The Galactic Core


galactic coreWhen we look inward toward the center of the Milky Way, the galactic core is obscured in visible light by intervening dust clouds, but infrared light penetrates the dust. This composite false-color infrared image of the center of our galaxy reveals a new population of massive stars and new details in complex structures in the hot ionized gas swirling around the central 300 light-years.It combines the sharp imaging of the Hubble Space Telescope‘s Near Infrared Camera and Multi-Object Spectrometer (NICMOS) with color imagery from a previous Spitzer Space Telescope survey done with its Infrared Astronomy Camera (IRAC).

In this new data astronomers now see that the massive stars are not confined to one of the three known clusters of massive stars in the Galactic Center, known as the Central cluster, the Arches cluster, and the Quintuplet cluster. These three clusters are easily seen as tight concentrations of bright, massive stars in the image. The unattached stars may have formed in isolation, or they may have originated in clusters that have been disrupted by strong gravitational tidal forces.

The winds and radiation from these stars form the complex structures seen in the core, and in some cases, they may be triggering new generations of stars. IN the upper left large arcs of ionized gas form linear filaments suggesting the influence of locally strong magnetic fields.

The lower left region shows pillars of gas sculpted by winds from hot massive stars in the Quintuplet cluster.

Near the center of the image ionized gas surrounding the supermassive black hole at the center of the galaxy is confined to a bright spiral embedded in a circum-nuclear dusty donut-shaped torus.

Image Credit: NASA / ESA

The Egg Nebula


egg nebulaThe Egg Nebula (aka CRL 2688) is the last gasps of a dying, Sun-like star. This picture superimposes visible light and infrared data from Hubble.

Objects like the Egg Nebula expel carbon and nitrogen—elements crucial for life—into space. Studies of the Egg Nebula show that such dying stars eject matter at high speeds along a preferred axis and may even have multiple jet-like outflows. The signature of the collision between this fast-moving material and the slower, out-flowing shells is the red glow of hydrogen molecules.

Image Credit: NASA

An Old Star Cluster


An ancient globuleThis is NGC 6535, a globular cluster 22,000 light-years away in the constellation of Serpens (The Serpent). It’s about one light-year across.

Globular clusters are tightly bound groups of stars which orbit galaxies. The Latin word globulus, from which these clusters take their name, means a small sphere.  A large mass in the rich stellar centre of a globular cluster pulls the stars inward to form a ball of stars.

Globular clusters are generally very ancient objects that form around the same time as their host galaxy. Thus far, no new star formation has been observed within amy globular cluster. The lack of young stars explains the abundance of aging yellow stars in this image, most of them containing very few heavy elements.

Image Credit: NASA