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Andrew Mann

🧪🔭⭐ #exoplanets #exoplanet #youngplanets New paper from our group and @madysonbarber.bsky.social today! We report a brand-new planet around a <50 Myr star—adding to a very small (but rapidly growing!) population of the youngest known transiting planets. Paper: arxiv.org/pdf/2511.10734

arxiv.org
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1 прямых ответов · 10 сообщений

Andrew Mann

🧪🔭⭐ #exoplanets #exoplanet Planet radius vs orbital period, color-coded by age. contours = the Kepler population. The new planet in this paper is marked with a ⭐. Even without statistics, your eyes will notice something: Young planets are big. Much bigger than the planets Kepler typically found.

Ответ для Andrew Mann
Andrew Mann

🧪🔭⭐ “Isn’t that just observational bias? Aren’t young stars noisy, so you only find the large planets?” Partially true: we miss the small ones around young stars. Here’s the key point: The excess of large planets cannot be explained by bias. In fact, the bias works in the opposite direction.

Ответ для Andrew Mann
Andrew Mann

🧪🔭⭐ Here’s a simple way to see it. In TIDYE, we’ve surveyed <10,000 young stars. Among them, we’ve found ~a dozen planets in the 4–12 Earth-radius range. Now take 10,000 Kepler stars and randomly draw planets of similar sizes. You should expect… ~3 planets. Not 12. That’s already a big difference.

Ответ для Andrew Mann
Andrew Mann

🧪🔭⭐ Our sensitivity to planets around young stars is much worse than Kepler’s sensitivity to planets around older stars. More noise. More variability. Less precise light curves. This means: If anything, we should find fewer large young planets relative to Kepler—not more.

a man wearing a hat says " didn t see that one coming "ALT: a man wearing a hat says " didn t see that one coming "media.tenor.com
Ответ для Andrew Mann
Andrew Mann

🧪🔭⭐ #exoplanets #exoplanet #youngplanets To blame this trend on observational bias, you’d have to assume that Kepler somehow missed large planets. But that’s impossible: Large, short-period planets are where Kepler is most sensitive. That’s the last part of parameter space it would ever miss.

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Ответ для Andrew Mann
Andrew Mann

Therefore the simplest, most physically sensible explanation is: 👉 Young planets really are larger. They shrink with time.

an elderly woman wearing glasses and a yellow sweater has the words it shrinks above herALT: an elderly woman wearing glasses and a yellow sweater has the words it shrinks above hermedia.tenor.com
Ответ для Andrew Mann
Andrew Mann

🧪🔭⭐ And this fits beautifully with everything else we know; • Mass measurements (mostly from JWST scale height) of young planets show they’re “puffy” • Models predict significant radius contraction over 10–500 Myr ui.adsabs.harvard.edu/abs/2024arXi... arxiv.org/abs/2503.17364

a stuffed snowman is sitting on top of a blue blanket with the word mango on itALT: a stuffed snowman is sitting on top of a blue blanket with the word mango on itmedia.tenor.com
Ответ для Andrew Mann
Andrew Mann

🧪🔭⭐ The big takeaway: TIDYE is revealing a population of very young, very inflated planets that Kepler simply couldn’t show us. Because of their size, we also expect to find a lot more in the upcoming survey space. There's a lot of <50 Myr stars out there!

a shark is sitting at a table with a sign that says " a lot "ALT: a shark is sitting at a table with a sign that says " a lot "media.tenor.com
Ответ для Andrew Mann
Gijs D Mulders

Any chance you can get density measurements for these planets from radial velocity masses? That would really nail it down, otherwise it could also be planet engulfment/scattering/mergers etc.

Ответ для Gijs D Mulders
Andrew Mann

RV is nigh impossible on these but scale height masses work. The small number with masses are very low mass, as we’d expect. Engulfment would leave other signatures. Scattering too, in terms of the level of MMR and general dynamics at 100-300 myr. Basically those are very unlikely.