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Posts by astrafoxen

A fox sitting calmly on rocky ground illuminated by warm, low sunlight during dusk or dawn.

A fox sitting calmly on rocky ground illuminated by warm, low sunlight during dusk or dawn.

A fox peeks out from behind rocky terrain, its alert eyes focused forward in a natural, rugged environment.

A fox peeks out from behind rocky terrain, its alert eyes focused forward in a natural, rugged environment.

Grid of four photos of foxes, each standing on rocky terrain with dry bushes and shadows in a sunny outdoor setting.

Grid of four photos of foxes, each standing on rocky terrain with dry bushes and shadows in a sunny outdoor setting.

Spotted: curious locals on Cerro Pachón 👀🦊

At NSF–DOE Rubin Observatory, it’s not just about galaxies and asteroids. Sometimes foxes wander by to check out what we’re up to, reminding us we’re part of a bigger ecosystem right here on Earth.

Science is wild. Sometimes literally! 🔭🧪

4 days ago 70 11 0 0

the answer is yes :>

3 weeks ago 1 0 1 0
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arxiv.org/abs/2603.150... This coming May the weird goose-egg shaped dwarf planet Haumea will eclipse two (!) distant stars, from our perspective - one of them being way brighter than the star that gave us a glimpse of its ring system back in 2017! There's a lot to be learned here, potentially.

4 weeks ago 51 11 4 0

more love for TNOs <3

3 weeks ago 12 1 1 0
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luhman 16

2 months ago 152 34 1 0
Artistic illustration of ZTF J1239+8347, an extremely tight binary brown dwarf system that is undergoing mass transfer, where the more massive component (the accretor) directly pulls material from the less massive component (the donor). Material pulled from the donor is concentrated into a narrow stream of gas that flows directly into the accretor's atmosphere, heating up to a very high temperature of 8900 K and creating a bright blue hotspot in the accretor's atmosphere.

Due to the extremely small separation between the components (center-to-center separation of ~170,000 km), both are tidally deformed into teardrop shapes pointing toward each other. In addition, both components orbit and rotate extremely quickly with a period of 57.41 minutes, which further deforms them into oblate teardrops (oblateness ~10%).

Both components are L-type brown dwarfs, having temperatures a bit above 1000 K. This temperature makes them glow orange-red in visible wavelengths, though the slightly hotter accretor glows slightly more orange (ignoring its bright blue hotspot). Due to their extremely fast rotation, the components' atmospheres are highly turbulent and extremely windy, dominated by numerous bands over their latitudes. Numerous convection cells and vortices are depicted on their poles, inspired by brown dwarf atmosphere simulations.

Due to the highly oblate shapes of the brown dwarfs, internal light is blocked out by their thicker equators, resulting in a darker and more opaque equator (gravity darkening). The gravity darkening effect is depicted for the donor but not for the accretor, whose equator glows bright blue to yellow due to the hotspot being smeared across the accretor's equator via strong zonal winds.

Artistic illustration of ZTF J1239+8347, an extremely tight binary brown dwarf system that is undergoing mass transfer, where the more massive component (the accretor) directly pulls material from the less massive component (the donor). Material pulled from the donor is concentrated into a narrow stream of gas that flows directly into the accretor's atmosphere, heating up to a very high temperature of 8900 K and creating a bright blue hotspot in the accretor's atmosphere. Due to the extremely small separation between the components (center-to-center separation of ~170,000 km), both are tidally deformed into teardrop shapes pointing toward each other. In addition, both components orbit and rotate extremely quickly with a period of 57.41 minutes, which further deforms them into oblate teardrops (oblateness ~10%). Both components are L-type brown dwarfs, having temperatures a bit above 1000 K. This temperature makes them glow orange-red in visible wavelengths, though the slightly hotter accretor glows slightly more orange (ignoring its bright blue hotspot). Due to their extremely fast rotation, the components' atmospheres are highly turbulent and extremely windy, dominated by numerous bands over their latitudes. Numerous convection cells and vortices are depicted on their poles, inspired by brown dwarf atmosphere simulations. Due to the highly oblate shapes of the brown dwarfs, internal light is blocked out by their thicker equators, resulting in a darker and more opaque equator (gravity darkening). The gravity darkening effect is depicted for the donor but not for the accretor, whose equator glows bright blue to yellow due to the hotspot being smeared across the accretor's equator via strong zonal winds.

My favorite binary brown dwarf system, ZTF J1239+8347! These two red-hot dwarfs orbit so closely together that one devours gas from its partner and becomes superheated with a brilliant blue glow.

Handdrawn over 2 days. (1/5; see my explanation!)
en.wikipedia.org/wiki/ZTF_J12...
#spaceart #sciart

3 weeks ago 81 20 3 1
Figure 31 of Showman et al. 2020 - Global circulation models of isolated brown dwarfs with a dual-band radiative transfer scheme, coupled to a cloud cycle, showing the development of highly time-variable turbulence and cloud patchiness. Shown is the total outgoing IR flux, which varies locally by a factor of two due to local variations in cloud opacity and temperature structure. The characteristic size of the turbulent structures decreases with decreasing rotation period (increasing rotation rate). From Tan (2018) and Tan & Showman (submitted)

Figure 31 of Showman et al. 2020 - Global circulation models of isolated brown dwarfs with a dual-band radiative transfer scheme, coupled to a cloud cycle, showing the development of highly time-variable turbulence and cloud patchiness. Shown is the total outgoing IR flux, which varies locally by a factor of two due to local variations in cloud opacity and temperature structure. The characteristic size of the turbulent structures decreases with decreasing rotation period (increasing rotation rate). From Tan (2018) and Tan & Showman (submitted)

Figure 31 of link.springer.com/article/10.1...

(there's a ton of juicy hot Jupiter and BD atmosphere simulations in this)

3 weeks ago 14 2 1 0
Video

Finally, here's a lil timelapse of my progress (with reference images) from start to finish!

(5/5; i should really start recording speedpaints instead of just screenshotting bits of my progress...)

3 weeks ago 15 0 1 0
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* BDs are oblate due to fast rotation; their thicker equators absorb more internal light and appear darker (gravity darkening)
* Although the blue hotspot is ~300x more luminous than both BDs combined, BDs have very low albedos (<1%) so they only reflect a little bit of the hotspot's light.
(4/5)

3 weeks ago 8 0 1 0

now onto the science of whatever the heck is going on in my art of ZTF J1239! It's mostly inspired by the Caltech illustration, with some changes for better scientific accuracy:
* both BDs have bands & turbulence since they rotate extremely fast
* BDs are tidally distorted into teardrop shapes
(3/5)

3 weeks ago 8 0 1 0
A screenshot of the Wikipedia article for ZTF J1239+8347 (https://en.wikipedia.org/wiki/ZTF_J1239%2B8347), showing my artwork on the right side.

A screenshot of Caltech's official artwork is shown to the left of my artwork, overlaid with the text "Caltech ver. can't be used apparently :("

A screenshot of the Wikipedia article for ZTF J1239+8347 (https://en.wikipedia.org/wiki/ZTF_J1239%2B8347), showing my artwork on the right side. A screenshot of Caltech's official artwork is shown to the left of my artwork, overlaid with the text "Caltech ver. can't be used apparently :("

I didn't put a signature or watermark for this one since I made this for Wikipedia (basically, make this public domain). This is the only time I'm doing this for my art. The original Caltech illustration unfortunately couldn't be used for Wikipedia because of its vague copyright info.

(2/5)

3 weeks ago 10 0 1 0
Artistic illustration of ZTF J1239+8347, an extremely tight binary brown dwarf system that is undergoing mass transfer, where the more massive component (the accretor) directly pulls material from the less massive component (the donor). Material pulled from the donor is concentrated into a narrow stream of gas that flows directly into the accretor's atmosphere, heating up to a very high temperature of 8900 K and creating a bright blue hotspot in the accretor's atmosphere.

Due to the extremely small separation between the components (center-to-center separation of ~170,000 km), both are tidally deformed into teardrop shapes pointing toward each other. In addition, both components orbit and rotate extremely quickly with a period of 57.41 minutes, which further deforms them into oblate teardrops (oblateness ~10%).

Both components are L-type brown dwarfs, having temperatures a bit above 1000 K. This temperature makes them glow orange-red in visible wavelengths, though the slightly hotter accretor glows slightly more orange (ignoring its bright blue hotspot). Due to their extremely fast rotation, the components' atmospheres are highly turbulent and extremely windy, dominated by numerous bands over their latitudes. Numerous convection cells and vortices are depicted on their poles, inspired by brown dwarf atmosphere simulations.

Due to the highly oblate shapes of the brown dwarfs, internal light is blocked out by their thicker equators, resulting in a darker and more opaque equator (gravity darkening). The gravity darkening effect is depicted for the donor but not for the accretor, whose equator glows bright blue to yellow due to the hotspot being smeared across the accretor's equator via strong zonal winds.

Artistic illustration of ZTF J1239+8347, an extremely tight binary brown dwarf system that is undergoing mass transfer, where the more massive component (the accretor) directly pulls material from the less massive component (the donor). Material pulled from the donor is concentrated into a narrow stream of gas that flows directly into the accretor's atmosphere, heating up to a very high temperature of 8900 K and creating a bright blue hotspot in the accretor's atmosphere. Due to the extremely small separation between the components (center-to-center separation of ~170,000 km), both are tidally deformed into teardrop shapes pointing toward each other. In addition, both components orbit and rotate extremely quickly with a period of 57.41 minutes, which further deforms them into oblate teardrops (oblateness ~10%). Both components are L-type brown dwarfs, having temperatures a bit above 1000 K. This temperature makes them glow orange-red in visible wavelengths, though the slightly hotter accretor glows slightly more orange (ignoring its bright blue hotspot). Due to their extremely fast rotation, the components' atmospheres are highly turbulent and extremely windy, dominated by numerous bands over their latitudes. Numerous convection cells and vortices are depicted on their poles, inspired by brown dwarf atmosphere simulations. Due to the highly oblate shapes of the brown dwarfs, internal light is blocked out by their thicker equators, resulting in a darker and more opaque equator (gravity darkening). The gravity darkening effect is depicted for the donor but not for the accretor, whose equator glows bright blue to yellow due to the hotspot being smeared across the accretor's equator via strong zonal winds.

My favorite binary brown dwarf system, ZTF J1239+8347! These two red-hot dwarfs orbit so closely together that one devours gas from its partner and becomes superheated with a brilliant blue glow.

Handdrawn over 2 days. (1/5; see my explanation!)
en.wikipedia.org/wiki/ZTF_J12...
#spaceart #sciart

3 weeks ago 81 20 3 1
Find_Orb Orbit determination software

Masses of perturbing objects (Sun, all planets, etc.) are included by default in the Find_Orb software for my orbital integration. www.projectpluto.com/find_orb.htm...

1 month ago 0 0 0 0

what the actual heck, an (almost) contact binary brown dwarf????

1 month ago 10 2 0 0

The shape of the near-Earth asteroid 2000 RS11 is inevitably compared to that of comet 67P.

But it has to have formed differently, since nothing is sublimating off of the rock pile.

RS11 remains unusual as compared to other contact-binary asteroids.

bsky.app/profile/agas...

1 month ago 7 1 1 0

(I used Find_Orb to do the orbital calculations, supplying it with astrometry from the MPEC announcement, and then plotted each orbital element over time in Python)

1 month ago 5 0 0 0
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Six graphs showing how each orbital element of Saturn's Gallic moon S/2023 S 54 changes over time (1950-2050). The graphs are arranged in 3 rows, 2 columns.
From top to bottom, the left column shows eccentricity, argument of pericenter, and semi-major axis. 
For the right column, going from top to bottom shows inclination with respect to ecliptic, ascending node, and longitude of pericenter (aka, the sum of ascending node and longitude of pericenter).

Six graphs showing how each orbital element of Saturn's Gallic moon S/2023 S 54 changes over time (1950-2050). The graphs are arranged in 3 rows, 2 columns. From top to bottom, the left column shows eccentricity, argument of pericenter, and semi-major axis. For the right column, going from top to bottom shows inclination with respect to ecliptic, ascending node, and longitude of pericenter (aka, the sum of ascending node and longitude of pericenter).

For fun, I decided to check how the orbit of one of Saturn's newest moons changes over time. The Gallic group moon S/2023 S 54 shows a sinusoidal oscillation in eccentricity and inclination with an offset phase. Kozai mechanism perhaps?

I'll defer the work to the folks at JPL since that's their job

1 month ago 13 0 2 0

welp, I need to update the irregular moons diagram for Wikipedia now...

1 month ago 3 0 0 0

Saturn 285, Jupiter 101. Time to invoke the mercy rule.

en.wikipedia.org/wiki/Moons_o...

1 month ago 74 18 6 1
MPEC 2026-F14 : ELEVEN NEW SATURNIAN SATELLITES We are the official body that deals with astrometric observations and orbits of minor planets (asteroids) and comets.

...and the MPC just announced 11 new moons of Saturn. minorplanetcenter.net/mpec/K26/K26...

1 month ago 12 2 0 1
A meme edit of the Capn' Crunch cereal box, with the name edited to say "Oops! All Carmes!". Inclination values ranging from i=163 to 165 degrees are common among Carme group moons.

A meme edit of the Capn' Crunch cereal box, with the name edited to say "Oops! All Carmes!". Inclination values ranging from i=163 to 165 degrees are common among Carme group moons.

That's a lot of Carmes.
Every new Jovian moon announcement in a nutshell:

1 month ago 5 0 0 0

Four more irregular satellites of Jupiter dropped so far today

S/2011 J4 [a=0.07, e=0.14, i=27.5, H=16.8]
S/2018 J5 [a=0.16, e=0.31, i=165.3, H=17.0]
S/2024 J1 [a=0.16, e=0.31, i=162.9, H=16.9]
S/2011 J5 [a=0.16, e=0.21, i=164.7, H =17.2]

www.minorplanetcenter.net/mpec/RecentM...

1 month ago 27 6 4 3

Just updated the Wikipedia article on Kallichore with new information and graphics! Crazy that we might finally get a close view of one of Jupiter's tiny outer moons in 2031…

en.wikipedia.org/wiki/Kallich...

I really want Juice to flyby Kallichore, pleaseplease let it happen

1 month ago 20 1 0 0
Direct physical and astrometric characterisation of a kilometre-scale Jovian moon for a potential JUICE flyby Jupiter’s irregular satellites are thought to be relics of the early outer Solar System, yet their small sizes and large distances make them challenging to characterise, limiting their feasibility for...

Rizos et al. recently posted HST and occultation results on Kallichore! New diameter of 3.8 km, elongated shape of a/b > 1.53, albedo of 0.037, and reduced orbital uncertainty by 80% (though still 9x above the ±30 km threshold to greenlight the JUICE flyby...)
www.researchsquare.com/article/rs-8...

1 month ago 0 0 0 0
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yw! Your art has been a big inspiration for me :3

1 month ago 1 0 1 0
Diagram showing where on Earth will Haumea's 2026 May 4 occultation will be visible. The occultation will be visible in regions between the orange dashed lines (representing the edges of Haumea's shadow as it passes over Earth). The red dashed lines represent the uncertainty in the position of Haumea's shadow, and the blue dashed lines represent a conservative "minimum diameter" (not using the long axis) for Haumea's shadow width.

Diagram showing where on Earth will Haumea's 2026 May 4 occultation will be visible. The occultation will be visible in regions between the orange dashed lines (representing the edges of Haumea's shadow as it passes over Earth). The red dashed lines represent the uncertainty in the position of Haumea's shadow, and the blue dashed lines represent a conservative "minimum diameter" (not using the long axis) for Haumea's shadow width.

Haumea's 2026 occultation will be visible from plenty (populated?) places (Africa, Europe, Asia). Its long axis will also be visible, so the occultation will occur over a larger area (Sam mentioned this in mailing list) and should fully constrain Haumea's 3D shape. lesia.obspm.fr/lucky-star/o...

1 month ago 1 0 0 0
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Haumea Flyby Deviantart.com image by Astra-Planetshine

I personally headcanon Haumea's equator to be pretty jagged with ridges, considering that it's quite close to rotational breakup and has previously undergone rotational fissioning. Something like this 2017 Haumea art by @astraplanetshine.bsky.social (gorgeous btw) www.deviantart.com/astra-planet...

1 month ago 5 2 2 0

FACTS

1 month ago 1 0 0 0
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Haumea Flyby Deviantart.com image by Astra-Planetshine

I personally headcanon Haumea's equator to be pretty jagged with ridges, considering that it's quite close to rotational breakup and has previously undergone rotational fissioning. Something like this 2017 Haumea art by @astraplanetshine.bsky.social (gorgeous btw) www.deviantart.com/astra-planet...

1 month ago 5 2 2 0

paper on Quaoar's shape, hmm

...it uses the outdated shape from Kiss et al. 2024 instead of the newer, less elongated shape from Proudfoot et al. 2025 B(

Haumea paper is hype tho. Possibility of hydrostatic equilibrium or equatorial ridge? Looking forward to its upcoming 2026 May 4 occultation!

1 month ago 1 2 2 0