Jiachen Liu
@jiachenliu.bsky.social
PhD candidate at Peking University (she/her) | working on atmospheres on Earth, terrestrial planets, and sub-Neptunes! https://jiachenliu-atmos.github.io/
Very proud of my student Collin Cherubim for his discovery of an atmosphere on the habitable-zone exoplanet LHS 1140 b! www.science.org/doi/10.1126/... www.nytimes.com/2026/07/16/s...
Astronomers Find an Atmosphere on a Nearby Earthlike Planet
It’s the first potentially habitable world known to host an atmosphere, making it a lead contender in the search for life beyond our solar system.
nytimes.com
I compared the Venot 2019 reduced chemical network with the minichem network to better understand how they perform as options for GCMs. The results are up now on arXiv and accepted to MNRAS. #exoplanets arxiv.org/abs/2604.15850
Benchmarking Two Chemical Networks used in General Circulation Models of Hot Jupiters
Chemical kinetics is becoming an increasingly vital component of hot Jupiter general circulation models (GCMs). Here we simulate the hot Jupiter WASP-96b using two chemical networks, a reduced chemica...
arxiv.org
🎉 The latest paper by the great Jiachen Liu (@jiachenliu.bsky.social) on chemical transport in the atmosphere of K2-18b is now up on the arXiv. 🎉 arxiv.org/abs/2604.07987
Three-dimensional transport-induced chemistry on temperate sub-Neptune K2-18b, Part II: the combined effects of atmospheric dynamics and chemical reactions
The upper atmospheres of temperate sub-Neptunes are strongly influenced by atmospheric dynamics due to their cool equilibrium temperature and thereby longer chemical timescales than the atmospheric dynamical timescales. In this study, we used a three-dimensional (3D) general circulation model to investigate the transport-induced disequilibrium chemistry and vertical mixing on temperate gas-rich mini-Neptunes, using K2-18b as an example. We model K2-18b assuming 180 times solar metallicity and consider it as either a synchronous or an asynchronous rotator, exploring spin-orbit resonances of 2:1, 6:1, and 10:1. We find that the vertical transport affects the chemical structure significantly, making CO$_2$ and CO more abundant ($\sim$10$^{-3}$) in the upper atmosphere compared to the chemical equilibrium abundance (<10$^{-15}$), and horizontal winds further homogenize the chemical composition zonally in this region. Molecular abundances in the photosphere generally agree across different rotation periods. We employ a passive tracer in the model to estimate the one-dimensional (1D) equivalent eddy-diffusion coefficient ($K_{zz}$) of K2-18b, providing a parameter useful for future 1D atmospheric models. Additionally, synthetic transmission spectra generated from our model are compared with the JWST observations, and we find that our model can provide a comparable fit to the observations. This work offers a 3D perspective on transport-induced chemistry on a temperate sub-Neptune and derives vertical mixing parameters to support 1D modelling.
arxiv.org
This is a really thoughtful and helpful article about LLM use in science
Russ Schumacher @rschumacher.cloud · 6mo agoHopefully everyone is reading this (and maybe it's what @andrewdessler.com is commenting on). It touches on all of these issues and there aren't a lot of easy answers. ergosphere.blog/posts/the-ma...
A great paper examining the hot Jupiter HAT-P-30b, lead by final-year PhD student Alastair Claringbold (@exoarcturus.bsky.social), as a part of the BOWIE ALIGN program. The program aims to understand how migration history impacts atmosphere composition. #exoplanets www.arxiv.org/abs/2601.13104
BOWIE-ALIGN: Sub-solar C/O ratio and metallicity atmosphere of the misaligned hot Jupiter HAT-P-30b
We present the JWST NIRSpec/G395H transmission spectrum of the misaligned hot Jupiter HAT-P-30b from 2.8--5.2 $μ$m as part of the BOWIE-ALIGN survey, a comparative survey designed to probe the link be...
arxiv.org
Paper day! A new paper on existence of subNeptune magma oceans, arising from a collaboration between Cambridge and my group. Lead author Robb Calder is Oli Shorttle's doctoral student. subNeptune Magma Oceans are getting to be a hot topic! arxiv.org/abs/2512.05816
Most Rocky Sub-Neptunes are Molten: Mapping the Solidification Shoreline for Gas Dwarf Exoplanets
Sub-Neptunes are the most common type of detected exoplanet, yet their observed masses and radii are degenerate with several interior structures. One possibility is that sub-Neptunes have silicate/iro...
arxiv.org
w/ Oli Shorttle, @johannateske.bsky.social & Eliza Kempton we reviewed our current understanding and prospects for peaking on the inside of small #exoplanets in "Constraining exoplanet interiors using observations of their atmospheres": www.science.org/stoken/autho... & arxiv.org/abs/2510.08844 🔭🧪⚒️☄️
Keith Smith@drkeithsmith.bsky.social · 12mo agoHow can we tell what's inside an #exoplanet? @timlichtenberg.bsky.social et al review how a planet's atmosphere interacts with its interior. Atmospheric observations can distinguish between lava worlds, water worlds, temperate surfaces or supercritical interiors. ☄️ www.science.org/doi/10.1126/...
We observed the habitable zone planet TRAPPIST-1e with JWST to search for an atmosphere. You've seen the headlines, now let's dive into the science! 🧪 THREAD (1/N) #Exoplanets 🔭
A rocky planet in its star’s ‘habitable zone’ could be the first known to have an atmosphere – here’s what we found
The largest telescope in space has been trained on a rocky exoplanet.
theconversation.com
Update on the atmosphere vs no atmosphere debate for TRAPPIST-1 b and c -- here's a nice and (IMO) conclusive result from Gillon and Ducrot et al.: no thick atmosphere on either planet. arxiv.org/pdf/2509.02128
arxiv.org
Happy to share the first paper from the SPACE Program, led by my student Angelique Kahle! she observed a hot little sub-Neptune, HD 86226c (Rp = 2.3 Re; equilibrium temp = 1300 K). arxiv.org/pdf/2507.13439 The spectrum is *really* flat ! here's the amplitude compared to other gaseous planets.
My paper with Tom Evans-Soma and Nathan Mayne on magnetic drag models is now accepted and up on the arXiv. For a quick summary, look at the PDF of my Exoclimes poster that I shared last week. www.arxiv.org/abs/2507.08511
Geometric Considerations in Hot Jupiter Magnetic Drag Models
Magnetic fields are expected to impact the atmospheric dynamics of hot and ultra-hot Jupiters due to their increased ionization fractions, compared to that of cooler exoplanets, but our ability to mod...
arxiv.org
Just finished answering questions from my 10pm (local time) Exoclimes talk #ExoclimesVII — been following sessions into the night all week due to Canada time zone. Thanks to the LOC for enabling live audio & remote presentation. It eased the pain of missing in-person due to visa issues.
I recommend giving this paper by @jiachenliu.bsky.social, @astroduncan.bsky.social, and Jun Yang a close read: arxiv.org/abs/2506.23891. Sub-Neptunes like K2-18b lie in an interesting regime where both the radiative feedback and mixing of chemical tracers is important, I’m looking forward to Part 2!
Three-dimensional Transport-induced Chemistry on Temperate sub-Neptune K2-18b, Part I: the Effects of Atmospheric Dynamics
The low equilibrium temperatures of temperate sub-Neptunes lead to extremely long chemical timescales in their upper atmospheres, causing the abundances of chemical species to be strongly shaped by at...
arxiv.org
Jiachen Liu (@jiachenliu.bsky.social) has a very interesting paper out where she looks at the dynamics of K2-18b, modelled as a mini-Neptune. www.arxiv.org/abs/2506.23891
Three-dimensional Transport-induced Chemistry on Temperate sub-Neptune K2-18b, Part I: the Effects of Atmospheric Dynamics
The low equilibrium temperatures of temperate sub-Neptunes lead to extremely long chemical timescales in their upper atmospheres, causing the abundances of chemical species to be strongly shaped by at...
arxiv.org
My new paper, co-authored with Duncan Christie and Jun Yang, on 3D chemical kinetics simulations of K2-18b has been accepted by MNRAS! This is Part I of a series. In Part I, we examine the planet's atmospheric dynamics and its impact on the transport of passive tracers. arxiv.org/abs/2506.23891
Three-dimensional Transport-induced Chemistry on Temperate sub-Neptune K2-18b, Part I: the Effects of Atmospheric Dynamics
The low equilibrium temperatures of temperate sub-Neptunes lead to extremely long chemical timescales in their upper atmospheres, causing the abundances of chemical species to be strongly shaped by at...
arxiv.org
"The possible elimination of the lab, called GFDL, in concert with potential cuts to other NOAA operations, threatens irreparable harm not only to global understanding of climate change and long-range scenarios for the planet but to the country’s safety, competitiveness and national security."
White House Proposal Could Gut Climate Modeling the World Depends On
Potential funding cuts for NOAA and its research partners threaten irreparable harm not only to climate research but to American safety, competitiveness, and national security.
propublica.org
𝗡𝗼, 𝗮 𝗯𝗶𝗼𝘀𝗶𝗴𝗻𝗮𝘁𝘂𝗿𝗲 𝘄𝗮𝘀 𝗻𝗼𝘁 𝗷𝘂𝘀𝘁 𝗱𝗲𝘁𝗲𝗰𝘁𝗲𝗱 𝗶𝗻 𝗞𝟮-𝟭𝟴𝗯'𝘀 𝗮𝘁𝗺𝗼𝘀𝗽𝗵𝗲𝗿𝗲. K2-18b is back in the news, now with a bold claim that biosignature molecules (DMS and/or DMDS) have been 'detected at 3σ'. Most exoplanet astronomers are extremely sceptical about these claims, let's see why (1/n). 🔭🧪🪐 #exoplanet
An astonishing headline reporting on new observations from a team led to Nikku Madhusudhan claims they’ve found ‘hints of life’ on a planet orbiting a dwarf star some 124 light years away. What’s going on? (1/n) www.bbc.co.uk/news/article... 🔭 🧪
Promising hints of life found on distant planet K2-18b
Scientists find new but tentative evidence that a faraway world orbiting another star may be home to life.
bbc.co.uk
Shared some (highly skeptical) thoughts on today’s “habitable planet” #K218b news. Thank you @npr.org for the responsible reporting on this topic!
Max-Planck-Gesellschaft@maxplanck.de · last yr."I think this is one of those situations where extraordinary claims require extraordinary evidence": Laura Kreidberg @mpi-astro.bsky.social about signs of life beyond our #solarsystem. npr.org/2025/04/16/n... #exoplanets #K218b @npr.org @lkreidberg.bsky.social
My new paper with Feng Ding and Jun Yang has been accepted at ApJ: arxiv.org/abs/2504.05233. In this study, we find that lower-tropospheric radiative heating is necessary but not independently sufficient to form the NAIV. Instead, the dynamic heating induced by large-scale subsidence is essential.
Formation of Near-surface Atmospheric Inversion and Surface Inversion in Hothouse Climates
A hothouse climate may develop throughout Earth's history and its warming future and on potentially habitable exoplanets near the inner edge of the habitable zone. Previous studies suggested that near...
arxiv.org
