Introductory Astronomy Cosmology Galaxies And The Expanding Universe(1), Astrofizyka i kosmologia
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Dwarf Elliptical M32
Hubble Space Telescope's exquisite resolution has allowed astronomers to resolve, for the first time, hot blue
stars deep inside an elliptical galaxy. The swarm of nearly 8,000 blue stars resembles a blizzard of snowflakes
near the core (lower right) of the neighboring galaxy M32, located 2.5 million light-years away in the
constellation Andromeda.
Hubble confirms that the ultraviolet light comes from a population of extremely hot helium-burning stars at a late
stage in their lives. Unlike the Sun, which burns hydrogen into helium, these old stars exhausted their central
hydrogen long ago, and now burn helium into heavier elements.
Dwarf Elliptical M32
The observations, taken in October 1998, were made with the camera mode of the Space Telescope Imaging
Spectrograph (STIS) in ultraviolet light. The STIS field of view is only a small portion of the entire galaxy, which
is 20 times wider on the sky. For reference, the full moon is 70 times wider than the STIS field-of-view. The
bright center of the galaxy was placed on the right side of the image, allowing fainter stars to be seen on the left
side of the image.
Thirty years ago, the first ultraviolet observations of elliptical galaxies showed that they were surprisingly bright
when viewed in ultraviolet light. Before those pioneering UV observations, old groups of stars were assumed to
be relatively cool and thus extremely faint in the ultraviolet. Over the years since the initial discovery of this
unexpected ultraviolet light, indirect evidence has accumulated that it originates in a population of old, but hot,
helium-burning stars. Now Hubble provides the first direct visual evidence.
Nearby elliptical galaxies are thought to be relatively simple galaxies comprised of old stars. Because they are
among the brightest objects in the Universe, this simplicity makes them useful for tracing the evolution of stars
and galaxies.
History of Cosmology
Early Cosmology:
Cosmology is the study of the Universe and its components, how it formed, how its has evolved and what
is its future. Modern cosmology grew from ideas before recorded history. Ancient man asked questions
such as "What's going on around me?" which then developed into "How does the Universe work?", the
key question that cosmology asks.
Many of the earliest recorded scientific observations were about cosmology, and pursue of understanding
has continued for over 5000 years. Cosmology has exploded in the last 10 years with radically new
information about the structure, origin and evolution of the Universe obtained through recent
technological advances in telescopes and space observatories and bascially has become a search for the
understanding of not only what makes up the Universe (the objects within it) but also its overall
architecture.
Modern cosmology is on the borderland between science and philosophy, close to philosophy because it
asks fundamental questions about the Universe, close to science since it looks for answers in the form of
empirical understanding by observation and rational explanation. Thus, theories about cosmology operate
with a tension between a philosophical urge for simplicity and a wish to include all the Universe's features
versus the shire complexitied of it all.
Very early cosmology, from Neolithic times of 20,000 to 100,000 years ago, was extremely local. The
Universe was what you immediately interacted with. Things outside your daily experience appeared
supernatural, and so we call this time the Magic Cosmology.
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