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Abstract:
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The
sub ject
of
this
PhD
thesis
are
Typ e
I I
Cepheids.
Typ e
I I
Cepheids
are
pulsating
Population
I I
stars
with
masses
of
around
0.5
0.6
M
⊙
.
Their
mass
determines
where
they
are
p ositioned
on
the
Hertzsprung-Russell
diagram
(HRD),
that
is,
their
luminosity
and
e ective
temp erature.
These
stars
can
b e
found
in
the
Milky
Way,
the
Magellanic
Clouds,
and
in
other
distant
galaxies.
They
o ccupy
a
narrow
strip
on
the
HRD
which
is
called
the
instability
strip.
Here
the
radii
and
luminosity
change
p erio dically,
and
this
change
can
b e
seen
in
the
light
curves.
Because
of
their
age,
and
their
p osition
on
the
HRD,
these
variables
form
a
separate
p erio d-luminosity
relation
(
P L
relation).
Using
the
sp ectral
energy
distribution
mo dels
we
determined
in
this
thesis
the
e ective
temp eratures
and
luminosities,
and
from
evolutionary
mo dels
the
masses
and
radii,
for
Typ e
I I
Cepheids
and
anomalous
Cepheids
in
the
Large
and
Small
Magellanic
Clouds.
In
the
thesis,
the
rst
p erio d-
luminosity
relation
was
constructed
using
b olometric
magnitude
(
M
b ol
).
The
thesis
also
presents
the
reclassi cation
of
Typ e
I I
Cepheids
from
the
Milky
Way
using
the
Fourier
decomp osition
of
the
light
curves
measured
in
V
lter.
The
Fourier
decomp osition
was
used
to
calculate
the
Fourier
parameters,
which
were
then
used
to
compare
the
stars
from
the
Milky
Way
with
the
sample
of
known
Typ e
I I
Cepheids
and
anomalous
Cepheids
from
the
OGLE-I I I
catalogue
for
the
Large
Magellanic
Cloud.
From
the
59
stars
(taken
from
the
General
Catalogue
of
Variable
Stars),
18
turned
out
to
b e
anomalous
Cepheids,
1
anomalous
Cepheid
pulsating
in
the
rst
overtone,
11
classical
Cepheids,
2
p eculiar
W
Virginis
stars
or
classical
Cepheids,
and
7
were
found
not
to
b e
pulsating
stars
at
all. |