From a galaxy not so far away, NASA Hubble Space Telescope just released a stunning color image of a star cluster that glows in red, white and blue. Surprisingly, the colors that correspond to the flags of the United States, U.K., Australia, Cuba, France, Haiti, and 30 other nations are pretty close to accurate.
As reported in the Slate blog, the image was actually taken in 2009 and just released now. The star cluster NGC 1854 is located in the Dorado (The Dolphinfish.) The stars pictured are located about 135,000 light years away from Earth in what is actually a satellite galaxy of our Milky Way known as the Large Magellanic Coud (LMC). It’s one of the closest neighbors to our galaxy. Dorado is visible in the southern hemisphere and as reported in Tech Times, Scottish astronomers first viewed the star cluster NGC 1854 through a telescope on August 2, 1896.
The LMC is full of interstellar gas and dust, making it a breeding ground for new star formation. It is home to about 760 open and globular star clusters. Because the stars are in various stages of formation and evolution, Hubble and its ultra high resolution cameras are often used to study the star clusters.
Hubble And Stars In Red, White And Blue
The study of stars is the study of light. Light is part of what is called the electromagnetic spectrum, which is essentially electromagnetic radiation that is emitted in specific wavelengths that translate into light, both visible and invisible to the naked eye.
The stunning color photograph was taken by the Advanced Camera for Surveys (ACS) connected to the Hubble Telescope. The ACS records images in a specific region of the electromagnetic spectrum that includes visible light as well as near-infrared light. This image uses one green and one near-infrared filter to produce the red, white, and blue colors.
However, as noted in the Slate blog, the result comes close to the natural colors of the stars. The filters allow incoming light that occurs at specific wavelengths. By viewing specific sections – called “bandpasses” – of the spectrum, it is possible to separate out specific stars or star formations within clouds of gas such as those found in the LMC.
The Hubble image just released used a wide rather than a narrow bandpass to view a broad range of light waves. The blue and the red stars in the image are close to their natural color. The green filter used by the Hubble team actually filters light that is yellow to orange if seen in true color.
By viewing the star cluster in color, Hubble scientists are able to determine the temperature of the star. Blue light burns hot while red (near-infrared) light burns cooler. However the color alone can’t determine all the parameters in question. For example, a red star could be what is known as a red dwarf that is close by, or a red giant that is much farther away.
As the Slate piece notes, interstellar dust, which is relatively dense in the area of the photograph, can block the light of a star located behind it. That means some of the red stars in the Hubble picture may actually feature much hotter blue stars surrounded by dust that is absorbing some of their light energy.
The Future Of Hubble
Launched in 1990, New Scientist reported that NASA just gave Hubble a renewed lease on life with a 5-year plan to extend operations until June 2021. It will still be operational in 2018, when the next-generation space telescope, the James Webb Space Telescope (or JWST) is launched. Since Hubble views light in the visible and ultraviolet spectra, while JWST observes the infrared spectrum, it will give NASA and the world’s astronomers the ability to observe galaxies and stars in much more detail.
[Image via ESA/Hubble & NASA]