1. Ambartsumian’s method for determination of the temperature of the planetary nebulae nuclei
New method (modification of Zanstra’s method) for determination of the planetary nebulae’s central stars surface temperature giving the probabilistic definition of short wave energetic photons transformation into less energetic ones. This definition led to the determination of the radiative equilibrium of planetary nebulae (1932).
2. Ambartsumian principle of invariance
Development of light scattering theory in turbid medium, theory of Invariance. The principle of invariance was proposed for solving the radiative transfer problems. A very simple physical reasoning that the reflection properties of the semi-infinite plane-parallel medium do not change if a very thin layer of the same physical properties is added to its boundary gave an excellent base for creation of a new research method (1941-1942).
3. Ambartsumian’s j function
The main function defining the coefficient of reflection from semi-infinite medium by means of the principle of invariance. In the case of redistribution by frequencies it coincides with Chandrasekhar’s H function.
4. Ambartsumian’s hypothesis on the superdense matter
In 1949, a theoretical prediction of the phenomenon of expansion of stellar associations was made. In 1951, Ambartsumian carried out a statistics of Trapezium Orionis type systems and proved the disintegration of young stellar systems. He showed the nonthermal nature of the continuous emission observed in the spectra of non-stable stars and put forward an idea about new possible sources of stellar energy, the hypothesis of the superdense protostellar matter (1954). Theoretical studies of the hypothetical superdense degenerate protostellar matter led to development of principles of the theory of baryonic stars (1960-1961).
5. Ambartsumian’s hypothesis on the activity of galactic nuclei
In 1956, a hypothesis on the activity of galactic nuclei was proclaimed. The various forms of activity were presented as different manifestations of the same phenomenon of activity. The evolutionary significance of the activity in the galactic nuclei was emphasized and a further hypothesis was suggested on the ejection of new galaxies from the active galactic nuclei. The hypothesis on the superdense protostellar matter was engaged to explain the observational data.
6. Ambartsumian (or Byurakan) school in cosmogony
The hypotheses on superdense matter giving origin of stars and nebulae and on activity of galactic nuclei led to the establishment of new approach in cosmogonic interpretation of the evolutionary processes in the Universe. The Ambartsumian (Byurakan) school in cosmogony appeared, describing the evolution of cosmic matter from more dense states to less dense ones. In contrary, the widely accepted classical school describes the evolution of cosmic matter from less dense states to more dense ones (origin of the stars from gas and dust).
7. V.A. Ambartsumian Byurakan Astrophysical Observatory (BAO)
One of the most important astrophysical observatories in the former Soviet Union area and Middle East. It was founded in 1946 by V.A. Ambartsumian and became a world centre for astronomical science for a few decades. BAO is famous for its original research on stellar and galactic evolution, non-stable objects in the Universe, large surveys (search for new objects). It was named after V.A. Ambartsumian in 1998, at his 90th anniversary.
8. V.A. Ambartsumian Yerevan Astronomical Observatory
Yerevan Astrophysical Observatory is a small observatory in the centre of Yerevan, presently used for educational purposes. It was founded in 1932 and before the foundation of the Byurakan Observatory was the only astronomical centre in Armenia. YAO belongs to the Yerevan State University (YSU).
9. V.A. Ambartsumian Chair of Astrophysics at YSU
The Chair of Astrophysics is a part of the Faculty (Department) of Physics at the Yerevan State University. It was founded in 1944 by V.A. Ambartsumian. Since 1951, most of the Byurakan Observatory astronomers are graduates from the Chair of Astrophysics.
10. V.A. Ambartsumian (Armenian) Mirror Telescope (ZTA-2.6m)
The Byurakan Observatory 2.6m telescope was installed in 1975 and is operational since 1976. It is the largest telescope in the Middle East area. At present ZTA-2.6m has three main instruments: focal cameras ByuFOSC and SCORPIO, which have possibilities for both imaging and spectral observations, and VAGR multi-pupil spectrograph.
11. Ambartsumian asteroid
The asteroid #1905 discovered by T.M. Smirnova on 14 May 1972 in the Crimean Astrophysical Observatory (CrAO) was named after Ambartsumian.
12. V.A. Ambartsumian’s home-museum in Byurakan
V.A. Ambartsumian’s museum organized in his family house in Byurakan, built in 1950. After Ambartsumian’s death, in 1998, this house was transformed to a home-museum, where Ambartsumian’s furniture, belongings, books, etc. are being maintained as they were during his life. The museum is open for visitors.
13. V.A. Ambartsumian’s street in Yerevan
The former Gaidar street was named in 1998 after V.A. Ambartsumian.
14. V.A. Ambartsumian’s square in Yerevan
The square around the Yerevan Astronomical Observatory (former Ghukas Ghukasian square) was named after V.A. Ambartsumian in 2008.
15. V.A. Ambartsumian’s secondary school in Yerevan
A secondary school in Yerevan (No. 12, former Kirov school) was named after V.A. Ambartsumian in 1998.
16. V.A. Ambartsumian’s alley in Byurakan
The alley in the Byurakan Astrophysical Observatory located between Ambartsumian’s home-museum and the Observatory hotel.