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The solar mass (M ☉) is a standard unit of mass in astronomy, equal to approximately 2 × 10 30 kg (2 nonillion kilograms in US short scale). It is approximately equal to the mass of the Sun. It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. More precisely, the mass of the ...
At this rate, the Sun has so far converted around 100 times the mass of Earth into energy, about 0.03% of the total mass of the Sun. The Sun will spend a total of approximately 10 to 11 billion years as a main-sequence star before the red giant phase of the Sun. [ 135 ] At the 8 billion year mark, the Sun will be at its hottest point according ...
In this framework, the early Sun underwent an extended period of higher solar wind output. Based on exoplanetary data, this caused a mass loss from the Sun of 5−6 percent over its lifetime, [27] resulting in a more consistent level of solar luminosity (as the early Sun had more mass, resulting in more energy output than was predicted).
The choice of solar mass, M ☉, as the basic unit for planetary mass comes directly from the calculations used to determine planetary mass.In the most precise case, that of the Earth itself, the mass is known in terms of solar masses to twelve significant figures: the same mass, in terms of kilograms or other Earth-based units, is only known to five significant figures, which is less than a ...
Thus, the Sun occupies 0.00001% (1 part in 10 7) of the volume of a sphere with a radius the size of Earth's orbit, whereas Earth's volume is roughly 1 millionth (10 −6) that of the Sun. Jupiter, the largest planet, is 5.2 AU from the Sun and has a radius of 71,000 km (0.00047 AU; 44,000 mi), whereas the most distant planet, Neptune, is 30 AU ...
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.
Thus, the total mass loss each year is about (2–3) × 10 −14 solar masses, [33] or about 1.3–1.9 million tonnes per second. This is equivalent to losing a mass equal to the Earth every 150 million years. [34] However, since the Sun's formation, only about 0.01% of its initial mass has been lost through the solar wind. [6]
The mass/luminosity relation is important because it can be used to find the distance to binary systems which are too far for normal parallax measurements, using a technique called "dynamical parallax". [8] In this technique, the masses of the two stars in a binary system are estimated, usually in terms of the mass of the Sun.