The evaluation of the global atmospheric structure, variation, and loss rate is key to a better understanding of the physics that drives the current state of the Martian atmosphere. Operating for more than 2 Mars years, the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission has provided an unprecedented opportunity to study the spatial and temporal variability of the Martian upper atmosphere and ionosphere and their interaction with the solar wind under both nominal and disturbed conditions. One of the primary goals of the MAVEN mission is to characterize the atmospheric loss rates at Mars and understand the relations between those escape rates and solar drivers. Among the dominant atmospheric loss processes, photochemical escape is the major loss process of heavy atomic species, where the escape rate is not directly measured by MAVEN, requiring numerical models to constrain. This talk will present comprehensive modeling efforts of photochemical escape process and formation of the hot atomic coronae at Mars for various atmospheric conditions. The talk will also present the observed and modeled characteristics of the Martian upper atmosphere and ionosphere, that are relevant to the photochemical escape process.
The studies of planet formation have been heavily dominated by theoretical work because observing planets in formation was not possible. The situation is however gradually changing. Thanks to increasingly powerful observing facilities and techniques, we are now able to peer into the birthplaces of planets – so-called circumstellar disks – and routinely find signatures hinting at, and for a few systems direct evidence of, on-going planet formation. In this talk I will introduce how planet formation theories are being tested with and improved by observational data. In particular, I will present a specific example PDS 70, a 5-million-year-old young star surrounded by a disk of gas and dust with two accreting giant protoplanets detected across a broad range of wavelengths from optical to millimeter, offering a perfect test bed for planet-disk interaction and planet formation theories.
천문학은 우리 역사에 깊이 관여돼 있다. 그 중요성은 라대일 박사와 박창범 박사가 『단군세기』에서 ‘戊辰五十年五星聚婁’ 기록을 발굴하고 이를 천문학적으로 증명하면서 크게 부각됐다. 이것은 ‘BC 1733년 오성이 루 주위에 모였다’ 같이 해석되는 단군조선시대의 천문기록이다. 이런 사실이 우리 역사에 미치는 영향에 대해 알아보기로 한다. 또한 지금까지 우주의 역사는 대부분 서양의 관점에서 기술됐다는 점도 짚고 넘어가기로 한다. 가장 좋은 예가 교육과정에서 서양의 아리스토텔레스 4원소는 가르치면서 동양의 태호복희 5원소는 가르치지 않는다는 것이다. 그 결과 대한민국 국민 대부분이 학창시절 태극기의 원리를 제대로 배우지 못했다. 최소한의 태극기에 대한 지식도 알아보기로 한다.
Planet formation is the process where dust grains grow to pebbles,
planetesimals, and rocky planets or cores of gas giant planets in
protoplanetary disks. The process as well as the planetary properties
such as masses can be imprinted in disks, thus obtaining the detailed
disk structure is central to understand how the planet forming activity
proceeds in the entire regions of the disks. I will review the recent
results of disk observations mainly with the Atacama Large
Millimeter/submillimeter Array (ALMA). The fine disk
structures/substructures have been resolved with about 5-au resolution
of ALMA in dust continuum, and those images often show that the disks
consist of concentric annuli, or sometimes show the spiral arms or
strong non-axisymmetry. Combined also with the gas observations,
plausible mechanisms to explain those structures include the trapping of
dust particles at the local pressure maxima and the disk-planet