537 citations · 1.6k across the 24 of their papers we have counts for
20 papers · 1 filter
The dust-rich, gas-depleted protosolar disk as the birthplace of chondrules
Sota Arakawa, Hidekazu Tanaka, Toshihiko Kadono +3
Chondrules are the primary components of primitive meteorites known as chondrites, and understanding their formation and accumulation is essential for elucidating the history of pl…
A Trio of Giant Planets Orbiting Evolved Star HD 184010
Huan-Yu Teng, Bun'ei Sato, Takuya Takarada +11
We report the discovery of a triple-giant-planet system around an evolved star HD 184010 (HR 7421, HIP 96016). This discovery is based on observations from Okayama Planet Search Pr…
Planet-planet scattering in presence of a companion star
Francesco Marzari, Makiko Nagasawa, Krzyszof Goździewski
Planet Planet scattering is a leading dynamical mechanism invoked to explain the present orbital distribution of exoplanets. Many stars belong to binary systems, therefore it is im…
Secular evolution of close in planets: the effects of general relativity
Francesco Marzari, Makiko Nagasawa
Pairs of planets in a system may end up close to their host star on eccentric orbits as a consequence of planet planet scattering, Kozai or secular migration. In this scenario, gen…
The influence of general-relativity effects, dynamical tides and collisions on planet-planet scattering close to the star
F. Marzari, M. Nagasawa
Planet--Planet scattering is an efficient and robust dynamical mechanism for producing eccentric exoplanets. Coupled to tidal interactions with the central star, it can also explai…
Shock-Generating Planetesimals Perturbed by a Giant Planet in a Gas Disk
M. Nagasawa, K. K. Tanaka, H. Tanaka +3
We examined the excitations of planetesimals caused by the resonances of a giant planet in a protoplanetary gas disk. The highly excited planetesimals generate bow shocks, the mech…
Planets around the evolved stars 24 Booties and Libra: A 30d-period planet and a double giant-planet system in possible 7:3 MMR
Takuya Takarada, Bun'ei Sato, Masashi Omiya +10
We report the detection of planets around two evolved giant stars from radial velocity measurements at Okayama Astrophysical observatory. 24 Boo (G3IV) has a mass of $0.99\,M_{\odo…
A Pair of Giant Planets around the Evolved Intermediate-Mass Star HD 47366: Multiple Circular Orbits or a Mutually Retrograde Configuration
Bun'ei Sato, Liang Wang, Yu-Juan Liu +19
We report the detection of a double planetary system around the evolved intermediate-mass star HD 47366 from precise radial-velocity measurements at Okayama Astrophysical Observato…
Eccentricity Evolution Through Accretion of Protoplanets
Yuji Matsumoto, Makiko Nagasawa, Shigeru Ida
Most of super-Earths detected by the radial velocity (RV) method have significantly smaller eccentricities than the eccentricities corresponding to velocity dispersion equal to the…
Extrasolar Binary Planets II: Detectability by Transit Observations
K. M. Lewis, H. Ochiai, M. Nagasawa +1
We discuss the detectability of gravitationally bounded pairs of gas-giant planets (which we call "binary planets") in extrasolar planetary systems that are formed through orbital…
Revisiting Jovian-Resonance Induced Chondrule Formation
M. Nagasawa, K. K. Tanaka, H. Tanaka +3
It is proposed that planetesimals perturbed by Jovian mean-motion resonances are the source of shock waves that form chondrules. It is considered that this shock-induced chondrule…
Extrasolar Binary Planets I: Formation by tidal capture during planet-planet scattering
H. Ochiai, M. Nagasawa, S. Ida
We have investigated i) the formation of gravitationally bounded pairs of gas-giant planets (which we call "binary planets") from capturing each other through planet-planet dynamic…
Characterization of the KOI-94 System with Transit Timing Variation Analysis: Implication for the Planet-Planet Eclipse
Kento Masuda, Teruyuki Hirano, Atsushi Taruya +2
The KOI-94 system is a closely-packed, multi-transiting planetary system discovered by the Kepler space telescope. It is known as the first system that exhibited a rare event calle…
Toward a Deterministic Model of Planetary Formation VII: Eccentricity Distribution of Gas Giants
S. Ida, D. N. C. Lin, M. Nagasawa
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 Double Planetary System around the Evolved Intermediate-Mass Star HD 4732
Bun'ei Sato, Masashi Omiya, Robert A. Wittenmyer +10
We report the detection of a double planetary system orbiting around the evolved intermediate-mass star HD 4732 from precise Doppler measurements at Okayama Astrophysical Observato…
A Common Proper Motion Stellar Companion to HAT-P-7
Norio Narita, Yasuhiro H. Takahashi, Masayuki Kuzuhara +51
We report that HAT-P-7 has a common proper motion stellar companion. The companion is located at arcsec to the east and estimated as an M5.5V dwarf based on its colors. W…
Effects of Dynamical Evolution of Giant Planets on Survival of Terrestrial Planets
Soko Matsumura, Shigeru Ida, Makiko Nagasawa
The orbital distributions of currently observed extrasolar giant planets allow marginally stable orbits for hypothetical, terrestrial planets. In this paper, we propose that many o…
The Orbital Stability of Planets Trapped in the First-Order Mean-Motion Resonances
Yuji Matsumoto, Makiko Nagasawa, Shigeru Ida
Many extrasolar planetary systems containing multiple super-Earths have been discovered. N-body simulations taking into account standard type-I planetary migration suggest that pro…
Search for Outer Massive Bodies around Transiting Planetary Systems: Candidates of Faint Stellar Companions around HAT-P-7
Norio Narita, Tomoyuki Kudo, Carolina Bergfors +46
We present results of direct imaging observations for HAT-P-7 taken with the Subaru HiCIAO and the Calar Alto AstraLux. Since the close-in transiting planet HAT-P-7b was reported t…
On the various origins of close-in extrasolar planets
S. Marchi, S. Ortolani, M. Nagasawa +1
The extrasolar planets (EPs) so far detected are very different to the planets in our own Solar System. Many of them have Jupiter-like masses and close-in orbits (the so-called hot…