Big day - my PhD student, Zhen Wan’s paper “The Tidal Remnant of a Metal-Poor Globular Cluster” appeared in Nature

A big team effort with @sazabi_li @FadAstra @_sarahmartell_ @deniserkal @dougalmackey @alexanderpji @kwkuehn @norashipp @balbinotdd @JossBlandHawtho & more

We presented our observations of the Phoenix Stream. This used to be a globular cluster, a ball of about a million stars, by the gravitational action of the Milky Way has torn it into a 27,000 light year long stream. (Credit: J. Josephides (Swinburne Astro Prods) and S5 Collab.
)

Observed as part of the Southern Stellar Streams Spectroscopic Survey (S5 - https://s5collab.github.io ), We used the Anglo-Australian Telescope to get the speeds and chemistry of the stars in the stream. (Image from http://aao.gov.au )

This is where things get interesting. The Milky Way has about 150 globular clusters, and all of them have a minimal amount of chemical enrichment, something we (weirdly) call the “metallicity floor”. This tells use something about where and when they formed. but..

The stars in the Phoenix Stream are different - with less chemical elements. It really does fit with all the others.

To understand this, watch this -



- with added welsh accent.

So, it appears it the last of its kind, a remnant of an original population that has now been destroyed. In a billion years or so, Phoenix too will to be gone, merged completely into our Galaxy.

And I made this image, so the credit is me :)

We have a write up about the paper in Space Australia - https://spaceaustralia.com/feature/stars-time-forgot

And are on the (virtual) front page of the @smh (thx @liammannix ) https://www.smh.com.au/national/australian-scientists-discover-dying-building-block-of-milky-way-20200729-p55gin.html

And if you would like to see the paper in its “read-only” glory, @nature have provided a link -

https://rdcu.be/b5Wpe 

Enjoy!

Now, time for some coffee.

Coffee definitely needed -

“It really does fit with all the others.”

Should be

“It really *doesn’t* fit with all the others.”

Ugh...