How do stars - like our sun - form? Where do planets come from? - In the last years astronomers were able to uncover some of the fundamental processes related to these very questions. It showed that circumstellar disks and envelopes of gas, dust and ices are a natural byproduct of the formation process of young stars. These objects grow then more massive by accreting material from the disk, which itself is fed by the envelope in the early phases. In the course of several million years, the envelope is dispersed, infall onto the disk comes to a hold, and most matter is either accreted onto the young star or possibly built into planets.
In this book, astronomical observations of young low-mass stars are presented. Using data from modern telescopes the surrounding accretion disks and envelopes are investigated, and physical parameters, their possible dust compositions, and ice properties are derived. Some of the young stars seem to have masses in the range of only several Jupiter masses and might be among the least massive free-floating objects known today.
This book is intended for students in physics or astronomy who are interested in the formation of stars and planets.