Plate Nº 33 · recorded October 10, 2026
Space & AstronomyReported finding
Undergrad uncovers three isolated galaxies that stopped making stars
UC Berkeley freshman Julian Shapiro identified three isolated dwarf galaxies that have stopped forming stars—the first strong observational candidates for a predicted class of 'backsplash' galaxies.
By Nathan Brooks3 min read612 words
In brief
- Julian Shapiro, a UC Berkeley undergraduate, discovered three isolated, quenched dwarf galaxies now cataloged as Shapiro Dwarf Galaxies I, II, and III.
- The findings appear in The Astrophysical Journal in 2026 (DOI: 10.3847/1538-4357/ae99cb).
- Shapiro began the research while still in high school.
- The galaxies are proposed as candidate backsplash systems, with the Pinwheel Galaxy (Messier 101) as the primary host candidate.
- Shapiro won the 2025 Astronomical League National Young Astronomer Award and was named a 2026 Davidson Fellow.
A UC Berkeley undergraduate has identified three dwarf galaxies that float in cosmic isolation yet produce no new stars, a combination astronomers rarely see. Julian Shapiro, now in his first semester at the university, cataloged the objects as Shapiro Dwarf Galaxies I, II, and III in a paper published in The Astrophysical Journal in 2026.
The find offers some of the first observational evidence for a theoretical population called "backsplash" galaxies—small systems that once plunged through the gravitational pull of a massive neighbor, lost their star-forming gas, and were flung back out into deep space.
Why are these galaxies unusual?
Most dwarf galaxies fall into one of two categories. Isolated dwarfs, far from any large galaxy, typically retain cold gas and keep forming stars. Quenched dwarfs—those that have stopped forming stars—usually sit near a massive host whose gravity siphons off that gas.
"In isolation, these galaxies are expected to be actively forming stars, as there are no larger galaxies to strip their star-forming gas, but the galaxies I discovered break this rule," Shapiro said.
His three candidates are both isolated and quenched, a pairing astrophysicists have struggled to explain.
What is a backsplash galaxy?
Shapiro argues the trio may be among the first resolved backsplash galaxy candidates.
In the standard cosmological model, known as lambda-cold dark matter (ΛCDM), backsplash objects should be common. Small galaxies fall into a larger host's gravitational well, environmental forces strip their gas, and tidal forces hurl them back out into empty space.
Shapiro's primary suspect for the host is Messier 101, the Pinwheel Galaxy. One of the three, Shapiro Dwarf Galaxy II, sits close enough to spiral galaxy NGC 5585 that it could instead be a faint satellite rather than a backsplash system.
How did a high schooler pull this off?
Shapiro began the work while still in high school, using public archival telescope data and cosmological simulations to predict where backsplash dwarfs were most likely to lurk near a Milky Way–like galaxy.
He then searched telescope archives for matching sources and spent much of his time estimating distances to confirm true isolation.
"Building the foundational knowledge necessary to detect the galaxies, develop modeling and analysis code, and analyze the results in comparison to our cosmological model was a challenge," Shapiro noted. He credited open-access journals with making the project possible.
The work earned him the Astronomical League's National Young Astronomer Award in 2025 and recognition as a 2026 Davidson Fellow from the Davidson Institute.
What comes next?
Shapiro's paper lists the three galaxies as candidates, not confirmed backsplash systems. Definitive proof will require high-resolution space telescope measurements that map each object's exact position and motion.
Shapiro expects the new Vera C. Rubin Observatory to turn up many more such objects once it begins survey operations.
At Berkeley, he has joined the research group of astronomy professor Alex Filippenko, who praised the student's initiative.
"Julian conducted some remarkably sophisticated research while still in high school, which is highly unusual and was recognized with the prestigious Davidson Fellowship," Filippenko said. "I feel very fortunate that he chose UC Berkeley for his undergraduate studies in astrophysics, and especially that he decided to join my research team."
The pair plan to study the Hubble tension—the ongoing disagreement over how fast the universe expands—and to pursue follow-up observations of the Shapiro Dwarf Galaxies.
"Often, school curriculums provide limited introductions to astronomy, and it is difficult for students to find mentorship and build experience in the field," Shapiro said. "My paper demonstrates that public archival telescope data is a critical tool for new discoveries."
via Phys.org Space & Astronomy (Source)
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