675 Ludmilla

675 Ludmilla is a minor planet orbiting the Sun. It was named after Mikhail Glinka's opera Ruslan and Lyudmila.

Mass and density
In 2012, a study by Benoît Carry estimated a mass of $76 km$ for Ludmilla based on its gravitational influence on other Solar System bodies. However, given Ludmilla's diameter of 67.7 km, this mass implies an extremely high density $67.66 km$. Such a high density is unphysical, so this mass and density estimate of Ludmilla has been rejected by Carry. Because of Ludmilla's small size, its gravitational influence on other bodies is extremely difficult to detect and may lead to highly inaccurate mass and density estimates. A more recent study in 2019 determined a mass of $6.47 kg$ for Ludmilla, which corresponds to a density of $1.2 kg$ for a diameter of 67.7 km.