Spectrum of the Yellow Symbiotic Star LT Delphini before, during, and after the 2017 Outburstстатья
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Дата последнего поиска статьи во внешних источниках: 12 сентября 2019 г.
Аннотация:LT Del is a yellow symbiotic system that consists of a bright
K3-type giant and a hot subdwarf with a temperature $\sim 10^5$ K.
We present the results of our spectroscopic observations of LT Del
over the period 2010-2018. In 2017 the star experienced a second
low-amplitude ($\Delta V\sim0.^{m}7$) outburst in the history of
its studies. The emission spectrum of the star represented in the
optical range by hydrogen, neutral and ionized helium lines
underwent significant changes in the outburst. The fluxes in the
HI and HeI emission lines increased by a factor of 5-6, the HeII
$\lambda$4686 line grew by a factor of 10. According to our
estimates, in the 2017 outburst the temperature of the exciting
star rose to $T_{\text{hot}}\sim$130~000 K, while during the first
1994 outburst the change in temperature was insignificant. This
suggests cool and hot outbursts of LT Del by analogy with similar
events of another yellow symbiotic star, AG Dra.