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William Thompson

@wrtastro.bsky.social

1.1K followers 350 following 120 posts

Herzberg Instrument Science Fellow at the National Research Council in Victoria, Canada. Imaging exoplanets and writing #JuliaLang tools.

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William Thompson @wrtastro.bsky.social · Mar 3

Time for the promised thread on ε Eridani b!

I should emphasize this manuscript is a submitted draft—comments from the community are very welcome.

Bottom line: ε Eri b is likely a 1.0 Jupiter-mass planet, only 3.2pc away, on a 3.55 AU near-circular orbit, ~aligned with its debris disk. 🔭🪐🧪 [1/7]

Figure showing a the plausible orbits for Eps Eri b, and a panel showing the scale of the orbits relative to the outer debris disk model of Booth et al.

A three panel figure showing the statistical distribution of inclination versus mass for the planet, broken down by seven different combinations of data. The scatter points follow an m*sin(i) curve, except for a series that does not include any RV data. A small black concentrated region shows the full model, with 1 and 3 sigma contours. The planet's mass is quoted at 0.98 +- 0.09 Mjup, and inclination as 41 +- 7 degrees.

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William Thompson @wrtastro.bsky.social · 9d

Paper accepted to AJ! 🥳
Updated preprint coming to an arxiv server near you.

William Thompson @wrtastro.bsky.social · Mar 3

William Thompson @wrtastro.bsky.social · Sep 2

New position, same institution!

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William Thompson @wrtastro.bsky.social · Sep 2

First day as a Plaskett Fellow 😎

William Thompson @wrtastro.bsky.social · Aug 29

Last day as a Herzberg fellow 🥲

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William Thompson @wrtastro.bsky.social · Aug 29

Last day as a Herzberg fellow 🥲

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William Thompson @wrtastro.bsky.social · Aug 27

Very nice!

William Thompson @wrtastro.bsky.social · Aug 16

To make it work, I had to pass “--overcommit”
Story of my life…

William Thompson @wrtastro.bsky.social · Aug 15

#exoplanets As we speak, Octofitter is running on nearly 20,000 cores 😅 maybe a record for most exoplanet orbit fits run in parallel?

William Thompson @wrtastro.bsky.social · Aug 15

Probably nothing compared to TESS and Kepler though!

William Thompson @wrtastro.bsky.social · Aug 15

#exoplanets As we speak, Octofitter is running on nearly 20,000 cores 😅 maybe a record for most exoplanet orbit fits run in parallel?

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William Thompson @wrtastro.bsky.social · Jul 16

Unless it’s SQL!

William Thompson @wrtastro.bsky.social · Jul 14

These changes are breaking---See sefffal.github.io/Octofitter.j... for details. Thanks! [4/4]

Migration Guide · Octofitter.jl

Documentation for Octofitter.jl.

sefffal.github.io

William Thompson @wrtastro.bsky.social · Jul 14

We have a new concept of “observation variables” that makes it easy to model out instrument systematics like RV offsets and northangle/platescale uncertainties. This plugs into our improved cross-validation capabilities to test how different subsets of data impact results. [3/4]

William Thompson @wrtastro.bsky.social · Jul 14

We have a new API for constructing models and specifying priors, with much simpler syntax. It’s now really easy to e.g. add priors on mutual inclination between two bodies and other dynamical constraints. [2/4]

William Thompson @wrtastro.bsky.social · Jul 14

Octofitter v7, now released! This release overhauls the modelling syntax and add some powerful new capabilities for advanced users. [1/4]

(Octofitter is a package for Bayesian modelling of exoplanet orbits)

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Reposted by William Thompson

Brett Morris @brettmorr.is · Jul 14

The brightest star in Scorpius, Antares, is nearing the end of its 15 million year life. It's so large that the orbits of Mercury, Venus, Earth and Mars would be inside the star. 🔭🧪

Pilate et al. published brightness maps of the star, showing gigantic convective cells.

arxiv.org/abs/2507.08614

Relative brightness maps of Antares over the course of a year, showing the changing brightness and shapes of convective cells in the stellar photosphere.

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William Thompson @wrtastro.bsky.social · Jul 12

Direct imagers, what is your expectation for how speckles behave at high spectral resolution? Do they vary smoothly with wavelength?

We have an R11,000 cube at 10^-7 contrast to share soon, but I’m curious to hear people’s expectations first #instrumentation #exoplanets.

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William Thompson @wrtastro.bsky.social · Jul 10

Position of Epsilon Eridani b in-front/behind the star, and phase angle over time for those interested. Updated pre-print should be ready soon!

🔭 #exoplanets

a plot of a planet's position vs the star in 2D indicated as coloured lines. The line colour goes towards red or blue as the planet is in front of the star or behind. It is blue on the left, red on the right, and green, indicating 0, at the top and bottom. The separation is about 1000 milliarcseconds left or right increasing to about 1300 at top or bottom, creating an oval.

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William Thompson @wrtastro.bsky.social · Jul 6

There’s something very special about the gulf islands 🏝️

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William Thompson @wrtastro.bsky.social · Jul 3

Our JWST DDT was accepted 🥳

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William Thompson @wrtastro.bsky.social · Jul 2

Gorgeous!

Reposted by William Thompson

Jayke Samson Nguyen @astrojayke.bsky.social · Jul 2

Found some beautiful Neptune data digging through the Keck Observatory Archives! The pole isn't nearly as visible now as it was back in 2002.

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William Thompson @wrtastro.bsky.social · Jun 3

Thank you!

William Thompson @wrtastro.bsky.social · Jun 3

I was honoured today to give the Plaskett medal award talk to open this years Canadian Astronomical Society meeting in Halifax! Great to share our work on #exoplanets imaging and modelling 🔭

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Reposted by William Thompson

Heidi B. Hammel @hbhammel.bsky.social · May 27

Astonishing new videos of the Sun show coronal "rain" in (pink-tinted) hydrogen-alpha light. Obtained with advanced adaptive optics research supported by NSF, the National Solar Observatory, and New Jersey Institute of Technology. Details and more videos in the link in the first comment below.

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William Thompson @wrtastro.bsky.social · May 22

Link: sefffal.github.io/Octofitter.j...
Change log: github.com/sefffal/Octo...

Fig. credits:
* arxiv.org/abs/2504.11127
* arxiv.org/abs/2502.05359
* arxiv.org/abs/2502.20561

Thanks to:
* Dori Blakley
* Eric Nielsen
* William Roberson
* Zach Langford
* Eric Agol
* Sarah Blunt
* Clarissa R Do Ó

Home · Octofitter.jl

Documentation for Octofitter.jl.

sefffal.github.io

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