Mastodawn

Some additional technical & scientific information in the thread that follows, mostly cut & paste from the image caption on my Flickr account.

But first, a gratuitous video, doing the Ken Burns thing across the scene. No music here, but on my Instagram post, I've used Lalo Schifrin's theme from Bruce Lee's "Enter the Dragon". Super cheesy, but definitely appropriate 🙂

Take a listen there, if you're still on that hellsite 😬 https://www.instagram.com/reel/DUGFNWQDBzT/

The image is a near-IR colour composite of the protostellar outflow system HH288, aka The Dragon Jet, made using the NIRCam instrument on NASA/ESA/CSA James Webb Space Telescope.

The composite comprises five individual mosaics in the F150W, F200W, F356W, F444W, & F470N filters, spanning the wavelength range 1.3 to 5 microns. Bluer colours are shorter wavelengths; redder are longer. The image is rotated by approximately 50º clockwise from North up, East left, & covers 378 x 259 arcseconds.

HH288 lies in galactic plane in the constellation of Cassiopeia at a distance of roughly 2 kiloparsecs or 6500 light years from Earth.

The nickname comes from the hopefully-obvious resemblance to a Chinese dragon, or loong / 龍 / 龙 / 🐉.

The main horizontal flow comprising "the dragon", with its head & flames to the left & tail to the right, spans roughly 3 parsecs or 9.8 light years.

The red, orange, & yellow emission is mostly due to emission lines of shock-heated molecular hydrogen, although there is some additional emission from carbon monoxide.

The more diffuse yellow-orange glow around the waist of "the dragon" is likely reflection nebulosity from the central protostars driving the main flow.

The wider blue & green glow in the image is likely a mixture of reflection nebulosity & emission from polycyclic aromatic hydrocarbons associated with dust in the region.

The gas in the main flow is moving at speeds of 100-200 km/sec from its protostar, which is thought to be significantly more massive than the Sun, & likely less than a million years old.

However, there are at least two other outflows seen associated with "the dragon", one linear running from lower left to upper right, & another more chaotic from lower right to upper right.

Close inspection shows perhaps another two or three newly-discovered small flows as well.

Also obvious is the small cluster of young embedded stars towards the bottom edge of the image, which also appear to be ejecting jets of molecular hydrogen gas. For obvious reasons, I'm calling this "the dragon's egg" 🐲🐣🙂

For more information on our original discovery of HH288 & millimetre wavelength studies of it, see this 2001 paper I wrote with Frédéric Gueth & Peter Schilke: https://scixplorer.org/abs/2001A&A...375.1018G/abstract

An interferometric study of the HH 288 molecular outflow

We present an interferometric study of the CO line emission in the HH 288 molecular outflow. The IRAM Plateau de Bure interferometer was used to obtain an 11-field mosaic covering the whole flow ( ~ 2 pc) with an angular resolution of about 3.5'' (7000 AU at a distance of 2 kpc). The data were complemented with short-spacings derived from IRAM 30-m observations. The exciting source of HH 288, IRAS 00342+6347, is a young (dynamical age of the outflow =~ a few 10<SUP>4</SUP> years) intermediate-mass (bolometric luminosity =~ 500lsun , envelope mass =~ 6 to 30msun ) embedded protostar. This source is likely to be an intermediate-mass counterpart of a classical Class 0 low-mass protostar. HH 288 is actually a quadrupolar outflow, and the angular resolution provided by the interferometric observations allows us to rule out models involving limb-brightened walls of a wide-angle single flow to explain such a morphology. The presence of two protostars in the central condensation is the most appealing explanation to account for the presence of the two flows. While the small East-West flow has a quite simple morphology and kinematics, the large North-South flow includes several overlapping structures, created by successive ejection events. Large collimated limb-brightened cavities are observed, with high-velocity material located along or near the flow axis. The internal structure of HH 288, including morphological coincidence between the CO and H<SUB>2</SUB> emission, supports prompt entrainment at the head of large bow-shocks as the main formation process of molecular outflows from intermediate-mass protostars. Based on observations carried out with the IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).

NASA/ADS

The original data making up this image were taken by JWST between 26 & 30 January 2025 as part of the Guaranteed Time Observation programme #4548, PI Mark McCaughrean, JWST Interdisciplinary Scientist for star formation.

Image credit & copyright:
Mark McCaughrean (MPIA) / NASA, ESA, CSA / CC BY-SA 4.0

And there's more to come: we're currently writing up these JWST data for publication, but we also have new follow-up millimetre & radio observations coming up, using the IRAM 30m dish, the NOEMA interferometer, & the eVLA.

That's work being done in collaboration with Peter Schilke, Beth Jones, & Tatiana Rodríguez at the University of Cologne, & will be a great help in disentangling this very complex set of jets & outflows coming from several embedded protostars.

Oh, & as a brief coda, what looks like a "simple colour image" is, in fact, anything but. There's a lot of noise in the original data, partly due to the NIRCam electronics which struggle when the sky background is very low, & partly due to cosmic rays hitting the detectors.

Processing, aligning, & cleaning the five separate large mosaics, plus aligning them accurately, compressing the dynamic range, & colour compositing took about a month of manual work over Christmas.

But worthwhile.

@markmccaughrean very interesting!

Just a question as a physicist working also on data analysis: I assume that all these corrections include systematic uncertainties. Is that a problem only for precision analysis of JWST data or does that even affect more statistically limited/counting things style results?

@freyablekman Thanks, Freya. Interesting question.

Some of the pipeline flow is strictly quantitative, removing instrumental imprints, flux calibrating, & astrometric registration on the sky. It's those data that we use for the scientific analysis.

But they often have many non-astronomical features still in them, including electronic glitches & ripples. Removing them to make a colour image like this is much more like art than science, & you always need to check details against the originals.

@freyablekman I'm not quite sure what you mean though when you juxtapose "precision analysis of JWST data" with "more statistically-limited counting things style results"?

The aim is to be photon-noise limited in our astronomical data, albeit those photons may be background rather than the source under study. But we definitely have other sources of noise in the electronics & detectors, plus some pipeline induced, which often means we fall short.

@markmccaughrean I mean you must have measurements where the assumptions on that noise make the measurement worse? And measurements where that doesn’t matter so much? How is that assessed?

@freyablekman Ah, ok – yes. There are both stochastic & systematic errors in things like the flux calibration & astrometric registration, but one of the biggest systematics we usually have to deal with in such regions is our poor knowledge of the distance, which then affects our conversions from measured angles to sizes, & measured flux to intrinsic emission.

Both get folded into our errors, but astronomers are usually happy when we get things right to half an order of magnitude, so 😉

@markmccaughrean yeah I’m sure you are aware of the astronomy order of magnitude jokes.

(I work on LHC physics) We have both studies/results where systematic uncertainties are the most important and studies where they don’t matter, and of course the case in between.

That’s why I was wondering if that was true in JWST world as well, as you were talking about all these corrections. When we correct we never correct perfectly. And knowing those imperfections is super important and has a huge effect on how much science can be extracted

@freyablekman Probably less of an issue the kind of astronomy I do – if I can see it in a series of separate data sets, it must be real. Quite how far / bright etc. is secondary 🙂

But there are many fields (e.g. dark matter & energy surveys, exoplanet spectroscopy) where systematics & an understanding how well they're known are absolutely crucial, very much as it is for you.

@markmccaughrean 🙏 thanks for the explanation, I learned something new today

@freyablekman My pleasure – I always find it interesting & instructive to talk with scientists in other fields, as it helps hone my understanding.

I gave a talk about JWST at EMBL here in Heidelberg last year, & one of the questions was "why do you put subtended angles & not a physical scale bar on all your images?"

Took me a second before I realised that they, as microscopists, know the exact distance to their object of interest & thus scale, while it's often a lot less certain for us.

Simeon Schmauß Jan 29

@markmccaughrean Fantastic processing, Mark! This time was indeed well spent.
Since I've been playing with the JWST pipeline lately, did you apply any modifications over to the default products that would appear on MAST?

@stim3on Thanks, Simeon 🙂 Usually we apply a modified pipeline to our JWST data, extending dynamic range & tweaking astrometry. It wasn’t needed in this case though, so I started from the default latest MAST products. That said, I ended up leaving out a couple of wavelengths from the composite as they had bad background matching, something we’d need to fix manually. But there was a huge amount of post-pipeline processing needed, especially to clean various noise terms up 😬✌️

Simeon Schmauß Jan 29

@markmccaughrean I can only imagine, those badly matched backgrounds were the reason I didn't finish my last JWST processing attempt.
Later this year I hope to dig into the jwst pipeline (thankfully a lot of it is python) to see if I can improve things there. Probably not in a way that will be accurate enough for science products, but at least as an improved starting point for image processing.

@markmccaughrean Congratulations & thanks for the explainer, especially this:

"The main horizontal flow comprising "the dragon", with its head & flames to the left & tail to the right, spans roughly 3 parsecs or 9.8 light years."

So often we're told the object's distance from Earth but not its size. Gaining a sense of the object's size really adds to the wonder I experience looking at the image. JWST is an amazing instrument. I'm so happy that it was successfully deployed!

#Astronomy #JWST

@elaterite Thanks, Bob – that's very kind.

I agree completely – many astronomy image releases seem devoid of physical parameters & context, and while "9.8 light years" is perhaps also a very difficult scale for humans to grasp, it's better than nothing 🙂

As for a sense of relief at JWST safely deploying, err, yes 😳

@markmccaughrean Ha ha, as a mechanic / machinist I have a sense of JWST's mechanical complexity. I'm certain you, the astronomical community, as were we all, sitting on pins and needles and holding our collective breaths over that two week deployment period! And then there was the commissioning period. JWST is a stunning technical achievement! And the science being returned is mind-blowing!

@elaterite Yep, watching the launch from 5km away was pretty tense, but at least that was over pretty quickly. Reading the daily reports from STScI during the fortnight of deployment, then months of cooling, alignment, & commissioning was on another level though.

Images like this & the amazing science JWST is delivering are real tributes to the ~20,000 people in North America & Europe who worked on the mission for decades, & who keep it running today – we're all very grateful 👍

@markmccaughrean Indeed, three parsec long kudos to all! 👏 👏 👏

@elaterite @markmccaughrean

Steve Hersey Jan 29

Totally aside from the mind-blowing science the JWST is delivering, I cannot help exclaiming, "Space dragon 9 light-years long! Woohoo!"

@n1xnx @elaterite Coming (not very) soon from George R R Martin – "House Tagaryen Take on the Universe"!

@markmccaughrean @n1xnx 😂

Javier Manuel Martín Alonso Jan 29

@markmccaughrean Stunning HH288.If these jets are the 'emergency brake' saving a star from its own fury, then we are the survivors of the Sun’s wild coming-of-age dance. We are the stardust that stayed behind, the quiet resonance of a celestial party that threw fire 9 light-years away just so we could have a peaceful orbit. From frenzy came our cradle. 🐉✨☀️#JWST #Astronomy #StarFormationTriggered

Javier Manuel Martín Alonso Jan 31

@markmccaughrean Thanks for the favorite!

HH288: Perfect framing of triggered star formation physics. ✨

#JWST #Astronomy #Cosmology

Лафиэль Элентари Feb 1

@markmccaughrean
Awesome image. Hmm, maybe I should use it as my desktop wallpaper :)

https://flic.kr/p/2rTPMvp

Mark McCaughrean Feb 1

@Lafiel You are more than welcome – you can download it at the most appropriate resolution from my Flickr page at:

HH288, The Dragon Jet, as seen with JWST

Flickr

Estarriol, Terrorist Dragon Jan 29

@markmccaughrean @DrCarpineti

That is just beautiful.

rtn Jan 29

@markmccaughrean @DrCarpineti Best wallpaper ever! Ty!

@rtn You're most welcome – please feel free to use it (although note the CC BY-SA licence if you feel tempted to start selling posters 😉)

rtn Jan 29

@markmccaughrean It's solely for my own pleasure! 😊

@rtn Then it comes with my fullest blessing 🙂

ERM Jan 29

@rtn @markmccaughrean
Hello big fan I’m impressed with your profile. I also admire your good sense of humor here. I don’t normally write people here on my personal site , but I think you deserve this compliment….. I’d like to be your friend if you don’t mind give me a follow right away ★ and Privately mentioned me let's Chat better 👍.

ERM Jan 29

@markmccaughrean @rtn

Drey Jan 29

@markmccaughrean @DrCarpineti 👍

Trevor "Dust Mouth" Flowers Jan 29

@markmccaughrean 😻

@markmccaughrean @DrCarpineti

Birchbirch Jan 29

Congratulations! It's really stunning!

I don't know about you, Mark, but it looks kind of familiar to me... ;-)

@birchbirch @DrCarpineti Ha – that old déjà-vu will get you every time 🤪

Leon Cowle Jan 29

@markmccaughrean @malachy Immediately became my new desktop background -- absolutely stunning! Thanks for sharing.

@leoncowle @malachy We approve this message 👍

Jonas 🇩🇰 🇬🇱Jan 29

@markmccaughrean @DrCarpineti Batman sign

Ari "Two Sheds" Jackson Jan 29

@markmccaughrean Stunning! 😍

Vincent Privat 🇺🇦Jan 29

@markmccaughrean @DrCarpineti Thank you so much for releasing this magnificent picture in CC-BY-SA on Flickr. It now proudly illustrates HH288 wikidata item: https://www.wikidata.org/wiki/Q93337656 (no wikipedia article yet) 💖

HH 288

@VincentPrivat My pleasure. Over ten years ago, we went through a long debate at ESA about which CC licence to use as the default for image releases. We favoured CC BY, but our lawyers insisted on CC BY-NC.

As we knew that CC BY-SA was the minimum level of “permissiveness” that’d allow images to appear on Wikipedia, we argued & won that compromise.

That’s why I used CC BY-SA for my image: so it could end up on Wikipedia for people to share. Happy to know it’s there already 👍

Michael / マイケル 사자 🦁Jan 29

@markmccaughrean @DrCarpineti That is amazing!

@saja0486 Thanks – happy you like it. It took a lot of work to put it together & I’m pleased with the positive response 🙂👍

Michael / マイケル 사자 🦁Jan 31

@markmccaughrean Excellent hard work. The results are definitely worth it.

https://bsky.app/profile/astrobotjwst.bsky.social/post/3mdnh4a7ctj2d

Daniel Fischer Jan 31

@markmccaughrean The HH288 images are quite popular over on the blue side:

https://bsky.app/profile/cheribliss.bsky.social/post/3mdofqsqjgs2x

https://bsky.app/profile/israelvelazquez.bsky.social/post/3mdog4vblyc2h

https://bsky.app/profile/landru79.bsky.social/post/3mdnoyd5tw22a

https://bsky.app/profile/melina-iras07572.bsky.social/post/3mdnnzicnqc2j

No match for your careful processing, of course.

Astrobot JWST (@astrobotjwst.bsky.social)

🤖 image processing for #JWST 🔭 data (HH288_offset). RGB Filters: 470, 356, 150 PI: McCaughrean, Mark J., program 04548. CRVAL: 9.293072, 64.062915 Credits: NASA, ESA, CSA, STScI.

Bluesky Social

aburka 🫣Jan 31

@markmccaughrean @DrCarpineti looks like it's on fire!

Bodhipaksa Jan 31

@markmccaughrean @DrCarpineti That is just stunning. Thank you!

Mark McCaughrean Jan 31

@bodhipaksa @DrCarpineti Dragons are always magical, even when they're 10 light years long 😉