The SOCIETY for POPULAR ASTRONOMY
Electronic News Bulletin No. 368 2014 January 19
Here is the latest round-up of news from the Society for Popular Astronomy. The SPA is Britain's liveliest astronomical society, with members all over the world. We accept subscription payments online at our secure site and can take credit and debit cards. You can join or renew via a secure server or just see how much we have to offer by visiting http://www.popastro.com/ EARTH-MASS GAS PLANET Harvard-Smithsonian Center for Astrophysics
Astronomers have discovered the first Earth-mass planet that transits,
or crosses in front of, its host star. KOI-314c is the lightest planet to have both its mass and physical size measured. Surprisingly, although the planet weighs the same as Earth, it is 60 percent larger in diameter, meaning that it must have a very thick, gaseous atmosphere. The planet might have the same mass as Earth, but it is certainly not Earth-like and proves that there is no clear dividing line between rocky worlds like Earth and fluffier planets like water worlds or gas giants. The team gleaned the planet's characteristics using data from NASA's Kepler spacecraft. KOI-314c orbits a dim, red dwarf star located approximately 200 light-years away. It circles its star every 23 days. The team estimates its temperature to be 105 degrees Centigrade. KOI-314c is only 30 percent denser than water which suggests that the planet is enveloped by a significant atmosphere of hydrogen and helium hundreds of miles thick. It might have begun life as a mini-Neptune and lost some of its atmospheric gases over time, boiled off by the intense radiation of its star.
Weighing such a small planet was a challenge. Conventionally,
astronomers measure the mass of an exoplanet by measuring the tiny wobbles of the parent star induced by the planet's gravity. This radial velocity method is extremely difficult for a planet with Earth's mass. The previous record holder for a planet with a measured mass (Kepler-78b) weighed 70 percent more than Earth. To weigh KOI-314c, the team relied on a different technique known as transit timing variations (TTV). This method can only be used when more than one planet orbits a star. The two planets tug on each other, slightly changing the times that they transit their star. Rather than looking for a wobbling star, astronomers essentially look for a wobbling planet, Kepler saw two planets transiting in front of the same star over and over again. By measuring the times at which these transits occurred very carefully, they were able to discover that the two planets are locked in an intricate dance of tiny wobbles giving away their masses. The second planet in the system, KOI-314b, is about the same size as KOI-314c but significantly denser, weighing about 4 times as much as Earth. It orbits the star every 13 days, meaning it is in a 5-to-3 resonance with the outer planet. TTV is a very young method of finding and studying exoplanets, first used successfully in 2010. The planet was discovered by chance by the team as they scoured the Kepler data not for exoplanets, but for exomoons. The Hunt for Exomoons with Kepler (HEK) project scans through Kepler's planet haul looking for TTV, which can also be a signature of an exomoon. When astronomers noticed this planet showed transit timing variations, the signature was clearly because of the other planet in the system and not a moon. At first they were disappointed it wasn't a moon but then they soon realized it was an extraordinary measurement. NEW TYPE OFCELESTIAL OBJECT University of Toronto
An object located near and likely orbiting a very young star about 440
light years away from the Sun, is leading astrophysicists to believe that there is not an easy-to-define line between what is and is not a planet. Astronomers have very detailed measurements of the object spanning seven years, even a spectrum revealing its gravity, temperature, and molecular composition. Still they can't yet determine whether it is a planet or a failed star -- what we call a 'brown dwarf'. Depending on what measurement you consider, the answer could be either. Named ROXs 42Bb for it's proximity to the star ROXs 42B, the object is approximately nine times the mass of Jupiter, below the limit most astronomers use to separate planets from brown dwarfs, which are more massive. However, it is located 30 times further away from the star than Jupiter is from the Sun. Most astronomers believe that gas giant planets like Jupiter and Saturn formed by core accretion, whereby the planets form from a solid core that then accretes a massive gaseous envelope. Core accretion operates most efficiently closer to the parent star owing to the length of time required to first form the core. An alternate theory proposed for forming gas giant planets is disk instability -- a process by which a fragment of a disk gas surrounding a young star directly collapses under its own gravity into a planet. This mechanism works best farther away from the parent star.
Of the dozen or so other young objects with masses of planets observed
by the team, some have planet-to-star mass ratios less than about 10 times that Jupiter and are located within about 15 times Jupiter's separation from the Sun. Others have much higher mass ratios and/or are located more than 50 times Jupiter's orbital separation, properties that are similar to much more massive objects widely accepted to not be planets. The first group would be planets formed by core accretion, and the second group probably formed just like stars and brown dwarfs. In between these two populations is a big gap separating true planets from other objects. Astronomers say that the new object starts to blur this distinction between planets and brown dwarfs, and may lie within and begin to fill the gap. It's very hard to understand how this object formed like Jupiter did. However, it's also too low mass to be a typical brown dwarf; disk instability might just work at its distance from the star. It may represent a new class of planets or it may just be a very rare, very low-mass brown dwarf formed like other stars and brown dwarfs: a 'planet mass' brown dwarf. Regardless, it should spur new research in planet and star formation theories, and serve as a crucial reference point with which to understand the properties of young planets at similar temperatures, masses and ages. TRIPLE STAR SYSTEM COULD REVEAL SECRETS OF GRAVITY BBC News
Astronomers have discovered a triple star system which could reveal
the true nature of gravity. They found a pulsar with two white dwarfs all packed in a space smaller than Earth's orbit of the Sun. The trio's unusually close orbits allow precise measurements of gravity and could resolve difficulties with Einstein's theories. This triple system gives us a natural cosmic laboratory far better than anything found before for learning exactly how such three-body systems work and potentially for detecting problems with general relativity that physicists expect to see under extreme conditions. Pulsars emit lighthouse-like beams of radio waves that rapidly sweep through space as the stars spin on their axes and are formed after a supernova collapses a burnt-out star to a dense, highly magnetised ball of neutrons.
Using the Green Bank Telescope, the astronomers discovered a pulsar
4,200 light-years from Earth, spinning nearly 366 times per second. Such rapidly-spinning bodies are called millisecond pulsars - and are used by astronomers as precision tools for studying gravitational effects and other phenomena. Subsequent observations showed the pulsar is in a close orbit with a white dwarf star, and that pair is in orbit with another, more-distant white dwarf. Three-body systems are keenly studied because they allow competing theories of gravity to be tested. But until now the only known triple system containing a millisecond pulsar was one with a planet as the outer companion, causing only weak gravitational interactions. The gravitational perturbations imposed on each member of this system by the others are incredibly pure and strong. By precisely timing the arrival of the pulses, the scientists were able to calculate the geometry of the system and the masses of the stars. The pulsar's inner white-dwarf companion has an orbital period of less than two days, while the outer dwarf has a period of almost a year. The system gives the scientists the best opportunity yet to look for violations of the equivalence principle described by Einstein - which states that the effect of gravity on a body does not depend on the nature or internal structure of that body. This was famously illustrated by Galileo's dropping of two balls of different weights from the Leaning Tower of Pisa, and Apollo 15 Commander Dave Scott's dropping of a hammer and a falcon feather while standing on the Moon in 1971. Rather than drifting to the ground, the feather plummeted, falling as fast as the hammer. Without air resistance to slow the feather, both objects hit the lunar dust at the same time. While Einstein's theory of general relativity has so far been confirmed by every experiment, it is not compatible with quantum theory. Because of that, physicists expect that it will break down under extreme conditions. High-precision timing of the pulsar's "lighthouse" flashes will let astronomers hunt for deviations in the equivalence principle at a sensitivity several orders of magnitude greater than ever before. Finding a deviation would indicate a breakdown of general relativity and point us toward a new, correct theory of gravity. ALMA OBSERVES SUPERNOVA DUST FACTORY ESO
Galaxies can be remarkably dusty places and supernovae are thought to
be a primary source of that dust, especially in the early Universe. But direct evidence of a supernova's dust making capabilities has been slim up to now, and could not account for the copious amount of dust detected in young, distant galaxies. But now observations with ALMA are changing that. An international team of astronomers used ALMA to observe the glowing remains of Supernova 1987A , which is in the Large Magellanic Cloud, a dwarf galaxy orbiting the Milky Way about 160 000 light years from Earth. SN 1987A is the closest observed supernova explosion since Johannes Kepler's observation of a supernova inside the Milky Way in 1604. Astronomers predicted that as the gas cooled after the explosion, large amounts of dust would form as atoms of oxygen, carbon, and silicon bonded together in the cold central regions of the remnant. However, earlier observations of SN 1987A with infrared telescopes, made during the first 500 days after the explosion, detected only a small amount of hot dust. Using ALMA, the research team was able to image the far more abundant cold dust, which glows brightly in millimetre and submillimetre light. The astronomers estimate that the remnant now contains about 25 percent the mass of the Sun in newly formed dust. They also found that significant amounts of carbon monoxide and silicon monoxide have formed. Supernovae, however, can both create and destroy dust grains. As the shockwave from the initial explosion radiated out into space, it produced bright glowing rings of material, as seen in earlier observations with the NASA/ESA Hubble Space Telescope. After hitting this envelope of gas, which was sloughed off by the progenitor red giant star as it neared the end of its life, a portion of this powerful explosion rebounded back towards the centre of the remnant. At some point, this rebound shockwave will slam into these billowing clumps of freshly minted dust and it's likely that some fraction of the dust will be blasted apart at that point. It's hard to predict exactly how much — maybe only a little, possibly a half or two thirds. If a good fraction survives and makes it into interstellar space, it could account for the copious dust astronomers detect in the early Universe. ISS LIFE TO BE EXTENDED BBC News
NASA has won White House backing to extend the life of the
International Space Station for a further four years, until 2024. Construction of the ISS began in 1998 and is a joint venture between the US, Russia, Canada, Japan, and states in the European Space Agency (ESA). For the extension to happen, it will likely need the partners' support. Their current commitments run to 2020, but many engineers believe the station could work safely until at least 2028. NASA says that it is feasible to continue operating the ISS if some partners decided not to stay on board, but it expects them all to offer full support, even if the agreements took a few years to put in place. Certainly, Germany, Europe's biggest contributor to the ISS project is keen to see the $100bn orbiting platform operate for many years into the future.
At the moment, the station is solely reliant on Russian Soyuz capsules
to rotate the platform's six-person crew. NASA is therefore seeding American companies, including Sierra Nevada, to help them design and build alternatives. The mini-shuttle is known as the Dream Chaser and would launch atop an Atlas rocket from Cape Canaveral in Florida. It is envisaged that the vehicle will make its maiden voyage into orbit in 2016, in an autonomous configuration; and then fly its first manned mission in 2017. The Ariane 5 was originally conceived as a human launcher, and Europe spent considerable funds designing its own mini- shuttle called Hermes to go on top of the rocket. Budget constraints eventually led to the Hermes project being cancelled.
NASA SPACECRAFT FINDS ITS FIRST NEW ASTEROID
NASA
NASA's Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE)
spacecraft has discovered a never-before-seen asteroid -- its first such discovery since coming out of hibernation last year. NEOWISE originally was called the Wide-field Infrared Survey Explorer (WISE), which had made the most comprehensive survey to date of asteroids and comets. The spacecraft was shut down in 2011 after its primary mission was completed, but in September 2013, it was reactivated, renamed and given a new mission, which is to assist NASA's efforts to identify the population of potentially hazardous near-Earth objects (NEOs). NEOWISE also can assist in characterizing previously detected asteroids that could be considered potential targets for future exploration missions. NEOWISE's first discovery of its renewed mission came on Dec. 29 -- a near-Earth asteroid designated 2013 YP139. The mission's sophisticated software picked out the moving object against a background of stationary stars. As NEOWISE circled Earth scanning the sky, it observed the asteroid several times over half a day before the object moved beyond its view. 2013 YP139 is about 43 million kilometres from Earth. Based on its infrared brightness, scientists estimate it to be roughly 650 metres in diameter and extremely dark, like a piece of coal. The asteroid circles the Sun in an elliptical orbit tilted to the plane of our solar system and is classified as potentially hazardous. It is possible for its orbit to bring it as close as 300,000 miles from Earth, a little more than the distance to the Moon. However, it will not come that close within the next century. WISE discovered more than 34,000 asteroids and characterized 158,000 throughout the solar system during its prime mission in 2010 and early 2011. Its reactivation in September followed 31 months in hibernation. NEOWISE will continue to detect asteroids and comets. COUNTDOWN TO PLUTO NASA
One of the fastest spacecraft ever built -- NASA's New Horizons -- is
hurtling through the void at nearly one million miles per day. Launched in 2006, it has been in flight longer than some missions last, and it is nearing its destination: Pluto. Closest approach is scheduled for July 2015 when New Horizons flies only 10,000 km from Pluto, but the spacecraft will be busy long before that date. The first step, in January 2015, is an intensive campaign of photography by the Long Range Reconnaissance Imager or "LORRI." This will help mission controllers pinpoint Pluto's location, which is uncertain by a few thousand kilometres. LORRI will photograph the planet against known background star fields. The images will be used to refine Pluto's distance from the spacecraft, and then fire the engines to make any necessary corrections. At first, Pluto and its large moon Charon will be little more than distant pinpricks--but soon they will swell into full-fledged worlds. By late April 2015, the approaching spacecraft will be taking pictures of Pluto that surpass the best images from Hubble. By closest approach in July 2015, a whole new world will open up to the spacecraft's cameras. If New Horizons flew over Earth at the same altitude, it could see individual buildings and their shapes. SPA SOLAR SECTION October 2013 By Geoff Elston, SPA Solar Section Director I've been trying out a combination of a new full aperture solar filter (a "Sonnenfilter SF100" which I bought at the recent SPA 60th Anniversary Convention), UV/IR filter and a deep sky OIII filter when taking images of the Sun with a Canon D550 DSLR and 80mm f11 refractor. The OIII filter is said to act like a solar continuum filter and when ombined with a UV/IR rejection filter helps to improve the clarity of digital solar images. Rotation Nos. 2142 - 2143 There a significant rise in sunspot number in October, compared to the previous two months, and we had at least one, possibly two, naked eye sunspots. The Mean Daily Frequency went up from 2.80 last month to 5.10 this month and the Relative Sunspot Number more than doubled from 35.47 in September, to 71.65 this month. WHITE LIGHT ACTIVITY The first few days of October showed limited sunspot activity. AR1855, AR1856 and AR1857 were seen on the 5th, the first was nearing the W limb, and the second and third were still some way from the SE limb. As AR1857 approached the W limb it was followed by AR1861, AR1864 and AR1865 coming over the SE limb and putting on a fine display by the 10th. All three Active Regions showed signs of growth by next day. On the 13thSpaceweather.com website announced that AR1861 and AR1865, by then near the CM, were active with low-level C class flares due to their sunspot configuration. From mid-month onwards sunspot activity really picked up. AR1875 and AR1877 were seen near the SE limb on 19th. AR1875 was visible to the naked eye on the 24th was remained so even as it neared the NW limb on the 27th. The main spot showed a bright patch of photosphere with a trail of smaller spots behind it. AR1877 was possibly visible to the naked eye as well. AR1882 was much further east, towards the SE limb, and had about 16 umbrae embedded within the penumbrae. A patch of bright photosphere was also seen in the centre of the main spot. On the same day AR1884 and AR1885 were just over the SE or E limb and showed faculae being close to the limb. By the 30th the Sun was again very active, AR1882 was now at the CM behind a very complex group AR1885 and AR1879 coming over the E limb with bright faculae scattered around the two main sunspots. MDF: 5.10 R: 71.65 H-ALPHA ACTIVITY On the 5th plages and filaments were seen around AR1856 and AR1857 and a group of bright lengthy prominences were seen on the E limb. There was a substantial hedgerow prominence on the 7th. Numerous plages and small filaments were seen around AR1861, AR1864 and AR1865 on the 10th as were prominences along the S, E and W limbs. A broad dense prominence was also seen at the NW limb the following day. On the 15th a substantial prominence was seen at the S limb and a sizable arch prominence on the NW limb. Meanwhile AR1861, AR1864 and AR1865 still showed plages and filaments near them. The 17th saw some large and diverse prominences as well as spikes particularly along the SW limb, extending eastwards. AR1875 and AR1877 each showed several plages nearby and AR1877 had a large coiled filament just east of it on the 24th. Also seen on that same day were some filaments at the SE and SW limbs and there were several sizeable prominences visible. On the 25th a long curved filament was observed passing through AR1875, prominences and spikes were seen on the N and W limbs, and a bright highly active prominence on the SE limb. On the 31st several dark conspicuous filaments were seen near the E limb as well as a tree-like prominence on the W limb. MDF (P): 7.18 Go to the Solar Section link on the SPA homepage to see a selection of the many remarkable images and drawings made by the Section membership. Bulletin compiled by Clive Down
(c) 2014 the Society for Popular Astronomy
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Good Clear Skies
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Astrocomet
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Colin James Watling
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Astrocomet
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Colin James Watling
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Various Voluntary work-Litter Picking for Parish Council (Daytime) and also a friend of Kessingland Beach (Watchman)
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Profile: http://www.google.com/profiles/astrocomera
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Lyra Website: https://sites.google.com/site/lyrasociety/
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Real Astronomer and head of the Comet section for LYRA (Lowestoft and Great Yarmouth Regional Astronomers) also head of K.A.G (Kessingland Astronomy Group) and Navigator (Astrogator) of the Stars (Fieldwork)
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Information
Real Astronomer and head of the Comet section for LYRA (Lowestoft and Great Yarmouth Regional Astronomers) also head of K.A.G (Kessingland Astronomy Group) and Navigator (Astrogator) of the Stars (Fieldwork)
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Information
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