MAC November 2012 Magazine by MAC Realta

Midlands Astronomy Club Magazine

Sky Guide - Beginner’s targets for November The Milky Way arches overhead passing through Cassiopeia and Perseus. The Summer Triangle reluctantly departs in the west, but the Square in Pegasus is still high in the south-west. Aldebaran, the red eye of Taurus the bull and the yellow Capella stand prominently in the south-east, followed by Gemini and Orion which signal the approach of winter. November Meteors Two meteor showers can be seen this month, the Taurids and Leonids. The Taurids has an extended maximum that lasts for several days either side of November 12th when about 7-10 meteors an hour may be seen coming from the region near the Haydes and Pliades clusters. Taurids are slow-moving and bright making a more impressive display than the low numbers might suggest. The Leonid shower which peaks around November 17th. Radiating from the constellation Leo the Leonids are swift, stabbing meteors, often flaring at the end of their paths often leaving persistent trails. The waxing crescent moon will setting at early evening, leaving a dark night for the Leonid meteor shower. Telescope Targets High in the sky this the hexagonal shape representing a man chariot. The identity of

month is of Auriga driving a Auruga is

Issue 38 - November, 2012

somewhat shadowy, He is usually said to be Erichthonius, a lame king of Athens who invented the four-horse chariot. These is no mistaking the constellation’s brightest star, Alpha (α) Aurigae, better known as Capella and is the sixth-brightest star in the sky. Its name comes from the Latin meaning “little she-goat”, and the charioteer has traditionally be depicted carrying a goat on his left shoulder. Capella is actually a pair of yellow giants forming a spectrospic binary, 42 light years away. The stars Eta (η) Aurigae and Zete (ζ) Aurigae are know as the kids, the goats offspring, carried on the charioteer’s arm. Zeta (ζ) Aurigae is one of two extraordinary eclipsing binary stars in the this constellation. It consists of an orange giant some 150 times larger than the Sun, orbited by a much smaller blue-white star, about four times the diameter of our Sun. Normal Zeta (ζ) Aurigae shines at magnitude 3.7, but every 2 years and 8 months the small star is eclipsed by the red giant and the brightness falls by a third over a six week period. Even more extraordinary is Epsilon (ε) Aurigae, which has the longest known period of any eclipsing binary of 27 years. The main star

Auriga has many open clusters and other objects because the Milky Way runs through it. The three brightest open clusters are M36, M37 and M38, all of which are visible in binoculars or a small telescope in suburban skies. The clusters are about 4100, 4400, and 4200 light years distant, respectively. is an intensely luminous white supergiant shining with the light of over 100,000 Suns and large enough to contain the orbit of the Earth and lies about 2,000 light years away. Auriga is notable for an impressive trio of star clusters, M36, M37 and M38, all three being visible in the same field of view through a wide-angle binoculars. In binoculars they appear as fuzzy patches, but small telescopes resolve them into individual stars. Each cluster has its own distinct character.

years away. In binoculars it appears the most prominent of the Auriga clusters. The largest and richest of the Auriga clusters is M37, containing about 150 stars and is 4,200 light years away. At its centre is a brighter orange star. The most scattered of the clusters is M38, containing about 100 faint stars, 3,900 light years away. Well, that's about it for November, clear skies and happy hunting.

By Kevin Daly http://members.aol.com/kdaly10475/index.html

M36 is the smallest and most condensed of the trio, consisting of 60 or so stars lying 3,900 light

Club Notes

Latest Astronomy and Space News Kids Astronomy

Club Observing: The next club meets every 1st and 3rd Saturday of the month for our observing sessions held in the MAC grounds. If you wish to be informed of these sessions please email your name and mobile number to midlandsastronomy@gmail.com who will confirm if the session is going ahead (depending on weather).

Quizzes and Games

MAC is a proud member of

Monthly Sky Guide Three open clusters in Auriga, M37 (lower left), M36 (right of centre), and M38 (upper right). by Alexander Jäger

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Internet Highlights

Midlands Astronomy Club Magazine

Exercise your brain

contents

Theory of Relativity

The Moon’s water comes from the Sun ................................. 5

Planck's Theory

Gemini Observatory releases image of rare polar-ring galaxy ................................................................................ 7

It is invisible to the naked eye

Astronomers uncover a surprising trend in galaxy evolution ... 8

3. What happens to all objects that orbit the sun, the closer they get to the sun?

Credit & Copyright: Tony Hallas

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Kids Korner ....................................................................... 10

Quizzes and Games Exercise your brain ............................................................ 11

Monthly Sky Guide Beginners sky guide for this month .................................... 12

Internet Highlights Special content only available with the online version of the magazine ................................................................ 13

1 6

7. The ability of these celestial bodies to spin rapidly, yet at a very precise rate, once caused scientists to suggest that they were actually messages sent by distant aliens.

3 7

1 3

Neutron Stars Pulsars They rise higher normally They slow down

than

8. These huge clouds of helium and hydrogen serve as the birth place of stars.

They speed up They move normally

lower

than

4. If not for the gravitational effect of this planet, the Earth would most likely be frequently bombarded with cosmic debris. Venus Mercury Mars Jupiter 5. When a neutron star and a black hole orbit each other, the gases sucked off of the neutron star cause what kind of disk around the black hole before disappearing into it?

Quasars

Check your answers

Novas Nebulae Constellations Auroras 9. Which of these forces of our universe is the strongest? Weak Force Strong Force Gravity Hammons’ Force 10. While being sucked into a black hole, objects are stretched out by what force of gravity? Expansion Force Tidal Force

Chandrasekhar Disk

Miller - Urey Force

Double Disk

Relative Force

large disk of gas turns white hot just before entering the black hole itself.

Within the Iris, dusty nebular material surrounds a hot, young star. The dominant colour of the brighter reflection nebula is blue, characteristic of dust grains reflecting starlight. Central filaments of the dusty clouds glow with a faint reddish photoluminesence as some dust grains effectively convert the star's invisible ultraviolet radiation to visible red light.

Kids Section

Answer 1: Theory of Relativity. The theory of relativity established Einstein as one of the greatest minds that ever lived.

The Fetus Nebula ................................................................ 9 Front cover image: Like delicate cosmic petals, these clouds of interstellar dust and gas have blossomed 1,300 light-years away in the constellation Cepheus. Sometimes called the Iris Nebula and dutifully catalogued as NGC 7023 this is not the only nebula in the sky to evoke the imagery of flowers. Still, this remarkable image shows off the Iris Nebula's range of colours and symmetries in impressive detail.

Gray Orange

New model reconciles Moon's Earth-like composition with the giant impact theory of formation .................................... 8

It is not large enough

2. The corona, the uppermost part of our sun, is what colour to the naked eye? Yellow

Split-personality elliptical galaxy holds a hidden spiral............ 7

Answer 6: It is not large enough. Only stars far more massive than the Sun are capable of creating black holes.

Mercury’s surface is full of sulphur........................................ 6

Answer 2: It is invisible to the naked eye. The corona is an envelope of highly ionized gas that surrounds the chromosphere (2nd uppermost part) of our sun.

Diamond planet found—part of a whole new class? ............... 6

It is not impossible It is too close to the edge of the universe It has planets

Answer 7: Pulsars. These objects pulse out radio waves because of their immense rotational speed.

You can see more about the club and its events on www.midlandsastronomy.com or contact the club via e-mail at midlandsastronomy@gmail.com Meetings are informal and are aimed at a level to suit all ages.

Theory of Universal Evolution Theory of Expansion

Answer 8: Nebulae. After being born in these clouds of gas, the star then wanders out to live the rest of its days wherever gravity takes it.

All are welcome to attend. It also holds infrequent Observing Nights at its Observing Site in Clonminch, or at a member’s house (weather permitting) on the first Friday of every month..

Surprising black-hole discovery changes picture of globular star clusters ........................................................... 5

6. Why is it impossible for our sun to turn into a black hole eventually?

Answer 3: They speed up. The increase in speed is caused by the sun's gravity, which increases its effects on an object the closer the object gets to it, "slingshotting" the object around, keeping it in planetary motion.

Keeping an earthly eye on Io’s insane volcanic activity .......... 4

Accretion Disk

Answer 9: Strong Force. Contrary to popular belief, gravity is an extremely weak force relative to the others. Hammons' force however, does not exist.

Ultimate oxymoron: A small supermassive black hole ............ 3

SUDOKU

Funnel Disk

Answer 4: Jupiter. Jupiter, the most massive planet in our solar system, is larger than all of the other planets combined and doubled. Its great gravitational tug redirects most objects that would otherwise be on a journey towards Earth.

Armchair astronomers find planet in four-star system ............ 3

1. This theory by Albert Einstein explains why all "observers" have their own separate measure of time because of the finite speed of light.

Answer 10: Tidal Force. Miller and Urey are known for experiments in biology, relative and expansion forces are not forces of gravity.

Latest Astronomy and Space News

Answer 5: Accretion Disk. This

MAC meets on the first Tuesday of the month in the Presbyterian Hall, High Street, Tullamore from 8pm.

Midlands Astronomy Club Magazine

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Midlands Astronomy Club Magazine

Kid’s Korner Why is the sky dark at night? That question is not as simple as it may sound. You might think that space appears dark at night because that is when our side of Earth faces away from the Sun as our planet rotates on its axis every 24 hours. But what about all those other far away suns that appear as stars in the night sky? Our own Milky Way galaxy contains over 200 billion stars, and the entire universe probably contains over 100 billion galaxies. You might suppose that that many stars would light up the night like daytime!

is that no matter where you look in the night sky, you should see a star. Stars should overlap each other in the sky like tree trunks in the middle of a very thick forest. But, if this were the case, the sky would be blazing with light. This problem greatly troubled astronomers and became known as "Olbers' Paradox." A paradox is a statement that seems to disagree with itself.

To try to explain the paradox, some 19th century scientists thought that dust clouds between Until the 20th century, astronomers the stars must be absorbing a lot didn't think it was even possible to of the starlight so it wouldn't shine count all the stars in the universe. They thought the universe went on forever. In other words, they thought the universe was infinite.

through to us. But later scientists realized that the dust itself would absorb so much energy from the starlight that eventually it would glow as hot and bright as the stars themselves. Astronomers now realize that the universe is not infinite. A finite universe--that is, a universe of limited size--even one with trillions and trillions of stars, just wouldn't have enough stars to light up all of space. Although the idea of a finite universe explains why Earth's sky is dark at night, other causes work to make it even darker. Not only is the universe finite in size, it is also finite in age. That is, it had a beginning, just as you and I did. The universe was born about 15 billion years ago in a fantastic explosion called the Big Bang. It began at a single point and has been expanding ever since.

Besides being very hard to imagine, the trouble with an infinite universe

Above: This Hubble Space Telescope “deep field” image shows about 300 galaxies in a piece of sky only a few millimetres in size!!!

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http://www.marcsobservatory.com

Armchair astronomers find planet in four-star system The planet was first identified by citizen scientists participating in Planet Hunters, a Yale-led program that enlists the public to review astronomical data from NASA's Kepler spacecraft for signs of planets. Above: A cloud of gas and dust, called a nebula. This one NGC 604, glows with light from newly formed stars.

Because the universe is still expanding, the distant stars and galaxies are getting farther away all the time. Although nothing travels faster than light, it still takes time for light to cross any distance. So, when astronomers look at a galaxy a million light years away, they are seeing the galaxy as it looked a million years ago. The light that leaves that galaxy today will have much farther to travel to our eyes than the light that left it a million years ago or even one year ago, because the distance between that galaxy and us constantly increases. That means the amount of light energy reaching us from distant stars dwindles all the time. And the farther away the star, the less bright it will look to us.

A joint effort of citizen scientists and professional astronomers has led to the first reported case of a planet orbiting twin suns that in turn is orbited by a second distant pair of stars. Aided by volunteers using the Planethunters.org website, a Yaleled international team of a s tr onom e r s id e nti fie d a nd confirmed discovery of the phenomenon — called a circumbinary planet in a four-star system. Only six planets are known to orbit two stars, according to researchers, and none of these are orbited by distant stellar companions. "Circumbinary planets are the extremes of planet formation," said Meg Schwamb from Yale University in New Haven, Connecticut. "The discovery of these systems is forcing us to go back to the drawing board to understand how such planets can assemble and evolve in these dynamically challenging environments." Dubbed PH1, the planet was first identified by citizen scientists participating in Planet Hunters, a Yale-led program that enlists the public to review astronomical data from NASA's Kepler spacecraft for signs of planets. It is the project's first confirmed planet. The volunteers, Kian Jek of San Francisco, California, and Robert Gagliano of Cottonwood, Arizona, spotted faint dips in light caused by the planet as it passed in front of its parent stars, a common method of finding extrasolar planets. Schwamb led the team of professional astronomers that confirmed the discovery and characterized the planet, following observations from the Keck telescopes on Mauna Kea, Hawaii. PH1 is a gas giant with a radius about 6.2 times that of Earth, making it a bit bigger than Neptune.

"Planet Hunters is a symbiotic project, pairing the discovery power of the people with follow-up by a team of astronomers," said Debra Fischer of Yale. "This unique system might have been entirely missed if not for the sharp eyes of the public." PH1 orbits outside the 20-day orbit of a pair of eclipsing stars that are 1.5 and 0.41 times the mass of the Sun. It revolves around its host stars roughly every 138 days. Beyond the planet's orbit at about 1,000 astronomical units — roughly 1,000 times the distance between Earth and the Sun — is a second pair of stars orbiting the planetary system.

would like. The hard work of the Planet Hunters helps ensure that important discoveries are not falling through the cracks."

"The thousands of people who are involved with Planet Hunters are performing a valuable service," said Jerome Orosz from San Diego State University. "Many of the automated techniques used to find interesting features in the Kepler data don't always work as efficiently as we

Gagliano, one of the two citizen scientists involved in the discovery, said he was "absolutely ecstatic to spot a small dip in the eclipsing binary star's light curve from the Kepler telescope, the signature of a potential new circumbinary planet, Tatooine. It's a great honour to be a

Above: A family portrait of the PH1 planetary system. PH1 is depicted in this artist's rendition with the pair of eclipsing stars it orbits. The planet transits in front the larger of the two stars approximately every 138 days. Off in the distance, well beyond PH1's orbit, resides a second pair of stars bound to the planetary system. Planet Hunter, citizen scientist, and work hand in hand with professional astronomers, making a real contribution to science. It still continues to astonish me how we can detect, let alone glean so much information, about another planet thousands of light-years away just by studying the light from its parent star," said Jek. www.astronomy.com

Ultimate oxymoron: A small supermassive black hole Astronomers have identified the smallest supermassive black hole ever observed, and while it’s considered a shrimp as far as supermassive black holes go, this guy is still pretty big: the mass of the black hole in galaxy NGC 4178 is estimated to be about 200,000 times the mass of our Sun. But it was a surprise that this galaxy had a black hole at all. Astronomers using the Chandra XRay Observatory in conjunction with other observatories took a look at NGC 4178, a late-type spiral galaxy located about 55 million light years from Earth. It does not contain a bright central concentration, or bulge, of stars in

its centre, and so it was thought that perhaps this galaxy was one of the few that didn’t harbour a black hole. With using Chandra’s X-Ray vision, as well as infrared data the NASA’s Spitzer Space Telescope and radio data from the Very Large Array, Nathan Secrest, from George Mason University and his team identified a weak X-ray source at the centre of the galaxy, and also saw varying brightness at infrared wavelengths, suggesting that a black hole was actually in the centre of NGC 4178 and was pulling in material from its surroundings. The same data also suggested that light generated by this infalling material is heavily absorbed by gas and dust and was therefore surrounding a black hole.

They were able to estimate the size of the black hole by using the known relationship between the mass of a black hole and the amount of X-rays and radio waves it generates. While this is the lowest mass supermassive black holes ever observed, astronomers admit this is probably near the extreme lowmass end of being in the “supermassive” range. And as the team pointed out in their paper, there is increasing evidence that several late-type galaxies do host supermassive black holes, and that a classical bulge is not a requirement for a supermassive black hole to form and grow. www.universetoday.com

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Midlands Astronomy Club Magazine

Keeping an earthly eye on Io’s insane volcanic activity You fancy yourself an armchair astronomer? A group of California researchers have stepped it up a notch by monitoring the intense volcanic eruptions on Jupiter’s strangest moon Io from the comfort of their home. Io, the innermost of the four largest moons around Jupiter, or the Galilean moons, is the most volcanically active object in the Solar System with more than 400 active volcanoes spitting out plumes of sulphur and sulphur dioxide. Scientists think a gravitational tug-of -war with Jupiter is one cause of Io’s intense vulcanism. Researchers point out that most of the processes are not well understood. While Io’s eruptions can’t be seen directly from Earth, a team led by Frank Marchis, a researcher at the Carl Sagan Centre of the SETI Institute have come up with an unique c om b ina tion of E a r th-b a s e d telescope arrays and archival imagery from the Voyager and

To help find your way around the night sky, Skymaps.com makes available for free each month a map of the night sky. The Evening Sky Map is suitable for all stargazers including newcomers to astronomy and will help you to: • identify planets, stars and major constellations. • find sparkling star clusters, wispy nebulae & distant galaxies. • locate and follow bright comets across the sky. • learn about the night sky and astronomy.

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Midlands Astronomy Club Magazine

The Fetus Nebula

Although space missions Voyager and Galileo observed evidence of volcanic activity on Io, it was a faint blue plume at the edge of Io’s limb in a highly-enhanced image from Voyager that first offered evidence of the moon’s turbulent nature.

Planetary nebulae are the snowflakes of the night sky. No two are alike, yet every one comes from the same process, in this case the death throes of a middleweight star. One of the most beautiful and intriguing of nearby planetary nebulae is NGC 7008, the often-photographed Fetus Nebula in Cygnus. Compared to star clusters, many planetaries are small and faint, so stargazers must acquire a taste for these objects and a little patience and skill to see them well. But the rewards are worth it. Many planetaries have fascinating shapes and structures, each a testament to complex physical processes going on around the central star. One of the most beautiful and intriguing of nearby planetary nebulae is NGC 7008, the often-photographed Fetus Nebula in Cygnus. This mottled blue-green ellipse presents a small but lovely image to the patient observer armed with a small telescope.

Galileo probes, according to a press release. The team announced their findings at the 2012 Division of Planetary Sciences meeting today in Reno, Nevada. “Since our first observation of Io in 2001 our group became very excited about the technology. The technology has improved over the years, and the image quality and usefulness of those complex instruments has made them part of the essential instrument suite for large telescopes.” A faint blue plume on a grainy and highly enhanced image from Voyager 1 first hinted at Io’s d yna m ic na tur e. V oya ge r’s cameras showed a bizarre terrain of volcanic fields, dark spots and active plumes. Scientists nicknamed it the “Pizza Moon.” NASA’s Galileo probe observed more than 160 active volcanoes in various stages of eruption during its looping tour of the solar system’s largest planet.

The more telescopes looking at Io, the better time coverage we can obtain. AO observations from 810m class telescopes are a dramatic improvement in spatial resolution over previous groundbased observations. Soon they will not only be our only way to monitor Io’s volcanoes, but the best way. We should be making these observations more often.”

But crystal clear pictures from Galileo ceased in 2003. Observing a Moon-sized object at the incredible distance to Jupiter from Earth is a challenge because of the blurring caused by Earth’s stirring atmosphere. Since 2001, all large 8 to 10-meter telescopes have been equipped with adaptive optics that correct for that blur. Since 2003, Marchis and his team have gathered about 40 cycles of observations of Io in the nearinfrared showing details as small as 100 kilometres on the surface of the moon.

According to the team, observations reveal a series of young and energetic eruptions called outbursts. These events stand out indicating a high eruption temperature. Coincidentally, the team observed the awakening of the volcano Tvashtar while New Horizons slingshot past Jupiter on its way to Pluto. The eruption lasted from April 2006 to September 2007. Older observations from Galileo show a similar eruption pattern in 1999 lasting for 15 months.

“Spacecraft have only been able to capture fleeting glimpses of Io’s volcanoes, Voyager for a few months, Galileo a few years, and New Horizons a few days. Groundbased observations, on the other hand, can continue to monitor Io’s volcanoes over long time-scales.

“The episodicity of these volcanoes points to a regular recharge of magma storage chambers. This will allow us to model the eruption process and understand the how heat is removed from Io’s deep interior by this particular style of volcanic activity.”

The team found four additional eruptions including a previously unobserved active volcano in 2004. The new sporadic blast accounted for about 10 percent of Io’s average thermal output, according to Marchis. The outburst was more energetic than Tvashtar in 2001. While the team continues to study Io, they have noted that since September 2010, the crazily active moon has been mostly quiet. A dozen or so permanent, low temperature eruptions dot the globe but the team has not detected the young, fire fountain style eruptions seen before.

Like many planetary nebulae, NGC 7008 was first catalogued by William Herschel in the late 18th century. Though Herschel knew many planetary nebulae—in fact he invented the term for these nebulae because they resembled blue-green planets—Herschel did not classify it as such because of its odd appearance. He lumped it in with shapely bright emission nebulae like the Orion and Lagoon Nebulae. Later

astronomers

with

better

telescopes confirmed NGC 7008 was a planetary nebula, but were otherwise puzzled by this object. The nebula has at least two separate shells (see image below). The inner shell expands faster than the outer because of sporadic mass loss of the dying central star. The symmetry of the shells is further broken, possibly by interaction with the uneven interstellar medium. It all makes for a fascinating and richly-detailed object which strongly resembles the shape of an early-stage human fetus. This 10th-magnitude nebula looks best in a 6-inch or larger scope at 70-100x, though it is visible in a smaller scope. Use enough magnification to see the mottled, elliptical shape of the nebula without spreading its light too thinly in your field of view. A UHC or OIII filter helps improve the contrast. Look for the pleasing double star h1606 on the south edge of the nebula. These gold and blue stars are 9th and 10th magnitude, respectively, and spaced by 18 arc seconds. The nebula itself, by contrast, spans

Above: NGC 7008 also known as the Fetus Nebula is an interesting, colourful planetary nebula located at a distance of 2800 light years in northern Cygnus and spans about 1.3 light years. about 95 arc seconds along its major axis. Here’s what the nebula looks like in a small telescope… NGC 7008 lies about 2,800 light years from Earth and spans about 1.3 light years.

way. Start at 2nd-magnitude Alderamin, then hop 3.5º southwest to η (eta) Cephei. From there, hop 4° due south to find a 5th-magnitude golden-yellow star. Then use your finder to hop 3.5º southeast. The nebula should be near the centre of your field of view. www.oneminuteastronomer.com

The Fetus lies in the constellation Cygnus near the border with Cepheus, about halfway between brilliant Deneb and Alderamin (alpha Cephei). Its immediate neighbourhood is somewhat barren of bright stars to guide the

“The next giant leap in the field of planetary astronomy is the arrival of Giant Segmented Mirror Telescopes, such as the Thirty Meter Telescope expected to be available in 2021. It will provide a spatial resolution of 35 km in the near-infrared, equivalent to the spatial resolution of global observations taken by the Galileo spacecraft. When pointed at Io, these telescopes will offer the equivalent of a spacecraft flyby of the satellite. www.universetoday.com

Above: NGC 7008 as it appears in a small telescope.

Above: How to star hop to the Fetus Nebula (NGC 7008).

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Midlands Astronomy Club Magazine

Astronomers uncover a surprising trend in galaxy evolution

Surprising black-hole discovery changes picture of globular star clusters

A comprehensive study of hundreds of galaxies observed by the Keck telescopes in Hawaii and NASA’s Hubble Space Telescope has revealed an unexpected pattern of change that extends back 8 billion years, or more than half the age of the universe.

The scientists didn’t find the intermediate-mass black hole they were looking for, but instead found something very surprising — two smaller black holes in the cluster.

Astronomers thought disk galaxies in the nearby universe had settled into their present form by about 8 billion years ago, with little additional development since. The trend we’ve observed instead shows the opposite, that galaxies were steadily changing over this time period. Today, star-forming galaxies take the form of orderly disk-shaped systems, such as the Andromeda Galaxy or the Milky Way, where rotation dominates over other internal motions. The most distant blue galaxies in the study tend to be different, exhibiting disorganised motions in multiple directions. Blue galaxies - their colour indicates stars are forming within them show less-disorganised motions and ever-faster rotation speeds the closer they are observed to the present. This trend holds true for galaxies of all masses, but the most

massive systems always show the highest level of organisation. Researchers say the distant blue galaxies they studied are gradually transforming into rotating disk galaxies like the Milky Way. Previous studies removed galaxies that did not look like the wellordered rotating disks now common in the universe today. By neglecting them, these studies examined only those rare galaxies in the distant universe that are well -behaved and concluded that galaxies didn’t change. The researchers looked at all galaxies with emission lines bright enough to be used for determining internal motions. Emission lines are the discrete wavelengths of radiation characteristically emitted by the gas within a galaxy. They are revealed when a galaxy’s light

Above: This plot shows the fractions of settled disk galaxies in four time spans, each about 3 billion years long. There is a steady shift toward higher percentages of settled galaxies closer to the present time. At any given time, the most massive galaxies are the most settled. is separated into its component colours. These emission lines also carry information about the galaxy’s internal motions and distance. The team studied a sample of 544 blue galaxies from the Deep Extragalactic Evolutionary Probe 2 (DEEP2) Redshift Survey. Located between 2 billion and 8 billion lightyears away, the galaxies have stellar masses ranging from about 0.3 to 100% of the mass of our home galaxy. The Milky Way Galaxy must have gone through the same rough-and-tumble evolution as the galaxies in the DEEP2 sample and gradually settled into its present

New model reconciles Moon's Earth-like composition with the giant impact theory of formation The giant impact believed to have formed the Earth-Moon system has long been accepted as canon. However, a major challenge to the theory has been that Earth and the Moon have identical oxygen isotope compositions. A new model by the Southwest Research Institute accounts for this similarity in composition while also yielding an appropriate mass for Earth and the Moon. In the giant impact scenario, the Moon forms from debris ejected into an Earth-orbiting disk by the collision of a smaller protoplanet with the early Earth. Earlier models found that most or much of the disk material would have originated from the Mars-sized impacting body, whose composition likely would have differed substantially from that of Earth. The new models developed by Robin Canup involve much larger impactors than those previously

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considered. In the new simulations, both the impactor and the target are of comparable mass, each containing about four to five times that of Mars. The near symmetry of the collision causes the disk's composition to be extremely similar to that of the final planet's mantle over a relatively broad range of impact angles and speeds, consistent with the Earth-Moon compositional similarities.

The new impacts produce an Earth that is rotating 2 - 2.5 times faster than implied by the current angular momentum of the Earth-Moon system. However, Matija Cuk and Sarah Stewart show that a resonant interaction between the early Moon and the Sun - known as the evection resonance - could have decreased the angular momentum of the Earth-Moon system by this amount soon after the Moonforming impact. By allowing for a much higher initial angular momentum for the EarthMoon system, the Cuk-and-Stewart work allows for impacts that for the first time can directly produce an appropriately massive disk with a composition equal to that of the

state as the Sun and solar system were being formed. In the past 8 billion years, the number of mergers between galaxies large and small has decreased sharply. So has the overall rate of star formation and disruptions of supernova explosions associated with star formation. Scientists speculate that these factors may play a role in creating the evolutionary trend they observe. www.astronomy.com

planet's mantle. In addition to the impacts identified in Canup's paper, Cuk and Stewart show that impacts involving a much smaller, highvelocity impactor colliding into a target that is rotating very rapidly due to a prior impact can also produce a disk-planet system with similar compositions. The ultimate likelihood of each impact scenario will need to be assessed by improved models of terrestrial planet formation, as well as by a better understanding of the conditions required for the evection resonance mechanism. Canup used smoothed-particle hydrodynamics (SPH) to simulate the colliding planetary objects using 300,000 discrete particles whose individual thermodynamic and gravitational interactions were tracked with time. www.astronomy.com

An unexpected discovery by astronomers using the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) is forcing s c ie ntis ts t o r e t hink the ir understanding of the environment in globular star clusters, tight-knit collections containing hundreds of thousands of stars. The astronomers used the VLA to study globular cluster M22, a group of stars more than 10,000 lightyears from Earth. They hoped to find evidence for a rare type of black hole in the cluster’s centre. They wanted to find what scientists call an intermediate-mass black hole, more massive than the Sun’s mass, but smaller than the supermassive black holes found at the cores of galaxies. “We didn’t find what we were looking for, but instead found something very surprising — two smaller black holes,” said Laura Chomiuk from Michigan State University in East Lansing. “That’s

surprising because most theorists said there should be at most one black hole in the cluster.” Black holes, concentrations of mass so dense that not even light can escape, are left over after massive stars have exploded as supernovae. In a globular cluster, many of these stellar-mass black holes probably were produced early in the cluster’s 12-billion-year history as massive stars rapidly passed through their life cycles. Simulations have indicated that these black holes would fall toward the centre of the cluster, then begin a violent gravitational dance with each other, in which all of them or perhaps all but a single one would be thrown completely out of the cluster. “There is supposed to be only one survivor possible,” said Jay Strader of Michigan State University and the Harvard-Smithsonian Centre for Astrophysics. “Finding two

The Moon’s water comes from the Sun Comets? Asteroids? The Earth? The origins of water now known to exist within the Moon’s soil — thanks to recent observations by various lunar satellites and the impact of the LCROSS mission’s Centaur rocket in 2009 — has been an on-going puzzle for scientists. Now, new research supports that the source of at least some of the Moon’s water is the Sun, with the answer blowing in the solar wind. Spectroscopy research conducted on Apollo samples by a team from the University of Tennessee, University of Michigan and Caltech has revealed “significant amounts” of hydroxyl within microscopic glass particles found inside lunar soil, the results of micrometeorite impacts. According to the research team, the

hydroxyl “water” within the lunar glass was likely created by interactions with protons and hydrogen ions from the solar wind. “We found that the ‘water’ component, the hydroxyl, in the lunar regolith is mostly from solar wind implantation of protons,

Above: Astronomers have discovered two radio sources, likely to be black holes emitting ionized plasma jets, in the dense core of globular cluster M22. black holes instead of one in this globular cluster definitely changes the picture.” The astronomers suggest some possible explanations. First, the black holes themselves may gradually work to puff up the central parts of the cluster, reducing the density and thus the rate at which black holes eject each other through their gravitational dance. Alternatively, the cluster may not be as far along in the process of contracting as previously thought, again reducing the density of the core. which locally combined with oxygen to form hydroxyls that moved into the interior of glasses by impact melting,” said Youxue Zhang, Professor of Geological Sciences at the University of Michigan. Hydroxyl is the pairing of a single oxygen atom to a single hydrogen atom (OH). Each molecule of water contains two hydroxyl groups. Although such glass particles are widespread on the surface of the Moon — the researchers studied samples returned from Apollo 11, Apollo 16 and Apollo 17 missions — the water in hydroxyl form is not something that could be easily used by future lunar explorers. Still, the findings suggest that solar windderived hydroxyl may also exist on the surface of other airless worlds,

“Future VLA observations will help us learn about the ultimate fate of black holes in globular clusters,” Chomiuk said. The two black holes discovered with the VLA were the first stellar-mass black holes to be found in any globular cluster in the Milky Way Galaxy, and also are the first found by radio instead of X-ray observations. www.astronomy.com

like Mercury, Vesta or Eros… especially within permanentlyshadowed craters and depressions. “These planetary bodies have very different environments, but all have the potential to produce water,” said Yang Liu, University of Tennessee scientist and lead author of the team’s paper. The discovery of hydroxyl within lunar glasses presents an “unanticipated, abundant reservoir” of water on the Moon, and possibly throughout the entire Solar System. www.universetoday.com

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Midlands Astronomy Club Magazine

Diamond planet found— part of a whole new class?

Split-personality elliptical galaxy holds a hidden spiral

Dubbed 55 Cancri e, the rocky world is only twice the size of Earth but has eight times its mass—classifying it as a "super Earth," a new study says. First detected crossing in front of its parent star in 2011, the close-in planet orbits its star in only 18 hours. As a result, surface temperatures reach an uninhabitable 3,900 degrees Fahrenheit (2,150 degrees Celsius)—which, along with carbon, make perfect conditions for creating diamonds. NASA's Spitzer Space Telescope collected data on the planet's orbital distance and mass, and resulting computer models created a picture of 55 Cancri e's chemical makeup. "Science fiction has dreamed of diamond planets for many years, so it's amazing that we finally have evidence of its existence in the real universe," said study leader Nikku Madhusudhan, a postdoctoral researcher at Yale University. "It's the first time we know of such an exotic planet that we think was born mostly of carbon—which really makes this a fundamental gamechanger in our understanding of

what's possible chemistry."

planetary

At only 40 light-years away, in the northern constellation Cancer, the gemlike planet sits relatively near Earth. In dark skies, 55 Cancri e's host star is clearly visible to the naked eye. The new models fit studies that showed parent star was carbon—much more sun.

Centaurus A is the first elliptical galaxy to be found hiding a gassy spiral in its centre.

with previous 55 Cancri e's abundant in so than our

"If we make the assumption that the star and its surrounding planets are all born from the same primordial disk of material, then it

makes sense that the entire planetary system would be carbon rich," said Madhusudhan, whose study will appear in an upcoming issue of the journal Astrophysical Journal Letters. Princeton astronomer David Spergel believes the diamond-planet find probably represents the first discovery of a whole new class of planets whose chemistry has never been encountered. "Unlike our solar system, which is dominated by oxygen and silicates, this planetary system is filled with

Mercury’s surface is full of sulphur

sulphur-enriched minerals.

Recent findings from the MESSENGER mission have revealed variations in Mercury’s surface composition due to volcanism that occurred at different times, as well as a surprising concentration of elements like magnesium and sulphur — much more so than any of the other terrestrial planets.

“None of the other terrestrial planets have such high levels of sulphur. We are seeing about ten times the amount of sulfur than on Earth and Mars,” Weider said. “In terms of magnesium, we do have some materials on Earth that are high in magnesium. They tend to be ancient volcanic rocks that formed from very hot lavas. So this composition on Mercury tells us that eruptions of high-temperature lavas might have formed these high -magnesium materials.”

Named for the 17th-century Venetian composer, the southern half of Mercury’s Vivaldi basin is seen in this image acquired on August 26 by NASA’s MESSENGER spacecraft. The 213-km (132-mile) -wide crater’s smooth floor is contrasted by the incredibly rugged terrain beyond its outermost ring — a result of the ejected material that was flung out from the impact site and emphasized by the low angle of illumination.

scientists report that Mercury’s volcanic smooth plains differ in composition from older surrounding terrains. The older terrain has higher ratios of magnesium to silicon, sulphur to silicon, and calcium to silicon, but lower ratios of aluminium to silicon, suggesting that the smooth plains material erupted from a magma source that was chemically different from the source of the material in the older regions, The floor of the crater remained according to Shoshana Weider of relatively smooth due to molten the Carnegie Institution of material that erupted in the wake of Washington, the lead author on the impact event, flooding the basin. the paper. In results to be published in the Mercury’s surface was also found Journal of Geophysical Research, to be high in magnesium and

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The data was gathered with MESSENGER’s X-Ray Spectrometer (XRS) — one of two instruments designed to measure the

Above: An illustration of 55 Cancri e shows a surface of mostly graphite surrounding a thick layer of diamond. carbon," said Spergel, who was not involved in the new study. "While it's still unknown exactly what implication this will have on our understanding of evolution of planetary systems," he said, "there's no doubt it is an important step towards understanding the full diversity of planets." www.nationalgeographic.com

Most big galaxies fit into one of two camps: pinwheel-shaped spiral galaxies and blobby elliptical galaxies. Spirals like the Milky Way are hip and happening places with plenty of gas and dust to birth new stars. Ellipticals are like cosmic retirement villages, full of aging residents in the form of red giant stars. Now, astronomers have discovered that one well-known elliptical has a split personality. Centaurus A is hiding a gassy spiral in its centre. “No other elliptical galaxy is known to have spiral arms,” said Daniel E s p a d a fr om th e N a t io n a l Astronomical Observatory of Japan and the Harvard-Smithsonian Centre for Astrop hys ics in Cambridge, Massachusetts. “Centaurus A may be an old galaxy, but it’s still very young at heart.” Centaurus A isn’t your typical elliptical to begin with. Its most striking feature is a dark dust lane across its middle — a sign that it

swallowed a spiral galaxy about 300 million years ago. Centaurus A slurped that galaxy’s gases down, forming a disk that we see nearly edge on. From our point of view, any features in that disk have been hidden by the intervening dust. To tease out the disk’s structure, Espada and his colleagues used the sharp vision of the Smithsonian’s Submillimetre Array. This radio telescope can see through dust to pick up signals from naturally occurring carbon monoxide gas. By mapping the gas, the team unveiled two distinct spiral arms within the galaxy’s core. These gaseous tendrils have sizes and shapes similar to spiral arms in galaxies like the Milky Way. Also like the Milky Way’s spiral arms, they are forming new generations of stars.

Above: The giant elliptical galaxy Centaurus A shows a split personality because it hides a gaseous spiral at its core. When Centaurus A collided with a spiral galaxy 300 million years ago, it slurped up the spiral's gases, which formed a new spiral inside the larger galaxy. “Centaurus A has been given a new lease on life by that past merger,” said Espada. Computer simulations suggest that the spiral features might endure for hundreds of millions of years to come. Although Centaurus A is the first elliptical galaxy found to have spiral arms, it may not be the last. Because it’s only 12 million light-

years away, it’s relatively nearby and easy to study. The Atacama Large Millime tr e/subm illime tre Ar ray (ALMA) potentially can find more split -personality galaxies with its improved radio “vision.” “We definitely will use ALMA to search for other objects that are similar to Centaurus A,” said Espada. www.astronomy.com

Gemini Observatory releases image of rare polar-ring galaxy Such galaxies display a ring of stars, dust, and gas extending tens of thousands of light-years along an orbit nearly perpendicular to the main disk, although scientists are unsure of their formation.

abundances of many key elements in the top 2mm of Mercury’s crust. XRS detects emissions from elements in the 1-10 kiloelectronvolt (keV) range – specifically, magnesium, aluminium, silicon, sulphur, calcium, titanium, and iron. www.universetoday.com

What Gemini has captured is nothing short of poetry in motion: the colourful and dramatic tale of a life-and-death struggle between two galaxies interacting. All the action appears in a single frame, with the stunning polar-ring galaxy NGC 660 as the focus of attention. Polar-ring galaxies are peculiar objects. Astronomers have found only a handful of them, so not much is known about their origins. Most have an early-type spiral

system called a lenticular galaxy as the central showpiece. But NGC 660, which lies about 40 million light-years distant toward the direction of Pisces the Fish, is the only polar-ring galaxy known with what is called a late-type lenticular galaxy as its host. All, however, display a ring of stars, dust, and gas that extends tens of thousands of light-years across space along an orbit nearly perpendicular to the main disk.

Models of how polar-ring galaxies form offer two general scenarios: 1) a piercing merger between two galaxies aligned roughly at right angles, or 2) when the host galaxy tidally strips material from a passing gas-rich spiral and strews it into a ring.

dynamic body but either the “bloody” aftermath of one galaxy piercing the heart of another or the remains of a furious tidal struggle between two galaxies that shattered one galaxy’s “lamp,” scattered its dust and gas, and formed a colourful 40,000-lightyear-long ring of visual glory.

What you see in this new Gemini Legacy image, then, is not a single

www.astronomy.com

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