3 goldilocks zone planets around 1 star:

Originally posted by sonhouse
I wonder if any star twice the mass of Sol would also put out 25 times the light?

The physics of stars is almost entirely a function of mass, so yes, although it does also depend on age - which affects which nuclear reactions are taking place.
The sun is at least a second generation star, but I believe it still started out as mostly hydrogen.

Originally posted by twhitehead
The physics of stars is almost entirely a function of mass, so yes, although it does also depend on age - which affects which nuclear reactions are taking place.
The sun is at least a second generation star, but I believe it still started out as mostly hydrogen.

Second gen meaning it came out of a previous nova cloud and therefore was seeded with metals, I think that's what you mean.

Originally posted by sonhouse
I know it is an unlikely candidate for nova much less super, just using that as an example.

I wonder if any star twice the mass of Sol would also put out 25 times the light?

It seems weird there are these stars almost as big as our whole solar system or bigger and yet are still stars. Mind boggling.

http://earthsky.org/space/how-big-is-the-bigges ...[text shortened]... ond bigger than galaxies:

http://phys.org/news/2016-05-strongest-merging-galaxy-clusters.html

There's an upper bound of around 150 solar masses on how massive a population I or II star can be. I took a quick look at the Wikipedia page [1] and this limit seems to be observational rather than theoretical, the proposal is that their solar wind is so intense it blows of excess mass. However a star R136a1 has a measured mass of 315 solar masses, so this limit may not be true [2]. R136a1 has a surface temperature of 58,000 Kelvin and a luminosity 8.7 million times that of the sun.

Large population I stars use the CNO cycle to burn hydrogen. This was not available to the earliest stars and it is theorised that population III stars could grow to much larger masses. There's been an observation in June of last year of stars at a redshift of 6 to 7 which are population III candidates [3][4]. The population is ordered by decreasing metalicity, so the oldest, most metal poor stars are population III, population II are metal poor and the youngest stars called population I stars are metal rich.

[1] https://en.wikipedia.org/wiki/Stellar_mass
[2] https://en.wikipedia.org/wiki/R136a1
[3] https://en.wikipedia.org/wiki/Cosmos_Redshift_7
[4] https://arxiv.org/abs/1504.01734

I took a look at Wikipedia - the fount of all human knowledge - and according to it the nearest supernova candidate is IK Pegasi at 150 lightyears, which is a binary system pretty similar to Sirius, but the white dwarf is 0.2 astronomical units from the primary. The primary is 1.65 solar masses and the white dwarf 1.15. It's not expected to happen any time soon and by then the star's expected to have moved out of range. The next closest is a type II candidate and is Spica at 250 light years - also a binary, the two stars are so close together that they are deformed into ellipses. Spica A is a blue giant at 10 solar masses and Spica B has a mass of 6.5 solar masses. Spica A is classed as a Beta Cephei variable, but stopped pulsing in 1970.

See:
[1] https://en.wikipedia.org/wiki/IK_Pegasi
[2] https://en.wikipedia.org/wiki/Spica
[3] https://en.wikipedia.org/wiki/Beta_Cephei_variable

Originally posted by DeepThought
I took a look at Wikipedia - the fount of all human knowledge - and according to it the nearest supernova candidate is IK Pegasi at 150 lightyears, which is a binary system pretty similar to Sirius, but the white dwarf is 0.2 astronomical units from the primary. The primary is 1.65 solar masses and the white dwarf 1.15. It's not expected to happen any ...[text shortened]...
[2] https://en.wikipedia.org/wiki/Spica
[3] https://en.wikipedia.org/wiki/Beta_Cephei_variable

I think 250 ly away is pretty safe. And Pagasi must have a fairly fast velocity relative to us so not to worry about those.