Scientist, scholar of high
mathematics and astronomy. She was born on the 29th of November 1926
in Izmir. She was interested in mathematics starting from early ages. After
graduating from Ankara Girls High School she chose Istanbul University High
Mathematics and Astronomy Department for her undergraduate education. Eryurt’s
interest in astronomy appeared during her university years. She received her
first scientific fundaments there, including from foreign professors. Upon
graduation, also under the influence of her new enthusiasm of astronomy she
became an assistant of Prof. Dr. Tevfik Okyar Kabakçıoğlu who was responsible for opening a
department of astronomy in Ankara University. However, since there was no empty
position, she continued working for two years without any payment. She wrote
her PhD in Astrophysics again in Ankara University
Her research fields are astrophysics, structure and developments of stars, sun
models and neutrino problem.
As Dilhan Eryurt went to
USA after long years, she received the scholarship of National Academy of
Sciences and started to work in Goddard Space Research Institute of NASA at New
York. She became an associate professor under the supervision of Prof. Dr. A.
E. Kreirken at Ankara University, Department of Astrophysics. In 1959 she went
to Canada for two years, using the scholarship given to her by the
International Agency of Atom Energy. There she met real astrophysics. Prof. Dr.
Cameron suggested her three topics to make researches on and she chose hydrogen
stars. Later, since it was first necessary to calculate the opposite of a gas,
which consisted of hydrogen, she produced the computer software she was asked
for. The first thing she learnt with this work, which would later be published,
was the “fitting” method… Eryurt after her researches in Canada started to work
in Indiana University with a scholarship she received from USA. She worked with
Prof. Dr. M. Wrubel who was known with making star models in Indiana.
Prof. Eryurt, as she
also stated before, passed to NASA after Indiana. Working together with Dr.
Cameron who came there earlier, they analyzed all evolutions of low massed and
high massed stars. So that a giant dust and gas cloud in the space can
transform into a star, the nuclear heat in it must be increased and nuclear
energy can come into being. First phases of the star, phases of collapse make
it possible that the heat in the center is increased and the required heat is
obtained. For that, the mass of the star must reach a certain size so that it
can provide the necessary heat. If mass of the star cannot create this heat by
collapsing, nuclear reaction cannot begin. The problem in which Eryurt
especially was interested here was “What is the limit of low masses or what is
the limit of mass for small stars?” and she worked on this problem. The first
study of Eryurt on that issue was about stars which only consisted of hydrogen.
Dilhan Eryurt states the
meaning of this knowledge in the evolution of a star as the necessary
conditions for the formation of a star. During her researches in which she used
the method of “Fitting” Prof. Eryurt advanced by adding new options to the
program continuously. Thus, she developed the method of
fitting and as a result produced a new program. This was the most perfect
program of that period, but later her students developed this program by adding
whirling to it.
Prof. Eryurt made researches on the
evolution of the sun together with Prof. Cameron. Since the sun evolution model,
which was valid at that time, was criticized, it was necessary to produce a new
model, which included the latest theories. It was also decided to analyze heat,
intensity, radiation and the interaction between sun and planets with the new
model. It was accepted within the previous theory that the sun was colder in
its first formation and slowly reached its status of today. It was believed
that the sun was less bright during the period of four billion years after its
constitution and then slowly started to shine, thus reached its brightness of
today.
The most important aspect of Eryurt’s
study on this issue is that it was realized that the sun was much brighter than
now during its first constitution, its heat slowly decreased and later reached
its state of today. If it is necessary to explain shortly the special content
of this mechanism; the sun’s first bright then decreasing state depends on the
burning of hydrogen in it. After reactions of hydrogen started the superficial
heat slowly increases. As it is known the sun has burnt half of its hydrogen
until today and reached its state of today. In other words, this means a
decrease, which means there are 4.5 billions of years until the consumption of
sun. This new model, which is still valid is a discovery of Dilhan Eryurt to a
large extent. Thus Prof. Eryurt has contributed to the knowledge about the
constitution of the sun. The importance of this study is: If the earth came
into being during the brightest period of the sun, the elements which
constituted this planet were exposed to thousands of degrees heat for tens of thousands of years, which is a great and direct impact
to the physical and chemical properties of the earth. Naturally a similar
impact comes into question for our satellite, moon. This impact of high heat
was important for the Apollo Moon Trip Project designed to be realized in 1960s
because of the environment the astronauts would meet who would take this trip.
Eryurt was also interested in the issue of “neutrinos” aside from her works in
NASA institute about the constitution of stars and evolution of sun.
Dr. Dilhan Eryurt is
completely a “wonder-woman”. Because the word “evolution” can annoy even people
of today, let alone people 50 years ago. This is also possible to observe in
magazine articles, which explain her... Eryurt calls her achievement as
“evolution of stars” but journalists and authors continuously use the word “history
of stars”. Eryurt during her stay in USA came to Turkey for several times. Her
purpose was to transfer her knowledge and experience to Turkey and raise
students. But she learnt that this task was more difficult than the evolution
of stars. First she worked as a guest professor in Middle Eastern Technical
University in 1968 for one year. Aside from her courses she also organized
scientific gatherings. As she organized the 1st National Astronomy
Assembly only 25 people joined it. There was an association of astronomy
earlier in Turkey but that association organized touristic trips instead of
scientific gatherings. However, she witnessed that associations in USA always
organized scientific gatherings. During gatherings she joined there she told
about her scientific studies and attracted a very considerable attention. In
Turkey on the other hand, let alone gatherings, it was even difficult to give a
lecture on astrophysics, because there was nobody to listen to it…
Prof. Dr. Dilhan Eryurt
returned to METU Department of Physics in 1973 with a firm position and
established here the Department of Astrophysics. In 1988 she first served as
the Head of Physics Department in the Faculty of Science-Literature in METU,
later Dean of the same faculty for five years. She retired in 1993… Prof. Dr.
Dilhan Eryurt received the Apollo Achievement Award in 1969, which was given by
NASA. Later she worked in institutes which were responsible of developing the
first unmanned space vehicles to be orbited around the earth. Another
achievement award she received was TÜBİTAK’s “Service to Science and
Encouragement” in 1977…
