AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |
Back to Blog
Blue supercan4/6/2023 ![]() ![]() The dividing line is approximately 40 M ☉, although the coolest and largest red supergiants develop from stars with initial masses of 15–25 M ☉. The most massive blue supergiants are too luminous to retain an extensive atmosphere and they never expand into a red supergiant. If such a star can pass through the yellow evolutionary void it is expected that it becomes one of the lower luminosity LBVs. Depending on the exact mass and composition of a red supergiant, it can execute a number of blue loops before either exploding as a type II supernova or finally dumping enough of its outer layers to become a blue supergiant again, less luminous than the first time but more unstable. Higher mass red supergiants blow away their outer atmospheres and evolve back to blue supergiants, and possibly onwards to Wolf–Rayet stars. In the process they must spend some time as yellow supergiants or yellow hypergiants, but this expansion occurs in just a few thousand years and so these stars are rare. Lower mass blue supergiants continue to expand until they become red supergiants. Many of them become luminous blue variables (LBVs) with episodes of extreme mass loss. īlue supergiants are newly evolved from the main sequence, have extremely high luminosities, high mass loss rates, and are generally unstable. Expansion into the supergiant stage occurs when hydrogen in the core of the star is depleted and hydrogen shell burning starts, but it may also be caused as heavy elements are dredged up to the surface by convection and mass loss due to radiation pressure increases. These stars usually become blue supergiants, although it is possible that some of them evolve directly to Wolf–Rayet stars. O class and early B class stars with initial masses around 10–300 M ☉ evolve away from the main sequence in just a few million years as their hydrogen is consumed and heavy elements (with atomic numbers of 26 (Fe) and less) start to appear near the surface of the star. Supergiants are evolved high-mass stars, larger and more luminous than main-sequence stars. ![]() Rigel and the IC 2118 nebula which it illuminates. ![]()
0 Comments
Read More
Leave a Reply. |