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All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

The remaining large minor planets with unknown rotational properties - 31 Euphrosyne and 65 Cybele

Photoelectric photometry results are presented for 31 Euphrosyne and 65 Cybele. The rational properties of the asteroids were found to be quite similar, both in period and maximum amplitude. Evidence was found for an opposition effect for 65 Cybele. The B-V and U-B colors were determined to be plus 0.67 and plus 0.30 for 31 Euphrosyne, plus 0.73 and plus 0.23 for 65 Cybele. Recent observations of 65 Cybele occulting a star have shown evidence of a possible satellite for this minor planet.

Schober, H. J.↗
NASA NTRS1987

Detection of lambda = 2 cm emission from minor planet 704 Interamnia

Results are presented from a study of the 2 cm natural radio emissions from the class U asteroid 704 Interamnia. The study was performed with the NRAO VLA using 26 antennas in a compact hybrid configuration with baselengths from 0.1-2.2 km. The IF scans were centered at 14.97 GHz and 14.92 GHz. A brightness temperature plot is provided for 2 AU distance, assuming a 338 km diam for the asteroid. The scans revealed a surface dust layer at least 3 cm thick. Comparisons with spectra of 15 Eunomia, another rapidly rotating minor planet with a similar diameter reveals that this second object also has a surface dust layer a few centimeters thick.

Webster, W. J., Jr.↗
NASA NTRS1992

The IRAS Minor Planet Survey

This report documents the program and data used to identify known asteroids observed by the Infrared Astronomical Satellite (IRAS) and to compute albedos and diameters from their IRAS fluxes. It also presents listings of the results obtained. These results supplant those in the IRAS Asteroid and Comet Survey, 1986. The present version used new and improved asteroid orbital elements for 4679 numbered asteroids and 2632 additional asteroids for which at least two-opposition elements were available as of mid-1991. It employed asteroid absolute magnitudes on the International Astronomical Union system adopted in 1991. In addition, the code was modified to increase the reliability of associating asteroids with IRAS sources and rectify several shortcomings in the final data products released in 1986. Association reliability was improved by decreasing the position difference between an IRAS source and a predicted asteroid position required for an association. The shortcomings addressed included the problem of flux overestimation for low SNR sources and the systematic difference in albedos and diameters among the three wavelength bands (12, 25, and 60 micrometers). Several minor bugs in the original code were also corrected.

Tedesco, Edward F.↗
NASA NTRS1967

Minor planets. I.

Light curve set for Vesta obtained and compared with previous observations, discussing probable spherical shape deduction

Gehrels, T.↗
NASA NTRS1971

Physical studies of minor planets

Astronomical observations of the asteroids are discussed. The origin of asteroids and their interrelationships with comets, meteorites, and meteors are considered. Possible space missions and further topics of research are also discussed.

Gehrels, T.↗
NASA NTRS1971

Photopolarimetric observations of the minor planet Flora.

Review of the rotation period, phase coefficients, and polarization curve of the unusual asteroid Flora. It is an almost spherical asteroid whose period of rotation is probably 13.6 h, but may be only one half of this. Its surface layer consists of a dark material resembling lunar surface soil, but since the polarization curves of Flora and the moon, though generally similar, are not identical the surface of Flora must differ somewhat either in composition or in texture from that of the moon.

Veverka, J.↗
NASA NTRS1972

Minor planets and related objects. VIII - Deimos.

Evaluation of 12 polarization measurements of Deimos in blue light were obtained at phase angles between 5 and 31 deg. A well-developed negative branch, with minimum polarization approximately -1.5% near phase angle 11 deg, indicates that Deimos is not bare rock but has a particulate surface layer of dark dust or powder. The phase angle of inversion is 19.5 deg, and the slope of the positive branch is 0.26 plus or minus 0.01% per degree. On the basis of the slope-albedo law for the moon and the major asteroids, the geometrical albedo of Deimos in blue light should be 0.07 plus or minus 0.01, and the radius 5.4 plus or minus 0.8 km. These values are in good agreement with preliminary Mariner 9 data.

Zellner, B.↗
NASA NTRS1973

Minor planets and related objects. IX - Photometry and polarimetry of /1685/ Toro.

UBV photometry, lightcurves, a polarization-phase relation, and rotational polarization curves of Toro were obtained, June-August 1972. The average colors are B-V = 0.87 and U-B = 0.47 mag, showing some reddening with phase. The geometric albedo of Toro in the B filter is 0.14 which corresponds to an effective mean radius of 2.2 km plus or minus 0.4 (p.e.). The rotational polarization curves indicate that the lightcurves are mostly due to shape, but some albedo variation over the surface is detected as well. The shape is elongated, and probably irregular, with a cross-sectional area ratio of about 3.2, the maximum effective radius is 2.8 km and the minimum, 1.6 km.

Dunlap, J. L.↗
NASA NTRS1973

Minor planets and related objects. XIII - Long-term orbital evolution of /1685/ Toro.

The orbital evolution of (1685) Toro has been investigated over 5000 yr. The asteroid exhibits a locked resonance through an 8:5 commensurability with the earth for the first 3400 yr of integration and a locked resonance with Venus through a 13:5 commensurability for the last 1000 yr. Control of these resonances passes from the earth to Venus as the distance from the earth's orbit gets greater and the distance to Venus' orbit gets closer as a consequence of the precession of the argument of perihelion. The double resonance may give Toro the ability to avoid collisions with the earth and Venus at the present time but this is still uncertain. Mars perturbations could remove Toro from the deepest part of the resonance in about 3,000,000 yrs.

Williams, J. G.↗