Marie-Luise Steinmeyer

Scaling K2 VIII: Short-Period Sub-Neptune Occurrence Rates Peak Around Early-Type M Dwarfs We uniformly combined data from the NASA Kepler and K2 missions to compute planet occurrence rates across the entire FGK and M dwarf stellar range. The K2 mission, driven by targets selected by guest ...

Kepler mission: smaller stars have more short-period, small #exoplanets.

Theory: the smallest stars won’t have enough disk material to make small planets so there must be a turnover.

Kepler+K2: We have found a turnover!

Check out our newest Scaling K2 paper: arxiv.org/abs/2508.05734

🧵 1/9
🔭🧪☄️

High-altitude clouds on Neptune.

Photographed by the Voyager 2 spacecraft on 25 August 1989.

I had a great time at #exoclimes last week, learning a lot, meeting new people, and catching up with old friends. Now, I'm off to the coast for hopefully a successful whale watching experience 🐳

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:

An xkcd cartoon titled “Typical exoplanet system”. There’s a drawing of a star and several weird planets orbiting around it. The planets are labeled as follows: Giant planet orbiting so close that it’s actually rolling on the star’s surface. Hot Jupiter. Mini Neptune. Planet that could be habitable, if there’s a form of life that hates water but loves acid and being on fire. Cold Jupiter. Potentially habitable void. Hot Mars. Planet that may actually be in the habitable zone, according to a very optimistic modelling paper by some desperate postdocs. There’s a pulsar here but it’s probably fine. A water world paradise with beautiful oceans and warm- wait, no, we just got new measurements, it’s a hellish steam oven. Mini Pluto. Lukewarm Jupiter. Earthlike data artifact. Planet whose atmosphere is confirmed to contain atoms. Wet Saturn. Either a gas giant or a fist-sized rock, depending which calibration method you use. Faint dust cloud that will cause several papers to be retracted. Somehow this whole system is smaller than the orbit of Mercury?! Planet whose surface may host conditions suitable for rocks. Mouseover text: Sure, this exoplanet we discovered may seem hostile to life, but our calculations suggest it’s actually in the accretion disc’s habitable zone.

New exoplanet classification just dropped 🔭🧪

xkcd.com/3103/

Comic. [yellow sphere with icon that reads, CHECK ENGINE] [caption] This new sunspot cluster has raised concern among astronomers.

Check Engine

xkcd.com/3096/

I will be volunteering at the PlanetS exhibition at Fantasy Basel, the swiss comic con. I'm very excited to see such an event from the other side ☺️

Deep ALMA observations of 12CO emission from fifteen protoplanetary disks reveal a stunning range of structures in the gas morphology including gaps, rings and spirals. Credit: Richard Teague and the exoALMA Collaboration

I recently visited the ALMA observatory in Chile. While I was poking around the telescopes, ALMA researchers released amazing new views of planet-forming disks around young stars.

These are the most detailed images yet of new solar systems being born. 🧪🔭

public.nrao.edu/news/exoalma/

Just shared a new paper on the arXiv, led my @luiswel.bsky.social and me, on the challenges associated with detecting gases in exoplanet atmospheres. As the field pushes towards new and exciting opportunities, we thought it was time to talk about what it really means to “detect” something!

Infographic about the exoplanet K2-18b and its discovery with Kepler

So I know folks have heard the news about an exoplanet that might be “teeming with life”? 🌱

I created a series of infographics that aims to cover the key points of the research findings + some of the area where scientists are sceptical! 🧐

Meet K2-18b! 👋

#astronomy #exoplanet #scicomm

Mae Jemison wears a bright orange NASA space suit and holds her helmet for a photo

Since we’re all talking about it I want to blow up a real female space pioneer, Mae Jemison, an actual astronaut. She’s a graduate of Stanford and Cornel Medical School, served in the peace corps, started an educational nonprofit, and worked for the CDC researching vaccines. That’s a woman in space

Messier 2 - Wikipedia

I've also given out some globular clusters!

✨ Your star cluster is: Messier 2 ✨

It's so big and easy to see that it was discovered already in 1746. It's really old (12.5 billion years) and has tidal tails emanating from it that may be perturbed by the LMC iopscience.iop.org/article/10.3....

Is it only open clusters or can we also get globular clusters?

Congratulations 🎉

Congratulations!! 🎉

Ah yes, April Fool's day on arXiv. Enjoyed this one.

arxiv.org/abs/2503.22795

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From interstellar dust to habitable planets and the conditions for life.
Interdisciplinary lectures with perspectives from astronomy, cosmochemistry, geology, and astrobiology.
For more see: www.dust2dna.dk

The DSS galaxy (a red blob)

The Euclid galaxy (you can now see arms! detail! it's amazing)

The new EULICD data release is AMAZING! 🔭

Here's a before / after of a random galaxy I found in one of the new images, comparing against the Digitized Sky Survey.

I highly recommend taking a look around on ESA Sky - it's fun! Link: sky.esa.int/esasky/?targ...

From pebbles to planets From pebbles to planets

💫 We are all stardust. It takes millions of years for dust grains to form planets.

A six-minute ride into space revealed some secrets of planetary birth, showing how collisions trigger growth spurts in these baby planets.

🪨⏩🪐 From pebbles to planets: www.esa.int/ESA_Multimed...

Currently preparing a short presentation why I study the radius evolution of sub-Neptunes with different composition. This couldn't have come at better time.

🔭 The JWST Cycle 4 science program is out today! 🔭

Some truly exhilarating #exoplanet programs will be carried out by JWST starting in July 2025.

Let's take a look at some highlights. 🛰️🔭🪐

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Saturn Gains 128 New Moons, Bringing Its Total to 274 (Gift Article) The objects around the ringed planet are tiny, but some of them may have formed relatively recently in the solar system’s history.

Somewhat ridiculously, Saturn now has 128 new moons, bring its total to 274.

These are mostly tiny rocks, a few miles across, that orbit the planet backwards – but they might be evidence of a recent smashup in the planet's orbit.

Story by me in The New York Times

www.nytimes.com/2025/03/11/s...

Colored dots arranged in L shapes having the numbers 1, 3, 5, ..., 11 arranged into an 11x11 square.

#MathArtMarch Day 11: Proof
A visual proof that the sum of the first n positive odd integers is n*n, attributed to Nicomachus of Gerasa (c. 100 CE) in Roger B. Nelson's book "Proof Without Words."
#MathArt

Almost every postdoc I know working on open clusters in Europe keeps getting shit career news, and I assume it's similar for other fields.

It's as if academia doesn't want to retain a single specialist in this stuff. What are people planning to do with Gaia DR4? Make a doorstop? Seriouslyyyy

IAC discovers a super-Earth in the habitable zone of a nearby red dwarf An international team, led by a student from Instituto de Astrofísica de Canarias (IAC), has detected a super-Earth orbiting in the habitable zone of GJ 3998, a nearby red dwarf located 59 ly away. The new planet, named GJ 3998 d, is the third planet found in the system.

We discovered a new planet around GJ 3998, a red dwarf 59 ly away. The newly discovered planet, GJ 3998 d, is a super-Earth that resides in the optimistic habitable zone of its star. GJ 3998 d gets just 20% more instellation flux compared to what the Earth receives by the Sun. 🪐🔭 1/6

🎉 Congratulations to LPL Sagan Fellow Feng Long for the discovery of a 30 Myr-old primordial disk! 🚀 The gas inside the snowline is strikingly carbon-rich – key for planet formation. Don’t miss the paper and the press release! 🔗 #JWST #Exoplanets
news.arizona.edu/news/james-w...

Balloons are to Venus as rovers are to Mars.

They allow us to explore the planet up close, without having to deal with the crushing pressures and searing temperatures at the surface.

We will yet fly through the skies of Venus.

We will yet fly.

The signing of the “Outer Space Treaty” in 1967, effectively the only international space law we have.
1) The “treaty” itself doesn’t really have any teeth.
2) It was signed in a different era, when space capabilities and aspirations were radically different.
Houston, we have a problem.
🔭🧪🚀

Figure 5: Best fit models to one of one of Enceladus’ phase curves (filter 798 nm) for three different models: a pure single Henyey-Greenstein model with no additional opposition peak, shadow hiding model, and coherent backscattering model. Top panel shows the fits and the second panel shows the residuals of these best fits. It is clear that the model with no opposition peak is the worst fit to the data. The other two models produce, by eye, almost identical fits, which is expected since the functional forms are similar. However the residuals still show subtle differences. Using the LOO model selection statistic allows us to conclude that the coherent backscattering model is preferred by 7/12 of the phase curves, however not significantly. The corner plot showing the posteriors for the shadow hiding model are in Appendix A, Figure A.2.

*Newly Dr.* Kathryn Jones (+me and Kevin Heng) asks: "Planets show a sharp surge in brightness when directly opposite the Sun, and this peak is sharper for solid planets than for gas planets. Could we use this to detect rocky surfaces with JWST or HWO?" 🧪🔭🪐

tl;dr: no.

arxiv.org/abs/2502.14629

↘️ and here and animation of all multi-planet systems discovered in the Milky-way by #NASA #Kepler space telescope 2010-2013. All exoplanets shown together at same scale as our Solar system. 🔭🧪🎢 #space #earth #science credit: Ethan Kruse/NASA Goddard