Abstract
In this chapter, we cover the formation of protoplanetary disk as a natural byproduct of the gravitational collapse of a slowly rotating, hydrostatic cloud. We also summarise the structure of such a disk as it results from hydrostatic equilibrium and viscous accretion.
Highlights
In this chapter we look at the basic processes disk formation and of disk structure
Why do disks form in the first place? How will matter be distributed, radially and vertically? We will focus mainly on the structure of disks resulting from viscous evolution. Another important process affecting disk structure is external irradiation. As this is so strongly coupled with the spectral energy distribution we observe from protoplanetary disks, we will cover this part in the chapter on spectral energy distributions
The disk structure follows from radial and angular momentum conservation and the assumption that the vertical component of gravity from the star is balanced by the vertical gas pressure gradient
Summary
In this chapter we look at the basic processes disk formation and of disk structure. Why do disks form in the first place? How will matter be distributed, radially and vertically? We will focus mainly on the structure of disks resulting from viscous evolution. The original idea of a protosolar nebula dates back to Kant & Laplace in the 18th century who used the observed structure of the planetary system to propose the existence of a flattened structure around the Sun from which the planets formed, explaining both the flattened geometry and the aligned angular momenta of the Sun and the planetary orbits (nothing was known back about planetary rotation) The confirmation that such disks exist and that they are a common by-product of star formation dates back to the late 1980’s and early 1990’s, when the first mm images (Beckwith et al 1986, Sargent & Beckwith 1987, Rodriguez et al 1992) and spectroscopy The data shows that such protoplanetary disks are ubiquitous around newly formed stars (50% of stars show disk detection), but reveals the impact of disk irradiation and erosion by nearby hot O and B stars
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