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松本 侑士大学院理学研究科 惑星学専攻助教
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■ 論文- 2025年10月, The Astrophysical Journal Letters研究論文（学術雑誌）
- 2025年08月, The Astrophysical Journal研究論文（学術雑誌）
- 2025年08月, The Astrophysical Journal研究論文（学術雑誌）
- 2024年06月, The Astrophysical Journal Letters研究論文（学術雑誌）
- 2024年05月, The Astrophysical Journal研究論文（学術雑誌）
- 2023年05月, The Astrophysical Journal研究論文（学術雑誌）
- American Astronomical Society, 2023年03月, The Astronomical Journal, 165(3) (3), 131 - 131研究論文（学術雑誌）
- 2022年06月, Publications of the Astronomical Society of Japan, 74(4) (4), 904 - 922, 英語研究論文（学術雑誌）
- 2021年12月, The Astrophysical Journal研究論文（学術雑誌）
- 2021年10月, The Astrophysical Journal研究論文（学術雑誌）
- 2021年10月, Icarus研究論文（学術雑誌）
- 2021年02月, The Astrophysical Journal研究論文（学術雑誌）
- {EDP} Sciences, 2020年10月, Astronomy & Astrophysics, 642, A23 - A23
Context. Earth-sized planets were observed in close-in orbits around M dwarfs. While more and more planets are expected to be uncovered around M dwarfs, theories of their formation and dynamical evolution are still in their infancy.Aims. We investigate the giant impact stage for the growth of protoplanets, which includes strong scattering around low-mass stars. The aim is to clarify whether strong scattering around low-mass stars affects the orbital and mass distributions of the planets.Methods. We performed anN -body simulation of protoplanets by systematically surveying the parameter space of the stellar mass and surface density of protoplanets.Results. We find that protoplanets are often ejected after twice or three times the close-scattering around late M dwarfs. The ejection sets the upper limit of the largest planet mass. By adopting the surface density that linearly scales with the stellar mass, we find that as the stellar mass decreases, less massive planets are formed in orbits with higher eccentricities and inclinations. Under this scaling, we also find that a few close-in protoplanets are generally ejected.Conclusions. The ejection of protoplanets plays an important role in the mass distribution of super-Earths around late M dwarfs. The mass relation of observed close-in super-Earths and their central star mass is reproduced well by ejection.研究論文（学術雑誌） - Breaking Resonant Chains: Destabilization of Resonant Planets due to Long-term Mass EvolutionRecent exoplanet observations reported a large number of multiple-planet systems, in which some of the planets are in a chain of resonances. The fraction of resonant systems to non-resonant systems provides clues about their formation history. We investigated the orbital stability of planets in resonant chains by considering the long-term evolution of planetary mass and stellar mass and using orbital calculations. We found that while resonant chains were stable, they can be destabilized by a change of $\sim$10% in planetary mass. Such a mass evolution can occur by atmospheric escape due to photoevaporation. We also found that resonant chains can be broken by a stellar mass loss of $\lesssim1$%, which would be explained by stellar winds or coronal mass ejections. The long-term mass change of planets and stars plays an important role in the orbital evolutions of planetary systems including super-Earths.2020年03月[査読有り]
- Major components of chondrites are chondrules and matrix. Measurements of the2019年12月, The Astrophysical Journal
volatile abundance in Semarkona chondrules suggest that chondrules formed in a
dense clump that had a higher solid density than the gas density in the solar
nebula. We investigate collisions between chondrules and matrix in the surface
region of dense clumps using fluffy aggregate growth models. Our simulations
show that the collisional growth of aggregates composed of chondrules and
matrix takes place in the clumps well before they experience gravitational
collapse. The internal structure of chondrite parent bodies (CPBs) can be
thereby determined by aggregate growth. We find that the aggregate growth
generates two scales within CPBs. The first scale is involved with the small
scale distribution of chondrules and determined by the early growth stage,
where chondrules accrete aggregates composed of matrix grains. This accretion
can reproduce the thickness of the matrix layer around chondrules found in
chondrites. The other scale is related to the large scale distribution of
chondrules. Its properties (e.g., the abundance of chondrules and the overall
size) depend on the gas motion within the clump, which is parameterized in this
work. Our work thus suggests that the internal structure of CPBs may provide
important clues about their formation conditions and mechanisms.[査読有り]研究論文（学術雑誌） - Understanding chondrule formation provides invaluable clues about the origin2019年10月, The Astrophysical Journal
of the solar system. Recent studies suggest that planetesimal collisions and
the resulting impact melts are promising for forming chondrules. Given that the
dynamics of planetesimals is a key in impact-based chondrule formation
scenarios, we here perform direct $N$-body simulations to examine how the
presence of Jupiter affects the properties of chondrule-forming collisions. Our
results show that the absence/presence of Jupiter considerably changes the
properties of high velocity collisions whose impact velocities are higher than
2.5 km s$^{-1}$; high velocity collisions occur due to impacts between
protoplanets and planetesimals for the case without Jupiter; for the case with
Jupiter, eccentricities of planetesimals are pumped up by the secular and
resonant perturbations from Jupiter. We also categorize the resulting
planetesimal collisions and find that most of high velocity collisions are
classified as grazing ones for both cases. To examine the effect of Jupiter on
chondrule formation directly, we adopt the impact jetting scenario and compute
the resulting abundance of chondrules. Our results show that for the case
without Jupiter, chondrule formation proceeds in the inside-out manner,
following the growth of protoplanets. If Jupiter is present, the location and
timing of chondrule formation are determined by Jupiter's eccentricity, which
is treated as a free parameter in our simulations. Thus, the existence of
Jupiter is the key parameter for specifying when and where chondrule formation
occurs for impact-based scenarios.[査読有り]研究論文（学術雑誌） - Recent observations have revealed the eccentricity and inclinationIOP Publishing, 2017年07月, The Astronomical Journal, 154(1) (1), 27 - 27
distributions of close-in super-Earths. These distributions have the potential
to constrain their formation processes. In the in-situ formation scenario, the
eccentricities and inclinations of planets are determined by gravitational
scattering and collisions between protoplanets on the giant impact stage. We
investigate the effect of the initial eccentricities and inclinations of
protoplanets on the formation of close-in super-Earths. We perform $N$-body
simulations of protoplanets in gas-free disks, changing the initial
eccentricities and inclinations systematically. We find that while the
eccentricities of protoplanets are well relaxed through their evolution, the
inclinations are not. When the initial inclinations are small, they are not
generally pumped up since scattering is less effective and collisions occur
immediately after orbital crossing. On the other hand, when the initial
inclinations are large, they tend to be kept large since collisional damping is
less effective. Not only the resultant inclinations of planets, but also their
number, eccentricities, angular momentum deficit, and orbital separations are
affected by the initial inclinations of protoplanets.[査読有り]研究論文（学術雑誌） - 2017年03月, ASTROPHYSICAL JOURNAL, 837(2) (2), 英語[査読有り]研究論文（学術雑誌）
- 2017年01月, ASTROPHYSICAL JOURNAL, 834(2) (2), 英語[査読有り]研究論文（学術雑誌）
- 2016年03月, ASTROPHYSICAL JOURNAL LETTERS, 820(1) (1), 英語[査読有り]研究論文（学術雑誌）
- 2016年01月, ASTROPHYSICAL JOURNAL, 816(1) (1), 英語[査読有り]研究論文（学術雑誌）
- 2015年09月, ASTROPHYSICAL JOURNAL, 810(2) (2), 英語[査読有り]研究論文（学術雑誌）
- 2012年11月, ICARUS, 221(2) (2), 624 - 631, 英語[査読有り]研究論文（学術雑誌）
- 2025年09月, 遊・星・人, 34(3) (3), 204 - 211Blenderによる科学的可視化入門
- Abstract The KEPLER transit survey with follow-up spectroscopic observations has discovered numerous small planets (super-Earths/sub-Neptunes) and revealed intriguing features of their sizes, orbital periods, and their relations between adjacent planets. The planet size distribution exhibits a bimodal distribution separated by a radius gap at around 1.8 Earth radii. Besides, these small planets within multiple planetary systems show that adjacent planets are similar in size and their period ratios of adjacent planet pairs are similar as well, a phenomenon often dubbed as peas-in-a-pod in the exoplanet community. While the radius gap has been predicted and theorized for years, whether it can be relevant to the orbital architecture peas-in-a-pod is physically unknown. For the first time, we attempted to model both features together through planet formation and evolution processes involving giant impacts and photoevaporation. We showed that our model is generally consistent with the KEPLER results but with a smaller radius gap. The impact of Kubyshikina’s model for photoevaporation on our model is discussed.Cambridge University Press (CUP), 2021年08月, Proceedings of the International Astronomical Union, 17(S370) (S370), 251 - 256
- The rheology of two-dimensional crushable granular materials under shear is numerically studied using the discrete element method. We find that the mean fragment size changes as the shear strain increases while the shear stress is almost independent of this mean size. The fragment size distribution is found to follow a power law. In particular, the exponent in the intermediate fragment size regime becomes approximately – 11/6, which is almost independent of the shear rate.EDP Sciences, 2021年06月07日, EPJ Web of Conferences, 249, 07007 - 07007
- 2020年12月, SPICAサイエンス検討会最終報告書円盤鉱物学
- 2020年12月