Scientists have for the first time studied a white dwarf at the center of a planetary nebula, part of a scattered star cluster. They were able to discover how much mass it lost during its lifetime and thereby test modern models of stellar evolution.
How much mass does a star lose during its lifetime? An international research team led by Professor Klaus Werner from the Institute of Astronomy and Astrophysics at the University of Tübingen has studied the central star of a planetary nebula scattered in a star cluster for the first time. . Scientists sent a giant 10-meter telescope on the Canary island of La Palma to one of the bright stars of the scattered star cluster Messier 37. Like all stars located at the center of planetary nebulae, it is a white dwarf and in this case it is quite young.
Previously, the star was like our Sun. However, it exhausted its hydrogen reserves, turned into a red giant and then lost its outer shell, forming a planetary nebula. And only a small, dense core remains. One of the main mysteries regarding stars like the Sun is how much mass they lose during all these transformations. We believe that for our luminaires this figure is 50%. And if it was eight times heavier it would be 80%. However, the results of all these calculations are extremely complicated to verify.
Scattered star clusters help solve the mystery And then scattered star clusters come to the rescue. These groups of stars are born from the same cloud of gas and dust. Since then, they have traveled around the universe together. The luminaires in the group are of the same age, only differing in mass. And the greater the star’s mass, the faster it evolves. So, if one of the stars in a scattered cluster passes through the red giant phase and turns into a white dwarf, we can certainly calculate its age and, therefore, its initial mass compared to neighboring stars. These objects therefore make excellent targets for testing theories about stellar evolution.
The only problem is that there are only a few such objects in the entire Milky Way. And in general they are very weak. Therefore, it was not possible to study them properly before. And that’s why the latest research is so exciting. It revealed that the star at the center of the planetary nebula has 0.85 times the mass of the Sun. And at the beginning of his existence, he weighed 2.8 times more than him. Therefore, during evolution, it lost 70% of its mass, which coincides very well with existing theories.