Posted on by Fraser Cain

A Supernova in Progress

X-ray image of supernova SN 1970G. Image credit: NASA. Click to enlarge
Chandra image in the inset shows X-rays from SN 1970G, a supernova that was observed to occur in the galaxy M101 35 years ago. The bright cloud in the box in the optical image is not related to the supernova, which is located immediately to the upper right (arrow) of the cloud.

Before a massive star explodes as a supernova, it loses gas in a stellar wind that can last tens to hundreds of thousands of years, and creates a circumstellar gas shell around the star. The explosion generates shock waves that rush through this gas and heat it to millions of degrees. The X-rays from SN 1970G are likely due to this process.

By studying the spectrum and intensity of the X-rays from a supernova in the years after the explosion, astronomers can deduce information about the behavior of the star before it exploded. The observations of SN 1970G indicate that the progenitor star created its circumstellar shell by losing about one sun’s worth of gas over a period of about 25,000 years before the explosion.

Astronomers estimate that in another 20 to 60 years the shock waves will have traversed the shell and encountered the interstellar medium. At this time SN 1970G will make the transition to the supernova remnant phase of its evolution.

Original Source: Chandra X-ray Observatory

Posted on by Mark Mortimer

Book Review: Why Explore?

This book shows humans’ natural curiosity, their need to find out what is beyond their limits. Its premise is that exploring is good because it often leads to many new discoveries. This book also shows that when people ask questions, or when you are asking questions yourself, in a way you are exploring. Asking questions is like looking at something and knowing that there is something else to it. Exploring further extends your knowledge. So the next time someone is curious about what you’re doing or they are asking you a million questions, remember they are “exploring” and addressing a natural curiosity.

Each page of this picture book depicts one person questioning another on why they explore. When travelling is involved, the one staying behind argues that everything is O.K. right here so why travel? Fear of the unknown and its dangers keeps them home bound. For the ones leaving, the excitement of going, the fun of experimenting and the opportunity for a fresh start are what give them the impetus. The resonance of the book is that for people, it is natural to crave answers and to explore.

Understanding one’s own body and emotions is one of the greatest undertakings of any human. Whether young or old, they are always learning about themselves. Children, with their knack for asking the obvious, can shed more insight than a hundred doctoral candidates. As well, in helping children understand themselves, we understand ourselves better. This is the viewpoint taken by Lendroth and Moreiro. They show there is no one answer to the question, ‘Why Explore?”. Simply, for some there are many more advantages than in not exploring. The bigger quandary, though unaddressed, is why we keep questioning, why do we continually expect more.

A young child, 5 or 6 years old, would likely really enjoy reading this book with a learned adult. The large format, with reproductions of oil paintings filling every page’s background, makes for a visual treat. The short, rhyming text adds a sense of wonder and pleasure to challenging words like sharecropping and electron scattering. As children tend to be more curious with less patience, the few words and vivid art work would most likely well entertain them.

Picture books can teach children to count or recognize the primary colours. But more demanding books are those that try to broach the subject of emotions. Exploring and curiosity are such emotions and Susan Lendroth and Enrique Moreiro in their book Why Explore? comfortably and clearly let an older person discuss this concept with a younger one. After all, many of us, for whatever reason are not satisfied with the options at hand and are darn sure things could be better.

Review by Mark, Ariana and Lorelei Mortimer

Read more reviews online, or purchase a copy from Amazon.com.

Posted on by Fraser Cain

What’s Up This Week – November 28 – December 4, 2005

M74. Image credit: R. Jay GaBany. Click to enlarge.
Monday, November 28 – Tonight let’s begin by identifying the marker star we will need to make our first galaxy hop – Eta Pisces. The stars of this constellation are rather dim, but try this simple trick: the southernmost star in the “Great Square of Pegasus” is Gamma. You will find Eta about a handspan due east. By centering on Eta, shift east-northeast less than one fingerwidth…

The large spiral galaxy M74 was first observed by Pierre Mechain in 1780. This vague, misty-appearing deep sky object is probably one of the most difficult Messier objects you will ever try to find, but when you do – don’t be disappointed. Even the great John Herschel had trouble correctly identifying it! Even at 11th magnitude, its low surface brightness will make it appear as nothing more than a round, diffuse glow in small scopes, but larger ones will find a condensation towards the nucleus and just a whisper of spiral structure with excellent seeing conditions. Best of luck!

Tuesday, November 29 – Tonight let’s start with Mira and hop about three fingerwidths northeast to Delta Ceti. About one degree to the southeast you will discover our next galaxy – M77.

At magnitude 10, this bright, compact spiral galaxy can even be spotted with larger binoculars as a faint glow and is unmistakable as a galaxy in smaller scopes. Its small bright nucleus shows well in mid-sized scopes, while larger ones will resolve out three distinctive spiral arms. But this “Seyfert” galaxy isn’t alone… If you are using a larger scope, be sure to look for 11th magnitude edge-on companion NGC 1055 about half a degree to the north-northeast, and fainter NGC 1087 and NGC 1090 about a degree to the east-southeast. All are part of a small group of galaxies associated with the 60 million light-year distant M77.

Wednesday, November 30 – Tonight let’s go north for a mid-size scope challenge about two fingerwidths east-northeast of the beautiful double star Gamma Andromeda.

The 12th magnitude NGC 891 is a perfect example of a spiral galaxy seen edge-on. To the mid-sized scope, it will appear as a pencil-slim scratch of light, but larger telescopes will be able to make out a fine, dark dust lane upon aversion. Discovered by Caroline Herschel in 1783, NGC 891 contained a magnitude 14 supernova event recorded on August 21, 1986. Often considered a “missed Messier,” you can add this one to your Caldwell list as number 23!

Thursday, December 1 – Born today in 1811 was Benjamin (Don Benito) Wilson. He was the namesake of Mt. Wilson, California.

Tonight is New Moon and time for big scopes to get serious. Return to NGC 891 and head another degree or so to the southeast to take on the Abell 347 Galaxy Cluster. Here you will find a grouping of at least a dozen galaxies that can be fitted into a wide field view. Let’s tour a few…

The brightest and largest is NGC 910 – a round elliptical with a concentrated nucleus. To the northwest you can catch faint, edge-on NGC 898. NGC 912 is northeast of NGC 910, and you’ll find it quite faint and very small. NGC 911 to the north is slightly brighter, rounder, and has a substantial core region. NGC 909 further north is fainter, yet similar in appearance. Fainter yet is more northern NGC 906 and shows as nothing more than a round contrast change. Northeast is NGC 914, which appears almost as a stellar point with a very small haze around it. To the southeast is NGC 923 which is just barely visible with wide aversion as a round contrast change. Enjoy this Abell quest!

Friday, December 2 – Today in 1934, the largest mirror in telescope history began its life when the blank for the 200-inch telescope was cast in Corning, New York. But, tonight you won’t need aperture that large as we seek out two more sky gems – one for the north and one for the south.

Located in western Perseus just slightly less than one degree north-northwest of Phi, M76 is often referred to as “The Little Dumbbell.” Originally discovered by Messier’s assistant M?chain in September of 1780, Charles didn’t get around to cataloging it for another six weeks. What a shame it took him so long to view this fine planetary nebula! Its central star is one of the hottest known, but its resemblance to M27 is what makes it so fascinating. Looking very much like a miniaturization of the much larger M27, M76 is rather faint at magnitude 11, but is quite achievable in scopes of 114mm in aperture or larger. It is small, but its irregular shape makes this planetary nebula a real treat.

For our Southern Hemisphere friends, get thee out there and view Eta Carinae! First recorded by Halley in 1677, this nebular variable star left even the great Sir John Herschel at a loss to describe its true beauty and complexity This “slow nova” is filled with all the wonders the we “northerners” can only dream about…

Saturday, December 3 – Today in 1971, Soviet Mars 3 became the first spacecraft to make a soft landing on the red planet, and two years later on this same date the Pioneer 10 mission became the first spacecraft to fly by Jupiter. One year later on this same date? Pioneer 11 did the same thing!

Although we can’t land on Mars, we can certainly make the journey with our eyes as the planet is now very well placed in the early evening hours for viewing. Be sure to look for the deep, dark triangle of Syrtis Major highlighted by Hellas Basin. Perhaps at your viewing time it might be the long expanse of Amazonis Planitia or the “fingers” of Mare Erythraeum. Even if you don’t use a telescope, just seeing Mars shining so brightly is worth the trip outside! And Jupiter?

You’ll find it just before dawn…

Sunday, December 4 – Today in 1978, the Pioneer Venus Orbiter became the first spacecraft to orbit Venus. Is Venus still around? You bet. Just have a look right after sunset… You’ll find both it and the tender crescent Moon very close together…

Now wait until the Moon sets and let’s take on one more galaxy quest before we return to lunar studies. What shall we chose? Let’s try a very large and elusive galaxy that can be spotted with binoculars, and even unaided, from a very dark observing site – M33.

The “Triangulum Galaxy” is very misty, vague and also a totally wonderful galaxy for study. Just west of Alpha Triangulum, this galaxy is about the size of the full Moon, but it is so diffuse it’s sometimes hard to locate. Cataloged by Charles Messier in August 1764, M33 is often known as the “Pinwheel.” because of its distinguishable arm structure. As a part of our local galaxy group, M33 (NGC 598) is quite prized by amateurs for its ability to resolve. It has a distinct concentration toward the nucleus area plus a northern and southern “arm” that are within a small telescope’s capabilities. Telescopes ranging from 12.5″ to 16″ and larger will find a wealth of NGC and IC objects hiding within this fantastic galaxy, allowing us to study star clusters and nebulae almost 750,000 light-years away. It’s out there tonight!

My many thanks go to Ken and to all of you nice folks who take the time to write! Wishing you all clear, dark skies and may all of your journeys be at light speed… ~Tammy Plotner

Posted on by Fraser Cain

SOHO Celebrates 10 Years

SOHO is celebrating ten years in space on 2nd December. Image credit: SOHO Click to enlarge
The world’s flagship solar probe, the Solar and Heliospheric Observatory (SOHO), is celebrating ten years in space on 2nd December. Scientists are gathering at CCLRC Rutherford Appleton Laboratory on the anniversary of the launch to celebrate the achievements of SOHO which has revolutionised our understanding of our star, the Sun, and its impacts on the Earth.

The 12 instruments on board SOHO probe the Sun’s every detail. One, the Coronal Diagnostic Spectrometer (CDS), is led from the UK, another was partly built in the UK, and UK scientists are involved in the operations and research of all instruments. SOHO’s instruments are monitoring the complex, violent solar atmosphere, the charged gases that the Sun expels into space and examining the solar interior.

“Never before have we had such a detailed view of a star. All life on Earth is dependent on the Sun’s energy, and when the Sun ejects clouds into space which engulf the Earth it can have severe consequences for satellite systems, navigation, communication and power distribution systems. We need to understand how the Sun works and how to predict how its activity impacts on the Earth”, said Professor Richard Harrison, from the CDS team.

“SOHO has provided us with a comprehensive, detailed examination of a star over an extended period, and has operated superbly during that time. The advances generated by this mission are incredible”, commented Professor Len Culhane of the UCL Mullard Space Science Laboratory.

The mission has revealed the true nature of the Sun’s violent atmosphere as it flings clouds into space and as huge magnetic loops tie themselves in knots to generate solar flare explosions. Scientists have discovered that the solar atmosphere is riddled with Earth-sized explosions and occasional tornadoes and the mission has also revealed how the interior of the Sun rotates. SOHO has even discovered over 1000 comets as they pass close to the Sun – a world record. Sophisticated observations have allowed scientists to monitor the far-side of the Sun and instruments have enabled weather maps of the Sun’s atmosphere – probing temperatures, densities, solar wind speeds and even what the Sun is made of, from a distance of 150 million km.

Professor Keith Mason, Chief Executive Officer of the Particle Physics and Astronomy Research Council, the main funder of the UK involvement in the mission, said “SOHO continues to be a stunning success and over its extended lifetime has provided the scientific community and the public with a wealth of data about the Sun. Its success is testimony to the expertise of the scientists and industrialists, in the US and Europe, including the UK, that have worked on its design and operation.”

Original Source: PPARC News Release

Posted on by Fraser Cain

Upcoming Solutions for Near Earth Objects

Artist’s impression of ESA’s Hildalgo spacecraft. Image credit: ESA.Click to enlarge
Telescope facilities across the world are watching the skies for rocky remnants from outer space on a collision course with planet Earth. Currently one or two of these so called ‘Near Earth Objects’ [NEOs] are being recorded each day but fortunately for humankind the vast majority are the size of a human fist and pose no threat. Nevertheless, the presence of large impact craters on Earth provides dramatic evidence of past collisions, some of which have been catastrophic for the planet’s species, as was the case with the dinosaurs. This week, experts from across Europe and the US met in London to consider current and future efforts to monitor NEOs in order to better predict those with Earth impacting trajectories, since it is inevitable that a catastrophic collision will happen again in the future.

Professor Monica Grady, a leading expert on meteorites from the Open University explains, “It’s simply a question of when, not if, a NEO collides with the Earth. Many of the smaller objects break up when they reach Earth’s atmosphere and have no impact. However, a NEO larger than 1 km will collide with Earth every few hundred thousand years and an NEO larger than 6 km, which could cause a mass extinction, will collide with Earth every hundred million years. And we are overdue for a big one!”

NEO’s, remnants from the formation of the inner planets, range in size from 10 metre objects to those in excess of 1 km. It is estimated that 100 fist sized meteorites, fragments of NEO’s, fall to Earth on a daily basis but larger objects impact with Earth on a much less regular basis.

Professor Alan Fitzsimmons from Queens University Belfast is a UK astronomer (supported by the Particle Physics and Astronomy Research Council) involved in the study of NEO’s, using telescope facilities such as the European Southern Observatory’s Very Large telescope in Chile, the Isaac Newton Telescope in La Palma and the Faulkes Telescope in Hawaii. He said, “By the end of the decade as new dedicated facilities, such as the Pan-STARR project in Hawaii, come on line there will be a quantum leap in the discovery of NEO’s – with rates anticipated to increase to hundreds per day. This will provide us with a greater ability to determine which ones are on a potential Earth colliding trajectory.”

Studies of one such asteroid (Apophis), which was discovered in June2004, have shown that there is a low probability that this object will impact the Earth in 2036. This has raised a whole series of issues about the prospect of deflecting the asteroid before a very close approach in 2029. Government’s across the world are looking at the issue and in particular at the technologies and methods required to carry out an asteroid deflection manoeuvre in space.

The European Space Agency’s NEO Mission Advisory Panel (NEOMAP), of which Professor Fitzsimmons is a member, has selected “Don Quixote” as their preferred option for an asteroid deflecting test mission. Don Quixote would comprise two spacecraft – one of them (Hildalgo) would impact the asteroid at a very high relative speed while the second spacecraft (Sancho) would arrive earlier to monitor the effect of the impact to measure the variation of the asteroid’s orbital parameters. This attempt to deflect an incoming NEO would act as a precursor mission with the primary objective of modifying the trajectory of a “non-threatening” asteroid.

Richard Tremayne-Smith, from the British National Space Centre, heads up the coordination of UK NEO activity and helps provide an international lead on NEO efforts on the issue. He said, “NEO collisions are the only known natural disaster that can be avoided by applying appropriate technology – and so it is the interest of Governments across the World to take interest in this global issue. Here in the UK we take the matter very seriously and progress is being made in taking forward the recommendations of the UK NEO Task Force Report in an international arena.”

The current method of studying NEOs is achieved through a combination of 3 different methods:- the study of meteorites to understand their structure and composition; earth based astronomical observations of asteroids; and space based observations and encounters with asteroids.

Much can be understood about the nature of asteroids from the study of meteorites which are fragments of asteroids that have broken up and fallen to Earth. Professor Grady explains how the ground based study of meteorites is crucial to future plans for dealing with asteroids.

“In order to define successful strategies for deflecting asteroids that might collide with Earth, it is essential to understand the material properties such as the composition, strength and porosity of asteroids. By putting together such information with data from both ground based and space based studies we can begin to build an accurate picture of these diverse phenomena.”

UK scientists are involved in a number of other missions which will also be investigating the properties of asteroids and comets. This includes NASA’s Stardust mission which collected samples from Comet Wild 2 in January 2004. These samples are set to return to Earth in January 2006 and scientists from the Open University will be involved in their analysis. The European Space Agency’s Rosetta mission which is currently on route to Comet Churyumov-Gerasimenko will pass by two asteroids, Steins and Lutetia, before reaching its target in 2014, gathering data about their properties as it flies past.

Original Source: PPARC News Release

Posted on by Fraser Cain

Venus Express Photographs the Earth and Moon

Earth and Moon system as seen by VIRTIS-M. Image credit: ESA Click to enlarge
A recent check of the VIRTIS imaging spectrometer during the Venus Express commissioning phase has allowed its first remote-sensing data to be acquired, using Earth and the Moon as a reference.

After a successful in-flight checkout of the spacecraft’s systems in the first ten days of flight, the ESOC operations team is now verifying the health and functioning of all the Venus Express instruments. These observations were made as part of this checkout.

Of course the very large distance that Venus Express has travelled since its launch makes these images of limited interest to the general public, but to the scientific team it confirms the excellent operation of their instrument.

This gives them confidence of spectacular results when the spacecraft reaches Venus where similar measurements will be made hundreds times closer.

Only two weeks after the launch, VIRTIS, the Ultraviolet/Visible/Near-Infrared mapping spectrometer, has been able to make its first planetary observations, capturing the Earth-Moon system.

“The observations were made from 3.5 million kilometres away, with a phase angle of 65 degrees, meaning that 65% of the Earth’s disk was illuminated by the Sun, providing observations of both the day and night sides of the Earth,” explains Guiseppe Piccioni, one of the two Principal Investigators (PI).

These Earth observations will be used to test the instrument on a real planetary case, before Venus approach.

“A comparison of Venus spectra with Earth spectra with the same instrument will also be of interest for textbook illustration of the comparison between the two planets,” explained Pierre Drossart, the other PI.

The Moon has also been observed, providing additional observations of particular interest for calibrating the intrument.

The VIRTIS instrument on Venus Express is a twin of the same instrument on Rosetta, and similar observations were sent back by Rosetta in March 2005, so comparisons of the two sets of observations will be very useful for calibration purposes. The VIRTIS instrument is led jointly by INAF-IASF, Rome, Italy, and Observatoire de Paris, France.

Original Source: ESA Portal

Posted on by Fraser Cain

AMBER Instrument Combines Three Telescopes

Artist’s impression of the stellar object MWC 297. Image credit: ESO Click to enlarge
Using the newly installed AMBER instrument on ESO’s Very Large Telescope Interferometer, which combines the light from two or three 8.2-m Unit Telescopes thereby amounting to observe with a telescope of 40 to 90 metres in diameter, two international teams of astronomers observed with unprecedented detail the environment of two stars. One is a young, still-forming star and the new results provide useful information on the conditions leading to the creation of planets. The other is on the contrary a star entering the latest stages of its life. The astronomers found, in both cases, evidence for a surrounding disc.

A first group of astronomers, led by Fabien Malbet from the Laboratoire d’Astrophysique de Grenoble, France, studied the young 10-solar mass stellar object MWC 297, which is still in the very early stage of its life.

“This scientific breakthrough opens the doors to an especially detailed scrutiny of the very close environment of young stars and will bring us invaluable knowledge on how planets form”, says Malbet.

It is amazing to see the amount of details the astronomers could achieve while observing an object located more than 800 light-years away and hidden by a large amount of gas and dust. They found the object to be surrounded by a proto-planetary disc extending to about the size of our Solar System, but truncated in his inner part until about half the distance between the Earth and the Sun. Moreover, the scientists found the object to be surrounded by an outflowing wind, the velocity of which increased by a factor 9, from about 70 km/s near the disc to 600 km/s in the polar regions.

“The reason why the inner part of the disc should be truncated is not clear”, adds Malbet. “This raises new questions on the physics of the environment of intermediate mass young stars.”

The astronomers now plan to perform observations with AMBER with three telescopes to measure departure from symmetry of the material around MWC 297.

Another international team of astronomers [5] has just done this kind of observations to study the surroundings of a star entering the last stages of its life. In a world premiere, they combined with AMBER the light of three 8.2-m Unit Telescopes of the VLT, gaining unsurpassed knowledge on a B[e] supergiant, a star that is more luminous than our Sun by more than a factor 10,000. This supergiant star is located ten times further away than MCW 297 at more than 8,000 light-years.

The astronomers made the observations to investigate the crucial questions concerning the origin, geometry, and physical structure of the envelope surrounding the star.

These unique observations have allowed the scientists to see structures on scale as small as 1.8 thousandths of an arcsecond – that is the same as distinguishing between the headlights of a car from about 230,000 km away, or slightly less than 2/3 of the distance from the Earth to the Moon!

Armando Domiciano de Souza, from the MPI f??bf?r Radioastronomie in Bonn (Germany) and his colleagues made also use of the MIDI instrument on the VLTI [6], using two Unit Telescopes. Using their full dataset, they found the circumstellar envelope around the supergiant to be non-spherical, most probably because the star is also surrounded by an equatorial disc made of hot dust and a strong polar wind.

“These observations are really opening the doors for a new era of understanding of these complex and intriguing objects”, says Domiciano de Souza.

“Such results could be achieved only due to the spectral resolution as well as spatial resolution that AMBER offers. There isn’t any similar instrument in the world,” concludes Fabien Malbet, who is also the AMBER Project Scientist.

Original Source: ESO News Release

Posted on by Fraser Cain

Death Star Mimas and Its Giant Crater Herschel

Mimas standing in front of Saturn’s rings. Image credit: NASA/JPL/SSI Click to enlarge
Impact-battered Mimas steps in front of Saturn’s rings, showing off its giant 130-kilometer (80-mile) wide crater Herschel.

The illuminated terrain seen here is on the moon’s leading hemisphere. North on Mimas is up and rotated 20 degrees to the left. Mimas is 397 kilometers (247 miles) across.

The image was taken in visible green light with the Cassini narrow-angle camera on Oct. 13, 2005 at a distance of approximately 711,000 kilometers (442,000 miles) from Mimas and at a Sun-Mimas-spacecraft, or phase, angle of 112 degrees. The image scale is 4 kilometers (3 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Original source: NASA/JPL/SSI News Release

Posted on by Fraser Cain

Carthage Linea on Dione

Dione’s icy surface. Image credit: NASA/JPL/SSI Click to enlarge
Dione’s icy surface is scarred by craters and sliced up by multiple generations of geologically-young bright fractures. Numerous fine, roughly-parallel linear grooves run across the terrain in the upper left corner.

Most of the craters seen here have bright walls and dark deposits of material on their floors. As on other Saturnian moons, rockslides on Dione (1,126 kilometers, or 700 miles across) may reveal cleaner ice, while the darker materials accumulate in areas of lower topography and lower slope (e.g. crater floors and the bases of scarps).

The terrain seen here is centered at 15.4 degrees north latitude, 330.3 degrees west longitude, in a region called Carthage Linea. North on Dione is up and rotated 50 degrees to the left.

The image was taken in visible green light with the Cassini narrow-angle camera on Oct. 11, 2005, at a distance of approximately 19,600 kilometers (12,200 miles) from Dione. The image scale is about 230 meters (760 feet) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Original Source: NASA/JPL/SSI News Release