Subjects: Geosciences >> Space Physics Subjects: Physics >> Geophysics, Astronomy, and Astrophysics Subjects: Astronomy >> Galaxy and Cosmology submitted time 2024-06-02
Abstract: The Closeby Habitable Exoplanet Survey (CHES) employs state-of-the-art, high-precision astrometry and positioning technology at the microarcsecond level in space. Its primary objective is to conduct a thorough survey of approximately 100 FGK-type stars within the Sun’s proximity (within 10 parsecs), with the goal of detecting potentially habitable Earth-like planets or super-Earths. This pioneering mission involves a detailed census of habitable planets, providing intricate information on their numbers, true masses, and three-dimensional orbits. Notably, CHES marks a historic milestone as the inaugural international space exploration mission exclusively dedicated to the study of terrestrial planets within the nearby habitable zone. CHES’s payload features a cutting-edge optical telescope with a 1.2 m aperture, a field of view measuring 0.44°×0.44°, and a focal length of 36 m. The telescope utilizes a coaxial three-mirror TMA optical imaging system. Impressively, CHES is designed with a positioning measurement accuracy of 1 μas, solidifying its status as the most precise space exploration project globally in terms of positioning accuracy. To achieve the detection objectives of CHES, it is essential to refine and further substantiate the scientific goals through comprehensive argumentation. Overcoming three key technological challenges is crucial: advancing optical systems for large field of view, developing high-quality space telescopes with minimal distortion; breaking through measurement technology for stellar separations at the 10–5 pixel level; and achieving high stability in satellite system attitude control and thermal control precision. CHES stands on the threshold of groundbreaking discoveries, with the exciting prospect of revealing 50 Earth-like planets. This announces a significant leap forward in China’s space science exploration technology.
Subjects: Digital Publishing >> New Media submitted time 2023-10-08 Cooperative journals: 《中国传媒科技》
Abstract:随着现代信息技术不断发展,期刊与媒体进行媒介融合已经成为了时代发展主旋律。文章首先介绍了媒介融合内容,再从生产内容和传播方式两个方面介绍了期刊与媒体融合的现状,最后简单地介绍了期刊与媒体进行融合发展的创新模式,以便使天文学期刊可以获得更好的发展。
Subjects: Astronomy >> Star and Galactic System submitted time 2022-04-20
Abstract:
" We report the discovery of a massive protostar M17~MIR embedded in a hot molecular core in M17. The multiwavelength data obtained during 1993--2019 show significant mid-IR (MIR) variations, which can be split into three stages: the decreasing phase during 1993.03--mid-2004, the quiescent phase from mid-2004 to mid-2010, and the rebrightening phase from mid-2010 until now. The variation of the 22\,GHz H2O maser emission, together with the MIR variation, indicates an enhanced disk accretion rate onto M17~MIR during the decreasing and rebrightening phases. Radiative transfer modeling of the spectral energy distributions of M17~MIR in the 2005 epoch (quiescent) and 2017 epoch (accretion outburst) constrains the basic stellar parameters of M17~MIR, which is an intermediate-mass protostar (M~5.4 Msun) with accretion rate ~1.1x10^-5 Msun in the 2005 epoch and ~1.7x10^-3 Msun/yr in the 2017 epoch. The enhanced accretion rate during outburst induces the luminosity outburst ΔL≈7600Lsun. In the accretion outburst, a larger stellar radius is required to produce accretion rate consistent with the value estimated from the kinematics of water masers. M17 MIR shows two accretion outbursts (Δt∼9−20 yr) with outburst magnitudes of 2 mag, separated by a 6 yr quiescent phase. The accretion outbusrt occupies 83\% of the time over 26 yr. The accretion rate in outburst is variable with amplitude much lower than the contrast between quiescent and outburst phases. The extreme youth of M17 MIR suggests that minor accretion bursts are frequent in the earliest stages of massive star formation.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astronomical Instruments and Techniques submitted time 2022-03-15
Abstract:
High energy gamma-rays carry the fundamental information of the astrophysical sources in extreme conditions. The space detection of gamma-rays is distinguished by the wide energy range, the observation continuity as well as the high energy resolution. With the experience in constructing and running the DArk Matter Particle Explorer (DAMPE), we propose a new satellite mission——Very Large Area gamma-ray Space Telescope (VLAST). VLAST has an acceptance of ~10 m2·sr at GeV energies and ~ 1 m2·sr at MeV energies. Together with a much better energy resolution, VLAST is expected to increase the sensitivity of Fermi Large Area Telescope by a factor of 10. In this work, the main scientific objectives, the detection principle, the payload and the expected performance of VLAST are introduced.
"
"
"
Peer Review Status:Awaiting Review