dwarf galaxy pairs hubble space telescope images

Main article: Galaxy groups and clusters X-ray photo by Chandra X-ray Observatory of the Bullet Cluster. The X-ray continuum can arise from bremsstrahlung, either magnetic or ordinary Coulomb, black-body radiation, synchrotron radiation, inverse Compton scattering of lower-energy photons by relativistic electrons, knock-on collisions of fast protons with atomic electrons, and atomic recombination, with or without additional electron transitions. The origin of all observed astronomical X-ray sources is in, near to, or associated with a coronal cloud or gas at coronal cloud temperatures for however long or brief a period.Ī combination of many unresolved X-ray sources is thought to produce the observed X-ray background. Some Solar System bodies emit X-rays, the most notable being the Moon, although most of the X-ray brightness of the Moon arises from reflected solar X-rays.įurthermore, celestial entities in space are discussed as celestial X-ray sources. They include galaxy clusters, black holes in active galactic nuclei (AGN), galactic objects such as supernova remnants, stars, and binary stars containing a white dwarf ( cataclysmic variable stars and super soft X-ray sources), neutron star or black hole ( X-ray binaries). Several types of astrophysical objects emit X-rays. The results were presented on Tuesday at a meeting of the American Astronomical Society in Seattle, Washington.X-rays start at ~0.008 nm and extend across the electromagnetic spectrum to ~8 nm, over which Earth's atmosphere is opaque.Īstrophysical X-ray sources are astronomical objects with physical properties which result in the emission of X-rays. In that case, says Kallivayalil, sky watchers on Earth will have approximately 3 billion years to enjoy the Magellanic Clouds before they fade from sight. If such models prove unsuccessful, however, “then maybe we’ll have to say the clouds are not bound”, says Roeland van der Marel of STScI. Kallivayalil and her colleagues are also investigating whether a clumpy or otherwise asymmetrical distribution of dark matter within the Milky Way could account for the clouds’ speedy motion. The alternative explanation – that the Milky Way contains far more dark matter than expected and so causes the dwarfs to orbit more rapidly – would be equally surprising but may prove easier to accommodate. “The stream implies a bound orbit,” says Martin Weinberg of the University of Massachusetts in Amherst, US. If the clouds are not gravitationally bound to the Milky Way, astronomers will be hard pressed to explain the Magellanic stream – a river of neutral hydrogen gas that trails behind the Magellanic system and wraps around more than a quarter of the night sky. “I really wasn’t expecting them to be moving so fast,” says Nitya Kallivayalil of the CfA. If the two galaxies were orbiting the Milky Way – as many astronomers still believe – their velocities would have to be about 250 km/s. This yielded figures of 378 kilometres per second and 302 km/s for the Large and Small Magellanic clouds respectively. The astronomers used this information to calculate the clouds’ true 3D velocities through space, not just across our line of sight. The astronomers detected these tiny shifts by carefully aligning the clouds in each pair of images and then measuring the apparent change in the positions of several background quasars, bright objects powered by black holes devouring their surroundings. In those two years, both galaxies had shifted a minuscule amount, about one hundredth the width of one pixel in Hubble’s field of view. Recent observations of the Magellanic Clouds, a pair of nearby dwarf galaxies, reveal that they are moving too fast to be satellites of the Milky Way – unless our galaxy contains twice as much dark matter as thought.Īstronomers at the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Massachusetts, and the Space Telescope Science Institute (STScI) in Baltimore, Maryland, both in the US, compared Hubble Space Telescope images taken two years apart to make the most accurate measurements to date of the velocities of the Magellanic Clouds. The Milky Way’s two best-known companions may be nothing more than strangers passing by. (Image: NASA/ESA/Hubble Heritage/STScI/AURA) The Small Magellanic Cloud includes stellar nurseries such as N90, shown here in a newly released image by the Hubble Space Telescope

Dwarf galaxy pairs hubble space telescope images