Astronomy

Stellar systems

Observations of other stellar systems tell us how stars like our Sun are born, live and die. Newly-formed stars ionize the surrounding interstellar medium.

The evolution of stars can be modelled by statistical studies of the 100 billion stars in our galaxy, the Milky Way. At the end of their life stars often shed matter back into interstellar space, either through winds, as in the planetary nebula Abell 78 on the right, or in extreme cases through supernova explosions.

Other galaxies

Many astronomers visiting ING use telescopes to study galaxies outside the Milky Way. By taking images and spectra it is possible to determine how stars are distributed within other galaxies, and model how the galaxies rotate.

A INT image of Messier 51, also known as the Whirlpool galaxy, is shown to the left. This is a bright spiral galaxy, at the relatively close distance of 25 million light years from our own galaxy. The companion galaxy to the north is being disrupted by the gravitational force of the main galaxy.

Where matter is attracted by the strong gravitational forces associated with black holes, large amounts of energy are released which can be seen and measured as intensely bright light sources or explosions. Such activity has been found in the cores of distant galaxies as well as around stars in our own galaxy. For example, a spectrum of the nucleus of Messier 51 shows emission lines from the high-excitation plasma.

Our solar system

Our solar system contains not just the Sun and planets, but also a wide variety of other bodies. Of particular interest are comets, historically seen as harbingers of doom; more recently it has been suggested that the dinosaurs might have been wiped out as a result of a comet colliding with the Earth. Understanding the origin and nature of comets may be important for understanding the history of life on Earth.

On the left are the fragments of comet Shoemaker-Levy 9, which made the news in 1994 when they collided with the planet Jupiter. On the right is comet Hale-Bopp, dominant in the night skies in early 1997. Shoemaker-Levy 9 picture was taken by Jacobus Kapteyn Telescope and Hale-Bopp picture by CoCAM Camera , the wide field imaging facility of ING.

Cosmology

Images taken with long exposures at the WHT reveal galaxies so distant that their light has taken thousands of millions of years to reach us. By studying such galaxies, astronomers are able to look back in time to observe the Universe soon after its creation.

In the image to the right, the faint blue fuzzy spots are galaxies at the edge of the observable universe. These young galaxies, only recently created, are undergoing intense bursts of star-formation. The density of galaxies is found to be much higher in the early universe than it is now.