111 citations · 497 across the 18 of their papers we have counts for
7 papers · 1 filter
Spectroscopic evidence for a large spot on the dimming Betelgeuse
Sofya Alexeeva, Gang Zhao, Dong-Yang Gao +4
During October 2019 and March 2020, the luminous red supergiant Betelgeuse demonstrated an unusually deep minimum of its brightness. It became fainter by more than one magnitude an…
Photometric study and absolute parameters estimation of six totally eclipsing contact binaries
Kai Li, Qi-Qi Xia, Chun-Hwey Kim +6
High precision CCD observations of six totally eclipsing contact binaries were presented and analyzed. It is found that only one target is an A-type contact binary (V429 Cam), whil…
The first light curve modeling and orbital period change investigation of nine contact binaries around the short period cut-off
Kai Li, Chun-Hwey Kim, Qi-Qi Xia +5
In this paper, we present the first light curve synthesis and orbital period change analysis of nine contact binaries around the short period limit. It is found that all these syst…
The NLTE Analyses of Carbon Emission Lines in the Atmospheres of O and B type Stars
Sofya Alexeeva, Kozo Sadakane, Masayoshi Nishimura +2
We present a model atom for C I - C II - C III - C IV using the most up-to-date atomic data and evaluated the non-local thermodynamic equilibrium (NLTE) line formation in classical…
Photometric investigations on two totally eclipsing contact binaries: V342 UMa and V509 Cam
Kai Li, Qi-Qi Xia, Jin-Zhong Liu +6
By analyzing two sets of complete light curves of V342 UMa and three sets of complete light curves of V509 Cam, we determined that the two systems are both W-…
Contact binaries at the short period cut-off I. statistics and the first photometric investigations of ten totally eclipsing systems
Kai Li, Qi-Qi Xia, Raul Michel +5
The period distribution of contact binaries exhibits a very sharp short period cut-off at 0.22 days. In order to provide valuable information on this short period limit, we observe…
NLTE line formation for Mg\ione\ and Mg\ii\ in atmospheres of B-A-F-G-K stars
Sofya Alexeeva, Tatiana Ryabchikova, Lyudmila Mashonkina +1
Non-local thermodynamical equilibrium (NLTE) line formation for Mg I and Mg II lines is considered in classical 1D-LTE model atmospheres of the Sun and 17 stars with reliable atmos…