Questions tagged [size]

Questions regarding the physical dimensions of a celestial object.

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How big could a regular star in supergiant/hypergiant phase theoretically get, not counting quasi-stars?

For clarity, I'm not asking about the super-behemoths that are quasi-stars. I'm interested in knowing how large a regular star could theoretically get once it reached supergiant/hypergiant phase, ...
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Is a star with 2/3 solar masses and 9/10 solar radii still in the main sequence?

As far as I know, K-type and G-type stars (among others) grow in radius as they age, eventually leading to red giant phases. My question is, would a star that is about 0.66 solar masses and 0.94 solar ...
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Is is possible for a main sequence star to have 0.77 solar masses yet only be 0.54 solar radii?

I know ordinarily a star's mass and radius tend to be proportional, so a 0.5 solar masses star tends to be about 0.5 solar radii and have a density of 4.82 g/cm³, 3.42 or about three and a half times ...
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Expansion of space - how do we end up with an unobservable region?

I've just been answering a question on this issue,in physics SE,and realised that my answer conceals a point I don't myself understand. I understand that The expansion of metric isn't affected by ...
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How big is the Andromeda galaxy in the night sky? [duplicate]

If divide the distance to the sun by its diameter, I get the number 107.517 Likewise, if divide the distance to the moon by its diameter, I get the number 110.650 Both numbers are quite similar which ...
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How big is one arcsecond at various distances?

I've been reading this article https://en.wikipedia.org/wiki/Celestial_coordinate_system and a question came to my mind. The minimum units are seconds ( ″ ). I picture an angle of 1 second as being ...
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Regarding the age / size of the Universe [duplicate]

I believe the current estimated age of the Universe is around 14 billion years. I just read in another post on here that the diameter of the Universe is around 90 billion light years. This doesn't ...
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Why are event horizons described in Schwarzschild radii rather than diameters, and either way can they change equator to pole?

I never heard of Schwarzschild diameters, only of Schwarzschild radii. Why is it like this? Wouldn't it be better to portray the (possible) size of a black hole in a diameter? Either way, can we use ...
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1answer
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Is a literal instance of Russell's teapot possible?

Much has been said about Russell's teapot, and I accept as obvious that a teapot would be too small to be detectable in an orbit around the Sun by any reasonable method today, or by any method that ...
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Volume of the observable universe [duplicate]

What about the volume of the observable universe? Can we find it? And what is the result in cubic light years?
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How big can a planet get, with respect to its star for it to sustain life? [closed]

Earth is 108 times smaller than the sun in terms of its diameter while Jupiter is 10 times. Assuming Jupiter was located such that it could sustain life, theoretically how big a planet can get with ...
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What factors influence a star's temperature and density?

Assuming a relatively even proportion of mass and radius, a 0.25 solar mass and radius star would have a density of 22.5003 g/cm³, or about 16 times our Sun's density. However, there is obviously a ...
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Why could a gas planet not get much larger than Jupiter? [duplicate]

What is the maximum size for a gas giant?
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What are the necessary steps required for calculating the size of a star? [closed]

Title pretty much says it all. Basically, what exact variables are used, and what steps need to be taken, in the calculation of the size of a star? Preferably, some example data for how a the size of ...
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Why is the Moon's volume so small compared to the Earth's?

The Moon has 27.3% of the Earth's radius/diameter but only 2% of the Earth's volume. I don't quite get it why the Moon's volume is that small despite having more than a quarter the 2-dimensional size ...

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