October 7 N. I. Shakure turned 70 years old

R. A. Syunaev, Academician of the Russian Academy of Sciences, Director of the Institute of Astrophysics of the Society of Max Planck, Ch. scientific. sore. Iki RAS

I don’t know why, but when they ask about someone from my friends or good acquaintances, this person stands before my eyes as I met him for the first time or at the moment when he made the greatest impression on me. And Nikolai Ivanovich (Kolya), I still see a student who came from the Belarusian village, with burning eyes, quick in movements and in answers to any question (after all, it was not for nothing that he was running a hundred -meter in those days, participating in the championship of Moscow State University). I remember him in the dormitory of Moscow State University with his eldest son (who has long been a father) in my hands, I remember our disputes in the early 1970s, when we intensively worked together and wrote articles that we are still proud of, our meetings in his first room (knocked out by Yakov Borisovich Zeldovich simultaneously with a residence permit in Moscow) in the house of teachers of Moscow State University. No long ago. Tea kettles, drunk alternately with him and first in the room on the trade union, and then in the cooperative in the southwestern, long night calls. I remember Kolya on the top of the Etna volcano and speaking at the famous seminar under the leadership of Zeldovich, V. L. Ginzburg and I. S. Shklovsky at the Gaish at Moscow State University. I also remember how Yab (Zeldovich) told me that a new student had a new student and that it would be nice if we worked together. Yab was very interested in the theory of accretion on black holes and neutron stars, and until the end of his life the best interlocutor on this topic was a diploma on him, then a graduate student and employee N.I. Shakura. It is remarkable that Kolya is still led by the department of relativistic astrophysics of Gaish, who founded and led by Yab for many years.

I like the photo from Kolya at the board in the conference hall of the GASH, made almost 40 years ago in the 1970s, when we worked a lot together. This picture resembles the years when Kolya and I had interesting results, but there was neither time nor money for a regular visit to the hairdresser.

Kolya, like most of the students in the field of cosmology and relativistic astrophysics, was unusually very lucky. He met with Yab (undoubtedly, one of the most striking physicists who decide to start working in astrophysics from any earthly applications after successful work on weapons) in the era of “assault and onslaught” in this science, when he literally brought observational discoveries on his consequences every year. And Kolya succeeded that few people succeed: he is the author of the “standard theory of disco accretion on black holes and neutron stars”, the most cited article [1] in world theoretical astrophysics (in recent years more than a link on a day), details set in dozens of reviews, books and textbooks. In recent years, more than a third of references to this work have been in articles on protoplanetary discs in young star systems. And behind the back of Kolya, the first in the world and a widely cited model of spherical accretion of gas on a neutron star with a weak magnetic field (written together with Yab [2]), an article on the thermal instability of radiation-dominated aircraft discharge [3]; The publication of the ideas of the outflow of substance from the accretion discs with super -eddington luminosity, now observed in many quasars, and heating the external regions of the disks with the rigid radiation of its central zone, which manifests itself in disks around young stars; And much, much more.

70 years is a serious threshold. But the world of science knows a lot of people who remained productive even after 70. I am pleased that Kolya in recent years wrote in collaboration with K.A. Zveznov, P.K. Abolmasov and other even younger colleagues a number of beautiful works on the theory of accretion and interpretation of observation. These works are already recognized and widely cited. I would like to wish Kal to continue to work actively, to speak at conferences with new ideas and brilliant reviews and continue to amaze young students and students who believe that “dinosaurs” with such a gigantic contribution to science, like that of Nikolai Ivanovich, could only exist in the distant past.

G. S. Bushing-Kogan,
doct. physical. sciences, ch. scientific. sore. Iki RAS

Shortly after admission to graduate school, my boss, Ya. B. Zeldovich, ordered his lecture on astrophysics, the course of which he gave at the physical faculty of Moscow State University. After the lecture, the students' reports on the work done were obeyed, which Yab also left me to listen to. There, for the first time, I saw Kolya Shakura, who sensed something sensiblely, while the rest of the students mumbled quite unintelligible.

In 1967, at the Congress of the International Astronomical Union in Prague, Yab talked about a study on an accretion on a neutron star, which they made with Kolya, about the fall of a substance on a neutron star without a magnetic field. Upon returning home, I suggested that Alik Friedman to consider a similar task in the presence of a strong magnetic field of a neutron star. There it was necessary to take into account various plasma effects that Alik was engaged in. By the end of 1967, the work was finished in black, I told about her a yab who took it without enthusiasm. He ordered us to justify some statements, in addition, he was coldly reacted to the idea of ​​a strong magnetic field of a neutron star. All this cooled our ardor, and the work was set aside. In the spring of 1968, the opening of the pulsars was announced, and Yab immediately ordered the work to publish in its original form. It is interesting that our article [4] entered the editorial office of the “Astronomical Journal” on August 19, 1968, simultaneously with an article by Yab and if an accretion on a star without a magnetic field [2]. After the brilliant defense of the diploma, Kolya entered graduate school, where, under the guidance of Yab, he took up the theory of disk accretion of a substance with a large angular moment on black holes. Disk accretion was considered earlier in connection with the formation of the planets, and in the work of D. Linden-Bella in 1969 [5] the Kvasar model, or the nucleus of the active galaxy, in the form of an ultra-massive black hole with an accretion disc was proposed. Then this model was pioneer, and now it has become generally accepted, confirmed by observations.

The main difficulty of the model was the need to account for turbulent viscosity, which is needed to create a stream of substance in a black hole to support the observed luminosity. In the work of Kolya, published in the “Astronomical Journal” in 1972 [6] and sent a year earlier, a simple phenomenological formula for the main component of viscous tension was first proposed, which determines the flow of mass from the accrementary disk into a black hole:

Trart = α p , (1)

where P is pressure, and α is a numerical coefficient less than a unit, estimated from observations. The simplicity and visibility of this formula made it very popular in all areas of astrophysics, where accretion discs are found, in protoplanetary and double systems, in the nuclei of galaxies.

However, a huge number of references to this formula do not fall on the original work in the “Astronomical Journal”, but on the subsequent article by the Shakuras together with R. A. Synyaev, published in 1973 in the European journal Astronomy and Astrophysics [1]. In addition to the obviously more popularity of this magazine compared to the “astronomical magazine”, in this article the theory of accretion is described much more and more accessible. In addition, it contains more astrophysical applications. Work on the 1973 article demanded from a number of enormous tension of forces. I remember how he completely exhausted came to our room at the Institute of Applied Mathematics and sat with a detached look without words and movements. This behavior was quite mysterious for me, since work on this article was carried out without discussions at seminars. Apparently, the Yab was one of the few, and perhaps the only person who was aware of this work, and, as always, gave valuable advice, comments and instructions.

It should be noted that already in an article by Linden-Bella of 1969 [5] you can find implicit traces of this formula (1). Linden-Bell suggested that the viscosity is determined by a chaotic magnetic field, which, in conditions of the equivalent of thermal and magnetic energy used by it, is precisely reduced to the formula (1). In the work of the Princet and Rice of 1972 [7], a slightly different phenomenological description of turbulent viscosity was considered, which did not have the simplicity and clarity of the formula (1) and therefore did not become distributed.

Kolya and I came out several works, which, perhaps, may not be good, but do not go into any comparison with the formula (1), which can rightfully be considered the main phenomenological formula in the theory of disk accretion.

A. M. Chereshchuk, Academician of the Russian Academy of Sciences, Director of the GAISH of Moscow State University

With Kolya Shakura, we studied together at the astronomical department of the physical faculty of Moscow State University. When I was already a graduate student, Kolya (under the leadership of academician Ya. B. Zeldovich) completed his thesis dedicated to the calculation of the X -ray spectrum with spherical accretion of the substance on a single neutron star without a magnetic field. This work was published by him together with Ya. B. Zeldovich in the Astronomical Journal in 1969 [2].

Later, already as a graduate student, Kolya also published, also in the “Astronomical Journal”, his first work on discus accretion of the substance on a relativistic object in a close double system [6]. I witnessed how Kolya sat for many days and weeks in the Gaish library, experiencing the “flour of creativity” when performing this wonderful work and writing an appropriate article. Then the publication of the now famous article by N. I. Shakura and R. A. Syunyaev followed on discs on black holes, where the effects of the componization of the spectrum of X -ray radiation were taken into account and a model of supercritical accretion was built [1]. The output of this work coincided with the beginning of systematic x -ray observations of the sky from the side of the American orbital specialized X -ray observatory Uhuru. Thanks to the work of N. I. Shakura and R. A. Syunyaev, the nature of numerous compact X -ray sources opened by this observatory was quickly understood. A conclusion was drawn on the opening of X -ray double systems, consisting of a normal optical star and an accreting relativistic object. In 1972, an article by IBVS was published in the International Express publication of the authors (A. M. Che-Ru-Retashuk, Yu.N. Efremov, N. E. Kurochkin, N. I. Shakura, R. A. Synyaev) [8], dedicated to the interpretation of the optical variability of one of the first open zealous dual systems-HZ Herkules systems. Based on the conclusions of the theory of discs, the authors showed that the main reason for the optical variability of this system is the effect of reflection, more precisely, the effect of warming the surface of the optical star with powerful x -ray radiation of the accreting neutron star. Now the study of the optical manifestations of X -ray double systems has grown into a separate direction of astrophysics, where a number of important results have been obtained. In particular, the masses of about three dozen stellar black holes were measured.

Currently, N. I. Shakur leads the department of relativistic astrophysics created in Gaish on the initiative of Ya. B. Zeldovich. The institute is proud of the presence in its composition of such a brilliant scientist. I really value many years of friendship with Kolya and cordially congratulate him on the 70th anniversary.

1. Shakura N.I., Syunyaev R. A. Black Holes in Binary Systems. Observational Appe their // Astronomy and Astrophysics, 1973. V. 24. P. 337–355.

2. Zeldovich Ya. B., Shakur N. I. X -ray radiation during the accretion of gas on a neutron star // Astronomical Journal, 1969. T. 46. P. 225–236.

3. Shakur N.I., Syunyaev R. A. A Theory of the Instabide of Disk Accretion on to Black Holes and the VariaBility of Binary X-Ray Sources, Galaactic Nuclei and Quasars // Mnras, 1976. V. 175. P. 613–632.

4. Bitter-Kogan G.S., Fridman A. M. On the mechanism of X-ray radiation of the neutron star // Astronomical Journal, 1969. T. 46. P. 721–724.

5. Lynden-Bell D. Galactic nuclei as collapse Old Quasars // Nature, 1969. V. 223. P. 690–694.

6. Shakura N. I. Dischemistry of gas accretion of a relativistic star in a tight double system, Astronomical Journal, 1972. T. 49. P. 921–929.

7. Pringle Je, Rees MJ Accretion Disc Models for Compact X-Ray Sources, Astronomy and Astrophysics, 1972. V. P. 1–9.

8. Cherepashchuk am, Efremov yu. N., Kurochkin Ne, Shakura Ni, Sunyaev Ra on the Nature of the Optical Varis of Hz Her = Her X1 // Information Bulletin On Variable Stars, 1972. V. 720. P. 1.

We express our gratitude for the work on photos
T. A. Birule and O. S. Bartunov