Thermally altered subsurface material of asteroid (162173) Ryugu

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.

Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03

https://doi.org/10.1038/s41550-020-01271-2

Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.

Cooling of compact stars with color superconducting quark matter

Noda, Tsuneo*; Yasutake, Nobutoshi*; Hashimoto, Masaaki*; Maruyama, Toshiki; Tatsumi, Toshitaka*; Fujimoto, Masayuki*

Acta Astronomica Sinica, 56(Suppl.), p.52 - 54, 2015/11

We show a scenario for the cooling of compact stars considering the central source of Cassiopeia A (Cas A). The Cas A observation shows that the central source is a compact star with high effective temperature, and it is consistent with the cooling without exotic phases. The Cas A observation also gives the mass range of . It may conflict with the current cooling scenarios of compact stars that heavy stars show rapid cooling. We include the effect of the color superconducting (CSC) quark matter phase on the thermal evolution of compact stars. We assume the gap energy of CSC quark phase is large ( MeV), and we simulate the cooling of compact stars. We present cooling curves obtained from the evolutionary calculations of compact stars: while heavier stars cool slowly, and lighter ones indicate the opposite tendency.

Thermodynamical description of hadron-quark phase transition and its implications on compact-star phenomena

Yasutake, Nobutoshi*; Noda, Tsuneo*; Sotani, Hajime*; Maruyama, Toshiki; Tatsumi, Toshitaka*

Recent Advances in Quarks Research, p.63 - 111, 2013/01

http://arxiv.org/abs/1208.0427

Degradation behaviour of fiber reinforced plastic under electron beam irradiation

Sonoda, Katsumi*; Yamamoto, Yasushi*; Hashimoto, Osamu*; Ono, Toshio*; Tomita, Haruhiko*; Udagawa, Akira; Egusa, Shigenori; Sasuga, Tsuneo; Seguchi, Tadao; Tamura, Naoyuki

Japanese Journal of Applied Physics, Part 1, 28(10), p.1950 - 1956, 1989/10

https://doi.org/10.1143/JJAP.28.1950

no abstracts in English

Degradation behavior of fiber reinforced plastics irradiated with electron beams

Sonoda, Katsumi*; Hashimoto, Osamu*; *; Ono, Toshio*; *; Udagawa, Akira; Egusa, Shigenori; Sasuga, Tsuneo; Seguchi, Tadao; Tamura, Naoyuki

EIM-87-152, p.11 - 24, 1987/00

no abstracts in English