For a while, scientists believed gas giant planets could only orbit at far distances from their stars. But some of these can orbit at incredibly close distances to their stars. A study led by a University of Arizona researcher laid groundwork for future research.
The research gives astronomers a good idea of the formation and makeup of what they call "hot jupiters." What takes Earth a year to orbit the sun, these giants can circle their stars in less than 10 days. And due to how close they are to their stars, they can be hot enough to vaporize iron.
The study used the Hubble Telescope to monitor 19 of these exoplanets. Because astronomers often have thousands of samples to draw information from, that sample size might not seem like a lot.
But 19 is a large number of exoplanets monitored. Those 19 were the only exoplanets the Hubble Space telescope monitored for what the researchers were looking for.
“So the way we study these planets in general is they are transiting planets so we can see them block some of the starlight," said Megan Mansfield, a University of Arizona researcher who led the research.
When the planet passes in front of the star, they can see how much light is blocked by their atmospheres. By seeing which wavelengths are being blocked, they can see what elements comprise their atmospheres.
"Even these big planets block maybe 1% of light from the star. What we are looking at when we are trying to look for signatures from all of these molecules, we're not just looking at how much light is being blocked overall, but like small changes of light that's blocked at different wavelengths. It's sometimes in the order of hundreds of parts per million."
Yet how these planets got so close is a mystery. One idea Megan mentioned is the gaseous planets formed farther away from their stars, then drifted closer due to outside influences.
But she says the study might give a hint into these planets origins.
“Depending on how far away from their star they formed, they might accrete different amounts of carbon vs oxygen vs other elements into their atmospheres. So we can try to sort of use the compositions of their atmospheres now to back out to see how they formed and how they got to where they are," she said.
There are still mysteries as to the ways solar systems can form, but this study gets researchers closer to the full story.
If there was a hot jupiter in our solar system, life on Earth, the only known example of life in the universe, might not exist.
