Leonid M. Ozernoy

Signatures of Exosolar Planets in Dust Debris Disks

We apply our recently elaborated, powerful numerical approach to the high-resolution modeling of the structure and emission of circumstellar dust disks, incorporating all relevant physical processes. Specifically, we examine the resonant structure of a dusty disk induced by the presence of one planet. It is shown that the planet, via resonances and gravitational scattering, produces (1) an asymmetric resonant dust belt with one or more clumps, intermittent with one or a few off-center cavities, and (2) a central cavity void of dust. These features can serve as indicators of a planet embedded in the circumstellar dust disk and, moreover, can be used to determine its major orbital parameters and even the mass of the planet. The results of our study reveal a remarkable similarity with various types of highly asymmetric circumstellar disks observed with the James Clerk Maxwell Telescope around Eridani and Vega. The proposed interpretation of the clumps in those disks as being resonant patterns is testable?it predicts the asymmetric design around the star to revolve, viz., by 12-16 yr-1 about Vega and 06-08 yr-1 about Eri.

Four cometary belts associated with the orbits of giant planets: a new view of the outer solar system's structure emerges from numerical simulations

Abstract Using numerical simulations, we examine the structure of a cometary population near a massive planet, such as a giant planet of the Solar system, starting with one-planet approximation (the Sun plus one planet). By studying the distributions of comets in semimajor axis, eccentricity, pericenter, and apocenter distances, we have revealed several interesting features in these distributions. The most remarkable ones include (i) spatial accumulation of comets near the planetary orbit (which we call the ‘cometary belt’) and (ii) avoidance of resonant orbits by comets. Then we abandon one-planet approximation and examine as to how a cometary belt is modified when the influence of all the four giant planets is taken into consideration. To this end, we simulate a stationary distribution of comets, which results from the gravitational scattering of the Kuiper belt objects on the four giant planets and accounts for the effects of mean-motion resonances. In our simulations, we deal with the stationary distributions computed, at different initial conditions, as 36 runs for the dynamical evolution of comets, which start from the Kuiper belt and are typically traced until the comets are ejected from the Solar system. Accounting for the influence of four giant planets makes the cometary belts overlapping, but nevertheless keeping almost all their basic features found in one-planet approximation. In particular, the belts maintain the gaps in the (a,e)- and (a,i)-space similar to the Kirkwood gaps in the main asteroid belt. We conclude that the large-scale structure of the Solar system is featured by the four cometary belts expected to contain 20–30 millions of scattered comets, and only a tiny fraction of them is currently visible as Jupiter, Saturn, etc. family comets.

Precision measuring of velocities via the relativistic Doppler effect

Just as the ordinary Doppler effect serves as a tool to measure radial velocities of celestial objects, so can the relativistic Doppler effect be implemented to measure a combination of radial and transverse velocities by using recent improvements in observing techniques. A key element that makes a further use of this combination feasible is the periodicity in changes of the orbital velocity direction for the source. Two cases are considered: (i) a binary star; and (ii) a solitary star with the planetary companion. It is shown that, in case (i), several precision Doppler measurements employing the gas absorption cell technique would determine both the total orbital velocity and the inclination angle of the binary orbit disentangled from the peculiar velocity of the system. The necessary condition for that is the measured, at least with a modest precision, proper motion and distance to the system.

Indicator of Exo-Solar Planet(s) in the Circumstellar Disk Around β Pictoris

Our efficient numerical approach has been applied to modeling the asymmetric circumstellar dust disk around β Pictoris as observed with the HST/STIS. We present a new model on the origin of the warping of the β Pic disk. We suggest that the observed warp is formed by the gravitational influence of a planet with a mass of about 10 masses of Earth, at a distance of 70 AU, and a small inclination (∽ 2.5°) of the planetary orbit to the main dust disk. Results of our modeling are compared with the STIS observations.

Is SGR A* Underfed, Underefficient, or Underdone ?

We argue that the wind from IRS 16 and He I stars in the central 1 pc of the Galaxy is responsible for the peculiar features of accretion onto a putative black hole at the Galactic center. What makes Sgr A* unique is not that it is just underfed but, in addition, it has a much lower efficiency of accretion and possibly a lower mass, compared to the AGN case.

Recurrent Starbursts or Intermittent Starburst/AGN Phenomena at the Galactic Center ?

Recently, I summarized arguments, both old and new, that the Galactic center has experienced a starburst in a recent past (Ozer noy 1994a). Here I propose a likely mechanism — collisions between giant molecular clouds — that might induce (recurrent) starbursts. Taken together, these two approaches seem to indicate that the history of the central part of our Galaxy can be described as recurrent starbursts or intermittent Seyfert activities/ starbursts.

Starbursts in our home galaxy

I discuss a scenario of a recent (5 to 8 Myr ago) modest starburst in a central region of the Milky Way galaxy. By incorporating a collision of two giant molecular clouds within the central molecular zone (r≲0.6 kpc), this scenario combines formation of massive stars close to the center of the Galaxy with an opportunity to have X-ray massive binary successors at very large distances from the center.

Resonant Gaps in the Scattered Cometary Population of the Trans-Neptunian Region

Our numerical simulations of the Edgeworth-Kuiper belt objects gravitationally scattered by the four giant planets accounting for mean motion resonances reveal numerous resonant gaps in the distribution of the scattered population.

CURRENT CONSTRAINTS TO SGR A * MASS

This paper describes the recent new results dealing with constraints to, or evaluations of, the mass of a putative black hole at the Galactic center obtained by several different methods.