14.12.2000
17:57

Global Computer Model of Organism

09.12.2000
13:47

Hypersound Engine in the Process of Testing

30.11.2000
14:08

Airplane with Inverse Arrow-Shaped Wing Profile is to be undergone to its 3rd stage of Trial at the end of November

23.11.2000
11:58

Engines Provided by Russia to America

20.11.2000
11:55

Russian Army Will Get a New Helicopter

09.11.2000
13:00

For the first time the cloning of a mammal was done in Russia

31.10.2000
08:19

First Crew Started to the International Space Station (ISS)

19.10.2000
14:00

Break-Through into the Earth's History, or Drilling the Bottom of Lake Baikal

10.10.2000
16:02

Zhores I. Alferov is Nobil Prize 2000 winner in Physics!

07.10.2000
22:14

Famous Soviet Astrophysicist Celebrates his 55th Anniversary

05.10.2000
00:39

Moscow Government Provides Grants

04.10.2000
20:21

All-Moscow seminar of Astrophysicists

04.10.2000
18:11

Russia Leads the Way to the Space

28.09.2000
14:15

Negative magnetic permeability predicted russian scientist

21.09.2000
19:04

Unprecedented case in the History of Russian Science: Presentation Made - Money Paid!

14.09.2000
17:12

E2K - the best russian processor

31.08.2000
20:06

Gravitational Wave Astronomy: in Anticipation of First Sources to be Detected

29.08.2000
19:23

All-Moscow Seminar of Astrophysicists will take place on 8 september

All-Moscow Seminar of Astrophysicists
(ASA)

The seminar is supported by the grant of Federal Programm "Integration"

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annotation of talk
Bisnovatyi-Kogan G.S. (SRI)
ADAF is diad -- is Advection alive?

Recent papers discussing advection-dominated accretion flows (ADAF) as a solution for astrophysical accretion problems should be treated with some caution because of their uncertain physical basis. The suggestions underlying ADAF involve ignoring the magnetic field reconnection in heating of the plasma flow, assuming electron heating due only to binary Coulomb collisions with ions. Here we analyze the physical processes in optically thin accretion flows at low accretion rates including the influence of an equipartition random magnetic field and heating of electrons due to magnetic field reconnection. The important role of the magnetic field pointed out by Shvartsman comes about because the magnetic energy density, E_m, increases more rapidly with decreasing distance than the kinetic energy density, E_k (or thermal energy density). Once E_m grows to a value of order E_k, further accretion to smaller distances is possible only if magnetic flux is destroyed by reconnection. For the smaller distances it is likely that there is approximate equipartition, E_m=E_k. Dissipation of magnetic energy is associated with the destruction of magnetic flux. We discuss reasons for believing that the field annihilation leads to appreciable electron heating. Such heating significantly restricts the applicability of ADAF solutions, and it leads to a radiative efficiency of the flows of 25% of the standard accretion disk value. Detailes is here

29.08.2000
16:51

Colloquium "Black Holes - 2000"

29.08.2000
16:40

Greenhouse catastrophe. Realistic scenario.