New Stars

NGC 346This image taken by the Hubble Space Telescope shows a population of infant stars in the Milky Way’s satellite galaxy, the Small Magellanic Cloud, located 210,000 light-years away. Some of the stars in the nebula NGC 346 are still forming from gravitationally collapsing gas clouds, and they have not yet ignited their hydrogen fuel to sustain nuclear fusion. The smallest of these infant stars is only half the mass of the Sun.

Image Credit: NASA / ESA

NGC 602

The Small Magellanic Cloud is a satellite galaxy of the Milky Way about 200 thousand light-years from Earth. Near its outskirts lies a 5 million year young star cluster called NGC 602. This Hubble image of the cluster has been augmented by images from the Chandra X-ray Observatory and in the infrared from the Spitzer Space Telescope. The fantastic ridges and swept back shapes in the surrounding gas and dust strongly suggest that energetic radiation and shock waves from NGC 602’s massive young stars are eroding that material and are triggering a progression of star formation moving away from the cluster’s center.

Image Credit: NASA / ESA

A Pair of Nebulae in a Dwarf Galaxy

ngc-248The Hubble Space Telescope took this picture of two nebulas that to appear as one from our point of view. They’re in the Small Magellanic Cloud, a dwarf galaxy that is a satellite of the Milky Way. Intense radiation from the brilliant central stars is heating hydrogen in each of the nebulas, causing them to glow red. The pair, together called NGC 248, were discovered in 1834 by the astronomer Sir John Herschel. NGC 248 is about 60 light-years long and 20 light-years wide.

Image Credit: NASA / ESA

NGC 299

The Toucan and the clusterNGC 299 is an open star cluster located within the Small Magellanic Cloud about 200,000 light-years away. Open clusters are groups of stars  of which formed from the same massive cloud of gas and dust and are loosely held together by gravity. All the stars have roughly the same age and composition, but they vary in their mass because they formed at different positions within the cloud.

Image Credit: ESA / NASA

NGC 346

NGC 346NGC 346 is the brightest star-forming region in the Small Magellanic Cloud galaxy about 210,000 light-years away from Earth. The light, stellar wind, and heat given off by massive stars have spread the glowing gas within and around this star cluster, forming the surrounding wispy, cowbell-like structure of the nebula.

Image Credit: NASA

Getting to the Source

magellanic_streamBack in the 1970s, radio astronomers detected a band of gas that wrapped almost half way around our Milk Way galaxy. Since the origin seemed to be in one or the other of the Large and Small Magellanic Clouds, two nearby satellite galaxies, the gas was named the Magellanic Stream. Recent observations using the Hubble Space Telescope have sources of the gas stream.

Most of the gas was stripped from the Small Magellanic Cloud about 2 billion years ago, but a second region of the stream originated more recently from the Large Magellanic Cloud. This was determined by using Hubble‘s Cosmic Origins Spectrograph to measure the amount of heavy elements, such as oxygen and sulfur, at six locations along the Magellanic Stream. The heavy elements were detected by their absorption of ultraviolet light from distant quasars. There was a low amount of oxygen and sulfur along most of the stream, matching the levels in the Small Magellanic Cloud roughly 2 billion years ago, when the gaseous ribbon is thought to have formed, but there are much higher level of sulfur in a region of the stream that is closer to the Magellanic Clouds, suggesting that the Large Cloud may be a more recent source too.

Image Credit: NASA

The Magellanic Clouds in UV

During my early days working at Goddard Space Flight Center, I designed one of the subsystems in the instrument that normally serves as the viewfinder on the Swift satellite, the Burst Alert Telescope. There are two other instrument aboard, an X-ray Telescope and a UV Optical Telescope. The Swift mission team has used the UVOT to create detailed images of the two galaxies nearest the Milky Way, the Large and Smaller Magellanic Clouds.


A Dwarf Galaxy

This infrared light picture of the Small Magellanic Cloud galaxy was assembled using data from the Herschel Space Observatory, a European Space Agency-led mission, and NASA’s Spitzer Space Telescope. The Large and Small Magellanic Clouds are the two biggest satellite galaxies of our home galaxy. They are considered dwarf galaxies compared to the big spiral of the Milky Way.

By combining data from Herschel and Spitzer, the irregular distribution of dust in the Small Magellanic Cloud becomes clear. A stream of dust called the galaxy’s “wing” extends to the left in the picture, and a vertical line of star formation is on the right.

The colors in this image indicate temperatures in the dust in the Cloud. Regions where star formation is at its earliest stages or is shut off are cooler. Warm spot occur around new stars heating surrounding dust. The coldest areas and objects are red, corresponding to infrared light taken up by Herschel’s at 250 microns (A micron is 0.000001 m). Herschel 100 and 160 micron data shown in green indicates warmer areas.1 The warmest spots appear in blue and are derived from 24 and 70 micron data from Spitzer.

Image Credit: ESA/NASA/JPL