arXiv subjects

Su Wang

Publications and source records attributed to Su Wang.

93 records · Page 6Linked to original sources

arXiv2012

Possible Origin of the Damocloids:the Scattered Disk or a New Region?

The Damocloids are a group of unusual asteroids, recently enrolling a new member of 2010 EJ104. The dynamical evolution for the Damocloids may uncover a connection passage from the Main Belt, the Kuiper Belt and the scattered disk beyond. According to our simulations, two regions may be considered as possible origin of the Damocloids: the scattered disk, or a part of Oort cloud which will be perturbed to a transient region locating between 700 AU and 1000 AU. Based on the potential origin, the Damocloids can be classified into two types, with relation to their semi-major axes, and about 65.5% Damocloids is classified into type I which mainly originate from Oort cloud. Whether the Damocloids is inactive nuclei of Halley Family Comets may rely on their origin.

astro-ph.EP↗

arXiv2010

Forming Habitable Planets around Dwarf Stars: Application to OGLE-06-109L

Dwarf stars are believed to have small protostar disk where planets may grow up. During the planet formation stage, embryos undergoing type I migration are expected to be stalled at inner edge of magnetic inactive disk ($a_{\rm crit} \sim 0.2-0.3 ~$AU). This mechanism makes the location around $a_{\rm crit}$ a sweet spot of forming planets. Especially, $a_{\rm crit}$ of dwarf stars with masses $\sim 0.5 M_\odot$ is roughly inside the habitable zone of the system. In this paper we study the formation of habitable planets due to this mechanism with a model system OGLE-06-109L. It has a $0.51 M_\odot$ dwarf star with two giant planets in 2.3 and 4.6 AU observed by microlensing. We model the embryos undergoing type I migration in the gas disk with a constant disk accretion rate ($\dot M$). Giant planets in outside orbits affect the formation of habitable planets through secular perturbations at the early stage and secular resonance at the later stage. We find that the existence and the masses of the habitable planets in OGLE-06-10L system depend on both $\dot M$ and the speed of type I migration. If planets formed earlier so that $\dot M$ is larger ($\sim 10^{-7} M_\odot $ yr$^{-1}$), terrestrial planet can not be survived unless the type I migration rate is an order of magnitude less. If planets formed later so that $\dot M$ is smaller ($\sim 10^{-8} M_\odot $ yr$^{-1}$), single and high mass terrestrial planets with high water contents ($\sim 5% $) will be formed by inward migration of outer planet cores. A slower speed migration will result in several planets by collisions of embryos, thus their water contents are low ($\sim 2%$). Mean motion resonances or apsidal resonances among planets may be observed if multiple planets survived in the inner system.

astro-ph.EP↗

arXiv2009

Dynamics and Eccentricity Formation of Planets in OGLE-06-109L System

Recent observation of microlensing technique reveals two giant planets at 2.3 AU and 4.6 AU around the star OGLE-06-109L. The eccentricity of the outer planet (ec) is estimated to be 0.11(+0.17,-0.04), comparable to that of Saturn (0.01-0.09). The similarities between the OGLE-06-109L system and the solar system indicate that they may have passed through similar histories during their formation stage. In this paper we investigate the dynamics and formation of the orbital architecture in the OGLE-06-109L system. For the present two planets with their nominal locations, the secular motions are stable as long as their eccentricities (eb; ec) fulfill eb^2 + ec^2 < = 0.3^2. Earth-size bodies might be formed and are stable in the habitable zone (0.25AU-0.36AU) of the system. Three possible scenarios may be accounted for formation of eb and ec: (i) convergent migration of two planets and the 3:1 MMR trapping; (ii) planetary scattering; (iii) divergent migration and the 3:1 MMR crossing. As we showed that the probability for the two giant planets in 3:1 MMR is low (~3%), scenario (i) is less likely. According to models (ii) and (iii), the final eccentricity of inner planet (eb) may oscillate between [0-0.06], comparable to that of Jupiter (0.03-0.06). An inspection of eb, ec secular motion may be helpful to understand which model is really responsible for the eccentricity formation.

astro-ph.EP↗