Yunnan Observatory

Kunming, China

Yunnan Observatory

Kunming, China
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Gao Z.F.,Urumqi Observatory | Gao Z.F.,University of Chinese Academy of Sciences | Gao Z.F.,Nanjing University | Wang N.,Urumqi Observatory | And 4 more authors.
Astrophysics and Space Science | Year: 2011

In this paper, we consider the effect of Landau levels on the decay of superhigh magnetic fields of magnetars. Applying 3P2 anisotropic neutron superfluid theory yield a second-order differential equation for a superhigh magnetic field B and its evolutionary timescale t. The superhigh magnetic fields may evolve on timescales ~(106-107) yrs for common magnetars. According to our model, the activity of a magnetar may originate from instability caused by the high electron Fermi energy. © 2011 Springer Science+Business Media B.V.

Liu X.W.,China West Normal University | Liu X.W.,Beijing University of Technology | Xu R.X.,Beijing University of Technology | Van Den Heuvel E.P.J.,University of Amsterdam | And 4 more authors.
Astrophysical Journal | Year: 2015

The origin of the 6.67 hr period X-ray source, 1E161348-5055, in the young supernova remnant RCW 103 is puzzling. We propose that it may be the descendant of a Thorne-Żytkow Object (TŻO). A TŻO may at its formation have a rapidly spinning neutron star as a core and a slowly rotating envelope. We found that the core could be braked quickly to an extremely long spin period by the coupling between its magnetic field and the envelope, and that the envelope could be disrupted by some powerful bursts or exhausted via stellar wind. If the envelope is disrupted after the core has spun down, the core will become an extremely long-period compact object, with a slow proper motion speed, surrounded by a supernova-remnant-like shell. These features all agree with the observations of 1E161348-5055. TŻOs are expected to have produced extraordinarily high abundances of lithium and rapid proton process elements that would remain in the remnants and could be used to test this scenario. © 2015. The American Astronomical Society. All rights reserved.

Zhang X.,Yunnan Observatory | Zhang X.,Armagh Observatory | Chen X.,Yunnan Observatory | Han Z.,Yunnan Observatory
Astrophysics and Space Science | Year: 2010

Mass is a fundamental parameter, but the masses are not well known for most hot subdwarfs. We propose a method of determining the masses of hot subdwarfs. Using this method, we studied the masses of hot subdwarfs from the ESO supernova Ia progenitor survey and the Hamburg quasar survey. The study shows that most of the subdwarf B stars have masses between 0.42 and 0.54 M⊙, whilst most sdO stars are in the range 0.40~0. 55 M⊙. Comparing our study to the theoretical mass distributions of Han et al. (Mon. Not. R. Astron. Soc. 341:669, 2003), we found that sdO stars with mass less than ~0. 5 M⊙ may evolve from sdB stars, whilst most high-mass (>0. 5 M⊙) sdO stars result from mergers directly. © 2010 Springer Science+Business Media B.V.

Han Z.,Yunnan Observatory | Chen X.,Yunnan Observatory
Proceedings of the International Astronomical Union | Year: 2012

Type Ia supernovae (SNe Ia) are believed to be thermonuclear explosions of carbon-oxygen white dwarfs at a mass close to the Chandrasekhar limit. However, a white dwarf at birth has a significantly lower mass and needs to accrete mass to grow to the limit for the explosion. Various progenitor models have been proposed and those models play an important role in our understanding of SNe Ia and cosmology. © International Astronomical Union 2013.

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