Space agencies NASA and ESA released a new image taken by the Hubble Space Telescope of the spiral galaxy NGC 691, the eponymous galaxy for the galaxy group where it belongs.
In the image released by the ESA/ Hubble website, the composite photo captures the NGC 691 in stunning detail. The galaxy in the image is a part of the NGC 691 galaxy group, a cluster of gravitationally bound galaxies located about 120 million light-years from Earth.
An Impressive, Multilayered Image
The photo was taken by the Wide Field Camera 3 (WFC3) installed onboard the Hubble Space Telescope. With the massive and distant object being observed by the WFC3, it used a range of filters which are then combined to generate the released photo. ESA explains that each filter only allows a specific wavelength of light to be processed by the WFC3. Different imaging data collected through different filters were then colored by "specialised visual artists" who are capable of making informed choices regarding color choices corresponding to each filter.
"By combining the coloured images from individual filters, a full-colour image of the astronomical object can be recreated. In this way, we can get remarkably good insight into the nature and appearance of these objects," ESA said in the press release.
The WFC3 is the latest and most technologically advanced imaging equipment onboard the Hubble Space Telescope, replacing its predecessor, the Wide Field and Planetary Camera 2 (WFPC2), during the first spacewalk, STS-125 space mission on May 14, 2009. According to the Space Telescope Science Institute (STScI), it has two separate light paths, each with a specific wavelength range admitted through its channel. One is a channel for ultraviolet and optical light, the latter using charge-coupled devices to capture images ranging from 200 to 1000 nanometers. The other is a near-infrared detector array that captures images from 800 to 1700 nanometers in wavelength.
The NGC691 Galaxy Group
The spiral galaxy NGC 691 is an "unbarred spiral galaxy," since it does not have a central bar-shaped structure in the middle of it. Also, given its distance, it is estimated to be about 130,000 light-years across, compared to our own Milky Way galaxy, whose estimated visible diameter is between 100,000 to 200,000 light-years.
NGC691 was first discovered by William Herschel, the German-born British astronomer, and musician who also discovered Uranus in 1781.
A report published in 2013 states that NGC 691 has a multiple ring structure, with three of these rings benign detected by infrared sensors and were computed to have diameters of 1.03, 1.67, and 2.79 arcminutes. An arcminute, approximately the resolution of a human eye, is an angular measurement equivalent to 1/60th of a degree, or 60 arcseconds. In perspective, the Sun and the Moon approximately 30 arcminutes of angular diameters are viewed on Earth, according to the Swinburne University of Technology in Australia.
Other members of the NGC 691 galaxy group include the elliptical galaxy NGC 680, the barred spiral galaxy IC 167, and the spiral galaxy NGC 694.
Read also: Exoplanet Discovery: NASA's Hubble Space Telescope Witnesses Growing, Feeding Giant Planet
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