Investigated
Is the unseen companion in J0008+0128 a supermassive neutron star in the mass gap?Source
A red giant star is orbiting an unseen object that may weigh nearly three Suns.
Nov 11, 2026
Source mix
1 of 4 institutional
Image: scientificamerican.com
The Story
J0008+0128 has a massive unseen companion, but its true identity still rests on orbital inference.
A red giant’s motion and Gaia astrometry reveal an unseen compact companion, but the available mass range overlaps more than one kind of stellar remnant. The supermassive-neutron-star interpretation is favored by the study, not conclusively identified, and the unusually wide orbit remains difficult for standard formation models.
- What is establishedThe companion’s gravitational influence and a broad mass range are measured from the binary’s motion.
- What remains openThe data do not yet decisively separate a supermassive neutron star from a low-mass black hole or another compact-remnant interpretation.
- The study combines radial velocities from LAMOST and APOGEE with Gaia astrometry to derive the companion’s orbit and mass range.
- The inferred mass spans 1.8–2.8 solar masses, with a best-fit value of 2.20 solar masses, and potentially occupies the mass gap.
- The study reports no absorption features from an additional component, supporting the companion’s invisibility in the available spectra.
Deeper Insight
J0008+0128, a red giant system, hides a dark object between neutron stars and black holes. Our categories miss strange survivors.
A red giant traces a dark companion across a 1,218-day orbit, and the numbers point to an object between familiar neutron stars and black holes. It could be a neutron star weighing up to 2.8 Suns, or a small black hole. Either way, the mass gap may be less a boundary than a blind spot.
- What it could changeA confirmed neutron star here could rewrite models of stellar death and the physics of ultra-dense matter.
- How it touches todayUnseen companions already show how much our picture of the mass gap depends on difficult binary measurements.
- Our futureThe strangest objects in the universe could keep hiding between the categories built to find them.
- The study’s inferred companion could reach 2.8 solar masses and has an unusually wide, roughly 1,218-day orbit that challenges expected formation pathways.
- A review reports that observations cannot yet confidently establish whether the neutron-star/black-hole mass gap is real or absent, partly because binary mass measurements carry uncertainties.
- The system’s mass would constrain the equation of state of dense neutron-star matter if the companion is genuinely a supermassive neutron star.
Sources · 4
- 1 Journals & institutions
- 2 News reporting
- 1 Other / unclassified
What do these mean?
- Journals & institutions. Published in a peer-reviewed journal, or from a university, government body, court or other institution.
- News reporting. Journalism: newspapers, magazines and news sites.
- Other / unclassified. A site we have not classified yet. This says nothing good or bad about it.
Featured · Primary source · science.org
Discovery of a likely supermassive neutron star in a remarkably wide binary
Journal · peer-reviewed
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Scientists Discovered An ‘Invisible’ Object In Space. It’s Challenging Our Understanding of the Cosmos
News reporting
Scientists have discovered a bizarre “invisible” object in space that challenges our understanding of stellar evolution and could help resolve longstanding astronomical mysteries, according to a study published on Wednesday in Science Advances . Its orbit and mass are so strange, in fact, that researchers ran thousands of simulations and couldn’t reproduce them. The hidden object is likely an ultr
Read sourceAnalysis · raa-journal.org
On the Neutron Star/Black Hole Mass Gap and ...
Other
## On the Neutron Star/Black Hole Mass Gap and Black Hole Searches Yong Shao 1,2 1 Department of Astronomy, Nanjing University, Nanjing 210023, China; [email protected] 2 Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210023, China Received
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