Or maybe even a little better. 0.6 microns = 600 nm is in the visible, of course.

JWST's IFOV is about 0.031 arcsec (NIRCAM), compared to HST ACS WFC of 0.05 arcsec, 0.028 arcsec for the HRC (no longer working), and 0.04 arcsec for WFC3 STIS.

Though I'm not sure how JWST is defining their resolution with respect to the PSF at any given wavelength.

For amusement purposes only, I have taken a shot of Pluto from New Horizons and a shot of Jupiter from JWST and adjusted their sizes to show what kind of details we could expect from a Pluto JWST image. Pluto is only 1.7% the diameter of Jupiter, but assuming we can get similar resolution we should see some real features. And since we already have closeups we can probably deconvolute a better picture than Hubble did without prior knowledge of the surface.

Click to view attachment

Unless you deliberately blurred the images, this kind of simulation always massively overestimates how many details you would really be able to see. Just FYI.

Any specific expectations about the ice giants and their satellite systems? NASA published a teaser story in 2020 that promised that "soon after its launch", Webb would "unlock the secrets of the atmospheres" of the ice giants, but did not go into much detail, or said anything about the satellites.

https://www.nasa.gov/feature/goddard/2020/e...-webb-telescope

Thanks to all for your insight !

Uranus, Neptune, and the uranian satellites will indeed be studied by JWST soon/already. I don't notice Triton being mentioned, but maybe it's hidden in another proposal, or maybe it didn't make the cut for Cycle 1; it's certainly a worthy target that wouldn't be ignored indefinitely.

https://www.stsci.edu/jwst/science-executio...rams/cycle-1-go

https://www.stsci.edu/jwst/science-executio...on.html?id=1585
https://www.stsci.edu/jwst/science-executio...on.html?id=1598
https://www.stsci.edu/jwst/phase2-public/1786.pdf

I would expect some outstanding science to result. To some extent, we won't know what spectroscopy in JWST's wavelengths is capable of until we get the first results, but the potential is excellent.

Right, because the shrunk pixels don't get affected by the PSF of the telescope? Here's one with a 5 pixel Gaussian applied.

Click to view attachment

Pluto is a target in the first Observing Cycle with a program lead by Emmanuel Lellouch so we'll know in about a year I'd say?

https://www.stsci.edu/jwst/science-executio...on.html?id=1658

JWST images the Phantom Galaxy M74 Webb inspects the heart of the Phantom Galaxy

In the M74 views there is a circular cavity in the dust and gas at all wavelengths, visible at about the 7:00 position angle. Has there been any comment about that, or is it just a random coincidence in the distribution?

I would guess that a large supernova took place at the center of that region long ago. We have something like that close to us, the Veil Nebula, which is not visible to the naked eye but is a whopping 3° of arc in diameter (6 full Moons wide).

There are still plenty of stars inside that volume. If the supernova interpretation is correct, it would be like a wind that blew dust and certain gas out to the edge, but of course have no perceptible force on dense things like stars.

Interesting interview of Scott Acton on the commissioning of the telescope (wavefront sensing): https://spectrum.ieee.org/james-webb-space-telescope-mirror

First Webb image of Mars:

https://www.newscientist.com/article/233851...ctures-of-mars/

Re: image at top of article: "while the longer wavelength image reveals information about heat emitted from the Martian surface and atmosphere, as well as the concentrations of carbon dioxide in the atmosphere (bottom right, above)."

Note that the Hellas Basin (lower left of the lower right) shows up darker, which is "cooler", but i would have expected that low elevation area to be warmer. But i wonder if the thicker column of atmosphere (CO2) would have an effect?

---Bill

Better unpaywalled link is https://www.esa.int/Science_Exploration/Spa...s_of_Red_Planet

4.3 microns is not quite thermal IR, and there is an CO2 absorption there, so I would guess the 4.3 micron signal is correlated to elevation at least in part.

Seems odd that they didn't show the same FOV between the two wavelengths.

Thanks, Mike. That is a much better link. This initial Webb Data Dribble frequently has loose ends and we may get better data later.
Still, these are a wonderful preview of incredible images and data to come.

--Bill

This release describes the darker appearance of Hellas in detail. In a phrase, "higher pressure leads to a suppression of the thermal emission at this particular wavelength range."

https://blogs.nasa.gov/webb/2022/09/19/mars...-of-red-planet/

First Webb imagery of Neptune:

https://webbtelescope.org/contents/news-rel...46#section-id-2

Just for reference, here are images from the VLT and Hubble. Of interest is the storm system shown with white clouds. And note that Webb is imaging in infrared wavelengths and is looking at things differently.

--Bill

I'd wondered why the ring arcs aren't visible, but assuming models 2 and 3 are on the money (#2: 820.1118 deg/day & #3: 820.1121 deg/day), the arcs are obscured by Neptune's disc.

Obs time: 2022-07-12 06:52:35

Click to view attachment

Ian, remember this is a NIR view of Neptune, and the rings/ring arcs may look different at those wavelenghts. I've not noticed anything more on this.

--Bill

On Europa and Enceladus, which will be studied for plume signatures, for the first of certainly more than one time, in November and December:

I'm curious about JWST's ability to identify the signature of complex organics, and how calibration work would even be performed to determine their spectra. With a somewhat unconstrained number of possible organic compounds to look for, that seems like a lot of laboratory work involving unusual conditions to develop a catalog of reference spectra. This would seem like a need that has perhaps never existed before, but will be needed for interpreting JWST spectra of many objects, including Titan, comets, nebulae, exoplanet atmospheres, protoplanetary discs, and maybe more.

One may think of Europa's and Enceladus's plumes as two more "exo"planet atmospheres for JWST to study. It's interesting to note that JWST will provide a kind of data that even missions that visit those worlds will not. Maybe we'll see the spectra published in 2023, but understanding them seems like it could be a long game.

Hey,

An excerpt from the article https://blogs.nasa.gov/webb/ , describing an observation of the Wolf-Rayet 140 binary star, or more precisely the cosmic dust shells surrounding it, might give some clues to this :

“With the Medium-Resolution Spectroscopy (MRS) mode on MIRI, we obtained the first spatially resolved mid-infrared spectra of a dust-forming WR binary in our observation of WR 140, and were able to directly probe the chemical signatures of its dust shells. Broad and prominent features in the spectral lines at 6.4 and 7.7 microns told us that the dust was composed of compounds consistent with Polycyclic Aromatic Hydrocarbons (PAHs). This carbonaceous material plays an important role in the interstellar medium and the formation of stars and planets, but its origin is a long-standing mystery. With the combined results of JWST’s MRS spectra and MIRI imaging, we now have evidence that WR binaries can be an important source of carbon-rich compounds that enrich the interstellar environment of our galaxy, and likely galaxies beyond our own.”

Of course, we have to take into consideration the big difference between plumes coming from satellites in our solar system and the dust envelopes around a binary star located at light years...

If the report that I dare to make between the observations of these two very different targets is nevertheless valid, it will not be necessary to forget the technical problem, still under investigation, for the MRS mode of MIRI.

It's funny, Q, I also saw this story shortly after I posted. While it's definitely an interesting result, it is presented with qualifiers, "consistent with Polycyclic Aromatic Hydrocarbons," which indicates an educated hypothesis, but not proof, and also not very specific. I guess we're going to want to know a lot more about organics in the plumes of Europa and Enceladus, but of course, you take what you can get, and it's impressive that this sort of result can be had from light years away. We also have, in the case of Enceladus, some previous in situ sampling, and with Europa we expect that within a decade, so we will get to cross-reference one kind of data with another.

Images of Pillars of Creation. Link

That new IR view of The Pillars adds anothee dimension.

JWST does Titan!

Pretty impressive. Must be raining up there.

https://blogs.nasa.gov/webb/2022/12/01/webb...rns-moon-titan/

P

Brilliant inages by Keck and Webb, note that the extreme 300km atmospheric depth is shown from surface to haze top.. And Webb clearly shows surface features.
Well done!

Some understated drama from the NASA blog post linked to by antipde:



Somewhat off-topic: I'm reasonably confident that a social compact exists under which scientists who agree to let their scheduled observations be bumped for urgent requests from higher profile projects get something in return, but it must be complex and fraught.

Have any authors knowledgeably explored this topic for novels of manners ... or perhaps slasher fiction? /off-topic

Or even weirder- hailing? (Now I'm wondering, was hail damage ever modeled for dragonfly's rotors?)

Based on Cassini's monitoring, it seems that it rains on any given location on Titan only once in several decades or centuries, although when it does, the volume is extremely heavy. Despite Titan's 100% coverage in haze, the presence of clouds like these is quite rare at any given place and time. Preparing a future mission for rain seems to be like preparing a mission to Earth for hurricanes.

Here are the abstracts from the JWST "First Science Results" conference held last week. These abstracts are, of course, much more broad than deep or detailed, but there's still plenty of interesting stuff here.

https://www.stsci.edu/files/live/sites/www/...-compendium.pdf

Poster abstracts from the same event:

https://www.stsci.edu/files/live/sites/www/...esentations.pdf

The TRAPPIST-1 abstracts include the fact that one transit is not sufficient for detecting atmospheric molecular composition, there's some optimism that four transits may be sufficient, but also a note that features on the star TRAPPIST-1 introduced some unexpected noise that is much larger than the expected signal from a transiting planet's atmosphere. (Perhaps it is nonetheless distinguishable from atmospheric absorption features?) Again, publications from before the JWST indicate that measuring the atmospheric composition would benefit, ideally, from observations made during dozens of transits, per planet – more than is likely feasible.

There's been an interruption in the function of the NIRISS instrument on the JWST. The updates have been few and probably reflect a lack of certainty on the ground. A loss of that instrument would entail a serious loss of science, but this last update makes it sound like the team is optimistic pending more information.

https://blogs.nasa.gov/webb/2023/01/24/near...rations-update/

NIRISS is back online. This update doesn't say much about the cause of the glitch, but it must not have involved hardware in any serious way.

https://www.stsci.edu/contents/news/jwst/20...ence-operations

EDIT:

Apparently, a galactic cosmic ray was the cause. No way to stop those, but I'm glad that they could roll with the punches.

https://www.inverse.com/science/niriss-update

Silicate clouds in a hot Jupiter via this news release:

https://webbtelescope.org/contents/news-rel...3/news-2023-105

The Cycle 2 observation plans are taking shape. General Observers approvals are listed here:

https://www.stsci.edu/jwst/science-executio...vers/cycle-2-go

It's impossible to summarize this succinctly, but I'll note a few:

A plan to coordinate JWST observations of Io with one of Juno's close passes.
Comprehensive spectra of Europa such as JWST can perform.
Observations of Jupiter Trojans.
Attempt to characterize Enceladus's plumes.
More TRAPPIST-1 plans (but not so many as in Cycle 1, it seems?).
Attempt to characterize the rocky surface of terrestrial planet LHS 3844 b.
Attempt to characterize the galaxy farthest known before JWST.

And hundreds more…

Bonsoir,

It's probably not lost on you, but the news still belongs here.

JWST detects a huge plume rising from Enceladus

https://www.nasa.gov/feature/goddard/2023/w...-moon-enceladus

Nicolas Biver * made this remark on a French forum, and I quote:

"It's just one more resolute observation between those made by Cassini and Herschel more than 10 years ago, which showed that encelade was ejecting ~8x10^27 water molecules per second (250 kg or liter/s) to feed a torus of water vapor ~50000km in cross-section diameter and encompassing encelade's orbit (238000 km in circumference.

So whether it's the distance LosAngeles - Buenos-Aires when it's just the tip of the iceberg... whose total diameter exceeds the Earth-Moon distance,.... it's all a question of knowing which part of the water vapor cloud we're talking about!

As the JWST pixel (in the IR) is much smaller than Herschel's, the image of the water vapor cloud is more resolute."

*N. Biver : Doctorate in astrophysics, having participated, among other things, in the European Rosetta space mission

Current Webb NIRCam images of Saturn:

And another recent Saturn image from Webb:

A Webb Uranus image from April 2023.
And what do we make of that bright, bright cloud at 8:30 on the limb?

It's important to remember how sensitive these details are to the choice of wavelength, and comparing JWST images to those from other, seemingly-comparable telescopes, and be misleading, and I think this is actually a great example of it.

Uranus is very dark in certain IR wavelengths that are absorbed by methane. Among the many wavelengths available to JWST, the rings are comparatively much brighter in some of those, and high, "white" clouds may also be much brighter. The ratios can be much more dramatic than in images from Voyager, Hubble, or Keck. And I think that's the real story here. Probably nothing here is actually different from what was going on with Uranus at the time that images were being captured by Hubble and Keck, but the IR is showing us something very different. And then the people who are making the aesthetic choices in how to present the imagery are maybe doing something subtly deceptive by producing outputs that almost resemble the way we've been used to seeing Uranus and Neptune with these rare, isolated differences.

I am well aware of Webb's multispectral IR capability, and so forth, but it impressed me that this cloud was bright enought to cause diffraction spikes. In the Neptune image there is a cloud at 5:30 that may be be forming spikes, but they are indistinct. In the Jupiter image the somewhat linear polar aurorae are forming a diffraction spike at 90 and 270*. So despite the choice of colors used to create this image and how this image was processed, the presence of the spikes certainly suggests that this cloud is intrinsically bright.

--Bill

I know that cosmology and galaxies and so on is not the center of gravity of this board's discussion topics, but here's a nice overview of what JWST has been revealing about the early universe.

The TL;DR is: It looks like stars and galaxies evolved significantly faster at the beginning of the universe than theories had previously estimated, but not so much faster that everything we thought we knew was necessarily wrong.

https://www.pnas.org/doi/10.1073/pnas.2311963120

Stargaze, the current Cosmological model is based on our best interpretation(s) of available data. I fully expected Webb to expand that data and I anticipate that our model(s) will be changing.

--Bill

Yeah, that's certainly true of the messier stuff, like galaxy formation, which depends on all sorts of details like feedback and interactions. It's complicated enough that you can't just write down what will happen based on the fundamental laws of physics - you have to make all sorts of assumptions/guesses about what's important. No doubt Webb will help a lot there.

The bigger picture of cosmology (baryons, dark matter/energy, flatness, GR; what's usually referred to as "the cosmological model") is much more secure (apart from that niggly Hubble tension...).

CO2 ice detected on the surface of Europa:

https://www.nasa.gov/feature/goddard/2023/n...r-s-moon-europa

Candidate giant exoplanets around metal polluted white dwarfs.

https://arxiv.org/pdf/2401.13153.pdf

Given that only 4 WDs were in the survey and they found 2 candidates,
this potentially represents to first of many similar discoveries. WD
planets have been elusive - maybe not any more!

P