HD 3167 b is a super-Earth about 154 light-years away. A year there lasts less than one Earth day: it races around its star in roughly 23 hours. The dayside is hot enough to melt rock into a lava ocean. But the James Webb Space Telescope saw something else. The planet glows in infrared noticeably fainter than a bare, maximally hot rock should. The dayside is hundreds of degrees cooler than the expected maximum. The most plausible explanation is an atmosphere. It either reflects some of the starlight or carries heat over to the nightside, keeping the dayside from reaching its thermal limit. That is why HD 3167 b is called the coldest lava planet with an atmosphere. Among the ultra-hot worlds that have managed to hold onto gas, it receives the least stellar radiation. Closer to a star, an atmosphere is harder to keep: stellar wind and harsh radiation tend to strip it away. Here, one still seems to be present. What that envelope is made of is still unknown. It could be vaporized rock, carbon dioxide, carbon monoxide, or even water vapor. What is clear is that a lava world can keep an atmosphere where one was not expected.
Δεν υπάρχουν σχόλια:
Δημοσίευση σχολίου