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Astronomers using ALMA and NOEMA made the first definitive detection of a radioactive molecule in interstellar space. The radioactive part of the molecule is an isotope of aluminum. The observations reveal that the isotope was dispersed in space after the collision of two stars, which left a remainder known as CK Vulpeculae. This is the first time that a direct observation has been made of this element from a known source. Previous identifications of this isotope were from gamma ray detection, but their precise origin was unknown.
The team, led by Tomasz Kaminski (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), used the large millimeter of Atacama. / submillimeter Array (ALMA) and NOrthern Extended Millimeter Array (NOEMA) to detect a source of the aluminum-26 radioactive isotope. The source, known as CK Vulpeculae, was first seen in 1670 and, at the time, appeared to observers as a bright, red "new star". Although initially visible to the naked eye, it quickly faded away and now requires powerful telescopes to see the remains of this fusion, a dark central star surrounded by a halo of matter glowing that escapes from it.
348 years after the initial observed event, the remains of this explosive stellar melting led to the clear and convincing signature of a radioactive version of aluminum, known as the ; aluminum-26. It is the first unstable radioactive molecule definitely detected outside the solar system. Unstable isotopes have an excess of nuclear energy and eventually disintegrate into a stable form.
"This first observation of this isotope in a star-shaped object is also important in the broader context of galactic chemical evolution," notes Kaminski. "This is the first time that an active producer of the radioactive nuclide aluminum-26 has been directly identified."
Kaminski and his team detected the unique spectral signature of molecules composed of 26 aluminum and fluorine (26AlF) in the debris surrounding CK Vulpeculae, which is about 2000 light years from Earth. As these molecules rotate and tumble in space, they emit a distinct fingerprint of light at millimeter wavelength, a process known as the rotational transition. Astronomers consider that it is the gold standard for detections of molecules
The observation of this particular isotope provides new information on the fusion process that created CK Vulpeculae. It also demonstrates that the deep, dense inner layers of a star, where heavy elements and radioactive isotopes are forged, can be flipped and sunk in space by stellar collisions
"We observe the entrails of a torn star. "Astronomers also determined that the two stars that merged were of relatively low mass, one being a red giant star with a mass between 0.8 and 2.5 times that of our Sun.
Being radioactive, aluminum 26 will disintegrate to become more stable and, in this process, one of the protons of the nucleus will disintegrate into a neutron. During this process, the excited nucleus emits a very high energy photon, which we observe as a gamma ray.
Previously, gamma ray emission detections showed that about two solar masses of aluminum-26 are present in the Milky Way. but the process that created the radioactive atoms was unknown. Moreover, due to the detection of gamma rays, their precise origin was also largely unknown. With these new measurements, astronomers have definitely detected for the first time an unstable radioisotope in a molecule outside our solar system.
At the same time, the team concluded that the production of aluminum-26 by objects similar to It is unlikely that CK Vulpeculae is the main source of aluminum-26 in the way Milky. The mass of aluminum-26 in the CK Vulpeculae corresponds to about one-fourth of the Pluto mass, and since these events are so rare, it is highly unlikely that they are the only producers of the Isotope in the Milky Way. This leaves the door open for further studies on these radioactive molecules
Research paper
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The halo of the young galaxy offers clues on its growth and evolution
] Maunakea HI (SPX) July 25, 2018
A team of astronomers discovered a new way to unravel the mysteries of the formation and evolution of early galaxies .
In a study published in Astrophysical Journal Letters, lead author Dawn Erb of the University of Wisconsin-Milwaukee and his team – for the first time – used new capabilities at WM Keck Observatory on Maunakea, Hawaii to examine Q2343-BX418, a small, young galaxy located about 10 billion light-years from Earth.
This distant galaxy is an analog for younger galaxies … Read More
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