Most galaxies possess a majestic spiral or elliptical structure. About a quarter of galaxies, though, defy such conventional, rounded aesthetics, instead sporting a messy, indefinable shape. Known as irregular galaxies, this group includes NGC 5408, the galaxy that has been snapped here by the NASA/ESA Hubble Space Telescope.
English polymath John Herschel recorded the existence of NGC 5408 in June 1834. Astronomers had long mistaken NGC 5408 for a planetary nebula, an expelled cloud of material from an aging star. Instead, bucking labels, NGC 5408 turned out to be an entire galaxy, located about 16 million light-years from Earth in the constellation of Centaurus(The Centaur).
In yet another sign of NGC 5408 breaking convention, the galaxy is associated with an object known as an ultraluminous X-ray source, dubbed NGC 5408 X-1, one of the best studied of its class. These rare objects beam out prodigious amounts of energetic X-rays. Astrophysicists believe these sources to be strong candidates for intermediate-mass black holes.
Geminids of the South : Earth’s annual Geminid meteor shower did not disappoint, peaking before dawn on December 14 as our fair planet plowed through dust from active asteroid 3200 Phaethon. Captured in this southern hemisphere nightscape the meteors stream away from the shower’s radiant in Gemini. To create the image, many individual frames recording meteor streaks were taken over period of 5 hours. In the final composite they were selected and registered against the starry sky above the twin 6.5 meter Magellan telescopes of Carnegie Las Campanas Observatory in Chile. Rigel in Orion, and Sirius shine brightly as the Milky Way stretches toward the zenith. Near Castor and Pollux the twin stars of Gemini, the meteor shower’s radiant is low, close to the horizon. The radiant effect is due to perspective as the parallel meteor tracks appear to converge in the distance. Gemini’s meteors enter Earth’s atmosphere traveling at about 22 kilometers per second. via NASA
Despite being just 250 million light years from Earth—very close in astronomical terms—the new galaxies had been hidden from view until now by our own galaxy, the Milky Way.
Using CSIRO’s Parkes radio telescope equipped with an innovative receiver, an international team of scientists were able to see through the stars and dust of the Milky Way, into a previously unexplored region of space.
The discovery may help to explain the Great Attractor region, which appears to be drawing the Milky Way and hundreds of thousands of other galaxies towards it with a gravitational force equivalent to a million billion Suns.
Lead author Professor Lister Staveley-Smith, from The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR), said the team found 883 galaxies, a third of which had never been seen before.
Planetary nebula Hen 2-437 lies within the faint northern constellation of Vulpecula (The Fox). As an aging low-mass star like our sun transforms into a planetary nebula in the last stage of its life, when it becomes a red giant and casts off its outer layers of gas into space. Hen 2-437 hurls its ejected material out into diametrically opposed directions making it a bipolar nebula, featuring two icy blue lobes.
Sit back and watch a star explode. The actual supernova occurred back when dinosaurs roamed the Earth, but images of the spectacular event began arriving last year. Supernova 2015F was discovered in nearby spiral galaxy NGC 2442 by Berto Monard in 2015 March and was unusually bright – enough to be seen with only a small telescope. The pattern of brightness variation indicated a Type Ia supernova – a type of stellar explosion that results when an Earth-size white dwarf gains so much mass that its core crosses the threshold of nuclear fusion, possibly caused by a lower mass white-dwarf companion spiraling into it. Finding and tracking Type Ia supernovae are particularly important because their intrinsic brightness can be calibrated, making their apparent brightness a good measure of their distance – and hence useful toward calibrating the distance scale of the entire universe.
The featured video tracked the stellar disruption from before explosion images arrived, as it brightened, and for several months as the fission-powered supernova glow faded. The remnants of SN2015F are now too dim to see without a large telescope.