A brown dwarf is larger than a planet, but not large enough to be considered a star. Stars undergo fusion in their cores, but a brown dwarf lacks the mass necessary to initiate fusion. At the same time, they are more like stars than planets, and can have at atmospheric temperature of 2000 K. So these objects occupy a middle ground between star and planet.
Dark Star
So it is tempting to wonder what effect dark matter might have on the formation and evolution of stars themselves. The problem is we can’t be sure without an understanding of type of dark matter which exists. That hasn’t stopped some astronomers from speculating, however.
Star Dates
Determining the age of a star poses a bit of a challenge for astronomers. After all, stars exist over a timescale of billions of years, and they are light years away. We can’t use radiometric dating like we do for rocks and other objects on Earth. So just how do we determine the age of a star? It turns out that there are several ways, and it’s getting easier to do.
Cycle of Stars
The Sun’s magnetic field varies over time, which means the activity of the Sun varies. The earliest observation of this cycle was seen in sunspots. We can observe similar activity in other stars by observing what are known as their H-K cycles.
Consume Mass Quantities
A recent Cosmos episode not withstanding, there is no reason to suspect that entering a black hole would take you to an alternate universe. If you were to fall into a black hole, you would simply be in the black hole. What happens to you after that depends upon the nature of quantum gravity, which we still don’t fully understand.
Siblings
Stars don’t form alone. They form as part of a stellar nursery. We know this because we can see new stars forming in this way, such as in the Orion nebula. This means, of course, that our own Sun also formed in a stellar nursery with lots of other stars. There are stars out in the galaxy that are siblings to our Sun, and we think we know where a few of them are.
Eagle Eye
While many stars rotate at a slow pace, some stars rotate very rapidly. One of these is the star Altair, the brightest star in the constellation Aquilla.
Color Scheme
By the 1900s, physicists gave us an understanding of the relationship between the color of light a star gives off and its temperature. The coolest stars (with surface temperatures of about 2 000 K) glow dim red, while higher temperature stars glow orange, yellow, white and blue.
No Irish
It’s St. Patrick’s day, and that means many will celebrate their Irish heritage and wear the green. But stars never wear the green. You will never see a green star.