COMPONENTS OF THE UNIVERSE
STARS:
- Stars are the most plentiful objects in the visible universe.
- They provide the light and energy that fuels a solar system.
- Without stars, there would be no life.
- A star's brightness is known as its magnitude.
- Stars begin their lives as clouds of dust and gas called nebulae.
- The life span of a star depends on its size. Very large, massive stars burn their fuel much faster than smaller stars.
- Most average stars will blow away their outer atmospheres to form a planetary nebula.
- There are six types of stars: Main sequence stars, red giants, white dwarfs, brown dwarfs, variable stars, binary stars.
NEBULAE:
- A nebula is a cosmic cloud of gas and dust floating in space. More than one nebula are called nebulae.
- The universe started from nebulae.
- There are many different colors of nebulae.
- Emission nebula: A cloud of high temperature grass.
- Emission nebulae tend to be red in color because of the abundance of hydrogen.
- Additional colors, such as blue and green, can be produced by the atoms of other elements, but hydrogen is almost always the most abundant.
- Reflection nebula: A reflection nebula doesn't emit radiation of its own.
- They usually tend to be blue in color because of the way that the light is scattered.
- Dark Nebula: A dark nebula is a cloud of dust that blocks the light from other objects behind it.
- Planetary nebula: A shell of gas produced by a star that is about to die.
- Supernova Remnant: Created when a star dies on massive explosion
CLUSTERS:
- Some of the stars in the universe are part of multiple star systems known as star clusters.
- Most of them are where two stars orbit a center point of gravity.
- Astronomers have divided star clusters into two main types according to their shape and number of stars : Open clusters and globular clusters.
- Open clusters are also called galactic clusters.
- They usually contain somewhere between a dozen and a thousand stars.
- Open clusters are formed when several stars are formed at the same time from the same cloud of dust and gas.
- Unlike open clusters, globular clusters are much older and usually contain between ten thousand to a million stars, which are gravitationally bound in a tight concentration.
- Some star clusters, such as the Pleiades, have been known for some time. Others remained undiscovered until the invention of the telescope.
- Charles Messier was one of the first astronomers to observe and catalog star clusters along with other deep sky objects
GALAXIES:
- Galaxies are defined as large groupings of stars, dust, and gas held together by gravity.
- They're all mostly gigantic in size, while some are bigger than others.
- There are 4 classifications: Spiral, barred spiral, irregular, and elliptical.
- Spiral galaxies are characterized by a distinct flattened spiral disk with a bright center called the nucleus.
- A barred spiral galaxy is very similar to a spiral with one important difference.
- Elliptical galaxies vary in shape from completely round to extremely elongated ovals.
- Irregular galaxies have no discernable shape or structure.
- Astronomers have recently been working on a massive project to plot the locations of millions of galaxies in the universe.
- Hubble discovered that there was a correlation between the red shift of a galaxy and its distance. This is known today as the Hubble constant.
PULSARS:
- Pulsars are the strangest things in the universe.
- It is a star-like object that seemed to be emitting quick pulses of radio waves.
- They were named pulsars because of their rapidly pulsing nature.
- A pulsar is basically a rapidly spinning neutron star.
- A pulsar is formed when a massive star collapses exhausts its supply of fuel.
- Pulsars are still found today by using large radio telescopes.
QUASARS:
- Quasars are the brightest and most distant objects in the known universe.
- The most distant quasars observed so far are over 10 billion light-years away.
- They aren't exactly stars, but more of star-like objects.
- Astronomers still aren't sure of what these objects are though.
- With being the farthest things known, Quasars also have the largest red shift.
- We still completely don't know what quasars are, but the guesses say that they are produced by large black holes who consume matter in an acceleration disk.
- Another explanation for the quasars are that they are young galaxies.
- It is entirely possible that some or all of the quasars we see today may not even exist any more.
BLACK HOLES:
- Black holes are the most mysterious objects in the universe.
- Their characteristics go against the laws of physics.
- When a super massive star collapses into a black hole, it becomes so small that it no longer has any physical size
- Since light cannot escape from the massive beasts, they can't be seen.
- One way of searching for a black hole is to look for areas of space that exhibit a large amount of mass in a small, dark space.
DARK MATTER:
- Dark matter cannot be seen.
- Though we see many of the stars and galaxies, there are things that we don't see; things that affect us.
- Based on the speed that some of the galaxies are traveling at, they should be falling apart, but something is holding them together.
- "Some of the matter may exist in what is known as non-baryonic matter."
- The Hubble telescope, which helps us discover more things about the universe, also helps us to understand dark matter.
HR DIAGRAM
An HR Diagram shows the size, color, temperature, and brightness of a star.