Velocity streaming of IRAS main-sequence disk stars and the episodic enhancement of particulate disks by interstellar clouds
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Whitmire, Daniel P.↗
Engineering topics
Whitman, Patrick G.
Publications and source records attributed to Whitman, Patrick G..
Comet nongravitational forces and meteoritic impacts
We have considered those comets whose original orbits have been determined to be hyperbolic when only planetary perturbations are accounted for. It is found that formally unbound incident trajectories correlate most confidently with orbits that have small perihelion distances and move in a retrograde sense relative to planetary motion. Arguments are presented that these results are not due to measurement error or to selection effects. We conclude that the phenomenon is attributable to enhanced volatility leading to abnormally large nongravitational forces. Since the effect is absent in the prograde small-perihelia population, increased insolation is not the sole explanation. It is suggested that the significance of the retrograde correlation is connected with a larger energy of relative motion between retrograde comets and a population of prograde ecliptic meteoroids which impact the comet mantle exposing the underlying volatiles. The subsequent enhanced outgassing is the cause of the larger nongravitational forces.
Matese, John J.↗
A model of the galactic tidal interaction with the Oort comet cloud
A model of the in situ Oort cloud which is isotropic with a random distribution of perihelia directions and angular momenta is considered. The energy distribution adopted has a continuous range of values appropriate for long-period (greater than 200 yr) comets. The evolution of 1,000,000 comets are tracked as they are made observable by the galactic tidal torque. Detailed results are obtained for the predicted distribution of new comets. Predictions of observed distributions are presented and compared with the random in situ results as well as with the actual observed distributions of class I comets. The predictions are in reasonable agreement with actual observations and, in many cases, are significantly different from random when perihelia directions are separated into galactic northern and southern hemispheres.
Matese, John J.↗
Gravitationally unbound comets move in predominantly retrograde orbits
It is reported that unbound comets are more likely to move in retrograde orbits. It is suggested that this anomaly comes about because of the omission from the orbital energy determination of nongravitational effects arising from enhanced volatility.
Matese, John J.↗