Drew Weisserman

Drew Weisserman

@drewweisserman.bsky.social

McMaster Astronomy PhD student. send me pictures of your pets or I will steal them. he/him 🏳️‍🌈 check out my research: https://drewweis.github.io/

815 followers604 following1.5K posts

Drew Weisserman reposted

Ryan
@ryansimmons.bsky.social
Megan Swift@meganswift.bsky.social

Pittsburgh Zoo & Aquarium is set to trade gorillas with Boston’s Franklin Park Zoo. Frankie, Pittsburgh’s 7-year-old male western lowland gorilla, will head to Boston, and in exchange, Boston will send 33-year-old Little Joe the silverback @triblive.bsky.social 🦍

triblive.comPittsburgh Zoo to trade gorillas with Boston’s Franklin Park ZooPittsburgh Zoo & Aquarium is set to trade gorillas with Boston’s Franklin Park Zoo. Frankie, Pittsburgh’s 7-year-old male western lowland gorilla, will head to Boston, and in exchange, Bos...
Drew Weisserman
@drewweisserman.bsky.social

Paper day!!! 🎉 arxiv.org/abs/2604.07447 ⬇️ #exoplanets #astronomy It all starts with planets around really small stars (M dwarfs). There's some evidence that planets around these stars form fundamentally differently than around stars like our Sun. We think that planets around these stars may 1/

arxiv.orgSuper-Earth masses and stellar abundances from NIRPS reveal tentative evidence for water-rich formation around M dwarfsTracing the compositional link between terrestrial super-Earths and their host stars provides clues to their dominant formation pathway. By constraining the stellar abundances of refractory elements, we can predict the core mass fractions (CMFs) of their super-Earths. The level of agreement between this prediction and the planetary CMF derived from their masses and radii can reveal past formation processes, like mantle stripping and water-rich formation plus sequestration in the planet's core. Here, we present the first results from the Near Infrared Planet Searcher (NIRPS) GTO CMF subprogram: an intensive radial velocity campaign to refine masses and compute host stellar abundances of three hot super- Earths around M dwarfs (GJ 1132 b, GJ 1252 b, and LTT 3780 b), calculating masses of $1.69 \pm 0.15M_\oplus$, $1.54 \pm 0.18M_\oplus$, and $2.34 \pm 0.10M_\oplus$ respectively. We measure the CMFs of these and six further hot super-Earths with precise masses already available in the literature to 10-15% precision. We compare these to CMF predictions made from measuring the Fe, Mg, and Si abundances of their host stars measured from the NIRPS spectra. We find that the CMFs of these planets are smaller than expected from their host stellar abundances, to a statistically significant degree. This discrepancy is suggestive of significant reservoirs of water, and while these planets are too hot to harbor surface water, they likely have interior water mass fractions of $\sim$1%.
View full thread
Drew Weisserman
@drewweisserman.bsky.social

In short: - We measured the masses of several rocky planets around M dwarfs - We compare those planets to their host stars' abundances - The planets are underdense compared to what their host stars imply, which we interpret as being due to the presence of water inside these planets!! 12/

Drew Weisserman
@drewweisserman.bsky.social

Paper day!!! 🎉 arxiv.org/abs/2604.07447 ⬇️ #exoplanets #astronomy It all starts with planets around really small stars (M dwarfs). There's some evidence that planets around these stars form fundamentally differently than around stars like our Sun. We think that planets around these stars may 1/

arxiv.orgSuper-Earth masses and stellar abundances from NIRPS reveal tentative evidence for water-rich formation around M dwarfsTracing the compositional link between terrestrial super-Earths and their host stars provides clues to their dominant formation pathway. By constraining the stellar abundances of refractory elements, we can predict the core mass fractions (CMFs) of their super-Earths. The level of agreement between this prediction and the planetary CMF derived from their masses and radii can reveal past formation processes, like mantle stripping and water-rich formation plus sequestration in the planet's core. Here, we present the first results from the Near Infrared Planet Searcher (NIRPS) GTO CMF subprogram: an intensive radial velocity campaign to refine masses and compute host stellar abundances of three hot super- Earths around M dwarfs (GJ 1132 b, GJ 1252 b, and LTT 3780 b), calculating masses of $1.69 \pm 0.15M_\oplus$, $1.54 \pm 0.18M_\oplus$, and $2.34 \pm 0.10M_\oplus$ respectively. We measure the CMFs of these and six further hot super-Earths with precise masses already available in the literature to 10-15% precision. We compare these to CMF predictions made from measuring the Fe, Mg, and Si abundances of their host stars measured from the NIRPS spectra. We find that the CMFs of these planets are smaller than expected from their host stellar abundances, to a statistically significant degree. This discrepancy is suggestive of significant reservoirs of water, and while these planets are too hot to harbor surface water, they likely have interior water mass fractions of $\sim$1%.
View full thread
Drew Weisserman
@drewweisserman.bsky.social

That's what we're seeing here! We find that, surprisingly, you don't need a LOT of water to explain the differences between the planet and the star. In fact, water making up ~1% of the planet's mass is enough to explain it! We think any water would likely be sequestered inside the planet, since 10/

Drew Weisserman
@drewweisserman.bsky.social

these are REALLY hot planets, but we can't say for sure. Finally, we do a sanity check for future observers -- YOU DON'T NEED SO MUCH TELESCOPE TIME TO EXPAND THIS RESULT! Just get a larger planet sample with less precise masses instead, it's WAY more efficient than getting 200 RVs per target. 11/

Drew Weisserman
@drewweisserman.bsky.social

Paper day!!! 🎉 arxiv.org/abs/2604.07447 ⬇️ #exoplanets #astronomy It all starts with planets around really small stars (M dwarfs). There's some evidence that planets around these stars form fundamentally differently than around stars like our Sun. We think that planets around these stars may 1/

arxiv.orgSuper-Earth masses and stellar abundances from NIRPS reveal tentative evidence for water-rich formation around M dwarfsTracing the compositional link between terrestrial super-Earths and their host stars provides clues to their dominant formation pathway. By constraining the stellar abundances of refractory elements, we can predict the core mass fractions (CMFs) of their super-Earths. The level of agreement between this prediction and the planetary CMF derived from their masses and radii can reveal past formation processes, like mantle stripping and water-rich formation plus sequestration in the planet's core. Here, we present the first results from the Near Infrared Planet Searcher (NIRPS) GTO CMF subprogram: an intensive radial velocity campaign to refine masses and compute host stellar abundances of three hot super- Earths around M dwarfs (GJ 1132 b, GJ 1252 b, and LTT 3780 b), calculating masses of $1.69 \pm 0.15M_\oplus$, $1.54 \pm 0.18M_\oplus$, and $2.34 \pm 0.10M_\oplus$ respectively. We measure the CMFs of these and six further hot super-Earths with precise masses already available in the literature to 10-15% precision. We compare these to CMF predictions made from measuring the Fe, Mg, and Si abundances of their host stars measured from the NIRPS spectra. We find that the CMFs of these planets are smaller than expected from their host stellar abundances, to a statistically significant degree. This discrepancy is suggestive of significant reservoirs of water, and while these planets are too hot to harbor surface water, they likely have interior water mass fractions of $\sim$1%.
View full thread
Drew Weisserman
@drewweisserman.bsky.social

From there, we can calculate the fraction of the planet's mass that's in the core through some modeling of the planet's interior. We can then compare those to the "equivalent" core mass fractions that we get if the planet just had the same elemental abundances as the star. We get... 8/

Drew Weisserman
@drewweisserman.bsky.social

This!! It sure looks like our planets have less massive cores (and are thus less dense) than their host stars imply... (and we show that they do, statistically!) Earlier, we said if these planets are chronically underdense, that has to be because of something light making up part of the planet. 9/

Drew Weisserman
@drewweisserman.bsky.social

Paper day!!! 🎉 arxiv.org/abs/2604.07447 ⬇️ #exoplanets #astronomy It all starts with planets around really small stars (M dwarfs). There's some evidence that planets around these stars form fundamentally differently than around stars like our Sun. We think that planets around these stars may 1/

arxiv.orgSuper-Earth masses and stellar abundances from NIRPS reveal tentative evidence for water-rich formation around M dwarfsTracing the compositional link between terrestrial super-Earths and their host stars provides clues to their dominant formation pathway. By constraining the stellar abundances of refractory elements, we can predict the core mass fractions (CMFs) of their super-Earths. The level of agreement between this prediction and the planetary CMF derived from their masses and radii can reveal past formation processes, like mantle stripping and water-rich formation plus sequestration in the planet's core. Here, we present the first results from the Near Infrared Planet Searcher (NIRPS) GTO CMF subprogram: an intensive radial velocity campaign to refine masses and compute host stellar abundances of three hot super- Earths around M dwarfs (GJ 1132 b, GJ 1252 b, and LTT 3780 b), calculating masses of $1.69 \pm 0.15M_\oplus$, $1.54 \pm 0.18M_\oplus$, and $2.34 \pm 0.10M_\oplus$ respectively. We measure the CMFs of these and six further hot super-Earths with precise masses already available in the literature to 10-15% precision. We compare these to CMF predictions made from measuring the Fe, Mg, and Si abundances of their host stars measured from the NIRPS spectra. We find that the CMFs of these planets are smaller than expected from their host stellar abundances, to a statistically significant degree. This discrepancy is suggestive of significant reservoirs of water, and while these planets are too hot to harbor surface water, they likely have interior water mass fractions of $\sim$1%.
View full thread
Drew Weisserman
@drewweisserman.bsky.social

them to their host stars! We got a WHOLE bunch of telescope time on the NIRPS spectrograph to precisely measure the masses of 3 hot rocky super-Earths (and take another 6 planet masses from other studies because we took up enough telescope time already 😭) Really, check out these RV curves! 6/

Drew Weisserman
@drewweisserman.bsky.social

We ALSO use these data to precisely measure abundances of these planets' host stars from near-infrared spectra, using a new routine developed by my friend and collaborator Nicole Gromek (paper coming pretty soon!) Getting abundances is REALLY difficult for these cool stars, but we do our best! 7/

Drew Weisserman
@drewweisserman.bsky.social

Paper day!!! 🎉 arxiv.org/abs/2604.07447 ⬇️ #exoplanets #astronomy It all starts with planets around really small stars (M dwarfs). There's some evidence that planets around these stars form fundamentally differently than around stars like our Sun. We think that planets around these stars may 1/

arxiv.orgSuper-Earth masses and stellar abundances from NIRPS reveal tentative evidence for water-rich formation around M dwarfsTracing the compositional link between terrestrial super-Earths and their host stars provides clues to their dominant formation pathway. By constraining the stellar abundances of refractory elements, we can predict the core mass fractions (CMFs) of their super-Earths. The level of agreement between this prediction and the planetary CMF derived from their masses and radii can reveal past formation processes, like mantle stripping and water-rich formation plus sequestration in the planet's core. Here, we present the first results from the Near Infrared Planet Searcher (NIRPS) GTO CMF subprogram: an intensive radial velocity campaign to refine masses and compute host stellar abundances of three hot super- Earths around M dwarfs (GJ 1132 b, GJ 1252 b, and LTT 3780 b), calculating masses of $1.69 \pm 0.15M_\oplus$, $1.54 \pm 0.18M_\oplus$, and $2.34 \pm 0.10M_\oplus$ respectively. We measure the CMFs of these and six further hot super-Earths with precise masses already available in the literature to 10-15% precision. We compare these to CMF predictions made from measuring the Fe, Mg, and Si abundances of their host stars measured from the NIRPS spectra. We find that the CMFs of these planets are smaller than expected from their host stellar abundances, to a statistically significant degree. This discrepancy is suggestive of significant reservoirs of water, and while these planets are too hot to harbor surface water, they likely have interior water mass fractions of $\sim$1%.
View full thread
Drew Weisserman
@drewweisserman.bsky.social

see that planets with more iron are going to have a bigger core (and be more dense). Thus, stars with more iron (compared to silicates that form rock) should host planets with more iron (and thus have larger cores, and be denser)! But what if we DON'T see that? What if we see that planets around 4/

Drew Weisserman
@drewweisserman.bsky.social

these stars tend to be LESS dense than their host stars would imply? Well, then, there has to be some sort of light material that's making up a substantial chunk of these planets... like water 👀 For this work, we precisely measure masses of a bunch of rocky planets around M dwarfs, and compare 5/

Drew Weisserman
@drewweisserman.bsky.social

Paper day!!! 🎉 arxiv.org/abs/2604.07447 ⬇️ #exoplanets #astronomy It all starts with planets around really small stars (M dwarfs). There's some evidence that planets around these stars form fundamentally differently than around stars like our Sun. We think that planets around these stars may 1/

arxiv.orgSuper-Earth masses and stellar abundances from NIRPS reveal tentative evidence for water-rich formation around M dwarfsTracing the compositional link between terrestrial super-Earths and their host stars provides clues to their dominant formation pathway. By constraining the stellar abundances of refractory elements, we can predict the core mass fractions (CMFs) of their super-Earths. The level of agreement between this prediction and the planetary CMF derived from their masses and radii can reveal past formation processes, like mantle stripping and water-rich formation plus sequestration in the planet's core. Here, we present the first results from the Near Infrared Planet Searcher (NIRPS) GTO CMF subprogram: an intensive radial velocity campaign to refine masses and compute host stellar abundances of three hot super- Earths around M dwarfs (GJ 1132 b, GJ 1252 b, and LTT 3780 b), calculating masses of $1.69 \pm 0.15M_\oplus$, $1.54 \pm 0.18M_\oplus$, and $2.34 \pm 0.10M_\oplus$ respectively. We measure the CMFs of these and six further hot super-Earths with precise masses already available in the literature to 10-15% precision. We compare these to CMF predictions made from measuring the Fe, Mg, and Si abundances of their host stars measured from the NIRPS spectra. We find that the CMFs of these planets are smaller than expected from their host stellar abundances, to a statistically significant degree. This discrepancy is suggestive of significant reservoirs of water, and while these planets are too hot to harbor surface water, they likely have interior water mass fractions of $\sim$1%.
Drew Weisserman
@drewweisserman.bsky.social

form via something called "water-rich formation", where their planets form with, well, a lot of water vs. around bigger stars. This is what simulations predict, and on a demographics level we sort of see the signs of this. But how can we get more concrete observational evidence of this? 2/

Drew Weisserman
@drewweisserman.bsky.social

The answer is by comparing rocky planets around these M dwarfs to their host stars! See, planets form out of the same cloud of material as their stars, so they ~should~ have similar elemental abundances as their stars. Since planets should be made of just an iron core and a rocky mantle, we can 3/

Drew Weisserman reposted

Astrobites
@astrobites.bsky.social

From Evan Nelles Henderson: We use bottles, and sometimes a Brita, but how do planets store their water? The authors of today’s paper made a model to find out, and to evaluate whether certain planets are good at hanging on to their water or not. ⚛️ 🔭 ☄️ 🧪 astrobites.org/2026/02/17/h...

astrobites.orgHang On To Your Water, Super-Earths!We use bottles, and sometimes a Brita, but how do planets store their water? The authors of today’s paper made a model to find out, and to evaluate whether certain planets are good at hanging on to th...

Drew Weisserman reposted

E.J. Fagan
@ejfagan.com

People are reading this way wrong. Schumer detached DHS from the other five bills in return for a two week CR on the DHS bill. Now Democrats can make demands on DHS spending without having to shut down agencies covered in the other five bills. They have way more leverage to get real concessions.

John@johnlk.bsky.social

People just going out here saying the literal opposite of what happened. Thune caved! Thune did! This is a cave by Thune and Senate Republicans, any possible way you cut it.

Drew Weisserman reposted

Sahil Kapur
@sahilkapur.bsky.social

221-205, House passes the “motion to discharge” the Jeffries 3-year ACA funding extension. NINE (!) Republicans join unanimous Democrats in voting to advance it. This tees up a final House vote tomorrow; it’s poised to sail through.

Drew Weisserman reposted

Greg Pak
@gregpak.net

Replying to @gregpak.net

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reps.fyiFind Your RepresentativeFind your representatives. Learn how to find and connect with them. Stay informed about their bills, committees, and contributions.

Drew Weisserman reposted

Keegan Matheson
@keeganmatheson.bsky.social

John Schneider on his early mound visit to Max Scherzer: “I’ve been waiting for that moment since our first zoom call in the offseason.” “I thought he was going to kill me. It was great.” #BlueJays

Drew Weisserman reposted

Sean Casten
@seancasten.bsky.social

Replying to @seancasten.bsky.social

9. The promise of democracy is that it will fix mistakes. The threat of autocracy is that it sets those mistakes in stone. And we would all be better off with a SCOTUS that embraced the former rather than praising the latter. /fin