Sierra Grant
Carnegie Fellow at the Earth and Planets Laboratory. Protoplanetary + circumplanetary disks. Formerly at MPE, BU, and University of Michigan. She/her. #BiInSci 🏳️🌈✨🔭 Opinions are my own.
sierragrant.com
- @gcugno.bsky.social and I had a wonderful discussion with @goastromo.bsky.social for @setiinstitute.bsky.social LIVE about our work on the circumplanetary disk around CT Cha b!
- WATCH LIVE: youtube.com/live/t1pz56F...
- PRESS RELEASE DAY! Could not be prouder of this result and so happy that it's now out!!! 🤩✨ Thanks to the team at @stsci.edu for the wonderful write-up and image!
- #NASAWebb has found the first direct evidence of potential moon formation around a giant exoplanet. The discovery is shedding light on how such systems evolve and why moons could be potentially habitable worlds: bit.ly/46xGodN 🔭 🧪
- [Not loaded yet]
- Thank you! It was a fun journey to get here. Soon we'll be able to see if this carbon richness is the norm for these objects or not!
- [Not loaded yet]
- [Not loaded yet]
- Yes! Came out this morning -- the first chemistry study of a disk around a planetary-mass companion! Truly only possible with the power of MIRI MRS: angular resolution 🤝 spectral resolution
- What an incredible thing to do every week! And yay for hitting such a high number!
- Today is a special paper day for me: for the first time we can do chemistry in a circumplanetary disk around a planetary-mass companion! Gabriele Cugno and I used JWST to tease out the signal of CT Cha b, finding a rich carbon chemistry (7 molecules + 1 isotopolog detected)! arxiv.org/abs/2509.15209
- [Not loaded yet]
- We detect benzene (C6H6), which comes in the form of this fun ring!
- 🤯🤯🤯 circumstellar disk chemistry? No, circumPLANETARY disk chemistry! What an INCREDIBLE result! Check it out below ⬇️🧪🔭🪐
- Today is a special paper day for me: for the first time we can do chemistry in a circumplanetary disk around a planetary-mass companion! Gabriele Cugno and I used JWST to tease out the signal of CT Cha b, finding a rich carbon chemistry (7 molecules + 1 isotopolog detected)! arxiv.org/abs/2509.15209
- Thanks, Linn!! It still blows my mind too...!
- This C-rich chemistry is in stark contrast with the disk around the host star, CT Cha A, where we only find O-bearing molecules. CT Cha A fits in well with other Sun-like objects, while CT Cha b extends disk chemistry trends down to the planetary-mass regime.
- This started as preparation for Cycle 4 -- and made it possible for those proposals to succeed! Then it was just two people who were so excited to dig into the data and see where it led. I'm immensely proud of this work, grateful to have done this with Gabriele, and so excited for the data to come!✨
- Feel free to reach out if you have any questions about Carnegie! It's an amazing place to be a postdoc!
- The advertisement for Carnegie EPL's 2026 postdoctoral fellowship is out! aas.org/jobregister/... We are also happy to host external fellowships like NHFP, NSF, and 51 Peg b (the latter is due Oct 3rd, one month away!). Please feel free to reach out if you have questions. (1/2)
- 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
- 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
- [Not loaded yet]
- Or permanent jobs 😬
- Our cat, but now in spherical form 😍
- A spotted star, a (very!) misaligned planet, and awesome gifs, what more could you want?! 🤩
- TOI-3884 b is a planet around an M dwarf whose transits show persistent spot crossings. We show that the star's rotational and spot-crossing variations can be modeled with a misaligned planet transiting a large polar spot (confirming last week's results from Mori et al.) arxiv.org/abs/2506.11998
- Great work by Kielan Hoch and team on this incredible two-planet system!! We will revisit this target with MIRI-MRS next year to hunt for molecules in the disk around planet b, in a program led by Gabriele Cugno and me, and with Kielan's expertise on the system 🥳🪐
- Beautiful new results from my @stsci.edu colleagues Kielan Hoch and collaborators (on here: @mattkenworthy.bsky.social, @offallingstars.bsky.social , @bmacastro.bsky.social , @balmer.bsky.social) with JWST + MIRI www.theguardian.com/science/2025...
- 〰️〰️〰️〰️ New paper from @tamburo.bsky.social! 🤩
- Obligatory picture at the institute sign and new headshot for my first day as a Carnegie Fellow at the Earth and Planets Laboratory
- [Not loaded yet]
- Thanks, Andrew! Enjoy the upcoming group retreat!
- Shoutout to @tamburo.bsky.social for taking literally all professional photos that I've ever used 📸
- Our latest JWST (+ ALMA, VLTI-GRAVITY, IRTF-iSHELL) paper has been accepted in A&A! arxiv.org/abs/2406.10217 We investigated the short-separation DF Tau binary system. We find an unexpected disk around B with ALMA, with movement seen in ~2 months. The disks are < 3 au in radius.
- The JWST-MIRI spectrum is extremely line-rich with a forest of H2O lines. DF Tau A and B are not resolved with JWST, therefore the spectrum must be taken as the sum of both disks. We suggest that DF Tau B has a small cavity (~1 au) and that most of the emission is coming from A.
- However, there is a cold (< 200 K) H2O component with an extended emitting area that is likely coming from both disks. In short: we needed all the data we could get to study this enigmatic system!
- A mind-blowing result from the MINDS team! The disk around this small star is teeming with carbon-rich gas, further confirming how different the disks around low-mass stars are compared to their more massive siblings! Led by the awesome PhD student Aditya Arabhavi! webbtelescope.org/contents/new...
- I finally celebrated job news: I’m moving stateside (well, okay, federal-district-side)! In the fall I will start a three-year position as a Carnegie Fellow at Carnegie Science’s Earth and Planets Laboratory (EPL) in Washington, D.C. 🇺🇸
- [Not loaded yet]
- Thanks, Phil!!
- [Not loaded yet]
- Thank you!
- [Not loaded yet]
- Congratulations, Catherine!!! 🥳
- Wonderful article in Scientific American about water's cosmic journey, including some thoughts of my own!! 💧✨🔭 www.scientificamerican.com/article/jwst...
