{"id":324619,"date":"2026-03-11T18:57:21","date_gmt":"2026-03-11T18:57:21","guid":{"rendered":"https:\/\/www.newsbeep.com\/nz\/324619\/"},"modified":"2026-03-11T18:57:21","modified_gmt":"2026-03-11T18:57:21","slug":"oval-orbit-casts-new-light-on-black-hole-neutron-star-mergers","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/nz\/324619\/","title":{"rendered":"Oval orbit casts new light on black hole – neutron star mergers"},"content":{"rendered":"

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\"\u2022 Artist\u2019s<\/p>\n

<\/a><\/p>\n

image:\u00a0<\/p>\n

Artist\u2019s impression of an eccentric neutron star\u2013black hole binary. The neutron star\u2019s path is shown in blue and the black hole\u2019s motion in orange as the two objects orbit each other. The eccentricity shown here is exaggerated compared to the real system, GW200105, to make the effect on the orbital motion clearer.<\/p>\n

view more\u00a0<\/a><\/p>\n

Credit: Geraint Pratten, Royal Society University Research Fellow, University of Birmingham<\/p>\n

Embargoed copy of the research paper available on request<\/p>\n

Scientists have uncovered the first robust evidence of a black hole and neutron star crashing together but orbiting in an oval path rather than a perfect circle just before they merged. This discovery challenges long-standing assumptions about how these cosmic pairs form and evolve.<\/p>\n

Researchers from the University of Birmingham, Universidad Aut\u00f3noma de Madrid, and Max Planck Institute for Gravitational Physics published their findings today (11 Mar) in The Astrophysical Journal Letters.<\/p>\n

Most neutron star-black hole pairs are expected to adopt circular orbits long before merging. But the analysis of the gravitational-wave event GW200105 shows that this system travelled on an oval orbit long before merging to form a black hole 13 times more massive than the Sun. An oval orbit is something never seen before in this kind of collision.<\/p>\n

Dr Patricia Schmidt, from the University of Birmingham, said: \u201cThis discovery gives us vital new clues about how these extreme objects come together. It tells us that our theoretical models are incomplete and raises fresh questions about where in the Universe such systems are born.\u201d<\/p>\n

The researchers analysed data from LIGO and Virgo detectors using a new gravitational\u2011wave model developed at the University of Birmingham\u2019s Institute of Gravitational Wave Astronomy. This allowed them to measure both how \u2018oval\u2019 the orbit was (eccentricity) and any spin\u2011induced wobbling (precession). This is the first time these two effects have been measured together in a neutron star\u2013black hole event.<\/p>\n

Geraint Pratten, a Royal Society University Research Fellow from the University of Birmingham, said: \u201cThe orbit gives the game away. Its elliptical shape just before merger shows this system did not evolve quietly in isolation but was almost certainly\u00a0shaped by gravitational interactions with other stars, or perhaps a third companion.\u201d<\/p>\n

A Bayesian analysis comparing thousands of theoretical predictions to the real data, showed that a circular orbit is extremely unlikely, ruling it out with 99.5% confidence.<\/p>\n

Past analyses of GW200105, which assumed a circular orbit, underestimated the black hole mass and overestimated the neutron star mass. The new study corrects these values and finds no compelling evidence of precession, indicating that the eccentricity was imprinted by its formation rather than by spins.<\/p>\n

Gonzalo Morras, from the Universidad Aut\u00f3noma de Madrid and the Max Planck Institute for Gravitational Physics, said: \u201cThis is convincing proof that not all neutron star\u2013black hole pairs share the same origin. The eccentric orbit suggests a birthplace in an environment where many stars interact gravitationally.\u201d<\/p>\n

This discovery challenges the prevailing view that all neutron star\u2013black hole mergers arise from a single dominant formation channel and highlights the need for more advanced waveform models capable of capturing the full complexity of these systems.<\/p>\n

The study helps to explain the growing diversity seen in compact-binary mergers and opens the door to identifying even more unusual pathways as the number of gravitational-wave detections continues to grow.<\/p>\n

ENDS<\/p>\n

For more information, please contact the\u00a0press office\u00a0on +44 (0) 121 414 2772 or pressoffice@contacts.bham.ac.uk<\/a> \u00a0<\/p>\n

IMAGE CAPTION \u2013 please credit Geraint Pratten, Royal Society University Research Fellow, University of Birmingham:<\/p>\n

\tArtist\u2019s impression of an eccentric neutron star\u2013black hole binary. The neutron star\u2019s path is shown in blue and the black hole\u2019s motion in orange as the two objects orbit each other. The eccentricity shown here is exaggerated compared to the real system, GW200105, to make the effect on the orbital motion clearer.<\/p>\n

\u2018Orbital eccentricity in a neutron star \u2013 black hole merger\u2019 – Gonzalo Morras, Geraint Pratten, and Patricia Schmidt is published by The Astrophysical Journal Letters.<\/p>\n

Notes for editors:\u00a0\u00a0<\/p>\n

As well as being ranked among the world\u2019s top 100 institutions, the University of Birmingham\u00a0is the most targeted UK university by top graduate employers. Its work brings people from across the world to Birmingham, including researchers, educators and more than 40,000 students from over 150 countries.<\/p>\n

About the Max Planck Institute for Gravitational Physics<\/p>\n

The Max Planck Institute for Gravitational Physics (Albert Einstein Institute) based in Potsdam and Hannover, Germany, is a leading international research centre. The research programme covers the entire spectrum of gravitational physics: from the giant dimensions of the Universe to the tiny scales of strings. The unification of all these important research branches under one roof is unique in the world.<\/p>\n

About Universidad Aut\u00f3noma de Madrid<\/p>\n

Universidad Aut\u00f3noma de Madrid (UAM) is a public university with an outstanding international reputation for its high-quality teaching and research. Founded in 1968, it is recognized as one of the best Spanish universities in both national and international rankings. UAM has 8 Faculties\/Schools -Science, Economics and Business Studies, Law, Arts and Humanities, Medicine, Psychology, Teachers Training and Education and a School of Engineering, and several affiliated centres, offering a wide range of studies in humanities and scientific and technical fields. Currently it has about 30,000 students, 2,800 professors and researchers and nearly 1,000 administrative staff.<\/p>\n

\u00a0<\/p>\n

Journal<\/p>\n

The Astrophysical Journal Letters<\/p>\n

Method of Research<\/p>\n

Observational study<\/p>\n

Subject of Research<\/p>\n

Not applicable<\/p>\n

Article Title<\/p>\n

Orbital eccentricity in a neutron star \u2013 black hole merger<\/p>\n

Article Publication Date<\/p>\n

11-Mar-2026<\/p>\n

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.<\/p>\n","protected":false},"excerpt":{"rendered":"image:\u00a0 Artist\u2019s impression of an eccentric neutron star\u2013black hole binary. The neutron star\u2019s path is shown in blue…\n","protected":false},"author":2,"featured_media":324620,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[111,139,69,147],"class_list":{"0":"post-324619","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-new-zealand","9":"tag-newzealand","10":"tag-nz","11":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/324619","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/comments?post=324619"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/324619\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media\/324620"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media?parent=324619"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/categories?post=324619"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/tags?post=324619"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}