- 著者
- Shogo NISHIYAMA Tomohiro KARA Brian THORSBRO Hiromi SAIDA Yohsuke TAKAMORI Masaaki TAKAHASHI Takayuki OHGAMI Kohei ICHIKAWA Rainer SCHÖDEL
- 出版者
- The Japan Academy
- 雑誌
- Proceedings of the Japan Academy, Series B (ISSN:03862208)
- 巻号頁・発行日
- pp.pjab.100.007, (Released:2023-12-01)
The tremendous tidal force that is linked to the supermassive black hole (SMBH) at the center of our galaxy is expected to strongly subdue star formation in its vicinity. Stars within 1'' from the SMBH thus likely formed further from the SMBH and migrated to their current positions. In this study, spectroscopic observations of the star S0-6/S10, one of the closest (projected distance from the SMBH of ≈0''.3) late-type stars were conducted. Using metal absorption lines in the spectra of S0-6, the radial velocity of S0-6 from 2014 to 2021 was measured, and a marginal acceleration was detected, which indicated that S0-6 is close to the SMBH. The S0-6 spectra were employed to determine its stellar parameters including temperature, chemical abundances ([M/H], [Fe/H], [α/Fe], [Ca/Fe], [Mg/Fe], [Ti/Fe]), and age. As suggested by the results of this study, S0-6 is very old (≳10 Gyr) and has an origin different from that of stars born in the central pc region.
- 著者
- Chawanat Nakasan Kohei Ichikawa Putchong Uthayopas
- 出版者
- 一般社団法人情報処理学会
- 雑誌
- 研究報告ハイパフォーマンスコンピューティング(HPC)
- 巻号頁・発行日
- vol.2014, no.30, pp.1-6, 2014-07-21
This paper discusses the use of Multipath TCP (MPTCP), which is a TCP extension that allows multiple TCP flows to be associated to one application-layer logical connection, coupled with OpenFlow traffic engineering in a single stack to provide a comprehensive multipathing solution, with OpenFlow providing optimal path sets while MPTCP utilizing them. This design should be able to maximize bandwidth and network path utilization by allowing hosts to take advantage of presently-unused paths. Design of the testbed, also to be used by our research group in future projects, is also discussed in this paper. Finally, we discuss evaluation of network performance when using multiple paths, as well as concerns raised by our work. In summary, our system functioned as expected and provided feasible performance in small virtual network. This design should be scalable to benefit distributed file storage systems, data-intensive services, or any high-performance computing systems.This paper discusses the use of Multipath TCP (MPTCP), which is a TCP extension that allows multiple TCP flows to be associated to one application-layer logical connection, coupled with OpenFlow traffic engineering in a single stack to provide a comprehensive multipathing solution, with OpenFlow providing optimal path sets while MPTCP utilizing them. This design should be able to maximize bandwidth and network path utilization by allowing hosts to take advantage of presently-unused paths. Design of the testbed, also to be used by our research group in future projects, is also discussed in this paper. Finally, we discuss evaluation of network performance when using multiple paths, as well as concerns raised by our work. In summary, our system functioned as expected and provided feasible performance in small virtual network. This design should be scalable to benefit distributed file storage systems, data-intensive services, or any high-performance computing systems.