Takashi Ito

Takashi Ito
National Astronomical Observatory of Japan | NAOJ · Center for Computational Astrophysics

Sci. Dr.

About

114
Publications
7,026
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1,445
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Introduction
Takashi Ito currently works at the Center for Computational Astrophysics, National Astronomical Observatory of Japan. Takashi does research in Astronomy. Their current project is 'Terrestrial Planet Formation'.
Additional affiliations
November 2002 - May 2004
The University of Arizona
Position
  • Researcher
April 1995 - present
National Astronomical Observatory of Japan
Position
  • Professor (Assistant)

Publications

Publications (114)
Article
Significance The dwarf planet, Pluto, has stirred the imagination of the public and of planetary scientists due to its many unusual properties. Among these properties is its Neptune-crossing orbit whose stability is owed to an orbital resonance with Neptune. Less well understood is the role of the other planets. We demonstrate that the orbital arch...
Preprint
Many of the unusual properties of Pluto's orbit are widely accepted as evidence for the orbital migration of the giant planets in early solar system history. However, some properties remain an enigma. Pluto's long term orbital stability is supported by two special properties of its orbit that limit the location of its perihelion in azimuth and in l...
Article
The investigation of asteroids near the Sun is important for understanding the final evolutionary stage of primitive Solar system objects. A near-Sun asteroid (NSA), (155140) 2005 UD, has orbital elements similar to those of (3200) Phaethon (the target asteroid for the JAXA’s DESTINY+ mission). We conducted photometric and polarimetric observations...
Preprint
The investigation of asteroids near the Sun is important for understanding the final evolutionary stage of primitive solar system objects. A near-Sun asteroid, (155140) 2005 UD, has orbital elements similar to those of (3200) Phaethon (the target asteroid for the JAXA's $DESTINY^+$ mission). We conducted photometric and polarimetric observations of...
Preprint
Full-text available
Rotation periods of 53 small (diameters $2 < D < 40$ km) Jupiter Trojans (JTs) were derived using the high-cadence light curves obtained by the FOSSIL phase I survey, a Subaru/Hyper Suprime-Cam intensive program. These are the first reported periods measured for JTs with $D < 10$ km. We found a lower limit of the rotation period near 4 hr, instead...
Article
The authors regret that we found several typographic errors and inconsistencies in figures in the above article. Specifically, we would like make corrections in Abstract, Figs. 3, 5, 6, and References. All of the corrections are minor, and none of them gives any serious impacts on the discussions or conclusions of the article. The authors would lik...
Article
We present time-series optical spectroscopic observations of 3200 Phaethon during its 2007 return, complemented with R-band photometry. The spectral gradient centered around 0.55 μm varies between −5.0 %/0.1 μm and 0.6 %/0.1μm, indicating a B- or C-type color. Moreover, rotational modulation of the spectral slope of this asteroid suggests its surfa...
Preprint
Full-text available
The so-called Lidov-Kozai oscillation is very well known and applied to various problems in solar system dynamics. This mechanism makes the orbital inclination and eccentricity of the perturbed body in the circular restricted three-body system oscillate with a large amplitude under certain conditions. It is widely accepted that the theoretical fram...
Article
Full-text available
The circular restricted three-body problem, particularly its doubly averaged version, has been very well studied in celestial mechanics. Despite its simplicity, circular restricted three-body systems are suited for modeling the motion of various objects in the solar system, extrasolar planetary systems, and in many other dynamical systems that show...
Article
Itokawa particles, which are samples recovered from the S-complex asteroid 25143 Itokawa by the Hayabusa spacecraft, demonstrate that S-complex asteroids are parent bodies of ordinary chondrite meteorites. Furthermore, they clarify that the space-weathering age of the Itokawa surface is of the order of several thousand years. Traditionally, Q-type...
Article
Full-text available
To reproduce the orbits and masses of the terrestrial planets (analogs) of the solar system, most studies scrutinize simulations for success as a batch. However, there is insufficient discussion in the literature on the likelihood of forming planet analogs simultaneously in the same system (analog system). To address this issue, we performed 540 N-...
Article
Full-text available
Context. Distant trans-Neptunian objects are subject to planetary perturbations and galactic tides. The former decrease with the distance, while the latter increase. In the intermediate regime where they have the same order of magnitude (the “inert Oort cloud”), both are weak, resulting in very long evolution timescales. To date, three observed obj...
Preprint
Context: Distant trans-Neptunian objects are subject to planetary perturbations and galactic tides. The former decrease with the distance, while the latter increase. In the intermediate regime where they have the same order of magnitude (the 'inert Oort cloud'), both are weak, resulting in very long evolution timescales. To date, three observed obj...
Preprint
Full-text available
To reproduce the orbits and masses of the terrestrial planets (analogs) of the solar system, most studies scrutinize simulations for success as a batch. However, there is insufficient discussion in the literature on the likelihood of forming planet analogs simultaneously in the same system (analog system). To address this issue, we performed 540 N-...
Preprint
Itokawa particles, which are the recovered samples from the S-complex asteroid 25143 Itokawa by the Hayabusa spacecraft, demonstrate that S-complex asteroids are parent bodies of ordinary chondrite meteorites. Furthermore, they clarify that the space weathering age of the Itokawa surface is of the order of several thousand years. Traditionally, Q-t...
Article
Full-text available
In 2013, the well-known Chelyabinsk meteor entered the Earth's atmosphere over Chelyabinsk, Russia. It is estimated that the meteor exploded at altitude near 30 km, which damaged thousands of buildings and injured a thousand of residents. The estimated size of the meteor is approximately 20 m. Because the meteor approached to Earth from Sun directi...
Article
Since 2002, we have obtained size frequency distributions (SFDs) of main belt asteroids (MBAs), Hildas, and Jupiter Trojans (JTs) by using the 8.2-m Subaru Telescope equipped with the wide-field CCD cameras: Suprime-Cam (SC) or Hyper Suprime-Cam (HSC). After combining these SFDs with SFDs obtained from other surveys, we performed a comparative stud...
Article
Context. The near-Earth asteroid 3200 Phaethon (1983 TB) is an attractive object not only from a scientific viewpoint but also because of JAXA’s DESTINY ⁺ target. The rotational lightcurve and spin properties were investigated based on the data obtained in the ground-based observation campaign of Phaethon. Aims. We aim to refine the lightcurves and...
Article
Aims. Our aim in this paper is to try to discover if we can find any record of the Oort cloud formation process in the orbital distribution of currently observable long-periodic comets. Methods. Long-term simulations of tens of millions of comets from two different kinds of proto-Oort clouds (isotropic and disk-like) were performed. In these simula...
Preprint
Full-text available
The near-Earth asteroid 3200 Phaethon (1983 TB) is an attractive object not only from a scientific viewpoint but also because of JAXA's DESTINY+ target. The rotational lightcurve and spin properties were investigated based on the data obtained in the ground-based observation campaign of Phaethon. We aim to refine the lightcurves and shape model of...
Article
Full-text available
The near-Earth asteroid (3200) Phaethon is the parent body of the Geminid meteor stream. Phaethon is also an active asteroid with a very blue spectrum. We conducted polarimetric observations of this asteroid over a wide range of solar phase angles α during its close approach to the Earth in autumn 2016. Our observation revealed that Phaethon exhibi...
Article
Full-text available
We present a visible multi-band photometry of trans-Neptunian objects (TNOs) observed by the Subaru Telescope in the framework of Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) from March in 2014 to September in 2016. We measured the five broad-band (g, r, i, z, and Y) colors over the wavelength range from 0.4 um to 1.0 um for 30 known TNOs u...
Article
The formation of the four terrestrial planets of the solar system is one of the most fundamental problems in the planetary sciences. However, the formation of Mercury remains poorly understood. We investigated terrestrial planet formation by performing 110 high-resolution N-body simulation runs using more than 100 embryos and 6000 disk planetesimal...
Article
Full-text available
Apollo-type NEA (3200) Phaethon, classified at the B/F-type taxonomy, probably the main mass of the Phaethon-Geminid stream complex (PGC), can be the most metamorphic C-complex asteroid in our solar system, since it is heated up to ~1000 K by the solar radiation around its perihelion passages. Hence, its surface material may be easily decomposed in...
Article
Full-text available
Terms in the analytic expansion of the doubly averaged disturbing function for the circular restricted three-body problem using the Legendre polynomial are explicitly calculated up to the fourteenth order of semimajor axis ratio (α) between perturbed and perturbing bodies in the inner case (α<1) , and up to the fifteenth order in the outer case (α>...
Article
Full-text available
We review previously published and newly obtained crater size-frequency distributions in the inner solar system. These data indicate that the Moon and the terrestrial planets have been bombarded by two populations of objects. Population 1, dominating at early times, had nearly the same size distribution as the present-day asteroid belt, and produce...
Article
Full-text available
We present lightcurve observations and their multiband photometry for near-Earth object (NEO) 2011 XA3. The lightcurve has shown a periodicity of 0.0304 +- 0.0003 day (= 43.8 +- 0.4 min). The fast rotation shows that 2011 XA3 is in a state of tension (i.e. a monolithic asteroid) and cannot be held together by self-gravitation. Moreover, the multiba...
Article
We observed the main-belt asteroid (4507) 1990 FV from 2002 November to December at three observatories in eastern Asia. Its synodic rotation period turned out to be 6.58 ± 0.04 h and its lightcurve amplitude was 0.40 ± 0.03 mag when reduced to zero solar phase angle. Since our observations covered a relatively large solar phase angle range (2.3-13...
Article
Full-text available
The newly formed giant planets may have migrated and crossed a number of mutual mean motion resonances (MMRs) when smaller objects (embryos) were accreting to form the terrestrial planets. We investigated the effects of the planetesimal-driven migration of Jupiter and Saturn, and the influence of their mutual 1:2 MMR crossing on terrestrial planet...
Article
The Karin family is a very young asteroid family created by an asteroid breakup 5.8 Myr ago. Since the members of this family probably have not experienced significant orbital or collisional evolution yet, it is possible that they still preserve properties of the original family-forming event in terms of their spin state. As we carried out a series...
Article
We observed 43 young family asteroids (Karin, Iannini, Veritas) and 7 old family asteroids (Koronis, Themis) at Maidanak Observatory, then determined their rotation period, lightcurve amplitude, B-V, V-R, V-I colors.
Article
Meteor phenomena on the surface of Jupiter are observed as optical flashes. We introduce recent event recorded by Japanese amateur astronomers along with implication to the size distribution of small bodies in giant planet region.
Article
Full-text available
An analysis of truncation errors of the simplest symplectic integrator is revisited. We performed an analytical error estimate of this integrator within the framework of a canonical perturbation method, taking the two-body system as an example. Our study was motivated by the desire to remove any confusion in the derivation of this issue in one stan...
Article
Full-text available
Making a survey of Itokawids, i.e., meteor(oid)s originating from Apollo-type near-Earth Asteroid (25143) Itokawa, from among the multiple-station optical meteor orbit data, and employing several orbital similarity criteria, we found five Itokawid candidates. Furthermore, we classified the Itokawid candidates in meteorite types according to their p...
Article
Full-text available
Tens of thousands of sparse-in-time lightcurves from astrometric projects are publicly available. We investigate these data and use them in the lightcurve inversion method to derive new asteroid models. By having a greater number of models with known physical properties, we can gain a better insight into the nature of individual objects and into th...
Chapter
Most known asteroid families are considered very old and they have undergone significant collisional and dynamical evolution that mask the property of the original collisional events. However, members of young asteroid families are likely to preserve properties of the original collision. They serve as precious evidence of large-scale collisional di...
Chapter
The Hyper Suprime-Cam (HSC) survey with the 8.2-m Subaru telescope is a multi-color photometric survey. The survey has been designed to provide a fundamental data set for various areas of cosmology-related researches in the next decade. However, it is also able to cover more general science purposes. In this paper, we describe briefly a current pla...
Book
This invaluable volume set of Advances in Geosciences continues the excellent tradition of the Asia-Oceania scientific community in providing the most up-to-date research results on a wide range of geosciences and environmental science. The information is vital to the understanding of the effects of climate change, extreme weathers on the most popu...
Article
Recent lunar crater counting studies have revealed an asymmetric distribution of rayed craters on the lunar surface. The asymmetry is related to the synchronous rotation of the Moon, and there is a higher density of rayed craters on the leading hemisphere compared with the trailing hemisphere. Here we report the progress in our study to test the hy...
Article
Full-text available
Context. Recent lunar crater studies have revealed an asymmetric distribution of rayed craters on the lunar surface. The asymmetry is related to the synchronous rotation of the Moon: there is a higher density of rayed craters on the leading hemisphere compared with the trailing hemisphere. Rayed craters represent generally the youngest impacts. Aim...
Article
Full-text available
(832) Karin, an S-type main belt asteroid, is the largest member of a very young asteroid family: the Karin family. This asteroid is likely a large fragment of a disruption event in the main asteroid belt about 5.8 million years ago. We carried out a near-infrared photometric observation of this asteroid in 2006 February near its opposition, and ob...
Article
Full-text available
Apollo-type near-Earth asteroid 3200 Phaethon, having a small perihelion distance of q ˜ 0.14 AU, is classified as F- or B-type, one of subclasses among the C-complex (C-, G-, B-, and F-types) asteroids. The F/B-type asteroids and dehydrated CI and CM carbonaceous chondrites, which are regarded as being linked to each other, underwent a thermal his...
Article
We present a new experimental result of fragment spin-rate in impact disruption, using a thin glass plate. A cylindrical projectile impacts on a side (edge) of the plate. Dispersed fragments are observed using a high-speed camera and the spin rates of fragments are measured. We find that the measured fragment spin-rate decreases with increasing siz...
Article
We report our multi-band photometry of young family asteroids observed at Maidanak Observatory, Uzbekistan, from January to May 2006. Young asteroid families were created by single disruption events 5—8 Myr ago. They are extremely young compared with old asteroid families that were formed ~2 Gyr ago. Thus, members of young asteroid families likely...
Article
Recent lunar explorations have revealed that there is a signature of asymmetric crater distribution on the lunar surface, probably caused by the synchronous rotation of the Moon. In order to obtain the information about dynamical origin of the projectiles that created the asymmetry, we carried out a series of numerical integrations to reproduce the...
Article
Full-text available
Here we report a near-infrared (J, H, and K bands) spectroscopy of 832 Karin, the brightest asteroid among the Karin cluster group, which is thought to be the remnants of a collisional breakup only 5.8 million years ago. The spectroscopic observation was performed by the Subaru telescope with the Cooled Infrared Spectrograph and Camera for OHS on 2...
Article
Full-text available
We estimated the upper limit masses of an extrasolar planetary system, υ And. Doppler observation of extrasolar planets through the radial velocity displacement of their host stars can determine only lower limits of planetary masses and inevitably involves uncertainties due to the unknown line-of-sight inclination of planetary orbits, 1/ sin i. How...
Article
Full-text available
Context. The quasi-Hilda comets (QHCs), being in unstable 3:2 Jovian mean motion resonance, are considered a major cause of temporary satellite capture (TSC) by Jupiter. Although the QHCs may be escaped Hilda asteroids, their origin and nature have not yet been studied in sufficient detail. Of particular interest are long TSCs/orbiters. Orbiters –...
Article
Full-text available
Our planetary system is dynamically stable for the lifetime of the Sun according to long-term numerical integrations of the planetary orbits (2002, MNRAS, 336, 483). We first list up possible subsystems of a stable planetary system, and then discuss three forms of subsystems that may contribute to maintaining the stability of the system, and whose...
Article
Full-text available
Although it is more complicated to search for near-Earth object (NEO) families than main belt asteroid families, since differential orbital evolution within a NEO family can cause current orbital elements to drastically differ from each other, we have found that Apollo asteroids 1566 Icarus and the newly discovered 2007 MK 6 are almost certainly re...
Article
Full-text available
Context. The recently discovered Apollo-type near-Earth asteroid 2005 UD has been suggested to be a fragment of (3200) Phaethon. Aims. To test this hypothesis, we carried out photometric observations of 2005 UD using the 1-m telescope at Lulin Observatory. Methods. Multi-color photometry was used to compare the surface properties of (3200) Phaethon...
Article
Full-text available
We present current results of our long-term campaign to make photometric observations of the new-born Karin family asteroids, especially those of (832) Karin. Karin, an S-type main-belt asteroid, is the largest member of the Karin family. This asteroid is likely a large fragment of a disruption event in the main asteroid belt that occurred about 5....
Article
Full-text available
We review some of the major achievements of celestial mechanics in the twentieth century, and discuss some unsolved problems that are left to the twenty-first century. The four major research fields in celestial mechanics are treated: dynamical systems, three-body problems, solar system dynamics, and numerical methods. Over the past decades, celest...
Article
The mismatch between reflectance spectra of most common asteroids (S-type asteroids) and most common meteorites (ordinary chondrites) is thought to be caused by space weathering. Recent study of celestial mechanics has led to the discovery of a young group of S-type asteroids, “Karin cluster group”, which is thought to be remnants of a collisional...
Article
A large disruption in the main asteroid belt can cause a large flux, an “asteroid shower”, on the terrestrial planets. We quantitatively examine the hypothesis that such an event was the cause of the lunar late heavy bombardment (LHB). We performed numerical integrations of about 20,000 test particles starting in the vicinity of the ν6 secular reso...
Article
The impact crater record of Mars, Venus, Mercury and the Moon is owed to two populations of impactors that are distinguishable by their size distributions. We show that the impactors responsible for the 'old' population of craters were virtually identical in size distribution to the present main belt asteroids; the second impactor population, infer...
Article
Full-text available
Context. The recently discovered Apollo asteroid 2005 UD is the most likely candidate for being a large member of the Phaethon-Geminid stream Complex (PGC). Aims. Detecting more complex members like this should clarify the formation and evolution of the PGC. Methods. Our backward and forward (±10 000-yr) integration of the Kustaanheimo-Stiefel regu...
Article
Full-text available
Recent progress in asteroid surveys has revealed the fine structures down to sub-km in diameter of the size-frequency distributions (SFD) of main belt asteroids (MBAs), as well as near-Earth asteroids (NEAs). These SFDs can be compared with the SFD of lunar and planetary crater projectiles. The SFD of the projectiles that created the oldest craters...
Article
A near-Earth asteroid 2005 UD was discovered by Catalina Sky Survey in October 2005 Orbital parameters of this asteroid is very similar to those of 3200 Phaethon 3200 Phaethon has comet-like orbit and thought to be a parent body of meteor shower Orbital similarity of these asteroids may suggest that 2005 UD is a fragment of 3200 Phaethon To test th...
Article
We present the first results of a long-term campaign of photometric observations of the Karin family asteroids. This family is very compact, and is supposed to be extremely young, with an estimated age of about 5.8Myrs. The purpose of our observations is to determine the rotational properties, the colors and hopefully the overall shapes of the larg...
Chapter
We have carried out a near-infrared (J, H, and K bands) spectroscopy of the asteroid Karin with cooled infrared spectrograph and camera for OHS on the Subaru telescope. This asteroid is the brightest asteroid among the Karin cluster group, which is thought to be remnants of a collisional breakup only 5.8 million years ago. For different rotational...
Article
Full-text available
Insights into the history of the inner solar system can be derived from the impact cratering record of the Moon, Mars, Venus, and Mercury and from the size distributions of asteroid populations. Old craters from a unique period of heavy bombardment that ended ∼3.8 billion years ago were made by asteroids that were dynamically ejected from the main...
Article
Here we report a near-infrared spectroscopy of the newborn asteroid Karin. For different rotational phases, we derived different spectra such as reddened spectrum like that of S- type asteroid and un-reddened spectrum like that of ordinary chondrite.