An international research team including Takashi Moriya at DTA/NAOJ discovered the first recorded "ultra-stripped supernova," a rare, faint type of supernova that is believed to play a role in the formation of binary neutron star systems. These findings will advance our understanding of a wide variety of topics ranging from gravitational waves to the origin of precious metals like gold and platinum. This research was published in Science on October 12, 2018. (October 12, 2018 press release)

Using the powerful Japanese Subaru telescope, the Hyper Suprime-Cam (HSC) survey collaboration team has made and analyzed the deepest wide field map of the three-dimensional distribution of matter in the Universe. Led by Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) Project Assistant Professor Chiaki Hikage, a team of scientists primarily from Japan, Taiwan and Princeton University has used the gravitational distortion of images of about 10 million galaxies to make a precise measurement of the lumpiness of matter in the Universe. By combining this measurement with the European Space Agency Planck satellite’s observations of the cosmic microwave background, and other cosmological experiments, the team has been able to further constrain the properties of the “dark energy” that dominates the energy density of the Universe. (September 26, 2018 press release)

Summary

At the end of its life, a red supergiant star explodes in a hydrogen-rich supernova. By comparing observation results to simulation models, an international research team including Takashi Moriya at DTA/NAOJ found that in many cases this explosion takes place inside a thick cloud of circumstellar matter shrouding the star. This result completely changes our understanding of the last stage of stellar evolution. (September 4, 2018, press release)

Based on a new study of how near-Earth asteroid Phaethon reflects light at different angles, astronomers think that its surface may reflect less light than previously thought. This is an exciting mystery for the recently approved DESTINY+ mission to investigate when it flies past Phaethon.

The supercomputer Cray XC50, nicknamed NS-05 “ATERUI II” started operation on June 1, 2018. With a theoretical peak performance of 3.087 petaflops, ATERUI II is the world’s fastest supercomputer for astrophysical simulations. ATERUI Ⅱsimulates a wide range of astronomical phenomena inaccessible to observational astronomy, allowing us to boldly go where no one has gone before, from the birth of the Universe itself to the interior of a dying star.

Summary

Astronomers have tracked down the source of a gravitational wave and discovered the first observed kilonova: a nuclear furnace 100 million times brighter than the Sun producing thousands of times the entire mass of the Earth in heavy elements such as precious metals.

An international team of researchers has found evidence that the brightest stellar explosions in our Universe could be triggered by helium nuclear detonation near the surface of a white dwarf star. Using Hyper Suprime-Cam mounted on the Subaru Telescope, the team detected a type Ia supernova within a day after the explosion, and explained its behavior through a model calculated using the supercomputer ATERUI. This result was reported in Nature published on Oct. 5.

An international team of researchers has successfully recreated the formation of a massive black hole from supersonic gas streams left over from the Big Bang using a supercomputer ATERUI. Their study, published in this week’s Science, shows this black hole could be the source of the birth and development of the largest and oldest super-massive black holes recorded in our Universe.

A team of researchers in Japan modeled the two rings around Chariklo, the smallest body in the Solar System known to have rings. This is the first time an entire ring system has been simulated using realistic sizes for the ring particles while also taking into account collisions and gravitational interactions between the particles. The team’s simulation revealed information about the size and density of the particles in the rings. By considering both the detailed structure and the global picture for the first time, the team found that Chariklo’s inner ring should be unstable without help. It is possible the ring particles are much smaller than predicted or that an undiscovered shepherd satellite around Chariklo is stabilizing the ring. (Press Release: April 28, 2017)