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Hubble revisits an irregular dwarf galaxy bursting with young stars

This week’s image from the Hubble Space Telescope shows the quirky dwarf galaxy NGC 1705, an unusually shaped small galaxy located 17 million light-years away. Stars have formed in this galaxy across its entire lifetime, but the galaxy went through a very intensive period of star formation, called a starburst, approximately 30 million years ago. Many of the stars born during this period are now located around the central core or within the huge central star cluster.

This particular dwarf galaxy is an irregular shape, but it is still a useful object of study. Dwarf galaxies are thought to be some of the oldest galaxies, so studying them can help us learn about the early universe. This one was observed in order to learn about young stars.

Dwarf galaxy NGC 1705 in this image from the NASA/ESA Hubble Space Telescope.
The dwarf galaxy NGC 1705 featured in this image from the NASA/ESA Hubble Space Telescope lies in the southern constellation Pictor, approximately 17 million light-years from Earth. NGC 1705 is a cosmic oddball – it is small, irregularly shaped, and has recently undergone a spate of star formation known as a starburst. ESA/Hubble & NASA, R. Chandar

“The data shown in this image come from a series of observations designed to unveil the interplay between stars, star clusters, and ionized gas in nearby star-forming galaxies,” Hubble scientists write. “By observing a specific wavelength of light known as H-alpha with Hubble’s Wide Field Camera 3, astronomers aimed to discover thousands of emission nebulae – regions created when hot, young stars bathe the clouds of gas surrounding them in ultraviolet light, causing them to glow.”

This isn’t the first time that Hubble has imaged the galaxy NGC 1705. You can also see an image of the same galaxy below, as captured by Hubble in two observations in 1999 and 2000.

Dwarf galaxy NGC 1705, captured by Hubble in 1999 and 2000.
Dwarf galaxy NGC 1705, captured by Hubble in 1999 and 2000. NASA , ESA , and The Hubble Heritage Team (STScI /AURA ); Acknowledgment: M. Tosi (INAF, Osservatorio Astronomico di Bologna)

The striking difference in the quality and detail of the two images shows how much technology has developed in the last 20 years. The older image was taken using Hubble’s Wide Field and Planetary Camera 2, the predecessor to the Wide Field Camera 3 which took the newer image. The Wide Field Camera 3 was installed in 2009, during the final Space Shuttle mission to Hubble.

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