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Nienke van der Marel

@nienkemarel.bsky.social

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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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Nienke van der Marel @nienkemarel.bsky.social · Aug 6

Interview on the Chicken or Egg problem of planet formation on Forbes!

www.forbes.com/sites/bruced...

Planet Formation Theory Is Still Ensnared By A Chicken Or Egg Problem

Astronomers still debate how solar systems like ours could form planets like our own. How the very first planet formed has created a bit of a chicken or egg conundrum.

www.forbes.com

Nienke van der Marel @nienkemarel.bsky.social · Jul 22

There is now a planetesimal bearing my name!! Nice to meet you 6054 P-L!
And thank you IAU for making it happen.

www.astronomie.nl/nieuws/17-ni...

17 nieuwe ‘Nederlandse’ planetoïden

www.astronomie.nl

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Nienke van der Marel @nienkemarel.bsky.social · Jun 10

To clarify: I just do not know how it would help to strike, as all my tasks would still need to get done if I take a day off. I would just be punishing myself by having an even higher workload the rest of the week, so what is the point? Honestly curious about other people's thoughts.

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Nienke van der Marel @nienkemarel.bsky.social · Jun 10

Today was supposed to be a strike in the Netherlands on behalf of the higher education, against the major budget cuts. I think it got mostly cancelled due to the (completely coincidental) national train strike, but I was still wondering: is a strike the best way to protest as academics?

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Reposted by Nienke van der Marel

Rocky Worlds Meetings @rockyworlds.bsky.social · Jun 10

📣 Calling all rocky enthusiasts! We are thrilled to announce that the ROCKY WORLDS 4 Conference will take place 19-23 Jan 2026 in Groningen, NL 🇳🇱 This is the 4th Meeting in our series & we can't wait to see you there!

Abstract submission is NOW OPEN groningen2026.rockyworlds.org/groningen-2026

🪐☄️🔭

Screenshot from the home page of https://groningen2026.rockyworlds.org/groningen-2026. It is the Rocky Worlds symbol (a stylised cross-section of a planet) on a plain, pastel-yellow background with the following information:

Rocky Worlds 4
19-23 January 2026, Groningen, Netherlands
Abstract submission open

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Nienke van der Marel @nienkemarel.bsky.social · May 31

Moral of the story: don't ever let ChatGPT write your papers or proposals, because it will actually make up complete references, and will (initially) insist that they are real.

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Nienke van der Marel @nienkemarel.bsky.social · May 31

When I tell ChatGPT again that it is wrong, it finally admits that it cannot find the right paper and that I am probably looking for one of the actual van der Marel 2021 papers (which it lists correctly).

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Nienke van der Marel @nienkemarel.bsky.social · May 31

Like seriously: it is not just garbling of authors. THERE IS NO PAPER WITH THIS TITLE OR TOPIC. The DOI points to a non-existing wegpage.

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Nienke van der Marel @nienkemarel.bsky.social · May 31

It got worse. When I told ChatGPT that it was mistaken, it told me that it got confused by the journal name, which should be ApJ, not AJ. And then it produced the 'correct' paper (see below) WHICH DOES NOT EXIST AT ALL!!

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Nienke van der Marel @nienkemarel.bsky.social · May 31

Reviewing a proposal that cites one of my four 2021 papers. I checked the reference to see which one it is and the volume and page do not correspond to any of my papers. I asked ChatGPT and it claims is van der Marel & Mulders 2021 with a different volume and page. Did I reverse-engineer ChatGPT?

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Nienke van der Marel @nienkemarel.bsky.social · Apr 28

Tomorrow I will be at a 'talk show' on the great outdoors organized by TU Delft, talking about stories from observing nights at high altitude.

Nienke van der Marel @nienkemarel.bsky.social · Apr 24

Winner of two prizes at the Leiden Allegro ARC node competition, both the one for most requested hours (of all proposals combined) and for the smallest proposal 😁 #almacycle12

Nienke van der Marel @nienkemarel.bsky.social · Apr 24

The usual curve of proposal submissions on ALMA deadline day. It looks like we may end up a bit lower than last Cycle, unless we get a final sprint. I'm going to bet on 1560. What's your guess?
#almacycle12

Nienke van der Marel @nienkemarel.bsky.social · Apr 24

Looks like we are somewhat below the trend of last year. How many people are still submitting in the final 10 hours? #almacycle12

Nienke van der Marel @nienkemarel.bsky.social · Apr 22

It is that time of the year again:
#almacycle12

Nienke van der Marel @nienkemarel.bsky.social · Mar 31

Really happy that three of my master students have managed to get a PhD position this year! Curious to see where their research is going to bring them 💪

Reposted by Nienke van der Marel

★ govert schilling @govertschilling.nl · Mar 28

here's my story on the (largely dutch) discovery that most protoplanetary disks are small and may spawn super-earths (for the website of sky and telescope): 🔭
skyandtelescope.org/astronomy-ne...

Tiny Disks Shed Light on Super-Earth Origins

A team of astronomers has obtained high-resolution images of all known protoplanetary disks in the Lupus star-forming region.

skyandtelescope.org

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Nienke van der Marel @nienkemarel.bsky.social · Mar 27

Exactly! Always consider the biases in your sample.

Corey S. Powell @coreyspowell.bsky.social · Mar 27

A lot of cosmic exploration centers around "what's weird?" & "what's normal?"
Early studies of young stars showed an abundance of huge planetary systems forming. New observations show the opposite: Lots of small systems, much more compact than our solar system. 🧪🔭

www.astronomie.nl/nieuws/en/pr...

$Images of 73 protoplanetary discs in the Lupus star forming region (two of the images contain binary stars). Only a fraction of the discs extend beyond the orbit of Neptune, when compared to our own Solar System. Most of the observed discs are small and show no structures like gaps and rings. (c) Guerra-Alvarado et al. (c) Guerra-Alvarado et al. [high resolution]$

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

Nee, geen geluid, ik had het even snel in elkaar gezet en ik weet uit ervaring dat ik ga hakkelen bij zo'n opname, en dan moet het telkens weer opnieuw. Misschien doe ik dat later nog.

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

At 0.25" (~35 au) resolution, these small disks would remain 'unresolved': that means that they appear to be as large as the beam size and you cannot know whether they are indeed the beam size or much smaller. Their size would be listed as upper limit of <20 au. Now it's shown to be much smaller!

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

Before ALMA, there was no possibility to infer the disk size from such faint disks at all! For the brightest and largest ones we could measure them (somewhat) with SMA, but no more. However, these disks were mapped before with earlier ALMA observations at low-resolution, ~0.25" (Ansdell+2016/2018).

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

And I was working with ALMA Early Science data during grad school and I'm still amazed with what ALMA can do these days 😄

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

Please note, mas stands for milliarcseconds, not microarcseconds! It's still impressive of course.

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

To accompany the press release from this morning on the compact disks, I made a short 2 minute video that showcases the key result. Enjoy watching!

youtu.be/jvT1wD7yCec

How does a typical protoplanetary disk look like?

YouTube video by Nienke van der Marel

youtu.be

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Reposted by Nienke van der Marel

astronomie.nl @astronomienl.bsky.social · Mar 26

Protoplanetaire schijven zijn veel kleiner dan eerder gedacht.

Door Universiteit Leiden geleid onderzoek van Osmar M. Guerra-Alvarado et al., geaccepteerd voor publicatie in A&A.

www.astronomie.nl/ni...

$Beelden van 73 protoplanetaire schijven in het stervormingsgebied van Lupus (twee afbeeldingen bevatten dubbelsterren). Slechts een fractie van de schijven reikt verder dan de baan van Neptunus in ons eigen zonnestelsel. De meeste waargenomen schijven zijn klein en vertonen geen structuur zoals gaten en ringen. (c) Guerra-Alvarado et al.$

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