Gijs D Mulders
LightNews LightNews
banner
gijsmulders.com
Gijs D Mulders
@gijsmulders.com
300 followers 59 following 97 posts
Exoplanet Astronomy
Assistant Professor
Santiago de Chile
http://gijs.cl
\m/
Posts Replies Media Videos
Pinned
gijsmulders.com
Gijs D Mulders @gijsmulders.com · Jul 1
Why does the solar system not have super-Earths?

A thread #exoplanets ☄️
Reposted by Gijs D Mulders
emily.space
Ever wondered how many bins to choose when making a histogram of data? The answer is that you shouldn't choose a number of bins yourself! ☄️ #astrocode

Here's a little notebook explaining how to make less biased histograms:
Making histograms is a common way to estimate the true density distribution of a sample. But how can we choose the number of histogram bins? And if we get fancy and use kernel density estimation (KDE)...
Making histograms is a common way to estimate the true density distribution of a sample. But how can we choose the number of histogram bins? And if we get fancy and use kernel density estimation (K...
gist.github.com
December 19, 2025 at 9:19 AM
Reposted by Gijs D Mulders
sciencepolice.bsky.social
I'm very happy I woke up at 4am this morning to catch 3I/ATLAS right before its closest approach to Earth (today!) This interstellar visitor is traveling over 60 km/s ☄️

At 269 million km (1.8 AU), I took a series of 2.5 min exposures with my Seestar 🔭
December 18, 2025 at 4:13 PM
Reposted by Gijs D Mulders
bibianaprinoth.ch
The application for the ESO Summer Research Programme 2026 has just opened!

It‘s a six week programme in Garching close to Munich where pre-Ph.D students can work on a hands-on project.

Working at @eso.org is a fabulous experience, so please help me spread the word ✨

🔗 eso.org/sci/meetings...
ESO - SummerResearch2026
ESO is the European Organisation for Astronomical Research in the Southern Hemisphere. It operates the La Silla Paranal Observatory in Chile and has its headquarters in Garching, near Munich, Germany.
eso.org
December 17, 2025 at 1:12 PM
Reposted by Gijs D Mulders
toomanyspectra.bsky.social
the day is finally here: you can order my debut non-fiction, CLOUDY WITH A CHANCE OF STARSHIPS: HOW THE DRAKE EQUATION REVEALS THE ODDS OF LIFE IN THE COSMOS from B&N!!

www.barnesandnoble.com/w/cloudy-wit...
Cloudy with a Chance of Starships takes readers on an irreverent expedition through the marvelous world of astrobiology, using as a guide the most important equation in science since E=mc2. With an irresistible blend of wit, insight, and the latest cutting-edge research, Seven Rasmussen looks at the thrilling possibilities of life in the cosmos through the lens of the Drake equation, a seven-variable mathematical expression that calculates the number of civilizations in our galaxy that humans could potentially contact. First proposed in 1961 by astrobiologist and SETI scientist Frank Drake, the equation begins with simple and well-known numbers such as the rate of star formation in the Milky Way and the fraction of stars with planetary systems. It then wades into thornier topics such as the number of planets with environments suitable for life, the fraction of suitable planets on which life appears, and the likelihood of intelligent life emerging on a planet and becoming technological. It concludes with the truly unknowable average lifetime of a civilization. While we will never resolve all its variables, the Drake equation offers an invaluable road map to the questions and challenges that lie before us in our quest for alien life.
December 13, 2025 at 7:45 PM
Reposted by Gijs D Mulders
profsera.bsky.social
⭐️✨🔭Please help us get the message out about the 7th annual international ASPIRE program at @api.uva.nl. This summer 2026 school provides astronomy research experience for talented MSc students from countries where opportunities to move into a PhD program are limited. Applications are due 17 Dec! ⭐️✨🔭
ASPIRE
aspire.science.uva.nl
December 11, 2025 at 1:21 PM
gijsmulders.com
Equating giant planet occurrence rate of ~20% to the disk fraction, that means a timescale of ~10 Myr for giant planet formation!
emily.space Emily Hunt @emily.space · 24d
New paper led by Fabian Polnitzcky & with @sratzenboeck.bsky.social + @joaoalves.bsky.social: based on the ages of stars with infrared excess in Sco-Cen, it seems planet-forming disks last around twice as long as previous estimates suggest - giving twice as long for planets to form. 🔭☄️ #exoplanets
Their input source selection in the Sco-Cen region, showing stars with (blue) and without (orange) disks. The fraction of young stars with disks as a function of age, based on three different selection methods. All show that many stars appear to have disks to ages well beyond ~10 million years, with a median lifetime of ~5 million years!
December 9, 2025 at 2:53 PM
Reposted by Gijs D Mulders
emily.space
New paper led by Fabian Polnitzcky & with @sratzenboeck.bsky.social + @joaoalves.bsky.social: based on the ages of stars with infrared excess in Sco-Cen, it seems planet-forming disks last around twice as long as previous estimates suggest - giving twice as long for planets to form. 🔭☄️ #exoplanets
Their input source selection in the Sco-Cen region, showing stars with (blue) and without (orange) disks. The fraction of young stars with disks as a function of age, based on three different selection methods. All show that many stars appear to have disks to ages well beyond ~10 million years, with a median lifetime of ~5 million years!
December 9, 2025 at 10:57 AM
gijsmulders.com
Question for the #exoplanets crowd:

Does any one know where to find an updated version of this plot?

I'm looking for the "standard" exoplanet mass vs. semi-major axis plot, but with an overlay of which planets have a spectroscopic measurement of their atmosphere

wasp-planets.net/2020/09/29/w...
Which exoplanets do we have atmospheric spectra for?
Here’s an interesting plot created by Zafar Rustamkulov (@exoZafar), a PhD student at Johns Hopkins University. He has added up all the exoplanets for which we have either transmission spectr…
wasp-planets.net
November 19, 2025 at 12:21 AM
Reposted by Gijs D Mulders
pascucci.bsky.social
Enjoyed giving a UofA Origins talk on how protoplanetary disks evolve – featuring new results from ALMA and JWST. The recording is available here 👇
youtu.be/mdgGgnjVbb0
@uarizonalpl.bsky.social @stewardobservatory.bsky.social
Protoplanetary Disk Evolution in the ALMA–JWST Era (Ilaria Pascucci, UArizona/LPL)
YouTube video by Origins Seminars
youtu.be
November 5, 2025 at 4:10 PM
Reposted by Gijs D Mulders
Big congrats to Jennifer Burt, Xavier Dumusque, and Sam Halverson on finishing their epic (instant classic) Annual Reviews of Astronomy & Astrophysics article "Precise Radial Velocities"!
arxiv.org/abs/2511.01954
contains some great new graphics for talks on
#exoplanets #EPRV #DopplerSpectroscopy
November 5, 2025 at 7:20 AM
Reposted by Gijs D Mulders
kevinkhu.bsky.social
The NASA #Exoplanet Archive now has Gaia DR3 IDs! This should hopefully make your work and planning observations easier!

exoplanetarchive.ipac.caltech.edu
An image of the Gaia spacecraft logo in red with text above it that says Gaia DR3 IDs.
October 16, 2025 at 10:47 PM
Reposted by Gijs D Mulders
timlichtenberg.bsky.social
w/ Oli Shorttle, @johannateske.bsky.social & Eliza Kempton we reviewed our current understanding and prospects for peaking on the inside of small #exoplanets in "Constraining exoplanet interiors using observations of their atmospheres": www.science.org/stoken/autho... & arxiv.org/abs/2510.08844 🔭🧪⚒️☄️
Illustration of predicted interior structures of sub-Neptune exoplanets. Observed density and atmospheric constraints are interpreted in three scenarios, each with a gaseous envelope. Water worlds have a small metal core, rocky mantle, high-pressure ice layer, and possible liquid water ocean. Gas dwarfs have a larger metal core and a magma ocean. Global supercritical regimes have no clear boundaries between layers. Image credit: Mark A. Garlick.
October 13, 2025 at 12:27 PM
gijsmulders.com
How do giant planets influence the type of #exoplanets that form in the habitable zone?

A thread 1/🧵
Many Exoplanets
October 8, 2025 at 9:10 PM
Reposted by Gijs D Mulders
andrasgaspar.bsky.social
Our paper on the JWST/MIRI observations of the epsilon Eridani system, led by Dr. Schuyler Wolff, were published today! This is the last of the Archetypical Disks in our MIRI Survey, after Fomalhaut and Vega. Just like for those disks, our MIRI images reveal an extended inner asteroid disk!
Four color image of the eps Eri debris disk.
September 29, 2025 at 7:35 PM
Reposted by Gijs D Mulders
jjfplanet.bsky.social
I'm really excited about this one! It's fantastic working with Dr. Yayaati Chachan:
arxiv.org/abs/2509.20428
"Revising the Giant Planet Mass-Metallicity Relation: Deciphering the Formation Sequence of Giant Planets"
Lots of great nuggets her, including that even super-Jupiters are very metal-rich.
Revising the Giant Planet Mass-Metallicity Relation: Deciphering the Formation Sequence of Giant Planets
The rate at which giant planets accumulate solids and gas is a critical component of planet formation models, yet it is extremely challenging to predict from first principles. Characterizing the heavy...
arxiv.org
September 26, 2025 at 4:25 AM
Reposted by Gijs D Mulders
aussiastronomer.bsky.social
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...
A close-up photo of a box of cupcakes with gold candles spelling out ‘6000’. A group of smiling people - scientists, engineers, data analysts and writers - standing behind a table of goodies.
September 17, 2025 at 6:22 PM
Reposted by Gijs D Mulders
spectraltypos.bsky.social
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
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...
arxiv.org
September 17, 2025 at 3:05 PM
Reposted by Gijs D Mulders
emily.space
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
The Astrosky Ecosystem - Open Collective
We're building an open-source ecosystem of social media tools for the space science & astronomy communities.
opencollective.com
September 8, 2025 at 3:51 PM
Reposted by Gijs D Mulders
melina-iras07572.bsky.social
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.
Figure 1 of the pre-print. Three images of the same dust ring using different methods.
September 3, 2025 at 8:21 AM
Reposted by Gijs D Mulders
mattkenworthy.bsky.social
Proud supervisor moment: #LeidenObservatory graduate student Richelle van Capelleveen led one of two papers on our discovery of WISPIT 2b, 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 🔭 🧪
A series of concentric black and white ovals against a black background, with a dim red dot in the lower left of one of the paths of a black ring. The ovals are dust rings around a young star, and the red dot is a 5 Jupiter mass exoplanet called WISPIT 2b.
August 26, 2025 at 11:51 AM
Reposted by Gijs D Mulders
gabeweible.bsky.social
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 ☄️🔭🧪
Annotated false-color image of the WISPIT 2 system as seen in infrared light by the Large Binocular Telescope Interferometer (LBTI). The host star has been subtracted from the center of the image, with the inner lambda/D radius masked. Two bright circumstellar point sources are seen: CC1 - a superjovian protoplanet candidate(?) in the inner disk cavity, and b - a superjovian protoplanet in a disk gap further out. Three protoplanetary disk rings are also visible despite self subtraction from the KLIP-ADI algorithm (Rings 1, 2, and 3 in the companion paper by R. van Capelleveen et al.)
August 26, 2025 at 5:40 PM
gijsmulders.com
#achievement for the day

(please don't send me any more email)
August 20, 2025 at 10:04 PM
Reposted by Gijs D Mulders
jjfplanet.bsky.social
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....
ui.adsabs.harvard.edu
August 19, 2025 at 7:06 PM
gijsmulders.com
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
August 18, 2025 at 11:19 PM
Reposted by Gijs D Mulders
distantworlds.space
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 🔭
science.esa.int ESA Space Science @science.esa.int · Aug 13
The TRAPPIST-1 d exoplanet may be Earth-sized 🌍 but it has no Earth-like atmosphere.

Webb’s #NIRSpec has found no traces of molecules that are common in Earth’s atmosphere.

Read more 👉 www.esa.int/Science_Expl... 🔭 🧪
Illustration of a planet silhouetted in front of a star. The star shows a large eruption on one side and more wisps of red coming from its southern hemisphere. Two more planets appear in the background.
August 13, 2025 at 5:24 PM