Legacies of the Dust. A multiwavelength study of protoplanetary disks and young exoplanetary systems

Ignacio Bustamante Bengoechea

Departamento de Astrofísica

Año 2017

The curtain opens. A cold and dark molecular cloud enters the stage, opaque, invisible to the eye. Suddenly, the light changes, and under an infrared filter, the audience can finally see. The cloud now shines, bright, its filaments, clumps, global structure, all bare. Cosmic rays and far ultra violet irradiation can not penetrate it, its inner molecules protected. It gets colder inside, a fragile equilibrium set between pressure, temperature and gravity. Then, the inevitable. Maybe an external shock wave. Maybe the internal gradients in temperature. The cloud shakes, stumbles, and implodes. The equilibrium now lost, it collapses on itself in a myriad different parts. Molecular clumps and cores start to coalesce, their temperatures rising as the gas and dust concentrate in single spots. After a short time, these spots start to shine, bright, sparks of gas that light their surroundings. A new generation of stars has appeared.

Some larger, much larger than others, they coalesce, implode, shine, bright blue, hottest, biggest of them all… and fastest. Their little brothers take their time, much fainter than them. Much, much more numerous. The view zooms in one. The molecular core surrounds the baby star, its substance flowing down onto it. Not quite directly. The dust shifts. The gas twists. It turns, and rotates, surrounds the pup, caresses it, as it takes the shape of a disk. And all the while it feeds the toddler. It does not matter. The baby star cries, the highest, the strongest it’s ever gonna cry in its life. X-ray tears strike the disk that is feeding it, ultraviolet howls evaporates it. And the disk, finally, starts to undo itself.

But not in vane. It does so in its own terms. It transitions, the closest to the host breaks up, disappears, a hole emerging amid disk and star. Not entirely void, though. As it recedes further, the disk leaves part of itself behind. Small pieces of dust coalesce, unite, far from the star which is trying to destroy them. They collide with one another, get larger, evolve… and migrate. The very parental disk which saw them appear, now pushes them closer to their new holder. The disk finally submits, and gives way. The star now quiet, its new family around it, with big giant gas brothers, and little terrestrial sisters. A new planetary system has been born.

The legacies of the dust.

Datos de interés

Supervisores: Bruno Merín, Hervé Bouy
Universidad: Universidad Autónoma de Madrid Facultad de Ciencias Físicas; Centro de Astrobiología
Fecha de lectura: 22/06/2017