with nearly regolith-free ordinary chondrite and basaltic achondrite compositions, but its high optical geometric albedo seems inconsistent with an ordinary chondrite composition and may favor a V-class composition. Bacchus has less structural complexity at centimeter-to-decimeter spatial scales and its near-surface is more dense (either more metal, lower porosity, or both) than the average radar-detected near-Earth asteroid.

Affiliated with

Also associated with

No associations

Rating

Radar Observations of Asteroid 2063 Bacchus does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Radar Observations of Asteroid 2063 Bacchus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Radar Observations of Asteroid 2063 Bacchus will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1501785