北京大学科维理天文与天体物理研究所

Featured Science

Most Distant Quasar Discovered Sheds Light on How Black Holes Grow

A team of astronomers led by the University of Arizona has observed a luminous quasar 13.03 billion light-years from Earth – the most distant quasar discovered to date. Two KIAA astronomers, Linhua Jiang and Xue-Bing Wu, joined the research team.

New 3D view of the dense interstellar gas in Milky Way

An international research team of more than 50 astronomers (including KIAA faculty Ke Wang) led by the Max Planck Institute for Radio Astronomy in Bonn, Germany, used the APEX submillimeter telescope at 5100 m altitude in Chile to look deep into the galactic plane and measure the interstellar medium.

Spectroscopic confirmation of the most distant galaxy at redshift 10.957

An 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.

Elliptical accretion disk as a model for tidal disruption events: A Jerusalem bagel from ...

When 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.

New features of fast radio bursts revealed by FAST radio telescope

On 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.

LAMOST reveals the secret of lithium-rich stars

A 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.