Pillars of Creation

This image composite highlights the pillars of the Eagle nebula, as seen in infrared light by NASA's Spitzer Space Telescope (bottom) and visible light by NASA's Hubble Space Telescope (top insets).

The top right inset focuses on the three famous pillars, dubbed the "Pillars of Creation," which were photographed by Hubble in 1995. Hubble's optical view shows the dusty towers in exquisite detail, while Spitzer's infrared eyes penetrate through the thick dust, revealing ghostly transparent structures. The same effect can be seen for the pillar outlined in the top left box.

In both cases, Spitzer's view exposes newborn stars that were hidden inside the cocoon-like pillars, invisible to Hubble. These stars were first uncovered by the European Space Agency's Infrared Satellite Observatory. In the Spitzer image, two embedded stars are visible at the tip and the base of the left pillar, while one star can be seen at the tip of the tallest pillar on the right.

Image Credit: NASA/JPL-Caltech/STScI/ Institut d'Astrophysique Spatiale

Source: NASA

Read more »

Rosset nebula

This infrared image from NASA's Spitzer Space Telescope shows the Rosette nebula, a pretty star-forming region more than 5,000 light-years away in the constellation Monoceros. In optical light, the nebula looks like a rosebud, or the "rosette" adornments that date back to antiquity.

But lurking inside this delicate cosmic rosebud are so-called planetary "danger zones" (see spheres illustrations in figure 1). These zones surround super hot stars, called O-stars (blue stars inside spheres), which give off intense winds and radiation. Young, cooler stars that just happen to reside within one of these zones are in danger of having their dusty planet-forming materials stripped away.

While O-star danger zones were known about before, their parameters were not. Astronomers used Spitzer's infrared vision to survey the extent of the five danger zones shown here. The results showed that young stars lying beyond 1.6 light-years, or 10 trillion miles, of any O-stars are safe, while young stars within this zone are likely to have their potential planets blasted into space.

Radiation and winds from the super hot stars have collectively blown layers of dust (green) and gas away, revealing the cavity of cooler dust (red). The largest two blue stars in this picture are in the foreground, and not in the nebula itself.

This image shows infrared light captured by Spitzer's infrared array camera. Light with wavelengths of 24 microns is red; light of 8 microns is green; and light of 4.5 microns is blue.

Image Credit: NASA/JPL-Caltech/Univ. of Ariz

Source: NASA

Read more »

Spitzer Nets Thousands of Galaxies in a Giant Cluster

In just a short amount of time, NASA’s Spitzer Space Telescope has bagged more than a thousand previously unknown dwarf galaxies in a giant cluster of galaxies.

Despite their diminutive sizes, dwarf galaxies play a crucial role in cosmic evolution. Astronomers think they were the first galaxies to form, and they provided the building blocks for larger galaxies. They are by far the most numerous galaxies in our Universe, and are an important tracer of the large-scale structure of the cosmos. Computer simulations of cosmic evolution suggest that high-density regions of the Universe, such as giant clusters, should contain significantly more dwarf galaxies than astronomers have observed to date.

A team led by Leigh Jenkins and Ann Hornschemeier, both at NASA Goddard Space Flight Center in Greenbelt, Md., used Spitzer to study the Coma Berenices cluster, an enormous congregation of galaxies 320 million light-years away in the constellation Coma. The cluster contains hundreds of previously known galaxies that span a volume 20 million light-years across.

Jenkins, Hornschemeier, and their collaborators used data from Spitzer’s Infrared Array Camera (IRAC) to study galaxies at the cluster’s center. They also targeted an outlying region with the goal of comparing the galaxy populations in the different locations to see how environmental variations influence the evolution of galaxies. They stitched together 288 individual Spitzer exposures, each lasting 70 to 90 seconds, into a large mosaic covering 1.3 square degrees of sky.

The team found almost 30,000 objects, whose catalog will be made available to the astronomical
community. Some of these are galaxies in the Coma cluster, but the team realized that a large fraction had to be background galaxies. Using data taken with the 4-meter (13 foot) William Herschel Telescope on the Canary island of La Palma, team member Bahram Mobasher of the Space Telescope Science Institute, in Baltimore, Md., measured distances to hundreds of galaxies in these fields to estimate what fraction are cluster members.

Credit: NASA/JPL-Caltech/GSFC/SDSS

Source: NASA

Read more »