科学研究
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2024.10.24
Stellar physics and population in the open cluster lab (英文报告)
Open clusters provide an ideal laboratory for testing and calibrating our understanding of stellar physics and single stellar population. In this talk, I will discuss how astronomers use open clusters as a well-defined single population of stars to study the Milky Way disk and stellar evolution. Additionally, I will explore how open clusters can be used to validate pipeline results from large p...
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2024.10.23
The influence of GC evolution on the specific frequency in dwarf galaxies
The presence of large fractions of metal-poor stars in dwarf galaxies still belonging to GCs raises questions about cluster mass loss and their formation mechanisms. These high ratios of metal-poor GCs relative to the number of low-metallicity field stars could imply that clusters in dwarfs have not lost enough mass, compared to more massive galaxies, or that the formation of field stars was su...
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2024.10.22
Mapping the 3D Universe: From the Past to the Future, Bridging Theories and Observations
This collaborative talk introduces the recent work in COSMO-3D group at EPFL’s Laboratory of Astrophysics (LASTRO). Jiaxi Yu (PhD student) will begin with a historical review of cosmology. The Universe started from a Big Bang, followed by inflation. The emission of the first light of the Universe, cosmic microwave background (CMB), happened in an opaque and dark era of the Universe afterwards....
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2024.10.18
Gravitational Lensing in the Kerr Spacetime: An Analytic Approach for Light and High-Frequency Gravitational Waves
Current efforts of the Event Horizon Telescope aim at resolving the black hole shadow, mainly with the goal to probe the nature of the black hole and thus the underlying theory of gravity. Here, including other lensing features, in particular multiple images either of individual sources or in form of the so-called photon rings, will allow to place much tighter constrains on the spacetime parame...
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2024.10.17
Hypervelocity stars: energetic guys “kissed” by massive black holes
The so-called Hypervelocity stars (HVSs; with velocities even greater than 1000 km/s) were first predicted from the theoretical arguments of Hills (1988), and attributed to be the result of tidal interaction between a close stellar binary system and a supermassive black hole (SMBH) in the Galactic center, commonly referred to as the “Hills mechanism”. HVSs or High-Velocity stars (HiVels) can ...
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