Determine the maximum distance to a galaxy where RR Lyrae variable stars can be observed.

Variable stars of the RR Lyrae type (they are also called short-period Cepheids) are characterized by practically the same luminosity, independent of the period. The absolute magnitude of such stars M is +0.5. We will assume that by modern means such a star can be detected in another galaxy and its variability can be studied if it is not weaker than 27m. The distance to the star r, expressed in parsecs, can be found by the formula
log r = 1+ 0.2 (m – M).
It turns out that RR Lyrae stars can be observed at a distance of up to 3.2 Mpc.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.