Three planets found that are doomed to be eaten by their stars

The astronomy community was shocked in 1995 when the first planet was found. The planet was called a hot Jupiter because it was very close to its host star.

Jupiter is five times farther from the Sun than Earth, and takes twelve years to circle the sun. Many big planets are close to their stars and take mere days to travel around them.

That is cool, but what happens to the planets when their star dies? The stars swell up into red giants and become much larger than the Jupiters. What will happen to these planets?

It is what you would expect: They are doomed. The star will eat them.

It was very bad. Do we see any planets in danger?

The answer is obvious because you are reading this article. There are lots of mysteries despite the fact that planets in this situation have been found. They should be dropped down so close to their stars that they get engulfed in a matter of seconds. How do they get there when we find them? Did they form farther out? Can we see them getting closer? What happens when they get close to their stars?

Some of the questions may be answered by three new exoplanet discoveries. The outlook for these planets is not very good, but it is great for astronomy.

The planets were found in the data taken by TESS, which is looking for planets in the sky. The planet creates a mini-eclipse of its star when it sees the edge-on. It is possible to get the size of the planet, the orbital period, and more. Some planets that are dying and are already swelling up into red giants have been found.

There are three new exoplanets called TOI-2337b, TOI-4329b and TOI-2669b. The three host stars for these planets are much larger than the Sun, a sign that they are about to end. They would be classified as subgiants, but still short of the dozens or even hundreds of times bigger they will get when they become full-on red giants.

That is good! We are seeing these planets at the right time, as things start to cook. Some effects are seen.

The planets' mass was found by looking at how hard their gravity pulls on their stars. The density is given by the combination of size and density. It tells you what the planet is made of, or if it is weird.

Two of the planets are puffy. The mass of TOI-4329b and TOI-2669b makes them 1.5 times the size of Jupiter.

Why? They are hot. The star 4329b is getting more light and heat than the Earth does, and it is also inflated.

It doesn't appear to be inflated, so it is weird. It is 1.6 times larger than Jupiter. It is denser because it was blasted by 1,500 times more energy than Earth. It has a higher surface gravity. It is very close to the dying star because it is the shortest known planet in this position.

Inflation has to do more with the planet than the star. That is a good data point for understanding these planets.

What about the process of decay? The Moon will leave the Earth by about 4 centimeters per year if a star and close-in planet have complex gravitational interactions. The highest rate of decay should be 2337b, but it wasn't detected in the data. The other two don't have enough observations. It looks like more observations will be needed. It was unfortunate, but it was science.

The two puffy planets are good candidates for future observations to look into their atmospheres. The planet is between us and the star. Light from the star can travel through the transparent upper atmospheres of those planets before reaching us. Carbon dioxide, water, and so on absorb light at different colors, so it is possible to determine some of the components of the planetary atmospheres.

This is already done for planets around Sun-like stars. Is it possible that the newly discovered planets have different atmospheres because of their evolving stellar hosts? Future observations may reveal secrets.

I can understand if this sounds academic, but it hits close to home. The Sun will begin to die in 6 or 7 billion years, swelling up first into a subgiant and then a red giant. Recent work shows that the Earth is a goner, and that it will consume Mercury and Venus.

Our home world is very different from the new planets, but they are also very similar to us in that they will be eaten by their star. It is possible that learning about their fate will reveal something about us. It is worth examining if it is only for our own morbid self-interest.