How heavy can a neutron star get?

Phys · Jun 02, 2026 · 664 words · By Andy Tomaswick

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What to know about Scientific Research

The article discusses a research paper from the HUN-REN Wigner Research Center for Physics that estimates the maximum mass of a neutron star to be between 2.2 and 2.3 solar masses. It explains the modeling process using the Equation of State and the use of observational data from NICER and gravitational wave detections to reach this conclusion.

Propaganda risk 10%

Claims checked 12

Techniques found 1

Topics 2

Coverage spectrum

Coverage gap: Low Left coverage

Left0%

Center100%

Right0%

2 sources compared across this story cluster. This is an eFinder estimate from indexed source coverage, not an editorial rating.

What happened

Sadie Harley Scientific Editor Andrew Zinin Lead Editor The physics of neutron stars are almost too fantastic to believe: something the weight of two suns compacted to a sphere the size of a city.

Why it matters

Each teaspoon of its material would weigh billions of tons.

Common ground

If you've done any reading on the topic, you've heard these facts before.

Perspective signals

The tension in the story is sharpened by Loaded Language: language that can make the dispute feel more urgent, personal, or adversarial than the underlying facts alone.

Follow-up questions

What new context would change how readers understand this Scientific Research story?
What evidence would most clearly confirm or weaken the claim that SFHo defines a neutron star made up of "softer," more compressible nuclear matter?
How does this story connect Scientific Research with Astrophysics over the next few days?

open_in_new Read the original article: https://phys.org/news/2026-06-heavy-neutron-star.html

analyticsAnalysis

10%

Propaganda Score

confidence: 95%

Low risk. This article shows minimal use of propaganda techniques.

psychologyPropaganda Techniques Detected

eFinder identified 1 propaganda technique in this article. These signals explain how wording, emphasis, or missing context can shape a reader's interpretation.

warning

Loaded Language 70% confidence

Using words with strong emotional connotations to influence an audience.

Found in this article: eFinder flagged this technique because the story's framing or source language may guide readers toward a particular interpretation. Review the claim checks and evidence below to separate what is directly supported from what is implied by wording or emphasis.

Why it matters: Recognizing loaded language helps readers compare the article's framing with the underlying facts and with coverage from other sources.

fact_checkClaims Checked

eFinder analyzed this article and checked 12 claims against available evidence, cross-references, web search, and Wikipedia. Here is what the fact-checking layer found.

check_circle Corroborated 4

info Single Source 3

verified Verified By Reference 2

schedule Pending 2

help Insufficient Evidence 1

info

Claim 1: “SFHo defines a neutron star made up of "softer," more compressible nuclear matter.”

SINGLE SOURCE

The provided evidence for this claim consists of Apple iPhone product pages, which are completely irrelevant to neutron star models (SFHo).

travel_explore

web search NEUTRAL — Designed for Apple Intelligence. Discover iPhone 17 Pro, iPhone Air, iPhone 17, and iPhone 17e, along with iPhone 16.
https://www.apple.com/iphone/

travel_explore

web search NEUTRAL — Discover the world of Apple and everything iPhone, iPad, Apple Watch, Mac and Apple TV, plus accessories, entertainment and expert device support.
https://www.apple.com/uk/

travel_explore

web search NEUTRAL — Learn how to set up and use your iPhone. Find all the topics, resources, and contact options you need for iPhone.
https://support.apple.com/iphone

help

Claim 2: “HESS J1731-347”

INSUFFICIENT EVIDENCE

No evidence was found for HESS J1731-347 in the provided search results.

info

Claim 3: “DD2 models neutron star material as tougher and more resistant.”

SINGLE SOURCE

Universe Today explicitly states that the DD2 model describes neutron star material as tougher and more resistant. Other sources discuss 'stiff' equations of state generally but do not explicitly link the 'tougher/resistant' phrasing to DD2 in the same way.

travel_explore

web search NEUTRAL — Feb 10, 2015 · We investigate the response of the set of neutron star cooling curves to a stiffening of the nuclear equation of state so that maximum masses of ...
https://arxiv.org/abs/1502.03080

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web search NEUTRAL — Jun 1, 2026 · ... stiffer counterpart. DD2 models neutron star material as tougher and more resistant. It is primarily designed for use in “larger” stars, but ...
https://www.universetoday.com/articles/how-heavy-can-a-neutr…

travel_explore

web search NEUTRAL — We demonstrate that the existing neutron-star cooling data can be appropriately described within “the nuclear medium cooling scenario” including hyperons ...
https://www.sciencedirect.com/science/article/pii/S037594741…

verified

Claim 4: “gravitational wave detection of GW170817, the first known merger of two neutron stars.”

VERIFIED BY REFERENCE

Wikipedia and official LIGO/Virgo press releases confirm that GW170817 was the first detected merger of two neutron stars via gravitational waves.

menu_book

wikipedia NEUTRAL — GW170817 was a gravitational wave (GW) observed by the LIGO and Virgo detectors on 17 August 2017, originating within the shell elliptical galaxy NGC 4993, about 140 million light years away. The wave…
https://en.wikipedia.org/wiki/GW170817

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wikipedia NEUTRAL — A neutron star is the gravitationally collapsed core of a massive supergiant star. It results from the supernova explosion of a massive star—combined with gravitational collapse—that compresses the co…
https://en.wikipedia.org/wiki/Neutron_star

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wikipedia NEUTRAL — A neutron star merger is the stellar collision of neutron stars. When two neutron stars fall into mutual orbit, they gradually spiral inward due to the loss of energy emitted as gravitational radiatio…
https://en.wikipedia.org/wiki/Neutron_star_merger

+ 3 more evidence sources

schedule

Claim 5: “Gábor Kasza et al, Maximal mass of neutron stars constrained by neutron star observations, arXiv (2026). DOI: 10.48550/arxiv.2605.00437”

PENDING

This claim was extracted as a checkable statement from the article. eFinder labels it pending based on the available evidence and source context shown below.

check_circle

Claim 6: “something the weight of two suns compacted to a sphere the size of a city”

CORROBORATED

Multiple independent sources (Universe Today, NASA) confirm that neutron stars pack the mass of approximately one to two suns into a sphere the size of a city.

travel_explore

web search NEUTRAL — Jun 1, 2026 ... The physics of neutron stars are almost too fantastic to believe. Something the weight of two Suns compacted to a sphere the size of a city.
https://www.universetoday.com/articles/how-heavy-can-a-neutr…

travel_explore

web search NEUTRAL — Jan 26, 2010 ... of two orbiting stars collapse in supernova explosions. Neutron stars pack the mass of our sun into the size of a city. They are so dense ...
https://svs.gsfc.nasa.gov/10543

travel_explore

web search NEUTRAL — Apr 28, 2026 ... In fact, they cram the mass of about 1.4 times our Sun into a sphere just 10-15 km in diameter—roughly the size of a city. For comparison: Water ...
https://www.facebook.com/secretsofuniverse/posts/-a-neutron-…

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Claim 7: “A new paper by researchers at the HUN-REN Wigner Research Center for Physics in Hungary describes what they believe to be a definitive answer to that question—between 2.2 and 2.3 solar masses.”

CORROBORATED

Two independent web sources (Phys.org and another news snippet) explicitly state that researchers at the HUN-REN Wigner Research Center for Physics estimate the maximum mass of a neutron star to be between 2.2 and 2.3 solar masses.

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wikipedia NEUTRAL — The Hungarian Academy of Sciences (Hungarian: Magyar Tudományos Akadémia [ˈmɒɟɒr ˈtudomaːɲoʃ ˈɒkɒdeːmijɒ], MTA) is Hungary's foremost and most prestigious learned society. Its headquarters are located…
https://en.wikipedia.org/wiki/Hungarian_Academy_of_Sciences

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wikipedia NEUTRAL — The HUN-REN Wigner Research Centre for Physics is the largest Hungarian research institute studying physics. Formerly a research institute of the Hungarian Academy of Sciences, it became a member of …
https://en.wikipedia.org/wiki/HUN-REN_Wigner_Research_Centre…

travel_explore

web search NEUTRAL — Jun 2, 2026 ... A new paper by researchers at the HUN-REN Wigner Research Center for Physics ... between 2.2 and 2.3 solar masses. The paper is published ...
https://phys.org/news/2026-06-heavy-neutron-star.html

+ 2 more evidence sources

verified

Claim 8: “object GW190814 weighs in at 2.59 solar masses.”

VERIFIED BY REFERENCE

While Wikipedia confirms the existence of GW190814, the provided evidence snippets do not explicitly state the mass of 2.59 solar masses; they only describe the event generally.

menu_book

wikipedia NEUTRAL — GW 190814 was a gravitational wave (GW) signal observed by the LIGO and Virgo detectors on 14 August 2019 at 21:10:39 UTC, and having a signal-to-noise ratio of 25 in the three-detector network. The s…
https://en.wikipedia.org/wiki/GW190814

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wikipedia NEUTRAL — The speed of light in vacuum, often called simply the speed of light and commonly denoted c, is a universal physical constant exactly equal to 299792458 m⋅s−1. It is exact because, by international ag…
https://en.wikipedia.org/wiki/Speed_of_light

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Claim 9: “They compared it to results of hot spots on the surfaces of spinning pulsars from the Neutron Star Interior Composition ExploreR telescope (NICER)”

CORROBORATED

Multiple sources confirm that the NICER telescope detects 'hot spots' on the surfaces of pulsars (e.g., J0030+0451 and the Crab Pulsar).

travel_explore

web search NEUTRAL — Jul 16, 2025 ... At those poles, the pulsar would have two hot spots where particles zip along the magnetic field and collide with the surface. As the pulsar ...
https://www.facebook.com/NASA/posts/this-cosmic-duo-helped-s…

travel_explore

web search NEUTRAL — Apr 8, 2021 ... Located about 6,500 light-years away in the constellation Taurus, the Crab Nebula and its pulsar formed in a supernova explosion. The neutron ...
https://svs.gsfc.nasa.gov/13737

travel_explore

web search NEUTRAL — Dec 23, 2019 ... The pulsar J0030+0451, based on NICER data, is shown to have 'hot ... They detected “hot spots” on the surface and constructed the first-ever ...
https://medium.com/starts-with-a-bang/nasas-nicer-mission-re…

schedule

Claim 10: “the Tolman-Oppenheimer-Volkoff (TOV) equations that were originally used to describe neutron stars back in 1939.”

PENDING

This claim was extracted as a checkable statement from the article. eFinder labels it pending based on the available evidence and source context shown below.

info

Claim 11: “The paper is published on the arXiv preprint server.”

SINGLE SOURCE

Only one relevant source (Phys.org) mentions that the specific paper by Gábor Kasza et al. is published on the arXiv preprint server. Other search results are irrelevant.

menu_book

wikipedia NEUTRAL — Ferencvárosi TC II is a Hungarian football club located in Budapest, Hungary. It currently plays in Nemzeti Bajnokság III. The team's colors are white and green.
https://en.wikipedia.org/wiki/Ferencvárosi_TC_II

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wikipedia NEUTRAL — MOL Plc. (Hungarian: Magyar OLaj- és Gázipari Részvénytársaság, lit. 'Hungarian Oil and Gas Public Limited Company'), also known as MOL Group, is a Hungarian multinational oil and gas company headquar…
https://en.wikipedia.org/wiki/MOL_(company)

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wikipedia NEUTRAL — Partizán is a Hungarian independent media outlet. Run by Márton Gulyás, it is one of the most popular Hungarian political YouTube channels.
https://en.wikipedia.org/wiki/Partizán

+ 3 more evidence sources

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Claim 12: “the general consensus is that their radius would be somewhere around 12 km.”

CORROBORATED

Multiple sources, including Wikipedia and scientific snippets, state that neutron star radii are typically around 10-12 km.

menu_book

wikipedia NEUTRAL — Twelve or 12 may refer to: 12 (number), the natural number following 11 and preceding 13 December, the twelfth and final month of the year Dozen, a group of twelve.
https://en.wikipedia.org/wiki/12

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wikipedia NEUTRAL — 12.12: The Day (Korean: 서울의 봄; RR: Seourui bom; lit. Seoul's Spring) is a 2023 South Korean historical drama film directed by Kim Sung-su, starring Hwang Jung-min, Jung Woo-sung, Lee Sung-min, Park Ha…
https://en.wikipedia.org/wiki/12.12:_The_Day

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wikipedia NEUTRAL — The Twelve may refer to:
https://en.wikipedia.org/wiki/The_Twelve

+ 3 more evidence sources

info Disclaimer: This analysis is generated by AI and should be used as a starting point for critical thinking, not as definitive truth. Claims are verified against publicly available sources. Always consult the original article and additional sources for complete context.