Laura Kreidberg

Incredible opportunity from the MPG to start your own research group!

APEx research focuses on exoplanet atmosphere characterization, from the ground and space. Small planets, big planets, transits, direct imaging, theoretical modeling (1D, 3D, interior), instrumentation (esp ground-based high-res) - we love it all!

We have job opportunities in the APEx department at MPIA - please spread the word!

Postdocs: aas.org/jobregister/...
Tenure-track staff: aas.org/jobregister/...
Max Planck Research Group Leaders: aas.org/jobregister/...

+ happy to host ERC, Humboldt, and other third-party funds.

Rocky Worlds DDT Updates: Final Target List and Virtual Information Session

The Rocky Worlds DDT has published our final target list. Join us for an information session on September 15 to learn more about the 9 targeted planets and the goals of the program.

🔭 #exoplanets

My money is on bare rock for both planets - this simple explanation fits the data well, no fine-tuning needed. This may disappoint some folks, but I think it's amazing that we can measure this at all!! if atmospheres are rare on rocky planets orbiting M-dwarfs, that is a profound thing to know.

There *are* still some atmospheres that are compatible with the data, but the parameter space is shrinking - can't have too high surface pressure (> 1 bar) or too much CO2 (> 100 ppm or so). These scenarios are a bit finely tuned - a bare rock or thick, Venus-like atmosphere are easier to produce.

Histograms of the dayside and nightside temperature constraints for TRAPPIST-1b and c. The nightside of both planets is consistent with zero, implying no evidence for heat redistribution by an atmosphere.

Now, we have a joint thermal phase curve for the planets, finding no significant heat redistribution from dayside to nightside. Here are the constraints on dayside and nightside temperature (K) for the planets. Dayside is red, nightside is blue, top row is planet b, and bottom row planet c.

Previous measurements of thermal emission from planet b were consistent with either a bare rock or a thermal inversion in a CO2-rich atmosphere (arxiv.org/abs/2412.11627). Planet c was best fit by a moderately reflective surface or a thin atmosphere with not too much CO2.

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

Open Call for Expressions of Interest in Max Planck Directorships: Expressions of interest can be submitted until 31 October 2025.

Director at Max Planck - a unique position! The Open Call for Expressions of Interest in Max Planck Directorships is open now and can be submitted by the 31st of October 2025. ➡️ mpg.de/directors - Please share the Open Call among potential candidates.

Our paper on PSO J318 is finally out 💪 . I want to thank all of my coauthors who made this study possible 🙇 !! It could be that we see the first cloud seeding nuclei forming at the top of the atmosphere…?

arxiv.org/abs/2507.18691

gorgeous new JWST spectrum of the rogue planet PSO J318 from @paulmolliere.bsky.social ! Strong absorption at 10 microns likely due to small SiO particles, acting as seeds for cloud formation arxiv.org/pdf/2507.18691

you did it!!!! 🙌

Compared to other planets in this temperature range, HD 86226c is surprisingly featureless ... indicative of either very high metallicity (which might have helped it survive in this intense irradiation environment), or high-altitude clouds. Or both!

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.

@astroduncan.bsky.social did the impossible - he put magnetic fields in his models!! Check out this nice paper on how more realistic B fields impact hot Jupiter atmosphere circulation 🧲

Huge congratulations to @sophiavaughan.bsky.social for receiving the Michael Penston Prize from the RAS!!! Sophia is a pioneer in detecting reflected light from exoplanets. Congrats on this well-deserved recognition 😁🔭

Hi exoplaneteers! Please consider submitting an abstract for the Observation and Characterization of Extrasolar Planets session of this year's meeting of the German astronomical society (deadline is 31 July, you first need to register).

ag2025.astronomische-gesellschaft.de/view_splinte...

I had fun writing this with @stevensonanddone.bsky.social! thanks for being a great writing buddy!

Even though no atmospheres have been unequivocally detected, we're optimistic about the future! JWST's performance is excellent: with a larger sample of planets, more precise transmission spectra, and pushing to cooler targets, we are confident that atmospheres can be found (if they are there!).

The emission measurements are consistent with very hot daysides (ave. temp is 95% the maximum expected for a zero albedo bare rock). While some atmosphere scenarios are compatible with individual measurements, the ensemble of data is well fit by a simple picture where all the planets are bare rocks.

The transmission spectra are not (yet) precise enough to definitively detect molecules in many high MMW atmospheres. As a goal for future observations, we suggest a "five scale challenge" - reaching the precision needed to detect a CO2 feature in a nitrogen-rich atmosphere (like Earth's).

New paper out! This is a review of the published JWST observations of rocky exoplanets so far: arxiv.org/abs/2507.00933

Quick summary of the key points:

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...

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...

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!

Osiris revisited: Confirming a solar metallicity and low C/O in HD 209458b HD 209458b is the prototypical hot Jupiter and one of the best targets available for precise atmosphere characterisation. Now that spectra from both Hubble Space Telescope (HST) and James Webb Space T...

Super proud of Nora Bachmann for her first first-author paper, a deep dive into the classic hot Jupiter, HD 209458b! arxiv.org/abs/2506.16232

anyway that was nice distraction for an evening, now back to doomscrolling 🙈

I used to cibuildwheel, which makes pre-compiled versions of the code for multiple python versions, across linux, mac, and windows, and automatically uploads them to PyPI. None of this existed back in 2015!

Minor new release for batman today - if you've had issues with numpy2 incompatibility, please update your installation.

I don't get to code very often anymore and I'm always amazed by how much better the software development tools are than when batman was first written.

THE SECRETARY OF EDUCATION WASHINGTON, DC 20202 May 5, 2025 Dr. Alan Garber Office of the President Harvard University Massachusetts Hall Cambridge, MA 02138 Dr. Garber, The Federal Government has a sacred responsibility to be a wise and important steward of American taxpayer dollars. Harvard University, despite amassing a largely tax-free $53.2 billion dollar endowment (larger than the GDP of 100 countries), receives billions of dollars of taxpayer largess each year. Receiving such taxpayer funds is a privilege, not a right. Yet instead of using these funds to advance the education of its students, Harvard is engaging in a systemic pattern of violating federal law. Where do many of these "students" come from, who are they, how do they get into Harvard, or even into our country—and why is there so much HATE? These are questions that must be answered, among many more, but the biggest question of all is, why will Harvard not give straightforward answers to the American public? Harvard University has made a mockery of this country's higher education system. It has invited foreign students, who engage in violent behavior and show contempt for the United States of America, to its campus. In every way, Harvard has failed to abide by its legal obligations, its ethical and fiduciary duties, its transparency responsibilities, and any semblance of academic rigor. It had scrapped standardized testing requirements and a normalized grading system. This year Harvard was forced to adopt an embarrassing "remedial math" program for undergraduates. Why is it, we ask, that Harvard has to teach simple and basic mathematics, when it is supposedly so hard to get into this "acclaimed university"? Who is getting in under such a low standard when others, with fabulous grades and a great understanding of the highest levels of mathematics, are being rejected? Harvard has even been embroiled in humiliating plagiarism scandals, exposed clearly and plainly in the media, with respect to your then…

running the institution in a totally chaotic way. Harvard alumnus and highly successful hedge fund manager Bill Ackman noted that, under her leadership, Harvard has become "a political advocacy organization for one party." Ackman has called for the resignation of Pritzker, concluding that the "[t)he mismanagement here is Penny Pritzker" and noting that any serious corporation would have removed her after a litany of recent failings and the fact that, incredibly, "Harvard is not in a good financial position." According to Ackman, one of the world's foremost finance experts, Harvard's so-called S53 billion endowment is "massively overstated as far as what it's really worth," and Harvard has irresponsibly taken out $8 billion in debt. If this is true, it is concerning evidence of Harvard's disastrous mismanagement, indicating an urgent need for massive reform-not continued taxpayer investment. If Harvard prefers not to change, then Harvard should have no problem using its overflowing endowment to fund its bloated bureaucracy. At its best, a university should fulfill the highest ideals of our Nation, and enlighten the thousands of hopeful students who walk through its magnificent gates. But Harvard has betrayed this ideal. Perhaps most alarmingly, Harvard has failed to abide by the United States Supreme Court's ruling demanding that it end its racial preferencing, and continues to engage in ugly racism in its undergraduate and graduate schools, and even within the Harvard Law Review itself. Our universities should be bastions of merit that reward and celebrate excellence and achievement. They should not be incubators of discrimination that encourage resentment and instill grievance and racism into our wonderful young Americans. The above concerns are only a fraction of the long list of Harvard's consistent violations of its own legal duties. Given these and other concerning allegations, this letter is to inform you that Harvard should no longer seek GRANTS from the fede…

Federal Agencies. The Administration's priorities have not changed and today's letter marks the end of new grants for the University. These requests will advance the best interests of Harvard University, so it can reclaim its status as a respected educational institution for the future leaders of America. Thank you for your attention to this matter! Sincerely, Linda E. McMahon Secretary of Education

🚨🚨 Deranged letter from Education Secretary Linda McMahon to Harvard’s president, cutting off federal funding for any new grants.

Worth reading in full. It is NUTS.