Astronomers could soon be able to find rocky planets stretched out by the gravity of the stars they orbit, according to a group of researchers in the United States. The team, led by Prabal Saxena of George Mason University, describe how to detect these exotic worlds in a paper in the journal Monthly Notices of the Royal Astronomical Society.
Since the first discovery in 1993, more than 1800 planets have been found in orbit around stars other than our Sun. These ‘exoplanets’ are incredibly diverse, with some gaseous like Jupiter and some mostly rocky like the Earth. The worlds also orbit their stars at very different distances, from less than a million km to nearly 100 billion km away.
Scientists believe they have found a way to explain why there are not as many galaxies orbiting the Milky Way as expected. Computer simulations of the formation of our galaxy suggest that there should be many more small galaxies around the Milky Way than are observed through telescopes.
This has thrown doubt on the generally accepted theory of cold dark matter, an invisible and mysterious substance that scientists predict should allow for more galaxy formation around the Milky Way than is seen.
Now cosmologists and particle physicists at the Institute for Computational Cosmology and the Institute for Particle Physics Phenomenology, at Durham University, working with colleagues at LAPTh College & University in France, think they have found a potential solution to the problem.
Writing in the journal Monthly Notices of the Royal Astronomical Society, the scientists suggest that dark matter particles, as well as feeling the force of gravity, could have interacted with photons and neutrinos in the young Universe, causing the dark matter to scatter.
Scientists have used NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR), an orbiting X-ray telescope, to capture an extreme and rare event in the regions immediately surrounding a supermassive black hole. A compact source of X-rays that sits near the black hole, called the corona, has moved closer to the black hole over a period of just days. The researchers publish their results in Monthly Notices of the Royal Astronomical Society.
“The corona recently collapsed in towards the black hole, with the result that the black hole’s intense gravity pulled all the light down onto its surrounding disk, where material is spiralling inward,” said Michael Parker of the Institute of Astronomy in Cambridge, lead author of the new paper.
As the corona shifted closer to the black hole, the black hole’s gravitational field exerted a stronger tug on the x-rays emitted by the corona. The result was an extreme blurring and stretching of the X-ray light. Such events had been observed previously, but never to this degree and in such detail.
Astronomers investigating behaviour of the universe shortly after the Big Bang have made a surprising discovery: the properties of the early universe are determined by the smallest galaxies. The team report their findings in a paper published today in the journal Monthly Notices of the Royal Astronomical Society.
Shortly after the Big Bang, the universe was ionised: ordinary matter consisted of hydrogen with its positively charged protons stripped of their negatively charged electrons. Eventually, the universe cooled enough for electrons and protons to combine and form neutral hydrogen. This cool gas will eventually form the first stars in the universe but for millions of years, there are no stars. Astronomers therefore aren’t able to see how the cosmos evolved during these ‘dark ages’ using conventional telescopes. The light returned when newly forming stars and galaxies re-ionised the universe during the ‘epoch of re-ionisation’.
The Royal Astronomical Society (RAS) today expressed deep regret at the decision of the Science and Technology Facilities Council (STFC) to end support for two major astronomical telescopes. The decision, a consequence of ongoing real terms cuts to the UK science budget by the Government, will almost certainly see the Hawaii-based UK Infrared Telescope (UKIRT) cease operations in the autumn of 2013 and the James Clerk Maxwell Telescope (JCMT) do the same a year later, with the loss of around 40 jobs.
The Society however welcomed the decision to seek to continue UK involvement in the William Herschel Telescope (WHT), sited on the island of La Palma in the Canaries, which observes the sky in visible light. Without the WHT, UK astronomers would have been in the odd position of being unable to observe the northern hemisphere of the sky – in other words many of the stars and galaxies above our heads – at optical wavelengths. This access is also critical for instrument development and for observations that complement new radio observatories like the pan-European LOFAR array.
The Royal Observatory Greenwich, in association with Sky at Night Magazine, launches its 2012 Astronomy Photographer of the Yearcompetition today – kicking off its annual global search for the most beautiful and spectacular visions of the cosmos, whether they are striking pictures of vast galaxies millions of light years away, or dramatic images of the night sky taken much closer to home.
Entries to the competition must be submitted by midday on 29 June 2012 and the winning images will be showcased in the annual free exhibition at the Royal Observatory, Greenwich from 21 September 2012 to February 2013. Last year the competition, which was first launched in 2009, attracted a record number of entries with over 700 spectacular images submitted from around the world. The competition also saw its first UK overall winner, as amateur astronomer Damian Peach scooped the top prize for his incredibly detailed shot of Jupiter along with two of its 64 known moons, Io and Ganymede, showing the surface of the gas giant streaked with colourful bands and dotted with huge oval storms. Sir Patrick Moore, who is one of the competition judges, was impressed by the quality of entries describing Damian’s shot as a ‘very worthy winner against extremely strong competition’.
Fat doughnut-shaped dust shrouds that obscure about half of supermassive black holes could be the result of high speed crashes between planets and asteroids, according to a new theory from an international team of astronomers. The scientists, led by Dr. Sergei Nayakshin of the University of Leicester, publish their results in the journal Monthly Notices of the Royal Astronomical Society.
Supermassive black holes reside in the central parts of most galaxies. Observations indicate that about 50% of them are hidden from view by mysterious clouds of dust, the origin of which is not completely understood. The new theory is inspired by our own Solar System, where the so-called zodiacal dust is known to originate from collisions between solid bodies such as asteroids and comets. The scientists propose that the central regions of galaxies contain not only black holes and stars but also planets and asteroids.