Astrophysics

Gen 6 2022

Gli spasimi di morte delle supergiganti rosse

Per la prima volta, gli astronomi hanno ripreso in tempo reale la drammatica fine della vita di una supergigante rossa. Hanno osservato la rapida autodistruzione di una stella massiccia situata a 120 milioni di anni luce dalla Terra nella galassia NGC 5731 e le sue ultime fasi di morte prima di collassare in una supernova di tipo II. Guidato da ricercatori della Northwestern University e dell'Università della California, Berkeley (UC Berkeley), il team ha osservato la supergigante rossa durante i suoi ultimi 130 giorni prima della sua detonazione fatale. La scoperta, pubblicata sull'Astrophysical Journal, contraddice le idee precedenti su come…

In the ultraviolet the sky never turns black

Astrophysics

Nov 25 2021

In the ultraviolet the sky never turns black

L'universo è permeato da una luce universale. Non preoccupatevi, non sta diventando esoterico qui, e non sto parlando del fondo cosmico a microonde. Si tratta di una parte completamente diversa dello spettro, dall'altra parte, la gamma ultravioletta. Il cosiddetto fondo ultravioletto Lyman-alfa fu scoperto per la prima volta negli anni '60; la sua esistenza fu confermata nel 1971. Si forma quando particelle di luce di una certa frequenza (una frequenza di eccitazione dell'idrogeno) vengono disperse da atomi di idrogeno neutro. Tali fotoni emanano dal Sole in gran numero nel sistema solare. Le particelle di luce sono invisibili all'occhio perché sono…

The great barrier is real – for cosmic rays

Astrophysics

Nov 12 2021

The great barrier is real – for cosmic rays

The great barrier surrounding the core of the Milky Way is encountered in 2287 by the starship NCC-1701-A under the command of Captain James T. Kirk. Supposedly, it is impenetrable, and any ship that nevertheless dares to cross it will be destroyed. Kirk and his squad from the USS Enterprise prove the legend to be false. In fact, there is a kind of barrier around the galactic center - and this barrier is not an impenetrable wall. But, as astronomers have now discovered, it is an obstacle to cosmic rays. (altro…)

What is constructor theory and what does it seek to accomplish?

Astrophysics

Nov 4 2021

What is constructor theory and what does it seek to accomplish?

"When you have ruled out the impossible, what remains must be the truth, however improbable it may sound." Arthur Conan-Doyle had his famous detective Sherlock Holmes say this sentence. However, this sentence could also be used to summarize the basic principle of constructor theory, which the well-known quantum physicist David Deutsch and the Italian physicist Chiara Marletto have been developing for about ten years now. Deutsch first presented her principles in 2012, and since then it has raised great expectations, but of course has also been met with many skeptics. This is not because it provides the ultimate theory…

Astrophysics

Nov 2 2021

The Secret of the Black Ice

We are familiar with the physical states of water - solid, liquid and gas. However, in its solid phase, as ice, water can form more than a dozen different structures whose properties vary. The ordinary ice on the puddles that soon awaits us again in the northern hemisphere is just the tip of the iceberg. Scientists have now succeeded in producing an ice phase in the laboratory that is much darker than normal ice - superionic ice. This type of ice forms at extremely high temperatures and pressures, such as those found deep inside planets like Neptune and Uranus. Until…

Astrophysics

Ott 23 2021

What are time crystals?

Ice crystals are more orderly than flowing water - right? Wrong. There is a so-called translational symmetry in the liquid. That is, no matter where we look in the stream, it always looks the same. However, when the water freezes, its molecules arrange themselves in a fixed lattice. Now, if we look at a particular spot, there is either a molecule there (if we are lucky) - or not (if we caught the interstices of the crystal). The translational symmetry of the system is broken, the physicist says, in terms of spatial coordinates. Moreover, crystals are normally in the…

Black holes determine the evolution of the universe

Astrophysics

Ott 19 2021

Black holes determine the evolution of the universe

In principle, they can only be recognized by what you can't see - and yet black holes have a decisive effect on the evolution of the universe. That's according to a new study by an international team of researchers from the University of Bologna and elsewhere. The work, published in Nature Astronomy, focuses on the Nest200047 system - a group of about 20 galaxies at a distance of about 200 million light-years from Earth. The central galaxy of this system hosts an active black hole, around which the researchers observed many pairs of gas bubbles of different ages, some unknown…

Astrophysics

Set 23 2021

A planet at maximum fluffiness

It's not often that the word "fluffy" appears in a press release about a new astronomical discovery. It refers to the exoplanet WASP-127b, which orbits a star a good 500 light-years from Earth that is slightly larger than the Sun. An international team of astronomers has now not only detected clouds there, but also measured their height with unprecedented precision. WASP-127b is a so-called "hot Saturn" - a giant planet with a similar mass to Saturn, but unlike our (cold) Saturn, it orbits very close to its sun. During one orbit around its star, WASP-127b therefore receives 600 times more radiation…