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The disk of a Class 0 protostar is thought to be massive and hot. It is an accretion disk, which feeds the central protostar. [39] [40] The temperature can easily exceed 400 K inside 5 AU and 1,000 K inside 1 AU. [51] The heating of the disk is primarily caused by the viscous dissipation of turbulence in it and by the infall of the gas from the ...
When the Sun's orbit takes it outside the galactic disc, the influence of the galactic tide is weaker; as it re-enters the galactic disc, as it does every 20–25 million years, it comes under the influence of the far stronger "disc tides", which, according to mathematical models, increase the flux of Oort cloud comets into the Solar System by ...
The Solar System [d] is the gravitationally bound system of the Sun and the objects that orbit it. [11] It formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc.
In Fred Whipple's 1948 scenario, [4] a smoke cloud about 60,000 AU in diameter and with 1 solar mass (M ☉) contracted and produced the Sun. It had a negligible angular momentum, thus accounting for the Sun's similar property. This smoke cloud captured a smaller one with a large angular momentum.
The Sun is the star at the center of the Solar System.It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light and infrared radiation with 10% at ultraviolet energies.
A protoplanetary disk is a rotating circumstellar disc of dense gas and dust surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star. The protoplanetary disk may not be considered an accretion disk ; while the two are similar, an accretion disk is hotter and spins much faster.
Oort proposed that the bodies in this cloud replenish and keep constant the number of long-period comets entering the inner Solar System—where they are eventually consumed and destroyed during close approaches to the Sun. [5] The cloud is thought to encompass two regions: a disc-shaped inner Oort cloud aligned with the solar ecliptic (also ...
Illustration of the dynamics of a protoplanetary disk. The gas that collapses toward the center of the dense core first builds up a low-mass protostar, and then a protoplanetary disk orbiting the object. As the collapse continues, an increasing amount of gas impacts the disk rather than the star, a consequence of angular momentum conservation ...