Is it a trace of a supernova explosion caused by the first star? Detected by observing the Very Large Telescope VLT | sorae portal site to the universe

A research team led by Andrea Sacardi, a doctoral student at the Paris Observatory, has published research results on gas clouds that existed in the early universe. Among them are the stars of the first generation of the universe.“the first star”It also includes a gas cloud believed to have been left behind after the supernova exploded, and the research team says it was the first time the effects of the first star’s supernova explosion had been determined.

■ The discovery of a gas cloud identical to the expected chemical composition after the supernova explosion of the first star

Around us, there are various elements such as hydrogen and oxygen that make up water molecules, carbon and nitrogen that are necessary for life on Earth, and iron, gold and uranium that are used in the activities of human civilization. I’m here. However, only light elements such as hydrogen, helium, and a very small amount of lithium are believed to have existed in the earliest phase of the universe’s history, which is said to have begun with the Big Bang about 13.8 billion years ago.

Among the elements heavier than hydrogen and helium, which are together called “metals” and “heavy elements” in astronomy, elements up to iron result from nuclear fusion reactions inside stars, and elements heavier than iron result from violent phenomena such as supernovae. The bangs are believed to have been made together. The generated metal is released to the surroundings by stellar winds and supernova explosions, and is eventually inherited by new generations of stars, so the amount of metal in the universe will increase as the generational change in stars progresses. The various elements that support life and civilization have been produced by the stars over a long period of time.

Tracing its long history towards the past, the first generation of stars believed to have been born about 13.5 billion years ago, the “primary star” (first star, third star race).※) using only hydrogen and helium, which existed in the universe at the time. The first star, whose mass is believed to be equivalent to tens to hundreds of suns, must have produced metal for the first time in its interior, and when it exploded as a supernova, the metal should have been scattered around it.

This time, when the research team analyzed the chemical composition of several gas clouds that existed about 12 billion years ago (redshift z = 3 to 4), they found that among the elements produced inside stars, three gas clouds were found rich in chemicals. carbon and other materials, but it contains very little iron. According to the research team, the supernovae explosions caused by some first-generation stars have low energy, and although carbon, oxygen and magnesium that were present in the outer layers of stars are released, they are still present in the core. Studies have indicated that in some cases too little iron is released. The chemical compositions of the three gas clouds found here match those expected for such explosions.

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[▲ فيديو توضيحي لنتيجة هذا البحث بواسطة ESO (الإنجليزية)]
（Credit: IT）

Among the ancient stars found in the Milky Way, there are some so-called “metallic carbon-poor stars” with a high carbon-to-iron ratio. It has been suggested that the carbon-rich but metal-poor stars may be “second generation stars” that formed from material ejected by first generation stars, and are said to correspond with the material.

“For the first time in history, we have been able to determine the scientific implications of the first star’s explosion in gas clouds in deep space,” Sacardi commented. Professor Stefania Salvadori from the University of Florence, who was involved in the study, said: “Our results open up a new way to indirectly study the properties of the first stars, and they also completely complement the study of stars in the Milky Way.” There, he commented.

■ Analysis of light from quasars passing through gas clouds using ground-based telescopes

[▲ رسم بياني يوضح كيفية فحص التركيب الكيميائي لسحابة غاز (وسط) باستخدام كوازار (أعلى اليمين). يُظهر شريط قوس قزح طيف الكوازار. بعد المرور عبر سحابة الغاز ، يظهر الطيف خطوط امتصاص مظلمة (Credit: ESO / L. Calçada)]

In this study, quasars were detected by the multi-wavelength X-shooter spectroscopic instrument installed on the Very Large Telescope (VLT) at the Paranal Observatory (Chile) operated by the European Southern Observatory (ESO). user. A quasar is a type of active galactic nucleus (AGN) that emits powerful electromagnetic waves from a narrow region at the galactic center.

If there is a gas cloud between the quasar and Earth, some of the light emitted by the quasar will be absorbed by the material in the gas cloud. By conducting spectral observations to obtain the spectrum of celestial bodies (the intensity of each wavelength of electromagnetic waves) and examining the absorption lines (dark lines that appear when atoms and molecules absorb electromagnetic waves of specific wavelengths) that appear in the spectrum of quasars. It is possible to know the types and quantities of minerals present in gas clouds.

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Spectral monitoring equipment such as the X-shooter will also be installed in the European Very Large Telescope (ELT), a large 39-meter telescope currently under construction by ESO. By examining more gas clouds like the ones detected this time with ELT’s spectral observational equipment in more detail, Valentina Dodorico of the Italian National Institute of Astrophysics (INAF), who was involved in the research, said that “the mystery of the first star has been revealed.” I expect we will be able to clarify the nature of

* Based on the amount of metal present in the spectra, young stars with high metal content are classified as “Population 1”, and old stars with low metal content are classified as “Group II”. A star with little metal is called a metal-poor star, and a star with almost no metal is called a very poor star. Also, stars that do not contain metals, that is, stars of the first generation, are classified as “group III”, but they have not yet been found.

source

• Image credit: ESO/L. Calzada, M. Kornmesser, ESO/L. Way
• that – Astronomers have found distant gas clouds with remnants of the first stars
• Sacardi et al. Evidence for the first star-rich gas in high redshift absorbers (The Astrophysical Journal)

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