A mysterious new type of star nicknamed "old smoker" has been discovered hiding in the heart of our Milky Way galaxy, astronomers revealed on Friday. The international team of scientists behind the discovery had not been looking for such old stars during their 10-year survey, which took in hundreds of millions of stars across the sky. 'We don't fully understand'The old smokers were puffing right in the center of the Milky Way, a densely packed and metal-rich region called the Nuclear Stellar Disc. Those smoke puffs are thought to temporarily obscure the stars from our sight. The researchers spotted at least 21 old smokers but suspect there are many more out there.