![]() "This is extremely exciting and unexpected, especially since Neptune's previous period of low cloud activity was not nearly as dramatic and prolonged." "Even four years later, the images we took this past June showed the clouds haven't returned to their former levels," said Erandi Chavez, a graduate student at Harvard University's Center for Astrophysics who led the study when she was an undergraduate astronomy student at UC Berkeley. "We essentially saw cloud activity drop within a few months." "I was surprised by how quickly clouds disappeared on Neptune," said Imke de Pater, emeritus professor of astronomy at UC Berkeley and senior author of the study. The observations, which are published in the journal Icarus, further reveal a connection between Neptune's disappearing clouds and the solar cycle-a surprising find given that Neptune is the farthest major planet from the sun and receives only 1/900th of the sunlight we get on Earth.Ī University of California (UC) Berkeley-led team of astronomers discovered the abundance of clouds normally seen at the icy giant's mid-latitudes started to fade in 2019. ![]() Keck Observatory, along with views from space via NASA's Hubble Space Telescope show clouds are nearly gone with the exception of the south pole. ![]() Images from 1994 to 2022 of the big blue planet captured from Maunakea on Hawaiʻi Island through the lens of W. Keck Observatoryįor the first time in nearly three decades of observations, clouds seen on Neptune have all but vanished. Credit: Imke de Pater, Erandi Chavez, Erin Redwing (UC Berkeley)/W. The images are displayed using a Asinh function which, like a log-scale display, decreases the contrast between the features if displayed on a linear scale, only the brightest features would be visible. Afterwards, clouds appeared almost absent except near the south pole. As shown by this compilation of images at 1.63 µm (microns) obtained with the NIRC2 and adaptive optics system on the Keck II Telescope, Neptune had numerous cloud features organized in latitudinal bands from before 2002 through late 2019. TOI-1695$\,$b is a new sub-Neptune planet at the border of the M-dwarf radius valley that can help test formation scenarios for super-Earth/sub-Neptune-like planets.A dramatic change in Neptune’s appearance was observed in late 2019 and has persisted through June 2023. We derive a mean equilibrium planet temperature of $590 \pm 90\,$K. We report a 5.5-$\sigma$ detection of the planetary signal, giving a mass of $5.5 \pm 1.0\,$M$_\oplus$ and a radius of $2.03 \pm 0.18\,$R$_\oplus$. We use and compare different methods to reduce and analyse those data. We successfully detect a reflex motion of the star and establish it is due to a planetary companion at an orbital period consistent with the photometric transit period thanks to a year-long radial-velocity monitoring of TOI-1695 by the SPIRou infrared spectropolarimeter. With a transit depth of 1.3$\,$mmag, the radius of candidate TOI-1695.01 was estimated by the TESS pipeline to be 1.82$\,$R$_\oplus$ with an equilibrium temperature of $\sim 620\,$K. Kiefer and 41 other authors Download PDF Abstract:TOI-1695 is a V-mag=13 M-dwarf star from the northern hemisphere at 45$\,$pc from the Sun, around which a 3.134-day periodic transit signal from a super-Earth candidate was identified in TESS photometry. Download a PDF of the paper titled A sub-Neptune planet around TOI-1695 discovered and characterized with SPIRou and TESS, by F.
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