The FY 2027 NASA budget request hides its science cuts by omitting mission names instead of explicitly zeroing them out.
We did the work and found 54 missions cancelled in this proposal.
This is another extinction-level event for NASA science.
Full list: planetary.org/save-nasa-science
Pristine is in the eye of the beholder
We ran into the same problem too! So in SDSS we first preselect to bright candidates (mostly red giants) that are feasible to followup right now. But there is a big, big list for when ELTs come around.
Yes, it is common to describe the first metals as “pollution” of “pristine” big bang material. Of course, we like the metals too!
Mooooooon (ok mostly Earth so far)
🔭 Lastly, this was all part of @sdssurveys.bsky.social; it is thanks to the hard work of our collaboration that we had data products to search through! The dataset we used to find this star is going public this summer in SDSS DR20!
www.sdss.org/ancient-immi...
^it’s way more pristine than ANY galaxy seen by JWST, not just the average!
Part of the fun was taking the students up to Las Campanas Observatory, where I spent much of my postdoc years. Lots of mirror selfies and astrophotography was had, in addition to a pretty awesome spectrum of this star.
carnegiescience.edu/found-most-p...
This was an amazingly fun project because it was done with undergraduate students in a class at UChicago. We went looking for cool stuff in the Sloan Digital Sky Survey V, and they Found Cool Stuff, i.e. this star!
news.uchicago.edu/story/scient...
🔭 Paper day, and it’s a big one! We have found the most metal-poor object known in the universe. It’s a star, and it comes to us from our nearby friend the Large Magellanic Cloud. Out in Nature Astronomy today: rdcu.be/fbylI
SADLY my April Fool’s paper on this topic has been desk rejected by arxiv moderators!!
It’s truly insane that an object with metallicity upper limit <2% solar is being claimed as containing Pop III stars
As the Roman Proposal Lead, I think I'm not allowed to ask folks to bet on the final number of submissions for #RomanCycle1 right? 🤔
Our press officers were indeed severely disappointed by the images we had to offer
🔭 Paper day! Ani Chiti + MAGIC discovery the first highly carbon-enhanced star in an ultra-faint dwarf galaxy. We suggest most CEMP stars form in such places.
News article: news.uchicago.edu/story/ancien...
Paper: www.nature.com/articles/s41...
Arxiv version (updated soon):
arxiv.org/abs/2508.04053
Owing (probably) to some form of administrative error, I have made it to the final of the St Patrick’s Day Beard of Ireland competition.
If you'd like to vote for me you can do so below. Please feel free to share the link.
bsky.app/profile/keit...
The intact globular clusters are also [Fe/H] > -2.5, or [Fe/H] > -3 for disrupted streams! I really think there are no systems except those two metal-poor stars where the metallicity argument against Pop III works. (Claims of IMF variation at Z>0 I agree though)
It’s worth noting that there is in fact a simple way to test whether the IMF is universal for Pop III stars, which is that we have not found one yet anywhere. The expected number is hard but can be estimated for dwarf galaxies eg ui.adsabs.harvard.edu/abs/2018MNRA...
Well, there is a qualitative difference between logZ/Zsun > -3.5 and logZ/Zsun <-3.5, there are only two objects known below the latter limit. So it doesn’t make sense to invoke any extragalactic observations for this case
For those wondering, the double-peak lines on the right are because of the bad data reduction (adding two adjacent orders with bad wavelength calibration)
You can see a cutout of it below! It's the raw CCD image, which we then process into 1D spectra.
But on the other hand, extraordinary claims require extraordinary evidence. So, always check your raw 2D spectra before claiming you have found a PISN star! /fin
I'll say the original authors got pretty unlucky: the star is still very unusual, just not a PISN. They hit a confluence of like 3 unlucky data things. For a normal star we'd never have noticed. Heck I don't know if anyone would have looked into the (public) HDS data) if not for the theory paper.
Another group also found the same thing with UVES spectra, which was a huge relief to us.
ui.adsabs.harvard.edu/abs/2024ApJ....
So, to this day there remains no detection of any star with a PISN signature. (And this "nice easy" project I promised Pierre turned out to be much more complicated.)
Paper: arxiv.org/abs/2404.17078
Spectrum of the star from both Keck (black) and HDS (blue), showing Na D lines are consistent
Between all these things it's clear something has gone wrong in the original data reduction. Anyway long story short (i.e., learning how to use IRAF correctly which you do not want to hear about) the final HDS spectrum is completely consistent with what we got in HIRES (arxiv.org/abs/2404.17078)
2D spectrum showing Na D order, highlighting the ISM absorption, sky lines, and stellar lines
2D spectrum showing star is to the "left" side of the slit, relative to sky lines that fill the slit
Whenever this happens you have to look at the 2D spectrum. So I do, and you can indeed see by eye the stellar absorption lines (it's weak but there). It's also clear the star is observed off center in the slit, so finding sky regions to subtract is hard.
IRAF spectrum showing region around Na D with sky, cosmic ray, ISM, and stellar Na D
Josh is smart and suggests to look at the HDS spectrum. The pipeline is in IRAF (NO!). This is ancient astronomy knowledge, and I don't know what I'm doing, so I first extract without doing any processing (CR removal, sky subtraction) and see a Na D line. wtf?
After fixing the reductions it's clear our spectrum has a weak but significant Na D line. This is when you start thinking that you have given Will the wrong coordinates of the star to observe and wasted hours of Keck.