Planetary nebulae, butterflies among the stars

Planetary nebulae are probably the most beautiful objects we can see in the sky with the aid of a telescope. So called because of their fuzzy, planet-like appearance in the light of primitive telescopes, these huge clouds of the most varied shapes and colours expand around the dying stars of which they were once a part. Like pollen carried by a cosmic butterfly to renew the cycle of life, this element-rich gas synthesised by the dying core will mingle with the interstellar medium, where it will give rise to new stars, planets and, perhaps, beings that ponder about life and the universe.

Since our astonished discovery of these strange objects, two and a half centuries ago, we have made giant strides in understanding what they really are, until we concluded that one day this will be the fate of our Sun. And yet, there are still many questions to be answered. One of the biggest, and the one on which my research and that of my group is focused, could be summarised as follows: since stars are essentially spherical, how to explain that most of these singular beasts are not spherical at all? How to explain their intricate geometries, often arranged around a preferred axis? Throughout this seminar we will rejoice in the beauty of planetary nebulae and how our understanding of them has been changing while they expand, fading into the medium between the stars.