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Monday, June 15, 2015

Dwarf Spiral Galaxy NGC 6503

Dwarf Spiral Galaxy NGC 6503
Click on the image for full resolution (5.1 MB)

This Hubble Space Telescope image shows galaxy NGC 6503. The galaxy, which lies about 18 million light-years away is at the edge of a strangely empty patch of space called the Local Void. This new image shows a very rich set of colours, adding to the detail seen in previous images. This galaxy does not just offer poetic inspiration; it is also the subject of ongoing research. The Hubble Legacy ExtraGalactic UV Survey (LEGUS) is exploring a sample of nearby galaxies, including NGC 6503, to study their shape, internal structure, and the properties and behaviour of their stars. This survey uses 154 orbits of time on Hubble; by contrast, a typical Hubble observing programme lasts from a few to a few tens of orbits. The Local Void is a patch of space thought to be about 150 million light-years across that seems to be curiously devoid of galaxies. Astronomers using Hubble discovered that the emptiness of this region has quite an effect on the space around us – the Milky Way is being strongly pulled away from it by the gentle but relentless tug of other nearby galaxies. NGC 6503 lies right on the edge of this void. It has an almost non-existent central bulge surrounded by a massive halo of gas. The galaxy's central region is a good example of something known as a "low ionisation nuclear emission region", or LINER. These are less luminous than some of the brightest galaxies.
Emission from NGC 6503's heart is believed to be the result of a starved black hole that is only just being kept active, receiving a very small amount of infalling gas to keep its large appetite at bay. A previous image of NGC 6503 was released as a Hubble Picture of the Week back in 2010, taken by Hubble's Advanced Camera for Surveys. However, this new image, taken using Hubble's Wide Field Camera 3 (WFC3), shows NGC 6503 in striking detail and with a richer set of colours. Bright red patches of gas can be seen scattered through its swirling spiral arms, mixed with bright blue regions that contain newly-forming stars. Dark brown dust lanes snake across the galaxy's bright arms and center, giving it a mottled appearance. Installed in 2009 during the final Hubble servicing mission, SM4, WFC3 covers a wide range of the spectrum, from the ultraviolet all the way through to the near-infrared. Compared with its predecessor, the Wide Field and Planetary Camera 2 (WFPC2), it offers improved resolution and a wider field of view, and has led to a large number of stunning Hubble images since its installation.
Image Credit: NASA, ESA
Image enhancement: Jean-Baptiste Faure

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