Astronomers recently trained NASA’s Chandra X-ray Observatory on a strange radio formation that sits behind the dense band of stars, gas, and dust along the Milky Way’s plane. From our vantage the structure looks almost exactly like the musical symbol known as a treble clef, a resemblance that led researchers to call the whole scene the Treble Clef. Chandra and Germany’s eROSITA telescope both recorded the presence of gas heated to millions of degrees, the clear signature of a galaxy cluster, one of the largest objects in the universe. Further scrutiny of that gas showed the cluster is actually two separate clusters that ran into each other.

On March 4, 2024, a radio array in South Africa caught a flash that lasted only a few milliseconds and then vanished. MeerKAT, working with the MeerTRAP search system, logged it at 00:50 UTC and gave it the name FRB 20240304B. The pulse arrived stretched and delayed by free electrons along the path, with a dispersion measure near 2,458, a peak of about half a jansky, and a scattering time of 5.6 milliseconds at 1 gigahertz. Those numbers already hinted that the source sat far beyond nearly every localized burst on record.

Photo credit: International Gemini Observatory/NOIRLab/NSF/AURA/M. Rodriguez
Eight separate records from Chinese, Japanese, and Arabic observers place a new star in Cassiopeia between August 4-6, 1181. It stayed visible for 185 days, long enough for court astronomers to log it during the Genpei War in Japan and the reign of Henry II in England. One of only five Milky Way supernovae people recorded before telescopes existed, that guest star faded and left no obvious wreck for modern catalogs to claim.

Astronomers filed a strange spectrum of the white dwarf HS 0209+0832 in 1999 and left it there. Hubble had recorded roughly 100 chemical features that no catalog of the time could name. The star itself is the bare core of a low-mass sun that burned through its fuel, shed its outer layers, and settled into a compact remnant. At about 35,800 degrees, with a cooling age near five million years, it is still young as white dwarfs go, and still hot enough to strip gas from anything orbiting close in.

Golden elliptical galaxies fill the middle of the newest James Webb Picture of the Month, released this morning. They belong to the cluster MACS J0454.1-0300. Orange galaxies crowd one side of the frame and stretch into a broad arc around the brightest central members, while smaller reddish objects bend into short arcs even near the edges. A handful of bluish-white galaxies and a pair of sharp foreground stars sit in front of all of it.