Davide Castelvecchi
Gold, platinum, uranium and many of the rare-earth elements that are crucial to today’s high-tech gadgets are generated during the formation of black holes, astronomers have said. The collision of two small but dense stars simultaneously solved several cosmic mysteries, researchers announced at a press conference in Washington DC on 16 October. More than 30 papers have been published so far in five journals — Physical Review Letters, Science, Nature, Nature Astronomy and Astrophysical Journal Letters.
Astronomers watched as two neutron stars — small but very dense objects formed after the collapse of stars bigger than the Sun — collided and merged, forming a black hole, in a galaxy 40 million parsecs (130 million light years) away, according to two dozen researchers interviewed by Nature’s News team.
Neutron stars set to open their heavy hearts
The collision generated the strongest and longest-lasting gravitational-wave signal ever seen on Earth. And the visible-light signal generated during the collision closely matches predictions made in recent years by theoretical astrophysicists, who hold that many elements of the periodic table that are heavier than iron are formed as a result of such stellar collisions.
Neutron-star mergers are also thought to trigger previously mysterious short γ-ray bursts, a hypothesis that now also seems to have been confirmed.
Astronomers have good reasons to believe that they are looking at the same source of both the gravitational waves and the short γ-ray bursts, says Cole Miller, an astronomer at the University of Maryland in College Park, who was not involved in the research but who has seen some of the papers ahead of their publication.Bright object
The event was detected on Earth on 17 August, and triggered weeks of febrile, round-the-clock activity on all 7 continents, as more than 70 teams of researchers scrambled to observe the aftermath.
The collision was felt first as a space-time tremor by the Laser Interferometer Gravitational-wave Observatory (LIGO) in the United States and by its Italy-based counterpart Virgo, and seen seconds afterwards as a smattering of high-energy photons by NASA’s Fermi Gamma-ray Space Telescope.
Global networks of small telescopes will chase companion signals of gravitational waves
Alerted by the LIGO–Virgo team, astronomers then raced to find and study what was seen as a bright object in the sky using telescopes big and small, famous and obscure, on land and in orbit, and spanning the spectrum of electromagnetic radiation, from radio waves to X-rays.
Cody Messick was at his home at 08:41 local time (12:41 ut) on 17 August when he first found out about the event. “I remember standing on my stairs and looking at my phone, thinking: ‘Wow!” he says. Messick, who is a physicist at Pennsylvania State University in University Park, belongs to a small team of LIGO first-responders who receive frequent automated alerts from the two interferometers, which are based in Livingston, Louisiana, and Hanford, Washington. Normally, LIGO’s algorithms flag a potential signal in real time only if both interferometers detect it. Messick was surprised, because the message on his smartphone mentioned a strong signal — but one seen only at the Hanford site.
https://www.nature.com/news/colliding-stars-spark-rush-to-solve-cosmic-mysteries-1.22829
