About 4.5 million light-years from Earth in the Sextans constellation lies the small Sextans A galaxy. The above picture is a composite multi-wavelength capture by the ESA’s Herschel space observation mission. In it the purple areas are gases; blue areas represent young stars and the orange and yellow dots are newly formed stars heating up the dust. The environment in the Sextans A galaxy does not feature elements heavier than hydrogen and helium which is considered similar to that of our infant universe because it also lacks in heavy metals.
The Messier 82 (M82, NGC 3034) is a star-burst galaxy located about 12 million light-years away from Earth, in the Ursa Major constellation. The above image was captured using the x-ray spectrum by Chandra Observatory. The image below is of the same galaxy but this time it is a composite visible light image taken by NASA’s Hubble Space Telescope.
The Hubble Space Telescope has captured some astonishing views of the universe. This picture taken by its Wide Field Planetary Camera 2 is no slouch either, capturing a couple of galaxies in one shot. The main feature is the spiral galaxy NGC 6872 located about 300 million light-years away in the constellation of Pavo (The Peacock).
NGC 6872 is the second largest spiral galaxy discovered to date by humans. It spans over 500,000 light-years across, compared to the Milky way which is approximately 120,000 light years from end to end. This picture also captures the galaxy IC 4970 which can be seen causing a disruption in NGC 6872’s upper left spiral arm, as it transits through the larger spiral galaxy, helping it create new stars.
This magnificent galactic pyrotechnics light show involves a giant black hole, shock waves, and vast reservoirs of gas doing their magic in this spiral galaxy similar to our Milky Way, but some 23 million light years away from Earth in NGC 4258 (also known as M106). The large “arms” of this spiral galaxy are believed to be shock waves, generated by large black hole at the center, heating large amounts of gas equivalent to about 10 million suns. In this composite image of NGC 4258;
- radio data from the NSF’s Karl Jansky Very Large Array is represented by regions that are purple in colour
- X-rays from NASA’s Chandra X-ray Observatory are in blue
- infrared data from NASA’s Spitzer Space Telescope is in red
- optical data derived from NASA’s Hubble Space Telescope are the yellow and blue areas
Given the vastness of space and the universe, it is difficult to fathom the size of or the dimensions of these regions. But measuring and mapping the magnetic field, from light which was polarized when it was emitted by or scattered off dust and other surfaces, makes it possible to create a “map” using the technique of convolution. The ESA and NASA joint venture Planck satellite helped compile this view of the magnetic field of the Milky Way galaxy.
The dark band running horizontally across the center of the image corresponds to the galactic plane. The darker regions in the rest of the image correspond to stronger polarized emissions, and the striations indicate the direction of the magnetic field projected onto the plane of the sky.