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Andrew Sellek @andrewsellek.bsky.social · Aug 26

Wow, what a great image! Congrats to Richelle! With last week's 2MJ1612 it seems like accreting protoplanets are like buses: we wait 7 years since PDS70 and now two come along at once!

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Reposted by Andrew Sellek

Sierra Grant @sierragrant.bsky.social · Aug 7

Another MINDS JWST paper! We explore the stark transition from H2O-dominated spectra in Sun-like systems to the carbon-rich chemistry seen for low-mass objects. We don't know exactly what is driving this trend, but we explore the possibilities that may be acting in concert.
arxiv.org/pdf/2508.04692

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Reposted by Andrew Sellek

Sierra Grant @sierragrant.bsky.social · Aug 5

New MINDS paper from Nicolas Kurtovic, focused on binary systems. Spectra, extended emission, variability, multi-observatory analysis -- there's something for everyone!
arxiv.org/pdf/2508.02576

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Andrew Sellek @andrewsellek.bsky.social · May 12

I'm surprised no one here has mentioned the new A&A page limit. I can only expect that what would have been large monolithic papers will be broken up, further boosting the number. It may also increase quality and brevity, making each review less demanding, but I'll be curious to see how it plays out

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Andrew Sellek @andrewsellek.bsky.social · May 2

Based on a recent workshop series, hosted by Giovanni Rosotti, @cfmanara.bsky.social, Tom Haworth, and Megan Reiter, we summarised in @ojastro.bsky.social the latest results on a growing topic in protoplanetary discs - the role of external irradiation - and how we hope to answer the open questions:

The Open Journal of Astrophysics @ojastro.bsky.social · May 2

New Publication at the Open Journal of Astrophysics: "The past, present and future of observations of externally irradiated disks" by Planet formation environments collaboration: Megan Allen (U. Sheffield, UK) and 52 others

doi.org/10.33232/001...

The past, present and future of observations of externally irradiated disks | Published in The Open Journal of Astrophysics

By Planet formation environments collaboration, Megan Allen & 52 more. A review of research on the effects of the ultraviolet radiation environment on protoplanetary disc evolution and planet formatio...

doi.org

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Reposted by Andrew Sellek

Nienke van der Marel @nienkemarel.bsky.social · Mar 26

Super proud of my PhD student Osmar who discovered that the so-called 'compact disks' around young stars are REALLY REALLY small! Look at the full sample of Lupus disks, observed at 30 mas resolution with ALMA.

Protoplanetary discs are much smaller than previously thought

www.astronomie.nl

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Andrew Sellek @andrewsellek.bsky.social · Mar 11

Thanks for being the one ray of sunshine in my otherwise gloomy inbox of rejection!

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Andrew Sellek @andrewsellek.bsky.social · Feb 18

Never underestimate how hard this dilemma is to navigate... I spent around 3-4 months looking for the bug in our code a couple of years ago before finally deciding it was a real effect.

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Andrew Sellek @andrewsellek.bsky.social · Feb 11

Of course, there was the time we forgot to ask them out their names on them and had the fun puzzle to try to match up more than 50 pairs, having to resort to forensic analysis of how they drew hands, feet etc etc if the picture had changed a lot.

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Andrew Sellek @andrewsellek.bsky.social · Feb 11

Nice to see that some of our favourites are still on the website! chaosscience.org.uk/sponsors/#tr...

It was always an evening highlight to look at these back at the campsite and see what else changed (many fewer adjectives like "mad" and "evil", more "useful" or "anyone can be a scientist"!).

Sponsors – CHaOS

chaosscience.org.uk

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Reposted by Andrew Sellek

Dr Jared Jeyaretnam ⚛️🧪 @jaredjeya.github.io · Feb 11

I used to do science outreach with a group called CHaOS (see link!). We’d often ask kids to draw a scientist at the start and end of our sessions.

They’d often go from drawing an Einstein-esque mad scientist, to someone who looked at lot like themselves (or perhaps one of us) 😊

#AcademicChatter

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Andrew Sellek @andrewsellek.bsky.social · Jan 31

Ahh got it, thanks! Is there a reason there would only be an outflow from one source then? The discs look roughly equally bright on ALMA continuum? Presumably we can't get a good handle on their relative masses for such young sources though that know if that contributes...

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Andrew Sellek @andrewsellek.bsky.social · Jan 31

Nice work by Isaac! I bookmarked it on arXiv this morning to have a closer look later, but what line is tracing the outflows here? Is that a streamer feeding Aa and is it connected to the outflow?

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Reposted by Andrew Sellek

Ilaria Pascucci @pascucci.bsky.social · Jan 21

Congrats to my student Chengyan Xie 🎉 for his work analyzing Spitzer+JWST data on T Cha! 🌟 He uncovered dramatic changes in the star’s disk—inner disk eroding in an outburst, reshaping IR emission. This object deserves follow-up! 🪐✨ #JWST iopscience.iop.org/article/10.3...

iopscience.iop.org

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Reposted by Andrew Sellek

Kamber Schwarz @theschwarz.bsky.social · Jan 15

The accepted version of my SY Cha winds paper is now on arXiv: arxiv.org/abs/2409.11176! And if you are at #AAS245 I will discuss the results TODAY at 2 pm in Potomac 3-4 🧪🔭

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Andrew Sellek @andrewsellek.bsky.social · Dec 18

the isotopologues probe deeper in the disc, providing a truer picture of how much CO2 there is and if it is enhanced. But higher resolution images are needed to confirm if this is due to drift or can be explained with an as yet unresolved cavity. 4/4 @sierragrant.bsky.social @theschwarz.bsky.social

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Andrew Sellek @andrewsellek.bsky.social · Dec 18

However the strong CO2 is particularly exciting, because we see not only CO2 itself but potentially two of its isotopologues - 13CO2 and CO18O (more tenatively) - where one of the atoms has been replaced by a rarer isotope. The shapes and relative strengths of the emission features imply that... 3/4

The spectrum of CX Tau between 13.5 and 17.5 micron, with the continuum variations subtracted to provide a flat baseline, shown in black. The spectrum shows various spikes due to emission from different molcules, overlaid in different colours are the spectra of different molecules with properties that allow them to match these patterns. In the centre is a strong triangular feature from CO2, overlaid in green, while insets show emission attributed to 13CO2 and CO18O.

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Andrew Sellek @andrewsellek.bsky.social · Dec 18

Marissa found that CX Tau is an example of the discs with weak water but strong CO2. The weakness of the water is more or less in line with what one expects for given the disc's low accretion rate, though there is still evidence for cold water strong emission which may be connected to drift. 2/4

A zoom in on the spectrum around 23.9 microns showing a set of four water lines. CX Tau, in black, is compared to a disc with strong water,, DR Tau, in blue, showing that both show that the first and third lines are brighter than the other two, a pattern which indicates the presence of cold water.

A plot showing that the luminosity of the water lines for a sample of discs from the literature (grey points) is correlated with the luminosity produced by accreting material. CX Tau, indicated with a blue star, sits in line with this trend on the very left of the figure at low accretion luminosity and water line luminosity.

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Andrew Sellek @andrewsellek.bsky.social · Dec 18

The latest protoplanetary disk study by the MINDS collaboration using JWST-MIRI is out now! arxiv.org/abs/2412.127... Led by Leiden PhD student Marissa Vlasblom, it focusses on CX Tau, a disk for which the dust emission is much more compact than gas, suggesting dust grains have drifted inwards. 1/4

The spectrum of CX Tau showing how bright the disc emission is as a function of infrared wavelength. The disc gets brighter going from shorter wavelengths on the left to longer wavelenghts on the right, with a large bump at 10 micron due to Silicate dust grains. On top of the smooth continuum are a few weak lines, the most prominent ones being due to atoms such as HI and Ne or CO2. Inset panels show zoom-ins that demonstrate the presence of weak water features.

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Reposted by Andrew Sellek

Nienke van der Marel @nienkemarel.bsky.social · Dec 12

JWST MIRI has revealed that disks around very low-mass stars are hydrocarbon-rich but water-poor in the inner disk (Aditya Arabhavi). Result of dust traps? What are the implications for planets forming here? #NOVA25

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Andrew Sellek @andrewsellek.bsky.social · Dec 11

JWST mostly sees warm gas in the inner regions if protoplanetary discs. These discs are where planets form and the inner regions are especially important for rocky planets like Earth. So with such data we hope to learn what the building blocks of Earthlike planets are made of - how much water etc?

Andrew Sellek @andrewsellek.bsky.social · Dec 11

...(no resolved structure) and closest to models with no gap or a gap fairly close in and GW Lup has a ring at ~70au (from memory) and is closest to models with a gap at 30-60au (but not too far). But the difference is slight and the models are not tuned in M* or gap depth which may also play a role

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Andrew Sellek @andrewsellek.bsky.social · Dec 11

Thanks, Sierk! I would be of course cautious about trusting absolute values as our 1D estimates can't really account for how the molecules might be photodissociated differently, but hopefully the trends stand somewhat. But for the C-rich discs that come closest, CX Tau is extremely compact...

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Andrew Sellek @andrewsellek.bsky.social · Dec 11

The natural follow up being "How intensive are the simulations you need to run to keep yourselves warm?"?

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Andrew Sellek @andrewsellek.bsky.social · Dec 5

The location and shape of the continuum variations can acually tell us which silicate minerals most likely make up the dust. As far as I know, that hasn't been calculated in detail yet for GW Lup or DR Tau, but see Jang et al. 2024 for a exploration of dust in the PDS70 disc arxiv.org/abs/2408.16367

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