Osteopenia refers to bone density that is lower than normal peak density but not low enough to be classified as osteoporosis. Bone density is a measurement of how dense and strong the bones are. If your bone density is low compared to normal peak density, you are said to have osteopenia.steopenia refers to bone density that is lower than normal peak density but not low enough to be classified as osteoporosis. Bone density is a measurement of how dense and strong the bones are. If your bone density is low compared to normal peak density, you are said to have osteopenia.
The Milky Way is the second-largest galaxy in the Local Group, with its stellar disk approximately 100,000 ly (30 kpc) in diameter, and, on average, approximately 1,000 ly (0.3 kpc) thick.
The SMBH at the centre of the Milky Way is of 4.1 million solar mass, whereas the nearby Andromeda Galaxy contains a SMBH of 110-230 million solar mass. The largest SMBH in the Milky Way's vicinity appears to be that of the galaxy M87, containing 6.4 billion solar mass. The largest SMBH in the nearby Universe yet found is that of the galaxy NGC 4889, containing 21 billion solar mass.