ACTIVITY OF THE STAR TOI-1408 AND MASS LOSS BY THE ATMOSPHERES OF ITS EXOPLANETS

We considers the properties of the multiplanetary system TOI-1408, consisting of a hot Jupiter (planet (b), (1.86 ± 0.02) 𝑀Jup, (2.4 ± 0.5) 𝑅Jup) and a sub-neptune (planet (c), (2.22 ± 0.06) 𝑅⊕, (7.6 ± 0.2) 𝑀⊕) orbiting a star of spectral class F. Measurements of radial velocities indicate the existence of an additional celestial body with an orbital period of several thousand days. The TOI-1408 system makes it possible to study the migration processes of hot Jupiter-type planets in cases where a less massive planet (c) is closer to the star than a more massive one (b). Based on archival measurements of the TOI-1408 brightness (DASCH project), we made estimates of the length of the possible cyclic long-term variability of the object (equal to about 10 500 days). The analysis of the brightness variability of TOI-1408 according to the Kamogata Wide-field Survey (KWS) archive led to the detection of peaks in the power spectrum corresponding to a rotation period of about 7.5 days. Estimates of the mass loss of the planets atmospheres were obtained, which were established for two values of the parameter log 𝑅'HK (-4.94 and -4.59) corresponding to the maxima of the bimodal distribution of this parameter for low and high activity for stars of spectral class F. The mass loss of planet (b) (hot Jupiter) can reach 2.3 × 1011 g/s, and of the sub-neptune - planet (c) - 2.7 × 1010 g/s for the value log 𝑅'HK = -4.59. The obtained data are in good agreement with the results for exoplanets of the corresponding types (including for hot Jupiter HD 189733 b and warm Neptune GJ 436 b).

exoplanets, atmosheres, mass loss, activity, cycles