}

Garik in Israel: "The nucleosyesis of an explosion needs to create heavy elements"

2007/06/01 Roa Zubia, Guillermo - Elhuyar Zientzia Iturria: Elhuyar aldizkaria

Garik is an Armenian astrophysicist in Israel. He has travelled all over the world from one research center to another and currently works at the Astronomical Institute of the Canary Islands. Since his childhood he tells us about his relationship with astronomy. And through the stars it has led us to know the generation of heavy metals, last topic of investigation of Israel.
Astrophysicist Astrophysicist
Garik in Israel: "Nucleosenesis of an explosion is needed to create heavy elements"
01/06/2007 | Roa Zubia, Guillermo | Elhuyar Zientzia Komunikazioa
(Photo: G. G. Israel)
How did he become astrophysics?

I was about 15 years old when I started reading about astronomy. And I remember very well that one day I saw with my friends a sci-fi film in the Soviet Union. Before that day I only saw western style movies, my favorite movies. But that sci-fi film revolutionized my world. I was fascinated by the consequences of the theory of relativity. Especially I was surprised to know that if it was moving close to the speed of light time was slowing down. He was totally surprised.

This enigma led me to read sci-fi books. I read every day and night, all those who caught me. Then I started reading about astronomy. However, I had a very low level of mathematics and physics, and that's why I couldn't go to college after finishing high school. For a year I had to work in the village theater, while learning mathematics and physics at home. I had to study for a year to know enough to enter the Department of Physics at Jereban State University, Armenia. I became one of the best students in the department and, after completing my studies, I started a doctorate.

When did you go to the Instituto de Astrofísica de Canarias?

I did my doctoral thesis at the Biukaran observatory in Armenia. The thesis director was Professor Victor Ambartsumian, one of the most important astronomers in the world. In Ambartsumia he was president of the International Astronomical Association and the International Commission of Scientific Associations. He founded a school of theoretical astrophysics of the Soviet Union.

After finishing my doctorate in Armenia, I spent several years working in Holland, Belgium and Australia. Finally I arrived in the Canaries in 1997.

In Euskal Herria there is a great tradition, for example, in the field of engineering. But in astronomical research there is not much tradition; in general, astronomy is an amateur activity. Does the same happen in Armenia?

I know in Armenia a. C. C. III. That we were astronomers of the twentieth century. There are many ancient manuscripts in our museums. In addition, Armenia has an old observatory -- 10,000 years old or earlier. It is similar to the famous English Stonehenge, so many scientists look for ties between both. Armenians have worked for thousands of years in astronomy. There are other evidences such as Armenian names for constellations and planets of the Solar System.

He has carried out an astrophysical research in many places. Is there a perfect place for astrophysics in the world?
Garik Hawaii; Very Large Telescope at the telescope.
G. G. Israel Israel

Well, if you work on observation and want to be "close" to telescopes there are few options. Surely you will have to choose between Canaries, Chile or Hawaii. These are the best observatories in the world in astronomy.

What is your research in the Canary Islands?

My job is to investigate how chemical elements are created in space and how they evolve, in addition to developing observation tests that help develop theoretical models.

Heavy metals and heavy chemicals are produced in the stars. But not all stars are the same. Why?

The life of each star begins with a given mass, a determined rotation speed, and a specific chemical composition. These three parameters define the evolution of the star.

The stars are “factories” of chemical elements, in some way large furnaces. Therefore, there are more than one type of stars and there are workshops. To what extent can there be differences?

They are very different! For example, some heavy metals -- titanium, uranium, europio, etc.- cannot be created by a mass star like the Sun. For this purpose, stars of at least ten times more mass are needed.

Is it a question of masses?

Mainly yes. In some cases, the initial rotation speed of the star can also influence the final products of this element factory. And the initial chemical composition can also change the final composition (i.e., the evolution of the star). However, the most important parameter is the mass.

How is the Sun?
Mirador del Roque de los Muchachos in La Palma.
G. G. Israel Israel

Small energy workshop. The sun can form light elements such as carbon and nitrogen, but it will never form nickel, silver, or gold.

Astrophysicists give importance to iron. Why?

The reason is historical. Iron is not special in astrophysics. The iron of the stars is easy to measure and other elements of the iron group are not detected or detected with little precision.

Can it be a limit for defining heavy elements? That is, from the astrophysical point of view, are all heavy elements that are heavier than iron?

It is only a definition. However, it must be taken into account that the elements heavier than iron are not formed in massive stars by hydrostatic thermonuclear reactions. The formation of these elements requires at least the nucleosyesis of an explosion.

Therefore, in the supernovae are all the elements heavier than iron generated?

Heavy elements (called s-elements, such as barium) can be formed by a slow capture of neutrons, in layers of stars with mass of the Sun that have evolved a lot. These stars are called IGB. On the other hand, heavy elements can also form in expansion reactions, both in the interstellar environment and in the vicinity of stars that emit X-rays or gamma.

In what proportion are heavy elements generated in the supernovae?

In very small proportion. Most of the elements present in the supernovae have been created previously in hydrostatic thermonuclear reactions such as oxygen, magnesium, sulfur or silicon. The supernova contributes to the spatial dispersion of these elements. They account for 90% of the matter launched.

How do we know it? How do we detect elements in supernovae?
Garik in Israel on a telescope of the Atacama Desert.
G. G. Israel Israel

The matter released appears in the footprints of the supernovae. You can study the spectrum of these brands and measure the abundance of chemical elements. Spectra of stars close to the supernode can also be studied (for example, in binary systems). It is possible that a part of the matter emitted has been absorbed by the star and mixed with the matter of the atmosphere.

Does the presence on earth of uranium and other heavy metals mean that a supernova exploded near the Earth?

In no case. Uranium atoms are found in space, so they can be present in any astronomical body: asteroids, comets, planets outside the solar system, etc. Heavy atoms have arisen in many generations of supernovae in our galaxy. They have gathered in space throughout the year. Therefore, they will be present in any body that occurs with this matter.

How do they go from supernovae to Earth?

They don't. They are among the stars in a state of gas or dust. The planets and stars are made of this material (protostar material), so they have these elements from the beginning. Therefore, the chemical composition of the Sun is the same as that of this matter.

What do we not know about the creation of heavy elements?

There are many types of supernovae. We do not know what type produces a large amount of a certain chemical element and what does not. Theoretical models are not accurate and are not easy to investigate through observations.

Puente Roa, Guillermo
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