A good summary of the various caveats for the claims of large, early galaxies in Webb images from S&T.

In short, we need proper spectroscopy and ratios of massive to light stars may differ in the distant past from today, and it'll take time to sort through this.

With all the fanfare over the initial image presentstion, Webb is now settling into doing the science it was designed for. The images may not be as spectacular, but the science is significant.
In a manner of speaking, we are past the "pretty pictures" phase.

--Bill

Certainly! and good science will not be done in haste.

Bonsoir,

(Automatically translated from French)

In her blog Stacy Mac Gaugh gives us a new insight into the issue of the advanced redschift tops of many recent papers, which for many, could only turn out to be hasty, often fanciful announcements.

Until then, the debate revolved mainly on the validity of the z measurements by the photometric method that gives surprisingly high values to the redshift of relatively massive galaxies. All of this would appear to be a major violation of the standard cosmological model.

The "skeptics", and they seem to be quite numerous, ask body and cry, spectra for these objects. This technique applied to the determination of the remoteness of galaxies would lift doubts.

While the two methods (photometric shift in red on the one hand and spectroscopy on the other) could potentially give very different results, the JWST itself had not been directly implicated in the controversy. In a "fun" way, it is his remarkable performances that would also be in question...

https://tritonstation.com/2022/08/11/by-the-wayside/

Thanks for posting that. In an earlier post titled "JWST Twitter Bender", McGaugh makes the point that MOND predicts more massive galaxies at early cosmological ages than ΛCDM.

Stacy McGaugh is a man btw. https://astronomy.case.edu/faculty/stacy-mcgaugh/

Thank you sir(?...), and I apologize to Stacy.

https://blogs.nasa.gov/webb/2022/08/22/webb...inkId=178177184

Jupiter from JWST!!! Spectacular.

Phil

Can you please remind me what detail to expect for images of dwarf planets ?
Hubble can see some features of Ceres and can barely resolve Pluto.

Webb in the main IR wavelengths should match Hubble resolution in visible light. I'm unsure if Webb could/will show higher resolution if they took images just concentrating on its shortest wavelengths around 0.6 microns. The diffraction effect is less at 0.6 microns and the wavefront errors appear low enough to support higher resolving power. The F070W NIRCam filter might do the trick around 0.7 microns:

https://jwst-docs.stsci.edu/jwst-near-infra.../nircam-filters

With the dwarf planets I suppose Webb might be able to help learn to things spectroscopically using MIRI.

In general, the IR spectroscopic capabilities of Webb are unmatched, and will provide a superior capacity to that of missions that have actually visited those worlds. JWST will provide IR spectroscopy of Mars better than that of any spacecraft that has ever orbited Mars. Better of Saturn than Cassini. Etc. Of course the spatial resolution of JWST will not match the spatial resolution of MRO at Mars or Cassini at Saturn, but will still resolve and differentiate large features quite well.

For any specific target, it's another matter whether or not IR spectroscopy answers the question we would like to answer. Sometimes the composition of aerosols and surface units is addressed with spectroscopy and sometimes not. We really won't know before the observations are made. Surely it will answer some questions and leave some unanswered.

As scalbers noted, the spatial resolution of JWST is comparable to HST's visible-light resolution. The highest spatial resolution achievable with HST is in UV, which provides better diffraction limits than visible light. JWST won't beat that resolution. And ground-based observations, which already better spatial resolution than HST and JWST, will be even more impressive when the larger telescopes being constructed now begin operation in the next decade.

It seems safe to say that, when possible, taking the highest possible spatial resolution image of a target concurrent with the great spectral resolution of JWST will allow better science than either would produce alone.

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.

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 !