Documentary of the History channel's "The Universe" series, this episode from season 3 takes a look at the different types of Nebulas. From the Nebulas which give birth to Stars, to those which are the remnants of Stars now gone.
Watch Documentary; The Universe: Nebulas
In the beginning, the Universe was extremely hot and dense, but over time it began to cool and expand. Space filled with protons, neutrons and electrons, which are the building blocks of atoms. Over hundreds of thousands of years, stable atoms of hydrogen and helium evolved. These atoms then massed together in clouds called nebulae.
NGC 6240 - a particularly beautiful butterfly galaxy (sometimes also known as "Lobster Galaxy"). It is composed of a pair of lesser galaxies, which are in the process of merging into each other. These visually enthralling galaxies are located in the Ophiuchus Constellation, at a distance of roughly 400 million light-years from Earth. Ophiuchius is other wise known as the "Serpent Holder". The galaxies will eventually merge completely together within some tens, to hundreds of millions of years. When this finally happens, it is thought that the two giant black holes within these galaxies will drift toward one another, formaing an even bigger black hole.
Arp 148, cutely nicknamed Mayall's object, is the remains of a collision between two galaxies, what followed, was the formation of a circular ring galaxy and a long streak which is the other galaxy. The collision between the two original galaxies cause a shockwave which pulled matter into the central core, which subsequently caused it to expand into the ring shape you can see before you. Arp 148 is situated in Ursa Major,otherwise known as "the Great Bear" (Ursa means bear in Latin, and Major means larger), Arp148 is approximately 500 million light-years from Earth.
NGC 1569 is a hive of star birth activity, emitting huge bubbles and super-bubbles that permeate the main mass of NGC 1569. These events are involved in the creation of new stars and superluminous blue star clusters. Approximately 25 million years ago, NGC 1569 galaxy had a sudden onset of star birth , subsiding about the time of Earths early Human Ancestors.
In this new image, taken with the NASA/ESA Hubble Space Telescope, the bubble structure is formed by the galactic super-winds and outflows. Thes are caused by an immense input of power from collective supernova explosions.
The structures that look like bubbles in this image are made of hydrogen gas that glows when coming into contact with the galactic winds and radiation from other hot young stars and is tormented with supernovae shocks. The first supernovae blew up as the most massive stars reached the end of their lifetimes. This occured about 20-25 million years ago.
The environment in NGC 1569 very turbulent and the supernovae which produce the gaseous raw material nnecessary for the formation of further stars and star clusters, triggering their birth in swirls of gas.
Credits: ESA, NASA and Peter Anders (Göttingen University Galaxy Evolution Group, Germany)
NGC 1569 is a peculiar dwarf galaxy, which experienced a very high rate of star formation in the past 150 million years. At the moment, the star formation rate seems to decline a bit. At a distance of only 2.2 Megaparsec, it is the nearest starburst galaxy (you might have though M 82 was the nearest!). The outflow of gas from NGC 1569 has been studied in great detail. In my thesis (Chapter 8), I present maps of the high-velocity NEUTRAL hydrogen in NGC 1569, as well as a previously unknown nearby cloud of atomic hydrogen which might be colliding with NGC 1569.
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