At a distance of about 160 light years, the stellar association TW Hydrae is a benchmark for the study of pre-main sequence stars and their protoplanetary disks. Pre-main sequence stars are a few million years old stars, still gravitationally contracting and not powered yet by the thermonuclear reactions. They are often surrounded by disks of dust and gas called “protoplanetary
Pre-Main Sequence stars are young stars whose cores are not dense and hot enough to ignite the thermonuclear reactions that will power them for the rest of their evolution. These stars are sorted in three classes: the youngest stars are the class I sources, still embedded in an accreting envelope of gas; class II stars have dispersed their accreting envelope
Pre-Main Sequence stars are young stars (solar type pre-main sequence stars are younger than about 30 million years), that are often observed surrounded by a disc of haas and dust called “protoplanetary discs”. These discs can actively accreting matter onto the central star, with a complex process resulting from a complicated interplay between the gas of the disc and the
Observing how the light emitted by stars changes with the time can be an interesting hobby, but it can also be something more important: an important and powerful diagnostic for something that can be hardly studied with some other approach… This can be particularly important for pre-main sequence stars with protoplanetary disks. In these stars, in fact, important and
