Messier 105 or M105 (aka NGC 3379) is an elliptical galaxy located about 36 million light-years away in the constellation of Leo. Messier 105 is known to have a supermassive black hole at its core whose mass is estimated to be around 150 to 200 billion times the mass of our Sun.
Messier 91 is a barred spiral galaxy located in the constellation Coma Berenices. It’s part of the Virgo Cluster of galaxies and is about 63 million light-years away from the Earth. It was the last of a group of eight nebulae discovered by Charles Messier in 1781. Originally, M91 was a missing object in the Messier catalogue as the result a bookkeeping mistake by Messier. It was not until 1969 that amateur astronomer William C. Williams realized that M91 was the galaxy that had also be cataloged as NGC 4548.