Soon after the Big Bang, the Universe became a space filled with "stuff:" neutral gas, dark matter, and radiation. After several hundred million years, primitive structures began to form from the first chemical elements, creating the first massive stars and eventually the first galaxies.

Globular Clusters

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Two M31 GCs

Globular star clusters collections of thousands to millions of stars and are among the oldest objects in the Universe. These star clusters are almost spherical in shape and are held together by gravity. There are more than 120 such clusters known in the Milky Way, yet the nearby Andromeda galaxy, M31, has more than 400, and some giant elliptical galaxies contain well over a thousand. The oldest globular clusters trace the formation histories of the halos of galaxies. New globular clusters are thought to form when galaxies merge.

Galactic Structure

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RG astronomers have for many years used the CfA millimeter-wave telescope to study the distribution and motions of dense, star-forming molecular clouds throughout the Galaxy, and have by now obtained a fairly uniform survey of the entire molecular galaxy. This survey is widely used by Galactic astronomers and continues to yield new results on star formation and Galactic structure. They are also pioneering the use of very long baseline inteferometry to measure extremely precise trigonometric parallaxes and proper motions for masers within massive star forming regions, yielding their distances and 3-dimensional motions.

The Local Group

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Our Sun and all the stars we see in the night sky are within the Milky Way galaxy, and the Milky Way is within a neighborhood of galaxies known as the Local Group. Studies of Local Group galaxies show how the stars, gas, dust, and dark matter are structured, what they are made of, and what physical processes are taking place within them.

Active Galactic Nuclei

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Galaxies are large systems of stars, and most of the light we see comes from the stars. In addition to stars, many galaxies, perhaps most, contain a super-massive black hole in their center. As gas (and an occasional star) falls into the black hole, the falling matter is heated up and emits infrared and visible light and X-rays, often in jet-like features.

Supernova Remnants

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Keplar SNR

The collapse of a massive star and the resulting supernova explosion are dramatic events which both complete the stellar life cycle and regulate the structure of the Galaxy's interstellar medium. However, we don't yet fully understand how stars explode; constraints on the many complicated processes which occur during core collapse or thermonuclear detonation are desperately needed.