Submanyan Chandrasekhar received the 1983 Nobel Prize for calculating the Chandrasekhar limit of 1.4 solar masses, above which a white dwarf will collapse into a neutron star or black hole. Russell Hulse and Joseph Taylor Jr. received the 1993 Prize for discovering the first binary pulsar system, which provided evidence for gravitational waves. Raymond Davis Jr. and Masatoshi Koshiba received half of the 2002 Prize for detecting cosmic neutrinos from the Sun, helping solve the mystery of the missing neutrinos.

1. Nobel Prize in Astronomy. Part 2.

2. 1983
Submanyan Chandrasekhar received the Prize for his
research “on the structure and evolution of stars”. His
work helped us understand how stars age and die.
Chandrasekhar calculated what we now call
Chandrasekhar limit, which is equal to 1.4 Solar mass.
Chandrasekhar showed that if the dying star has a mass
of 1.4 Solar mass or less when it reaches the white dwarf
stage, it stays a white dwarf forever. A heavier star will
continue collapsing and eventually turn into a neutron star
or a black hole. You can find more information about
Chandrasekhar and his research in our post.

3. 1993
Russell Hulse and Joseph Taylor Jr. received the Nobel Prize “for the
discovery of a new type of pulsar, a discovery that has opened up new
possibilities for the study of gravitation”.
Back in 1974 American Astronomers Taylor and his graduate student
Hulse worked at the Arecibo Radio Telescope. While scanning the sky
in search of pulsars, the scientists discovered a fast rotating pulsar. But
there was something strange about that object. Its pulses were not
evenly spaced and the variations in pulses timing followed a pattern.
We see this kind of behavior in binary systems, where the two stars
orbit around the point in between them – their common centre of mass.
Hulse and Taylor realized that what they observed was not a single
pulsar, but a component of a binary system. We now call it Hulse-Taylor
binary. It was the first observation of a pulsar in the binary system.
Moreover, the second star also turned out to be a neutron star! Taylor
carefully studied the system for the next 15 years and noticed that its
orbit has decayed! The General theory of relativity predicts that two
orbiting bodies should emit gravitational waves. These waves carry
away energy and momentum, therefore the orbit decays over time. The
rate of the decay observed by Taylor was in good agreement with the
theory. It was the first evidence of the existence of gravitational
waves!

4. 2002
Raymond Davis Jr. and Masatoshi Koshiba received one half of the Prize “for the detection
of cosmic neutrinos”. Riccardo Giacconi received another half “for the pioneering
contributions to Astrophysics, which have led to the discovery of cosmic X-ray sources”.
Ray Davis was an American astrophysicist and a chief designer of the Davis experiment
(also known as Homestake experiment). Back in 1967 Bethe received the Nobel prize for the
explanation how stars make their energy via nuclear fusion. He showed that when a pair of
hydrogen nuclei collides, the reaction creates (among other things) an interesting particle
called neutrino. Neutrinos are (as the name suggests) electrically neutral and have an
extremely small mass. Therefore they fly freely through space without interacting with the
matter. The downside? They are hard to detect.
In the late 60s Davis designed the experiment to catch and count neutrinos coming from the
Sun. He captured neutrinos in the tank of dry-cleaning fluid installed underground in the old
mine. Surprisingly, the amount of neutrinos detected by the experiment was about three
times lower that the theoretically predicted.
Koshiba, inspired by the work of Davis, performed a similar experiment in Japan in the 80s.
His results were in conclusion with the the results of Davis. More than a half of neutrinos
were missing. Almost 20 years later, after repeating the experiment with the better
equipment, Koshiba finally solved the mystery of the missing neutrino. Turned out there are 3
types of neutrino, and a type of neutrino can change while the particle flies from the Sun to
the Earth! But Davis’s experiment was designed to detect only one type of neutrino!

5. 2006
John C. Mather and George F. Smoot received a Nobel
Prize “for the discovery of the blackbody form and
anisotropy of the cosmic microwave background
radiation”.
After the Cosmic Microwave Background Radiation (CMB)
was first discovered by Wilson and Penzias, there were
lots of unanswered questions. Many scientists pointed out
that if there are fluctuations in density of the matter (it is
not uniformly scattered across the Universe but
concentrated in galaxies), there should be fluctuations in
the CMB as well, or, in scientific words, that the CMB
should be anisotropic!
In 1989 COBE (Cosmic Background Explorer) satellite
was launched into Space. It’s goal was to carefully
measure and map the CMB. The two American
cosmologists, Mather and Smoot, were the leading
scientists of the COBE project. During its four years in
Space, COBE detected the very small but extremely
significant fluctuations of the temperature of the
background radiation. Those fluctuations are the footprints
of the variations in the matter density of the Early
Universe!

6. 2011
Saul Perlmutter, Brian P. Schmidt and Adam G. Riess
received the Prize “for the discovery of the accelerated
expansion of the Universe through observations of distant
supernovae”.
Everything started with the Big Bang and we live in the
expanding Universe, we all know that. But after the initial
BOOM one would expect the things to slow down a bit!
But the two independent teams of scientists, the first one
led by astronomers Schmidt and Riess and the other one
by Perlmutter, came to the same conclusion: our Universe
is accelerating, and the rate of this acceleration is
increasing. Sounds scary!
What astronomical discovery will be next to receive the
highest award?
Do you have your favourite (or most inspiring or even
hard-to-believe-in) astronomical discovery? Let our mobile
planetarium know!