The Activity of a Solar-Type Star TOI-1422 and Mass Loss of the Atmosphere of the Planet TOI-1422b

Abstract

Abstract The results of the analysis of the activity of a solar type star G2V TOI-1422 are presented and estimates of the loss of atmospheric matter of the planet TOI-1422b are made. The planet can be attributed to the type of hot Neptunes. Compared to other exoplanets of a similar mass range, it is expected that the planet has an extensive gas envelope. According to the long-term photometric survey of Kamogata Wide-field Survey (KWS) the TOI-1422 activity was analyzed and the existence of possible activity cycles of 1650–1680 days and 2450 days was suggested. The probable value of the rotation period P of the star lies in the range of 27 (+19, –8) days, observations of the KWS survey in the V filter indicate the most possible value for the period P = 32 days. Mass loss of the planet’s atmosphere is determined using an approximation formula corresponding to the model of atmospheric loss with an energy restriction. To estimate the flux of XUV photons analytical dependences were used linking the flux values and the parameter $$\log R_{{{\text{HK}}}}^{'}$$. Calculations have shown that the atmosphere matter loss of TOI-1422b is $$\dot {M} = 9.4 \times {{10}^{8}}$$ g/s; considering the existing errors in determining the parameters of the atmosphere it lies in the range from $$6.8 \times {{10}^{8}}$$ to $$1.4 \times {{10}^{9}}$$ g/s, and considering the uncertainty in the value of the chromospheric activity index—from $$8.3 \times {{10}^{8}}$$ to $$1.1 \times {{10}^{9}}$$ g/s.