The Astrophysical Journal<\/a>, reveals that WISE 0855\u2019s atmosphere is shaped by at least two distinct processes playing out simultaneously: water clouds at high altitudes that grow thicker and thinner as the object rotates, and deep chemical gases being dredged upward by convection from far below. Untangling those two signals\u2014previously impossible with older telescopes\u2014is what makes JWST data so powerful.<\/p>\n\u201cThis is the first time we\u2019ve been able to confirm that water clouds are becoming thinner and thicker on a nearby world,\u201d says Miles, an assistant professor at Steward Observatory. \u201cBefore JWST, we only had photometry, which mixed up the effects of clouds, chemistry, and temperature all together. Now we can actually distinguish them.\u201d<\/p>\n
Brown dwarfs occupy a strange middle ground. Too massive to be planets, too small to ignite as stars, they glow dimly with leftover heat from their formation. WISE 0855, at roughly 265 Kelvin\u2014colder than Earth\u2019s surface\u2014sits at the very bottom of that category, blurring the line further. At about twice Jupiter\u2019s mass and nearly the same size, it looks and behaves, in many ways, like a free-floating giant planet.<\/p>\n
Understanding its atmosphere requires looking at the world through what coauthor Mark Marley, director and department head of the Lunar and Planetary Laboratory at U of A, describes as a kind of screen door.<\/p>\n
\u201cThe photons go through the atmosphere and escape to space,\u201d Marley says. \u201cIt\u2019s like looking at the world through a screen door, where the screen is filtering out some of the light. We\u2019re learning about the world on either side of the screen\u2014but we also have to understand the screen itself.\u201d<\/p>\n
In this case, the screen keeps changing. As WISE 0855 rotates, different patches of its surface rotate into view, each with slightly different cloud cover and temperature, like watching a slowly turning patchwork of warmer and cooler regions. JWST\u2019s medium-resolution spectrograph was sensitive enough to track those differences across individual molecular features\u2014something no prior observatory could achieve for an object this cold. In addition to the variable temperatures that followed the rotation of the brown dwarf, the spectrograph also captured a rhythmic, wave-like signal tied to specific gases: carbon monoxide and phosphine. Those chemicals fluctuate because heat from deep inside the brown dwarf is constantly churning them upward toward the surface, the same way a pot of hot soup pushes warmer liquid up from the bottom.<\/p>\n
This kind of chemical signal is familiar to planetary scientists. On Jupiter, convective mixing dredges gases from deep, hot layers up into the visible atmosphere. The same process, called disequilibrium chemistry, has been observed in brown dwarfs before\u2014but watching it vary in real time, molecule by molecule, is new territory.<\/p>\n
\u201cWe\u2019re seeing water clouds getting thicker and thinner, and deep gases rising and falling, and we can actually watch them change in real time,\u201d Miles says.<\/p>\n
Miles says that the real value of this discovery isn\u2019t just what it tells us about WISE 0855 specifically, but what it suggests about planetary atmospheres more broadly. The basic physics of convection, clouds and chemistry that governs Jupiter also govern this cold, free-floating world more than seven light-years away. If that physics is universal, it applies to the gas giant exoplanets that astronomers are now beginning to study in earnest with JWST.<\/p>\n
\u201cEven though brown dwarfs are not true planets, they exhibit planet-like behavior,\u201d Miles says. \u201cThere is a spectrum of behaviors\u2014not a hard line between brown dwarfs and planets. Jupiter and this object look distinctly different, but they have similar weather patterns. There are basic physics and chemistry that can be applied across all of these worlds.\u201d<\/p>\n
For Miles, whose models were built on foundational work by theorists like Marley\u2014whose atmospheric models were themselves benchmarked against Jupiter\u2014the paper is as much a generational milestone as it is a discovery. \u201cA lot of my physical intuition on what is missing from the models is because of Mark\u2019s mentorship and hard work,\u201d she says. \u201cThis is a multi-year project. A lot of people contributed to make sure this could be done right.\u201d<\/p>\n
Miles looks ahead to logging more hours of baseline observations with JWST to pin down further details about WISE 0855\u2019s rotation and the three-dimensional nuances of its atmospheric movement. For now, the message is clear: weather happens everywhere, and some of our closest neighbors have skies worth watching.<\/p>\n
Source: University of Arizona<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"Share this Article You are free to share this article under the Attribution 4.0 International license. A Jupiter-sized…\n","protected":false},"author":2,"featured_media":646030,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[111,139,69,6251,147,392],"class_list":["post-646029","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-new-zealand","tag-newzealand","tag-nz","tag-planets","tag-science","tag-space"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/646029","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/comments?post=646029"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/646029\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media\/646030"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media?parent=646029"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/categories?post=646029"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/tags?post=646029"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}