Hubble Sees Beautiful Globular Cluster: NGC 1805 | Astronomy

The NASA/ESA Hubble Space Telescope has captured the brilliance of a globular cluster called NGC 1805.

This Hubble image NGC 1805, a globular cluster located 163,000 light-years away in the constellation of Dorado. The color image is made up of observations from Hubble’s Wide Field Camera 3 (WFC3) in the ultraviolet, near-infrared, and optical parts of the spectrum. Four filters were used to sample various wavelengths. The color results from assigning different hues to each monochromatic image associated with an individual filter. Image credit: NASA / ESA / Hubble / J. Kalirai.

Globular clusters are systems of very ancient stars, gravitationally bound into a single structure about 100-200 light-years across.

They are among the oldest known objects in the Universe and are relics of the first epochs of galaxy formation.

Globular clusters contain hundreds of thousands or perhaps a million stars. The large mass in the rich stellar center of a cluster pulls the stars inward to form a ball of stars. The word globulus, from which these clusters take their name, is Latin for small sphere.

It is thought that every galaxy has a population of globular clusters. Some, like the Milky Way, have a few hundred, while elliptical galaxies can have several thousand.

NGC 1805 is located approximately 163,000 light-years away in the southern constellation of Dorado.

Also known as ESO 85-32 and KMHK 459, it resides in the outskirts of the Large Magellanic Cloud, a satellite galaxy of our own Milky Way Galaxy.

NGC 1805 was discovered on September 24, 1826 by the Scottish astronomer James Dunlop.

“Usually, globular clusters contain stars which are born at the same time; however, NGC 1805 is unusual as it appears to host two different populations of stars with ages millions of years apart,” Hubble astronomers said.

“Observing such clusters of stars can help us understand how stars evolve, and what factors determine whether they end their lives as white dwarfs, or explode as supernovae.”

“The striking difference in star colors is illustrated beautifully in this Hubble image, which combines two different types of light: blue stars, shining brightest in near-ultraviolet light, and red stars, illuminated in red and near-infrared,” they said.

“Space telescopes like Hubble can observe in the ultraviolet because they are positioned above Earth’s atmosphere, which absorbs most of this wavelength, making it inaccessible to ground-based facilities.”