간행물
천문학회지 KCI 등재 SCOPUS Journal of The Korean Astronomical Society
- 발행기관 한국천문학회
- 자료유형 학술지
- 간기 반년간
- ISSN 1225-4614 (Print)2288-890X (Online)
- 수록기간 1968 ~ 2024
- 주제분류 자연과학 > 천문학 자연과학 분류의 다른 간행물
- 십진분류KDC 440DDC 520
권호리스트/논문검색
제51권 제2호 (2018년 4월) 2건
1.
2018.04
구독 인증기관 무료, 개인회원 유료
Heesu Yang, Su-Chan Bong, Kyung-Suk Cho, Seonghwan Choi, Jongyeob Park, Jihun Kim, Ji-Hye Baek, Jakyoung Nah, Mingzhe Sun, Qian Gong
In a solar coronagraph, the most important component is an occulter to block the direct light from the disk of the sun. Because the intensity of the solar outer corona is 10−6 to 10−10 times of that of the solar disk (I⊙), it is necessary to minimize scattering at the optical elements and diffraction at the occulter. Using a Fourier optic simulation and a stray light test, we investigated the performance of a compact coronagraph that uses an external truncated-cone occulter without an internal occulter and Lyot stop. In the simulation, the diffracted light was minimized to the order of 7.6 × 10−10 I⊙ when the cone angle c was about 0.39◦. The performance of the cone occulter was then tested by experiment. The level of the diffracted light reached the order of 6 × 10−9 I⊙ at c = 0.40◦. This is sufficient to observe the outer corona without additional optical elements such as a Lyot stop or inner occulter. We also found the manufacturing tolerance of the cone angle to be 0.05◦, the lateral alignment tolerance was 45 μm, and the angular alignment tolerance was 0.043◦. Our results suggest that the physical size of coronagraphs can be shortened significantly by using a cone occulter.
4,000원
2.
2018.04
구독 인증기관 무료, 개인회원 유료
Massive stars blow powerful stellar winds throughout their evolutionary stages from the main sequence to Wolf-Rayet phases. The amount of mechanical energy deposited in the interstellar medium by the wind from a massive star can be comparable to the explosion energy of a core-collapse supernova that detonates at the end of its life. In this study, we estimate the kinetic energy deposition by massive stars in our Galaxy by considering the integrated Galactic initial mass function and modeling the stellar wind luminosity. The mass loss rate and terminal velocity of stellar winds during the main sequence, red supergiant, and Wolf-Rayet stages are estimated by adopting theoretical calculations and observational data published in the literature. We find that the total stellar wind luminosity due to all massive stars in the Galaxy is about Lw ≈ 1.1 × 1041 erg s−1, which is about 1/4 of the power of supernova explosions, LSN ≈ 4.8 × 1041 erg s−1. If we assume that ∼ 1 − 10 % of the wind luminosity could be converted to Galactic cosmic rays (GCRs) through collisonless shocks such as termination shocks in stellar bubbles and superbubbles, colliding-wind shocks in binaries, and bow-shocks of massive runaway stars, stellar winds might be expected to make a significant contribution to GCR production, though lower than that of supernova remnants.
4,300원
