Activity of Two Young Stars of Solar Type with Planetary Systems from the Ursa Major Moving Group of Stars and the Stream Psc-Eri

High precision data from the archive of the TESS space mission are used as the basis of a study of the photometric variability of two young analogs of the Sun with planetary systems: the stars HD 63433 (TOI 1726), a member of the Ursa Major moving group of stars with an age of 414 million years and TOI 451 (CD-38 1467) from the Pisces-Eridani star stream (Psc-Eri) with an age of 120 million years. Manifestations of the activity of these stars with planetary systems are studied. Based on all the available observations we have estimated the rotational periods of the stars and the amplitudes of their brightness variability. The standard method has also been used to estimate the spottedness parameter A in an absolute measure. The areas of the spots on the surfaces of HD 63433 and TOI 451 greatly exceed the area of the spots on the Sun, 24500 m.s.h. and 12600-33200 m.s.h., respectively. The activity cycles of TOI 451 were estimated using data from the archive of the All Sky Automated Survey and indicated possible activity cycles of 125 and 1280 days. The data for HD 63433 suggest the existence of long-term changes in brightness, but are insufficient for quantitative estimates.