Can we weigh a star?
Determining the weight of an object as large as a star can be a difficult process. We know that stars can be some of the largest celestial bodies in our universe. Getting close enough to actually gather the weight or a sample of a star is currently impossible but we can still get an accurate reading of the weight of a star's mass by checking into the strength of its gravity.
As gravity will dictate how fast a planet of an orbit of specific size makes its way around the sun, it's possible to use Newton's law to measure the gravity based on orbit and then find the mass of a star.
Measuring stars that are alone without much directly orbiting it, can be more difficult however. Using Einstein's theory of gravity, scientists are able to hypothesize that any type of mass in the universe will distort the fabric of space and time which then affects light rays for any near masses passing by the star. As the rays of light heading into the star have to diverge from their straight line path, the distortions can actually tell the weight of a star. In a study in 2004 at team was actually able to detect the weight of a small red star 1800 light years away developing measurements for the distortions in light. They were able to compare the weight of the star to our own sun and determine that it had a mass of around 1/10 of the weight of our own local star.
Using these two theories and some careful calculations, we can often determine a fairly rough measurement of what a star could weigh. As we know our own sun is around 33,000 times the overall mass of our earth this can place it at roughly 2,000,000,000 metric tons. The sun then serves as a baseline for comparing the weight in other stars.