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At the center of the Sun, fusion power is estimated by models to be about 276.5 watts/m 3. [7] Despite its intense temperature, the peak power generating density of the core overall is similar to an active compost heap, and is lower than the power density produced by the metabolism of an adult human. The Sun is much hotter than a compost heap ...
The coolest layer of the Sun is a temperature minimum region extending to about 500 km above the photosphere, and has a temperature of about 4,100 K. [77] This part of the Sun is cool enough to allow for the existence of simple molecules such as carbon monoxide and water. [ 81 ]
This temperature is achieved in the cores of main-sequence stars with at least 1.3 times the mass of the Sun. [32] The Sun itself has a core temperature of about 1.57 × 10 7 K. [33]: 5 As a main-sequence star ages, the core temperature will rise, resulting in a steadily increasing contribution from its CNO cycle. [25]
The Sun is composed primarily of the chemical elements hydrogen and helium; they account for 74.9% and 23.8%, respectively, of the mass of the Sun in the photosphere.All heavier elements, colloquially called metals in stellar astronomy, account for less than 2% of the mass, with oxygen (roughly 1% of the Sun's mass), carbon (0.3%), neon (0.2%), and iron (0.2%) being the most abundant.
The temperature of the core region for a VLMS decreases with decreasing mass, while the density increases. For a star with 0.1 M ☉, the core temperature is about 5 MK while the density is around 500 g cm −3. Even at the low end of the temperature range, the hydrogen and helium in the core region is fully ionized. [4]
The surface abundance of Li on the Sun is 140 times less than the protosolar value (i.e. the primordial abundance at the Sun's birth), [18] yet the temperature at the base of the surface convective zone is not hot enough to burn – and hence deplete – Li. [19] This is known as the solar lithium problem.
Impermeable plasma is a type of thermal plasma which acts like an impermeable solid with respect to gas or cold plasma and can be physically pushed. Interaction of cold gas and thermal plasma was briefly studied by a group led by Hannes Alfvén in 1960s and 1970s for its possible applications in insulation of fusion plasma from the reactor ...
The Sun and planets of the Solar System (distances not to scale). The Solar System is the gravitationally bound system of the Sun and the objects that orbit it. It formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc.