Hidden Wonders: Discovering the Mysterious Garo 04 Star Cluster

Stuart Gary (0:00)

Stuart Gary: This is Space Time series 29 episode 121 full broadcast on 9 October 2026 coming up on Space Time, a mysterious star cluster discovered hidden deep inside the Milky Way's disc, the truth about Nazi Germany's infamous nuclear bomb project, and the chronic need for dark skies all. Ah, that and more coming up on, uh, Space Time.

Welcome to Space Time with Stuart G.

Astronomers have discovered a mysterious star cluster hidden in the crowded galactic disc of the Milky way galaxy, some 32,800 light years away. A report on the Pre press physics website arXiv.org claims the object, which has been named Garo 04, was first identified identified as an unusual collection of stars in observations by the Vista variables Navia Lakta and its extension or Triple VX survey. The inner regions of the Milky Way Galaxy, especially around the galactic plane and bulge, are crowded with stars, dense gas and dust lanes all rich in star forming activity. And the stars in these regions are traces of the Milky Way's chemical history and evolution. So examining these regions can reveal a lot about our galaxy's past mergers. The problem is dust blocks out optical wavelengths, so astronomers need to switch to infrared observations in order to peer through this thick cloak of dust. Near infrared surveys, uh, like the vvvx have revealed numerous previously hidden open and globular star clusters in these dust lanes.

The study's lead author Lisa Garra from the European Southern Observatory in Chile says the Garo four star cluster was detected by visually spotting a prominent clump of red giant stars in the VVVX infrared. Im further analysis using multiple survey databases, including the third guide data release provided precise positions and motions of these stars, and the two mass survey provided supplementary infrared photometry.

Cluster member stars all moved together through space in a similar directional speed, so the authors used this shared proper motion to statistically separate members of the cluster from unrelated foreground and background stars that left just 613, or around 29% of the original 2,145 stars in the field as likely members of the cluster.

Garrow and colleagues estimate the cluster is around 5 billion years old with lower metallicity than our Sun. Astronomers refer to all elements other than hydrogen and helium as being metals. The cluster moves on a nearly circular low tilt orbit around the galactic centre, staying close to the galactic disc at all times, thereby confirming that it is a disc cluster rather than a halo or bulge object.

Garo04 is too old to be a typical young open cluster, but at the same time it's not old or metal poor enough to be a classic globular cluster. And there's the weirdness. It joins a small but growing list of similar puzzling in between clusters which have been found in other surveys in recent times. Garris says the next step will be to undertake a more detailed chemical analysis and better disentangle the real nature of the cluster, classifying it as either a globular cluster, an open cluster, or some sort of in between intermediate class object. This is space time. Still to come, the truth about Nazi Germany's infamous nuclear bomb project and our chronic need for dark skies. It's more than just astronomy. All that and more coming up on, uh, space time.

The Manhattan Project was not just a question quest to build a nuclear bomb. It was a quest to build a nuclear bomb before Nazi Germany completed theirs.

One route to building an atomic bomb is to build a nuclear reactor to produce fissile material. But it's always been unclear how close the Nazis were to creating their own reactor. Their final attempted reactor, the B8 pile, used heavy water as a neutron moderator. Uh, the only source of heavy water at the time was the Norsk Hydro plant in Vermont, Norway, which was controlled by the Nazis from April 1940 until its destruction by Allied saboteurs and bombing in November 1944

The Nazi nuclear bomb project led by Werner Heisenberg, claimed that the B8 pile was just short of criticality when American forces found and dismantled it in 1945

After the war, Heisenberg and colleagues like Carl Friedrich von Wiesensacker claimed they had understood the physics of an atomic bomb, but deliberately steered the Uranium club project towards a uranium machine reactor rather than an atomic weapon. They claimed they had kept the effort under scientific control, avoiding the push for a massive industrial programme that could have produced an atomic bomb for Hitler and in some accounts implied passive resistance or reluctance rooted in moral scruples. But that claim has been largely dismissed as a post war rationalisation. There's virtually no real supporting evidence and mainstream historical consensus attributes the German nuclear programme's failure mainly to scientific incompetence and misjudgments by Heisenberg. There are also resource constraints, organisational problems and luckily a low priority from the regime rather than any real moral resistance from Heisenberg or his cohorts. The simple fact is Heisenberg and colleagues made significant errors in their calculations on the critical mass and practical requirements. The evidence shows the programme was a, uh, genuine weapons related effort that simply stalled due to shortcomings, not sabotage.