Gijs D Mulders
@gijsmulders.com
📤 281
📥 55
📝 73
Exoplanet Astronomy Assistant Professor Santiago de Chile
http://gijs.cl
\m/
pinned post!
Why does the solar system not have super-Earths? A thread
#exoplanets
☄️
3 months ago
1
40
14
reposted by
Gijs D Mulders
Dr. Jessie Christiansen
8 days ago
Sometimes 2025 just feels like a lot, and you need an excuse to celebrate your fabulous team (and the whole exoplanet community!) reaching a new milestone… Happy 6,000 Confirmed Exoplanets Day, everybody!!!! (You may recognize the narrator of the video at the link! 🫣)
www.nasa.gov/universe/exo...
11
244
68
reposted by
Gijs D Mulders
Adam Rains
8 days ago
Paper day! You're doing ground-based high-resolution exoplanet transmission spectroscopy and want to analyse the planet—not the star or Earth's atmosphere. Is there a way to disentangle your spectrum *without* destroying the planet signal?
arxiv.org/abs/2509.12737
🧵⬇️ 🔭
#exoplanets
#astromethods
loading . . .
TSD: An inverse problem approach for recovering the exoplanetary atmosphere transmission spectrum from high-resolution spectroscopy
Our ability to observe, detect, and characterize exoplanetary atmospheres has grown by leaps and bounds over the last 20 years, aided largely by developments in astronomical instrumentation; improveme...
https://arxiv.org/abs/2509.12737
1
14
4
reposted by
Gijs D Mulders
Emily Hunt
17 days ago
For the last two years, I've been paying for the Astronomy feeds hosting myself. It has been a privilege to grow our community here, but I also shouldn't keep doing it for free 😅 That's why I'm delighted to announce that we now have a donations page on Open Collective! 🔭☄️
#astrophotography
loading . . .
The Astrosky Ecosystem - Open Collective
We're building an open-source ecosystem of social media tools for the space science & astronomy communities.
https://opencollective.com/the-astrosky-ecosystem
5
114
61
reposted by
Gijs D Mulders
Melina Thévenot🏳️⚧️
23 days ago
Seems like Ayumu Shoshi et al. did take a high-resolution ALMA image of the disk around IRAS 04125+2902.
arxiv.org/abs/2509.01896
This system also has the youngest transiting
#exoplanet
, discovered in November 2024 with TESS. Disk, planet orbit and outer stellar companion orbit are all misaligned.
0
14
3
reposted by
Gijs D Mulders
Matthew Kenworthy
about 1 month ago
Proud supervisor moment: #LeidenObservatory graduate student Richelle van Capelleveen led one of two papers on our
discovery of WISPIT 2b
#LeidenObservatory
a 5 Jupiter mass exoplanet clearing a path in a circumstellar disk. Laird Close and his team saw it in H-alpha, indicating gas accretion
#astrodon
🔭 🧪
12
175
57
reposted by
Gijs D Mulders
Gabe Weible
about 1 month ago
New protoplanet(s?) alert! I'm happy to share this LBTI image of WISPIT 2 from our team's paper led by Laird Close. Planet b was discovered at Hα with MagAO-X following the SPHERE disk discovery (R. van Capelleveen +), and CC1 might be a candidate 2nd (enshrouded?) protoplanet
#exoplanets
☄️🔭🧪
2
41
12
#achievement
for the day (please don't send me any more email)
about 1 month ago
0
0
0
reposted by
Gijs D Mulders
Jonathan Fortney
about 1 month ago
I think that mass-loss is important for sub-Neptunes and the "radius valley," but I do not think that "core-powered" escape is significant. We find that "Boil-off," right when the disk dissipates, and then XUV driven escape, are major influences.
ui.adsabs.harvard.edu/abs/2024ApJ....
loading . . .
https://ui.adsabs.harvard.edu/abs/2024ApJ...976..221T/abstract
1
8
5
Question for the radial velocity
#exoplanets
experts: Is there an animation that shows two spectra being shifted with respect to each other and the corresponding values of the cross correlation function changing? I think I’ve seen one in a talk but can’t find a nice animation online
about 1 month ago
1
10
4
reposted by
Gijs D Mulders
Dr Ryan MacDonald
about 1 month ago
We looked for an atmosphere on TRAPPIST-1d using JWST, but we didn't see any atmospheric absorption. So TRAPPIST-1d is quite different from Earth, despite lying just inside the habitable zone. The planet is either: ➡️ A bare rock. ➡️ Very cloudy. ➡️ Has a thin, Mars-like atmosphere.
#Exoplanets
🔭
add a skeleton here at some point
2
48
13
reposted by
Gijs D Mulders
Kevin Hardegree-Ullman
about 2 months ago
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 🔭🧪☄️
loading . . .
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 ...
https://arxiv.org/abs/2508.05734
2
51
20
reposted by
Gijs D Mulders
Steve Desch
about 2 months ago
I have a complaint about Avi Loeb's latest work and I want to speak to management.
medium.com/@steve.desch...
loading . . .
This is not the quality of pseudoscience infotainment to which I have grown accustomed
Teasing the public with fraudulent or self-deluded promises of aliens used to mean something. It took work. It meant slapping together…
https://medium.com/@steve.desch/this-is-not-the-quality-of-pseudoscience-infotainment-to-which-i-have-grown-accustomed-34268f892ba8
30
407
148
reposted by
Gijs D Mulders
Dr. Jessie Christiansen
about 2 months ago
Images from Palomar at 2 different infrared wavelengths last night - one that Saturn's methane atmosphere absorbs, and one the it reflects! (The faint point source is the moon, Tethys!) Taken by David Ciardi, Catherine Clark,
@lowbacca.bsky.social
and Miranda Felsmann; animated by me (and ezgif!)
loading . . .
6
297
75
reposted by
Gijs D Mulders
Dr. Jessie Christiansen
about 2 months ago
I really like this graphical summary of the architectures of planetary systems from
@sidereuskinch.bsky.social
's talk at From Transits to Trends!
0
16
6
reposted by
Gijs D Mulders
David Kipping
2 months ago
New paper! Allow me to introduce TARS = Torqued Accelerator using Radiation from the Sun. TARS (yes inspired by Interstellar!) is a rotating light sail that's capable of launching chip sats into interstellar space using only radiation from the Sun, so let's dive into how it works.
loading . . .
5
81
18
reposted by
Gijs D Mulders
Dr. Jessie Christiansen
2 months ago
The main takeaway of my talk, in the style of the ‘Behold my field of fucks and see that it is barren’ embroidery:
3
21
1
reposted by
Gijs D Mulders
2 months ago
What does the radius valley tell about the planet formation scenario around low mass stars? And how does it connect it with water worlds? To know more, come visit my poster #37 at SSW2025.
#sagan2025
#exoplanets
0
4
1
reposted by
Gijs D Mulders
Greg Gilbert
2 months ago
Want to learn about the relationship between planet size and orbital eccentricity? Read this thread! 🧪 🔭 🪐
1
5
2
reposted by
Gijs D Mulders
Institute of Astrophysics UC
3 months ago
Earn Your PhD at Earth's Premier Astronomy Hub! 🔭 ✅ Study under world-renown scientists ✅ Access legendary telescopes ✅ Join a global research network 🔗 Apply now:
astro.uc.cl/en/doctorado...
📅 Application period: From July 1st to August 1st, 2025 for March 2026 intake.
loading . . .
0
1
1
Interested in doing a Masters or PhD in one of the leading astronomical institutes in Latin America? Apply now to these fully funded positions!
aas.org/jobregister/...
🔭🧪☄️
#exoplanets
loading . . .
PhD and Master positions in Astrophysics at Pontificia Universidad Católica de Chile | American Astronomical Society
The Institute of Astrophysics at Pontificia Universidad Católica de Chile (IA-PUC) invites applications to our Ph.D. (4-yr) and Master’s (2-yr) programs, beginning March 2026, from talented students w...
https://aas.org/jobregister/ad/57236ddd
3 months ago
0
34
21
Why does the solar system not have super-Earths? A thread
#exoplanets
☄️
3 months ago
1
40
14
reposted by
Gijs D Mulders
Emily Hunt
3 months ago
More on DR4: it's expected to include "a few thousand" exoplanets, potentially doubling or tripping the number of known exoplanets! ☄️
#exoplanets
3
28
9
reposted by
Gijs D Mulders
Emily Hunt
3 months ago
Finding out about Gaia at
#EAS2025Cork
! ☄️ Just announced: Gaia DR4 will be released in December 2026!
1
96
38
reposted by
Gijs D Mulders
Dr. Jessie Christiansen
3 months ago
#exoplanets
#jobs
📣 I'm advertising for a postdoc! Come work with me in sunny SoCal on the Roman Galactic Exoplanet Survey Project Infrastructure Team. You'll help build the pipeline for Roman* occurrence rates. *Launches NEXT YEAR! Please RT & share with your networks!
aas.org/jobregister/...
loading . . .
Postdoctoral Scholar - Roman Galactic Exoplanet Survey PIT | American Astronomical Society
IPAC, part of the Physics, Math, and Astronomy Division at Caltech, provides science operations, user support, data and archive services, and scientific vision to maximize discovery with observatories...
https://aas.org/jobregister/ad/a3fe5316
10
94
53
reposted by
Gijs D Mulders
Ilaria Pascucci
3 months ago
Twelve ALMA/AGE-PRO papers just out! Exploring how gas and dust evolve in disks 🌟🌀 — Congrats to all authors! 🎉 NRAO press release:
public.nrao.edu/news/alma-pl...
0
9
5
reposted by
Gijs D Mulders
Astrobites
4 months ago
From Kaz Gary: For Pride Month, Astrobites is interviewing one transgender astronomer every week. This week we interviewed Dr. Eliot Halley Vrijmoet, a postdoctoral fellow at Smith College! 🔭✨☄️
astrobites.org/2025/06/06/e...
loading . . .
Transgender in Astronomy: Interview with Dr. Eliot Halley Vrijmoet
For Pride Month, Astrobites is interviewing one transgender astronomer every week. This week we interviewed Dr. Eliot Halley Vrijmoet, a postdoctoral fellow at Smith College!
https://astrobites.org/2025/06/06/eliot-vrijmoet-interview/
2
121
30
reposted by
Gijs D Mulders
Dr. Jessie Christiansen
4 months ago
Hey, the paper is online! 🎉🪐🔭
#exoplanet
Check out the shiny new NASA Exoplanet Archive and ExoFOP paper, which covers all the updates to our data and services since Akeson+2013. Please update your .bib files and cite accordingly!!
arxiv.org/abs/2506.03299
loading . . .
The NASA Exoplanet Archive and Exoplanet Follow-up Observing Program: Data, Tools, and Usage
The NASA Exoplanet Archive and the Exoplanet Follow-up Observing Program service are two widely used resources for the exoplanet community. The NASA Exoplanet Archive provides a complete and accurate ...
https://arxiv.org/abs/2506.03299
2
82
22
reposted by
Gijs D Mulders
Dr. Jessie Christiansen
4 months ago
Fewer than 100 planets to go! 👀🪐🔭✨
9
119
14
Reboost for
#astronomy
and
#exoplanet
feed 🔭☄️🪐
add a skeleton here at some point
5 months ago
0
4
3
Reboost for the
#astronomy
feed
add a skeleton here at some point
5 months ago
0
2
0
reposted by
Gijs D Mulders
Institute of Astrophysics UC
5 months ago
Now hiring: 2 Tenure‑Track Faculty Positions | Institute of Astrophysics, Pontificia Universidad Católica de Chile (PUC) – Santiago, Chile 🇨🇱 Full details & submission:
astro.uc.cl/en/noticias/...
#FacultyPosition
#Astrophysics
#AcademicJobs
#ResearchCareers
#PUC
#Chile
0
3
2
reposted by
Gijs D Mulders
Chris Lintott
5 months ago
A new, thorough reanalysis of the data that led to claims of biosignatures on K2-18b from
@luiswel.bsky.social
& friends - a nicely written lesson on why this stuff is hard. They find no significant evidence for DMS, the gas the Cambridge team claimed to have found.
arxiv.org/abs/2504.21788
loading . . .
The Challenges of Detecting Gases in Exoplanet Atmospheres
Claims of detections of gases in exoplanet atmospheres often rely on comparisons between models including and excluding specific chemical species. However, the space of molecular combinations availabl...
https://arxiv.org/abs/2504.21788
6
122
48
reposted by
Gijs D Mulders
Andrew Mann
5 months ago
New results from the Young Worlds Lab!
arxiv.org/abs/2504.13262
So you measured a stars' rotation period using a TESS light curve, how good is it? That's the question we wanted to answer with this paper. 🔭🧪⭐🌌
#exoplanets
loading . . .
Quantifying the Limits of TESS Stellar Rotation Measurements with the K2-TESS Overlap
The Transiting Exoplanet Survey Satellite (TESS) has provided stellar rotation periods across much of the sky through high-precision light curves, but the reliability and completeness of these measure...
https://arxiv.org/abs/2504.13262
1
32
7
reposted by
Gijs D Mulders
ESO
5 months ago
1/ Using ALMA, in which ESO is a partner, the exoALMA project has revealed exquisite images of young solar systems. By studying the motion of the gas astronomers may find signs of planets in the making. Read more in this
@thenrao.bsky.social
release:
public.nrao.edu/news/exoalma/
🔭 🧪
#exoplanets
1
60
21
reposted by
Gijs D Mulders
William O. Balmer
5 months ago
<The Biggest Planet We Know Is Doomed> I don't know if that's good enough clickbait but I am intensely proud of Gavin Wang (recent Goldwater winner!) whose paper "A Revised Density Estimate for the Largest Known Exoplanet, HAT-P-67 b" was accepted to AJ and is on arXiv:
arxiv.org/abs/2504.13997
1
28
11
reposted by
Gijs D Mulders
Dr Ryan MacDonald
5 months ago
In summary, the paper engages in statistical hacking to hit the magical '3σ'. Now here's where the bad science communication comes in. The University of Cambridge put out a press release making bold claims about a detection of possible biosignatures.
www.cam.ac.uk/stories/stro...
loading . . .
Strongest hints yet of biological activity outside the solar system
Astronomers have detected the most promising signs yet of a possible biosignature outside the solar system, although they remain cautious.
https://www.cam.ac.uk/stories/strongest-hints-of-biological-activity
1
99
17
reposted by
Gijs D Mulders
Dr Ryan MacDonald
5 months ago
The Bayes factor for DMS and DMDS (both combined) in this paper is 2.62, which falls in the 'no evidence' category. We normally don't start using the word 'detection' until we have B > 150. So how did this get spun into a 3σ detection? (the next post is a little technical, bear with me!)
5
100
10
reposted by
Gijs D Mulders
Dr Ryan MacDonald
5 months ago
𝗡𝗼, 𝗮 𝗯𝗶𝗼𝘀𝗶𝗴𝗻𝗮𝘁𝘂𝗿𝗲 𝘄𝗮𝘀 𝗻𝗼𝘁 𝗷𝘂𝘀𝘁 𝗱𝗲𝘁𝗲𝗰𝘁𝗲𝗱 𝗶𝗻 𝗞𝟮-𝟭𝟴𝗯'𝘀 𝗮𝘁𝗺𝗼𝘀𝗽𝗵𝗲𝗿𝗲. K2-18b is back in the news, now with a bold claim that biosignature molecules (DMS and/or DMDS) have been 'detected at 3σ'. Most exoplanet astronomers are extremely sceptical about these claims, let's see why (1/n). 🔭🧪🪐
#exoplanet
38
1140
486
reposted by
Gijs D Mulders
seven rasmussen
6 months ago
the Ivory Tower model of science fails to build the public trust we desperately need right now my latest for Scientific American:
www.scientificamerican.com/article/scie...
loading . . .
What Science Owes to Society
Science cannot operate like a black box and expect the trust of the public
https://www.scientificamerican.com/article/scientists-need-to-speak-out-beyond-the-classroom-and-the-lab/
1
21
4
⚠️ Job alert ⚠️ Two faculty positions at the Institute of Astrophysics at UC Chile. All areas of
#astronomy
welcome!
aas.org/jobregister/...
loading . . .
Faculty Position(s) at the Institute of Astrophysics (IA), Pontificia Universidad Católica de Chile (PUC) | American Astronomical Society
The Institute of Astrophysics (IA) at Pontificia Universidad Católica de Chile (PUC) invites applications to fill at least two faculty positions at the assistant or associate professor level, dependin...
https://aas.org/jobregister/ad/2dc79bab
6 months ago
1
27
12
reposted by
Gijs D Mulders
Sky & Telescope
6 months ago
A team of astronomers has obtained high-resolution images of all known protoplanetary disks in the Lupus star-forming region.
buff.ly/e4loZXz
. .
#astronomy
#exoplanets
#cosmology
#protoplanetarydisks
#planetformation
loading . . .
Tiny Disks Shed Light on Super-Earth Origins
An team of astronomers has obtained high-resolution images of all known protoplanetary disks in the Lupus star-forming region.
https://buff.ly/e4loZXz
1
52
9
Postdoctoral Fellowship opportunities in
#astronomy
at my new employer, UC Chile
aas.org/jobregister/...
If you are interested in writing a proposal to work on
#exoplanets
or planet formation with me, get in touch!
loading . . .
Postdoctoral Fellowships in Astrophysics at Pontificia Universidad Católica de Chile | American Astronomical Society
The Institute of Astrophysics at Pontificia Universidad Católica (IA-PUC) and the Center of Astro-Engineering of the Universidad Católica (AIUC) invite applications for sponsoring postdoctoral researc...
https://aas.org/jobregister/ad/6112764d
6 months ago
2
16
5
reposted by
Gijs D Mulders
Nienke van der Marel
6 months ago
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
loading . . .
How does a typical protoplanetary disk look like?
YouTube video by Nienke van der Marel
https://youtu.be/jvT1wD7yCec
1
13
2
reposted by
Gijs D Mulders
Nienke van der Marel
6 months ago
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.
loading . . .
Protoplanetary discs are much smaller than previously thought
https://www.astronomie.nl/nieuws/en/protoplanetary-discs-are-much-smaller-than-previously-thought-4477
3
55
17
Do
#exoplanets
evolve over time? ☄️ A thread 1/🧵
loading . . .
6 months ago
3
74
19
@bot.astronomy.blue
signup
6 months ago
0
0
0
reposted by
Gijs D Mulders
seven rasmussen
6 months ago
brownie in motion or whatever einstein said happy birthday man
4
91
16
reposted by
Gijs D Mulders
astrafoxen
7 months ago
I spent almost 2 hours painstakingly copying the orbits of all 128 Saturnian moons from the announcement MPEC and reformatting them for visualization... Behold, here are the orbits of ALL 128 MOONS OF SATURN. This isn't just a moon system—it's a literal asteroid belt around Saturn! 🧪🔭☄️
91
2267
485
JWST cycle 4 results seem to be out, RIP hopes and dreams 💀
7 months ago
1
10
0
reposted by
Gijs D Mulders
Bernardita Ried Guachalla
7 months ago
2. Pontifical Catholic University of Chile: This university's Institute of Astrophysics offers advanced research opportunities and hosts several astronomical observatories, including the Manuel Foster Observatory.
astro.uc.cl
loading . . .
Inicio - Instituto de Astrofísica
El instituto de astrofísica UC es uno de los principales centros de investigación en astrofísica en Chile. Este cuenta con programas de Licenciatura, Magister y Doctorado.
https://astro.uc.cl
1
5
1
Load more
feeds!
log in