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Tue, 2020-12-15When a star passing closely enough by a supermassive black hole is disrupted by tidal forces, the stellar debris falls onto the black hole triggering a tidal disruption event (TDE). It is commonly assumed that the accretion disk that forms circularizes efficiently, because of the relativistic apsidal precession and interactions between the crossing streams of matter. This picture is challenged by observations of the optical/UV spectra and the total bolometric output of the TDEs. If the circularization is inefficient, which is suggested by some numerical simulations, such low angular momentum accretion flow should result in a formation of an elliptical accretion disk. Such a model, with radiation originating from the shocks at the self-intersection of streams and being called self-crossing shock model in the community, was proposed by Tsvi Piran and colleagues.
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Tue, 2020-12-15An international team of astronomers, led by Professor Linhua Jiang at KIAA, obtained near-infrared spectra and successfully measured the redshift of a very faint galaxy 13.4 billion light-years away, the most distant astrophysical object known to date. Meanwhile, the team also detected a burst signal with a duration of minutes from the galaxy, which can be explained as an ultraviolet flash associated with a gamma-ray burst (GRB). These results are important to understand the formation of stars and galaxies in the very early Universe). Two papers based on the results were recently published in Nature Astronomy.
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Fri, 2020-11-27KIAA postdoc Hassen Yesuf won a PKU Outstanding Postdoc Award while postdoc Rui Xu won a second 2-year PKU Boya Fellowship.
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Thu, 2020-11-26Dr.Xu received her PhD from the Department of Astronomy at Peking University in 2017. She was awarded her first Hubble Fellowship to work at University of Wisconsin-Madison with Prof. Alex Lazarian.
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Tue, 2020-11-24On November 21, 2020, the opening ceremony of Chinese Space Station Telescope Peking University Science Center (CSST PKU Center) was held at the Yingjie Exchange Center of Peking University.
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Fri, 2020-11-06On October 29th and November 4th, 2020, the research journal “Nature” published two articles on FRBs using FAST: 1) “Diverse polarization angle swings from a repeating fast radio burst source” and 2) “No pulsed radio emission during a bursting phase of a Galactic magnetar”. In both works, researchers from Kavli Institute for Astronomy and Astrophysics (Peking university), National Astronomical Observatory (Chinese academy of science), and University of Nevada formed the core team.
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Wed, 2020-10-28A recent study revealed the actual evolutionary stage of lithium-rich stars by the Chinese astronomers is published in the Nature Astronomy on Oct.5. Yutao Zhou, the LAMOST Fellow from the department of astronomy at PKU, is involved in this study as the co-first author. By combining the LAMOST spectra with the asteroseismic data from Kepler, they find that most lithium-rich stars are located at the evolutionary stage of red clump instead of the red giant branch as previously thought. The findings challenge the previous theories of lithium enrichment, which is vital to resolve the problem of lithium origin.
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Fri, 2020-09-25On September 25, the winners of the 2020 "XPLORER PRIZE" are announced. Subo Dong, an Associate Professor at KIAA is listed among the 50 awardees this year.
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Thu, 2020-09-24Astronomers have found that the key to understanding galaxies with "extreme" sizes, either small or large, may lie in their surroundings. In two related studies, an international team found that galaxies that are either "ultra-compact" or "ultra-diffuse" relative to normal galaxies of comparable brightness appear to reside in dense environments, i.e., regions that contain large numbers of galaxies. This has led the team to speculate that these "extreme" objects could have started out resembling normal galaxies, but then evolved to have unusual sizes through interactions with other galaxies.
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Thu, 2020-08-06"This new study is a great example of how flexibility in observation scheduling allows NASA and ESA missions to study objects that evolve relatively quickly and look for longer-term changes in their average behavior," said Michael Loewenstein, a coauthor of the study and an astrophysicist for the NICER mission at the University of Maryland College Park and NASA's Goddard Space Flight Center (GSFC) in Greenbelt, Maryland. "Will this feeding black hole return to the state it was in before the disruption event? Or has the system been fundamentally changed? We're continuing our observations to find out.” Two KIAA astronomers, Prof. Luis Ho and Ruancun Li, also participated in this discovery.
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