Sierra Grant

AAS Nova Celebrates 10 Years of Astronomy Research News AAS Nova turned 10 this year! For our 2,000th post, we're looking back on the past decade of astronomy research.

AAS Nova turned 10 this year! For our 2,000th post, we’re looking back on the past decade of astronomy research. aasnova.org/2025/10/03/a... @aas.org 🔭🧪

This is an illustration of a young planet with a surrounding disc of dust and gas, potentially forming moons. The planet, which appears red, is shown at lower right, enveloped by a cloudy disc. The host star appears at upper left, and glows yellow, with its own reddish disc of debris. The black background of space is speckled with stars. At the bottom of the illustration, graphics of molecules are listed in the following order: Acetylene, Carbon Dioxide, Ethane, Benzene, Hydrogen cyanide.

Moon formation drama, a bit more understood 🌚

The NASA/ESA/CSA James Webb Space Telescope has found evidence of a ‘construction yard’ for moons around a large exoplanet, CT Cha b, which lies 625 light-years from Earth.

Read more 👉 www.esa.int/Science_Expl... 🔭 🧪 ☄️

An image of the planetary companion CT Cha b shown as a red dot next to its parent star, with a spectrum from 12 to 16 microns from JWST showing several rotational and vibrational bands in emission for several carbon molecules.

Cugno and Grant @sierragrant.bsky.social with “A Carbon-rich Disk Surrounding a Planetary-mass Companion” detected using #JWST - an impressive detection of several different carbon molecules that are very promising for #exomoon formation around the directly imaged #exoplanet CT Cha b ☄

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!

NASA’s Webb Telescope Studies Moon-Forming Disk Around Massive Planet - NASA Science NASA’s James Webb Space Telescope has provided the first direct measurements of the chemical and physical properties of a potential moon-forming disk

Space Telescope Science Institute: NASA’s JWST Studies Moon-Forming Disk Around Massive Planet science.nasa.gov/science-rese...

SO PROUD OF MY (FUTURE*) WIFE @sierragrant.bsky.social

*FUTURE MEANING SUNDAY

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!

Birth of Worlds, Rise of Giants Join Carnegie postdocs Shubham Kanodia and Sierra Grant as they explore the secrets of distant worlds—from the birth of new planets to giant rule-breakers that defy expectations—in a special double…

TOMORROW: Two talks, one big night of discovery!

Join Earth & Planets Laboratory postdocs Sierra Grant & Shubham Kanodia as they reveal how planets are born—and the giants that defy the rules. #NeighborhoodLecture

📅 Sept 25 | 6:30 PM ET | DC & Online
🔗 RSVP: carnegiescience.edu/birth-worlds...

Three planeteers look through a mockup of a Curiosity rover wheel

The best part of my job is the people I get to work with 🪐💙

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!

We detect benzene (C6H6), which comes in the form of this fun ring!

Thanks, Linn!! It still blows my mind too...!

🤯🤯🤯 circumstellar disk chemistry? No, circumPLANETARY disk chemistry!

What an INCREDIBLE result! Check it out below ⬇️🧪🔭🪐

🪐🔭 JWST is letting us learn about disks around PLANETARY-MASS OBJECTS!!!

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!✨

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.

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

Feel free to reach out if you have any questions about Carnegie! It's an amazing place to be a postdoc!

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

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?! 🤩

Now published in AJ! We used Tierras to measure the 23-day rotation period of a K dwarf and found that the orbit of its transiting planet is aligned with the star's spin axis. Stay tuned as we measure true obliquities for a larger sample!

iopscience.iop.org/article/10.3...

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 🥳🪐

Advocacy Action Center The Planetary Society is organizing a new space constituency that is educated, empowered, and loud.

Save NASA Science: Please join me in signing this petition from The Planetary Society, urging Congress to reject the deep cuts to science that have been proposed by the administration. www.planetary.org/advocacy-act...

〰️〰️〰️〰️ New paper from @tamburo.bsky.social! 🤩

Sign the Petition Oppose the layoff of the NIST Atomic Spectroscopy Group

The data produced by this group has been an essential resource for so much great science. We use their data and websites to interpret our JWST spectra of protostars. It is exactly the kind of foundational investments the US should be making to advance science. www.change.org/p/oppose-the...

I received a heartbreaking email today: A paper in a special issue I’m editing is being retracted because one of its authors is afraid of losing their job and their legal status in the U.S. if they publish a scientific study on evolution. Yes, on evolution, nature's engine of diversity.