Chromospheric activity on the late-type star V1355 Ori using Lijiang 1.8-m and 2.4-m telescopes

Abstract

We obtained new high-resolution spectra using the Lijiang 1.8-m and 2.4-m telescopes to discuss the chromospheric activities of V1355 Ori as indicated in the behaviour in the Ca II H&K, H δ , H γ , H β , Na I D 1 D 2 , H α and Ca II infrared triplet (IRT) lines. The observed spectra show obvious emissions above continuum in the Ca II H&K lines, absorptions for the H δ , H γ , H β , and Na I D 1 , D 2 lines, variable behaviour (filled-in absorption, partial emission with a core absorption component, or emission above continuum) for the H α line, and weak self-reversal emissions in the strong filled-in absorptions of the Ca II IRT lines. We used a spectral subtraction technique to analyse our data. The results show no excess emission in the H δ and H γ lines, very weak excess emissions for the Na I D 1 , D 2 lines, excess emission in the H β line, clear excess emission for the H α line, and excess emissions for the Ca II IRT lines. The value of the ratio of EW 8542 /EW 8498 is in the range of 0.9 to 1.7, and it implies that the chromospheric activity might have been caused by plage events. The value of the ratio E Hα /E H β is above 3, and it implies that the Balmer lines would arise from prominence-like material. We also found time variations of light curves of equivalent widths (EWs) of the chromospheric activity lines in the Na I D 1 D 2 , Ca II IRT, and H α lines in particular. These phenomena can be explained by plage events, which are consistent with the behaviour of chromospheric active indicators.

Radio stars observed in the LAMOST spectral survey

“…The data indicate that these 14 radio stars have strong chromospheric activity emission. There have been many studies carried out on chromospheric activity in the Ca II IRT lines, Ca II H&K lines, and the Hα, Hβ and other hydrogen lines using the subtraction technique of nonactive templates (e.g., Montes et al 2000;Busà et al 2007;Frasca et al 2011Frasca et al , 2016Pi et al 2016). We believe more active objects can be detected if the subtraction technique is applied, and many active objects are missing without considering the spectral subtraction.…”

1SWASP J034439.97+030425.5: a short-period eclipsing binary system with a close-in stellar companion

“…New photometric observations of J0344 in BV RI-bands were carried out on 2016 December 22, using the 2k×4k PI1024 camera attached to the 2.4-m telescope at Gaomeigu observational station of Yunnan Observatories (YNOs, Fan et al 2015;Qian et al 2015b;Pi et al 2016).…”