5,476 research outputs found
Toward a Deterministic Model of Planetary Formation VII: Eccentricity Distribution of Gas Giants
The ubiquity of planets and diversity of planetary systems reveal planet
formation encompass many complex and competing processes. In this series of
papers, we develop and upgrade a population synthesis model as a tool to
identify the dominant physical effects and to calibrate the range of physical
conditions. Recent planet searches leads to the discovery of many
multiple-planet systems. Any theoretical models of their origins must take into
account dynamical interaction between emerging protoplanets. Here, we introduce
a prescription to approximate the close encounters between multiple planets. We
apply this method to simulate the growth, migration, and dynamical interaction
of planetary systems. Our models show that in relatively massive disks, several
gas giants and rocky/icy planets emerge, migrate, and undergo dynamical
instability. Secular perturbation between planets leads to orbital crossings,
eccentricity excitation, and planetary ejection. In disks with modest masses,
two or less gas giants form with multiple super-Earths. Orbital stability in
these systems is generally maintained and they retain the kinematic structure
after gas in their natal disks is depleted. These results reproduce the
observed planetary mass-eccentricity and semimajor axis-eccentricity
correlations. They also suggest that emerging gas giants can scatter residual
cores to the outer disk regions. Subsequent in situ gas accretion onto these
cores can lead to the formation of distant (> 30AU) gas giants with nearly
circular orbits.Comment: 54 pages, 14 Figures; accepted for publication in Astrophysical
Journa
Formation of Hot Planets by a combination of planet scattering, tidal circularization, and Kozai mechanism
We have investigated the formation of close-in extrasolar giant planets
through a coupling effect of mutual scattering, Kozai mechanism, and tidal
circularization, by orbital integrations. We have carried out orbital
integrations of three planets with Jupiter-mass, directly including the effect
of tidal circularization. We have found that in about 30% runs close-in planets
are formed, which is much higher than suggested by previous studies. We have
found that Kozai mechanism by outer planets is responsible for the formation of
close-in planets. During the three-planet orbital crossing, the Kozai
excitation is repeated and the eccentricity is often increased secularly to
values close enough to unity for tidal circularization to transform the inner
planet to a close-in planet. Since a moderate eccentricity can remain for the
close-in planet, this mechanism may account for the observed close-in planets
with moderate eccentricities and without nearby secondary planets. Since these
planets also remain a broad range of orbital inclinations (even retrograde
ones), the contribution of this process would be clarified by more observations
of Rossiter-McLaughlin effects for transiting planets.Comment: 15 pages, 16 figures, Accepted for publication in Ap
Comparison of toroidal viscosity with neoclassical theory
Toroidal rotation profiles are measured with charge exchange spectroscopy for a plasma heated with tangential neutral beam injection (NBI) in the Compact Helical System (CHS) heliotron/torsatron device [Ida et al., Phys. Rev. Lett. 67, 58 (1991)] to estimate the toroidal viscosity. The toroidal viscosity derived from the toroidal rotation velocity shows good agreement with the neoclassical toroidal viscosity plus the perpendicular viscosity ( [perpendicular]=2 m^2/s)
Migrasi Simbolik Wacana Kuasa Tubuh: Menguak Wacana Tubuh Dalam Ode Untuk Leopold Von Sacher-Masoch Karya Dinar Rahayu
The presence of Indonesian women writers with the dominant discourse of the power of body, presenting the pros and cons that would not go over. Female body is the language of women that can be poured through the writing of literary works. Helene Cixous brought the spirit of "writing the body" to motivate women authors to express himself through written discourse, which so far has been dominated by men. Cixous spirit is also promoted by Dinar Rahayu appear in the novel Ode untuk Leopold Von Sacher-Masoch. Dinar Rahayu voicing complexity of urban women's voices in this novel through several migration symbolic of the power of the female body. Migration is enriched by the presence of symbolic power in a sound body of Greek and Scandinavian mythology and Leopold voices in his work Venus in Furs. Through in-depth reading on the symbolic migration brought to the Ode untuk Leopold Von Sacher-Masoch through the voices of the characters and the particularities of naration techniques can be seen that this novel (as well as other sexist novels) is not merely a commodity that exploit sexuality pornography but rather an attempt to author urban female voices will be the "body power". This study uses content analysis method that begins with the reading of literature, heuristic and hermeneutic, and take advantage of intertextuality approach
Toward a Deterministic Model of Planetary Formation VI: Dynamical Interaction and Coagulation of Multiple Rocky Embryos and Super-Earth Systems around Solar Type Stars
Radial velocity and transit surveys indicate that solar-type stars bear
super-Earths, with mass and period up to ~ 20 M_E and a few months, are more
common than those with Jupiter-mass gas giants. In many cases, these
super-Earths are members of multiple-planet systems in which their mutual
dynamical interaction has influenced their formation and evolution. In this
paper, we modify an existing numerical population synthesis scheme to take into
account protoplanetary embryos' interaction with their evolving natal gaseous
disk, as well as their close scatterings and resonant interaction with each
other. We show that it is possible for a group of compact embryos to emerge
interior to the ice line, grow, migrate, and congregate into closely-packed
convoys which stall in the proximity of their host stars. After the disk-gas
depletion, they undergo orbit crossing, close scattering, and giant impacts to
form multiple rocky Earths or super-Earths in non-resonant orbits around ~
0.1AU with moderate eccentricities of ~0.01-0.1. We suggest that most
refractory super-Earths with period in the range of a few days to weeks may
have formed through this process. These super-Earths differ from Neptune-like
ice giants by their compact sizes and lack of a substantial gaseous envelope.Comment: 37 pages, 10 figures, accepted for publication in Ap
Analysis Of Students' Ability In Using English For Taking Order Procedure In Restaurant
The aim of this study to analyze students' English speaking skills in conducting taking orders procedure in restaurants. This study is conducted in order to overcome the problems encountered by the students in speaking activities in taking orders. To measure the ability of students in speaking English in taking orders, the researchers observed the procedures that the students did not perform and measure the students' competence of English language. Samples of this study are the fourth semester students in Hospitality courses Diploma Degree of Mataram Tourism Institute in Academic Year 2018/2019. The results of this study indicated that the level of completeness of the procedure in taking student orders in STP Mataram is in average. More than 50% students have conducted the appropriate procedure when taking orders in using English. From the result of data analysis in measuring the students' competence in speaking English, the mean score is 78.90 with standard deviation is 12.14. From the result, it is converted and get score 3.1. The score showed that the ability of English students from 40 students in STP Mataram classified as Good Criteria
Eccentricity Evolution of Extrasolar Multiple Planetary Systems due to the Depletion of Nascent Protostellar Disks
Most extrasolar planets are observed to have eccentricities much larger than
those in the solar system. Some of these planets have sibling planets, with
comparable masses, orbiting around the same host stars. In these multiple
planetary systems, eccentricity is modulated by the planets' mutual secular
interaction as a consequence of angular momentum exchange between them. For
mature planets, the eigenfrequencies of this modulation are determined by their
mass and semi-major axis ratios. But, prior to the disk depletion, self gravity
of the planets' nascent disks dominates the precession eigenfrequencies. We
examine here the initial evolution of young planets' eccentricity due to the
apsidal libration or circulation induced by both the secular interaction
between them and the self gravity of their nascent disks. We show that as the
latter effect declines adiabatically with disk depletion, the modulation
amplitude of the planets' relative phase of periapse is approximately invariant
despite the time-asymmetrical exchange of angular momentum between planets.
However, as the young planets' orbits pass through a state of secular
resonance, their mean eccentricities undergo systematic quantitative changes.
For applications, we analyze the eccentricity evolution of planets around
Upsilon Andromedae and HD168443 during the epoch of protostellar disk
depletion. We find that the disk depletion can change the planets' eccentricity
ratio. However, the relatively large amplitude of the planets' eccentricity
cannot be excited if all the planets had small initial eccentricities.Comment: 50 pages including 11 figures, submitted to Ap
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