Its Spring again and, as we move into slightly warmer weather with the still reasonably long nights, observing becomes rather more comfortable and we have an oppportunity to get out there with the telescopes and binoculars to take in the wonders of the Universe.

Of course, we now have our own society telescope and will take every opportunity to use this after each of the monthly talks. In the coming months both Jupiter and Saturn will be well placed for observing and these two objects can often provide the beginner with their most memorable and captivating glimpse of the heavens. But we won’t stop there and members will be given the chance to explore further.

We now also have the beginnings of a library with some books very kindly donated and some purchased out of society funds. Richard Davy has agreed to organise the library and futher details are available in this newsletter.

So, as you can see, the society is flourishing, with over 50 members at the last count, and we very much hope that the combination of talks, observing and the library will maintain interest in what has to be the very best free show on Earth !

Did I say Free ? Well, the night sky is free but the society has its costs and 1^st April is subscription renewal date. However, the good news is that the growing membership means that we can peg the subscription at £12.00 per year (including refreshments) while still being able to afford the main hall, the telescope and to start a library. We look forward to our third year with interest.

Meanwhile, I hope you enjoy this bumper edition of "Dark Matters" and I thank all the members who have contributed such interesting articles.

Clear Skies and Good Observing

Saturn and its satellite Titan remain prominent in the news as the Cassini spacecraft sent back remarkable pictures of the rings and then launched its Huygens probe down to the surface of the largest of Saturn’s moons, Titan.

A giant crater about the size of the Netherlands was spotted on Titan by the Cassini spacecraft as it made another planned fly-by.
 
The huge impact crater was seen, by the Cassini radar instrument, on Titan as the spacecraft flew within 1577 kilometres of the moon's surface on 15 February 2005.

This is the third close Titan fly-by of the mission and only the second time the radar instrument has examined Titan. It is the first time that the areas covered by Cassini's radar and the imaging camera overlapped. This overlap in coverage should be able to provide more information about the surface features than either technique alone.

The crater identified by the radar has an outer diameter of 440 kilometres and was seen before with Cassini's imaging cameras, but not in this detail. It resembles a large crater or part of a ringed basin, either of which could be formed when a comet or asteroid tens of kilometres in size crashed into Titan.

This is the first impact feature identified in radar images of Titan. The surface of Titan appears to be very young compared to other Saturnian satellites. In Titan's case, debris raining down from the atmosphere or other geological processes may mask or remove the craters.

The pattern of brightness suggests that there is topography associated with this feature; for example, in the centre of the image there appear to be mounds each about 25 kilometres across. Since they are dark on their lower edges that face away from the radar and bright on the opposite face, they must be elevated above the surrounding terrain.

A British-led team of astronomers have discovered an object that appears to be an invisible galaxy made almost entirely of dark matter - the first ever detected. A dark galaxy is an area in the universe containing a large amount of mass that rotates like a galaxy, but contains no stars. Without any stars to give light, it could only be found using radio telescopes. It was first seen with the University of Manchester's Lovell Telescope in Cheshire, and the sighting was confirmed with the Arecibo telescope in Puerto Rico. The unknown material that is thought to hold these galaxies together is known as 'dark matter', but scientists still know very little about what that is.

The international team from the UK, France, Italy and Australia has been searching for dark galaxies using not visible light, but radio waves. They have been studying the distribution of hydrogen atoms throughout the Universe. Hydrogen gas emits radiation that can be detected at radio wavelengths. In the Virgo cluster of galaxies, about 50 million light years away, they found a mass of hydrogen atoms a hundred million times the mass of the Sun.

Finding a dark matter galaxy is an important breakthrough because, according to cosmological models, dark matter is five times more abundant than the ordinary (baryonic) matter

that makes up everything we can see and touch.

The Lovell Telescope at Jodrell Bank Observatory where the dark galaxy was first detected. The graph shows the signal that was picked up by the telescope showing the peak at the 21 cm Hydrogen-Line emitted by the Hydrogen gas in the dark galaxy. Copyright University of Manchester.

Stour Astronomical Society has purchased a 10 inch reflecting telescope on a Dobsonian mount. This instrument provides excellent value in terms of light gathering ability and is both quick and easy to set up and use by beginners and advanced observers alike. First light was achieved at our February 2005 meeting and it has given many members their first telescope observing opportunity. We hope to be able to make good use of it in the coming months. The purchase was made possible partly from society funds and partly from generous donations received from both Cavendish Community Council and Cavendish Parish Council. We thank these organisations very much for their contributions.

Observing will be organised after every clear and dark evening at future monthly meetings. Those interested in arranging additional observing evenings should contact Chris Strellis.

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By Richard Davy

The SAS library is now fully established, thanks to some generous donations and growing society funds. It aims to be an ever expanding library so if you have any unwanted astronomy books, or are happy to put your books in the public domain then they will be gratefully received.

There are a variety of books, magazines and some DVDs and videos. These range from beginner guides to the night sky to books on astrophysical cosmology. For an amateur such as myself I can recommend Exploring the Starry Sky which guides you through the changing sky over the seasons, dividing the year into eight phases, and the Astronomy Now Guide to the Constellations which gives practical information on how to observe some of the objects seen better through binoculars.

The library will set up at each meeting and members can borrow items until the next meeting. If members are keen to keep books for longer all I ask is that they bring them back to give someone else the opportunity of borrowing them and they can take them home again if no one else wants them that month.

If you simply cannot wait until the next meeting, you are welcome to contact me to borrow books in between meetings.

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After 50 years of television astronomy the BBC’s Sky at Night team are launching a new monthly magazine featuring contributions from leading writers with articles covering the latest discoveries, astrophysics and equipment reviews. Every issue comes with a CD-ROM and 8-page pull out observing guide, a Patrick Moore masterclass, stunning pictures and a buyers guide. The first issue is out on 24 May 2005 but they don’t say how

By Chris Strellis

Star hopping is the technique of using stars as landmarks to blaze a path across the sky. Many amateur observers use star hopping to find deep-sky objects. You don't need a computerized drive, electricity or special gadgets of any kind. All you need is a dark sky and a good set of star charts. The best way to become good at star hopping is to do it. There are three rules when doing a star hop.

* Get a good finder scope

* Use good charts or Star Atlas

* Know how much sky you are seeing

The job of a finder scope is to allow you to accurately aim your telescope at a celestial object. A finder does this in one of two ways. It either shows the object or the star field where the object is located. The two best options in finder scopes are the traditional straight-through finder and the unit-power finders, commonly referred to as Telrads. The traditional straight-through finder uses aperture and magnification to show the object. And even if the object is too faint to be seen through the finder, it will show enough stars to identify the correct field. The big disadvantage of the traditional finder is that the image does not match your naked eye view of the sky. The view is usually inverted, which can be very disorienting. This is where the unit-power (1X) finder comes into play.

The Telrad and other examples of the 1X finder project a red circle or a red dot against a clear plastic screen. You look through the screen at the night sky and compare the view with that represented on a star chart. If you can identify a pattern of stars in the area of your target and center that area within the circle or against the dot, then your object should be visible in the telescope. Unit-power finders are very intuitive in their use. The view matches your view of the sky and the chart's representation. The disadvantage is that you rely on naked eye stars to aim the telescope. If you observe under light-polluted skies, a Telrad won't be of much assistance. The telescope may not be, either. Even if your aim is dead-on accurate, the object may not be visible through the sky glow.

A good set of star charts will do two things. First, the charts will translate easily to the naked eye view. It's important for beginning observers to use charts showing big chunks of sky on each page. If the charts show only a portion of the constellation in which your target resides, it will be difficult to match the chart to the naked eye view. Second, the charts will plot enough stars to make star hopping practical. If the chart only shows stars to 5th or 6th magnitude, some deep-sky objects won't have any nearby reference stars.

There are a lot of good beginning star charts from which to choose. The Sky Atlas 2000.0 charts by Wil Tirion and Roger Sinnott are excellent. This can be bought for around £25 from Amazon. Each chart usually includes at least one constellation in its entirety, making comparison with your naked eye view a breeze. Stars to magnitude 8.5 are plotted which means you'll be able to use either your Telrad or traditional finder to aim the telescope. Areas of sky that overflow with bright deep-sky objects are given their own more detailed sections.

The key to matching naked eye, finder scope and telescope views to the star chart is knowing how much sky each is presenting. The naked eye view is pretty straightforward. The view through a 1X finder is fairly easy to match up too. However, if you use a Telrad-style reflex finder that projects a circle against the sky, it's important to know how much sky is confined to that circle. A Telrad's outer circle encloses a four-degree area. The innermost circle is half-a-degree across, about the size of the full Moon. You can make a simple tool that will allow you to easily match the Telrad view with star charts. Draw a circular pattern on a clear transparency sheet equal in diameter to a four-degree section of sky on your charts. This overlay makes comparison of the two views very easy. It just happens that a straight-through 8X50 finder also shows four-to-five degrees. Your overlay can be used for either device.

Finally, you will have to match the view through the eyepiece to the chart. Begin by determining how much magnification your eyepiece provides:

Magnification = Telescope focal length (in millimeters) / Eyepeice focal length (in millimeters)

For instance, a 32-mm eyepiece provides 38X magnification in a telescope with a 1,220 millimeter focal length. That's the same focal length as an 8-inch, f/6 Dobsonian. A 16-mm eyepiece produces 76X in that same scope and a 8-mm eyepiece produces a 152X view.

Next, determine the true field of view of that eyepiece. You can determine the approximate true field of view for any eyepiece using this formula:

True Field = Eyepiece Apparent Field (in degrees) / Magnification

For example, a typical Plossl eyepiece has an apparent field of view of 52-degrees. A 32-mm Plossl in an 8-inch, f/6 Dob magnifies 38X. The true field of view (52/38) works out to about 1.4-degree. This is a good, wide field of view to use when looking for objects. Once you find the object, experiment with other eyepieces and magnifications until you find the one that presents the best view.

If you've got good charts, you know the field of view of your finder scope and eyepieces, then you're set to explore the night sky.

Some of the types of celestial objects you can view are:

THE MOON--Prepare for an awesome spectacle. The moon's disk has a pastel-cream and grey background, streamers of material from impact craters stretch halfway across the lunar surface, river-like rilles wind for hundreds of miles, numerous mountain ranges and craters are available for inspection. At low or high power the moon is continually changing as it goes through its phases. Occasionally you will be treated to a lunar eclipse. Note this is a very bright object in a telescope and some sort of moon filter, preferably a variable type, will save your eyes.

THE PLANETS -- Observation of planets will keep you very busy. You can see Jupiter with its great red spot change hourly, study the cloud bands and watch its moons shuttle back and forth. Study Saturn and its splendid ring structure, watch Venus and Mercury as they go through their moon-like phases. Observe Mars and see its polar cap changes or watch the dust storms and deserts bloom with life. Uranus, Neptune and Pluto can be seen easily with 8" or larger telescopes.

STAR CLUSTERS -- There are two types of star clusters- (1) open star clusters (also called galactic clusters) which are loosely arranged groups of stars, occasionally not too distinctive from the background stars, and (2) globular star clusters which are tightly packed groups of many millions of stars.

NEBULAE -- These are glowing clouds of gas falling into two types- (1) planetary nebulae which are relatively small ball-shaped clouds of expanding gases and are believed to be the remnants of stellar explosions, and (2) diffuse nebulae which are vast, irregularly-shaped clouds of gas and dust.

GALAXIES-- These are vast, remote "island universes" each composed of many billions of stars. Galaxies exist in a variety of sizes with regular and irregular shapes.

COMETS -- Magnificent comets are routinely visible through telescopes.

DOUBLE (BINARY) STARS -- These are pairs of stars orbiting around a common center of gravity, often of different and contrasting colors.

What you can see is dependent on a lot of factors. The most important of these for astronomy is aperture. Other important factors are optical quality, steadiness of your tripod and mount, seeing conditions, your location (city or rural), brightness of the object and your experience. You won't be able to see the American flag on the surface of the moon or black holes. You won't see as much color as you see in astrophotographs (photos of celestial objects) because these utilize long exposure times which allow the light and color to build up on the film.

Most telescopes can be used to see things on the Earth. You can use them for long distance terrestrial viewing, nature study, sports action, surveillance or general land usage. You can also easily photograph terrestrial objects since a telescope can be used as a long telephoto lens by attaching the body only of a 35mm SLR camera. T-Ring and T-Adapter accessories are also required.

Astrophotography is also a rich and rewarding experience. With many telescopes it is relatively easy, but takes patience and experience to produce excellent results. Taking your own astrophotographs is a thrill as you can share the results with others.

CCD IMAGING -- The last few years have brought to the amateur astronomer a large assortment of CCD (Charge Coupled Device) cameras. Electronic imaging opens up a whole new vista for amateur astronomers who can obtain images quickly and from urban locations.

Heavens Above.com

www.heavens-above.com/

Custom star maps and satellite pass predictions.

SkyMaps.com

Skymaps.com

Downloadable starmaps in PDF format.

Your Sky

www.fourmilab.ch/yoursky/

Generate custom planisphere-style star maps.

SkyView Café

www.skyviewcafe.com

Interactive star charts and sky info with Java applet.

The Observer's Sky Atlas by Erich Karkoschka (Springer-Verlag; New York; 1998). An overlooked but excellent guide to finding a choice selection of targets.

Stars and Planets: A Viewer's Guide by Gunter Roth (Sterling Publishing; New York; 1998). A fine guide with charts to selected deep-sky objects.

Star Hopping: Your Visa to Viewing the Universe by Robert Garfinkle (Cambridge University Press; Cambridge; 1994). The author provides 14 star-hopping tours for the telescope owner.

Star Hopping for Backyard Astronomers by Alan M. MacRobert (Sky Publishing; Cambridge, MA; 1993). Good charts and illustrations take you on 14 star-hopping tours of selected regions of the sky.

Turn Left at Orion by Guy Consolmagno and Dan M. Davis (Cambridge University Press; Cambridge; 2000). A great star-hopping guide to the sky's best 100 objects, with finder charts and eyepiece sketches of object appearances.

Freeware planetarium downloads for win 95/98/ME/XP.

http://www.hnsky.org/software.htm

Lists of most popular software.

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By Geoff Burling

The Big Bang has become an almost unanimously accepted model for the creation of the Universe but a number of vital questions remain, including "how large is the Universe ?, how old is it ? and when and how will it end ?, if it ever does". Answers to these seem to be playing games with the minds of cosmologists. Many have pronounced that they have discovered the secrets, only to have their theories contradicted within a matter of months.

At a time when telescopes were able to reach only into the relatively near parts of the Universe, distances to stars and galaxies were calculated either trigonometrically using parallax or with a technique pioneered by Henrietta Leavitt using Cepheid variables and a wealth of data was gathered regarding observable objects. One observer, Edwin Hubble, using the Mount Wilson telescope in the 1920’s and taking measurements of the spectra of galaxies, discovered that the redshift, that is the apparent displacement, due to the Doppler effect, of the wavelength of spectral lines emitted by these galaxies, was proportional to their distance. From this he deduced that the further away a galaxy is, the faster it is travelling away from us.

As telescopes, both optical and radio, improved, it became possible to observe objects with greater and greater redshifts, therefore travelling at faster velocities and, by corollary, further away from us. The space telescope bearing Hubble’s name has enabled more and more distant objects to be observed with speeds approaching 90% of the speed of light. The distances to these galaxies have been calculated or, more correctly, estimated using the "Hubble" relationship and, when expressed in light years give a direct indication of the age and size of the known Universe.

Of course, the distance vs. redshift relationship depends much upon that established earlier for the nearer objects. Even then, due to the inherent measurement uncertainties, these yielded significant variability in the "Hubble" constant. The traditional methods of parallax and Cepheid variables cannot be relied upon for measuring such vast distances, now approaching 12 to 15 billion light years. The angles are simply too small and Cepheid variables too faint and, therefore, another basis for distance measurement needed to be established.

One such method involves the use of phenomena known as supernovae. Literally, "bright new stars" these have been observable with the naked eye and, although extremely rare in our own galaxy (the last one was 300 years ago), are thought to occur, on average, at a rate of one per second throughout the observed Universe. Bright they certainly are, with luminosity exceeding that of the entire remainder of their home galaxies for the few days of their duration. The optical output, however, is thought to represent only about 0.01% of the total energy released, thus making them the most violent events in the Universe. The brightness is not questioned but the newness is probably incorrect. There are a number of causes but most involve the death of a star rather than its birth.

In fact, supernovae can now be graded into several types according to their cause and it is one of these that has proven to be important in the desire to measure distances to far galaxies. Known as type Ia, these supernovae are recognised by their spectra which are distinctive in lacking any lines for hydrogen but their important attribute, which makes distance measuring possible, is the apparent consistency of their luminosity. The presence of an object of known luminosity in a distant galaxy renders that distance readily calculable by the inverse square law of propagation of light. By measuring the intensity of the light received we can directly infer how far it has travelled and therefore the time it has taken to reach us.

Of course, the assertion that a particular type of supernova always produces a fixed amount of luminosity is key to this method of measurement and it owes its origins to the inspired work of Subrahmanyan Chandrasekhar who calculated an important property of certain types of stars known as white dwarfs. The "average" sized star, when its nuclear fuel is spent, is overcome by its own gravity and shrinks down to a size, possibly similar to that of the Earth. The matter of which the star is formed, increases in density to the order of magnitude of a million times that of water but Chandrasekhar calculated that there is a limit to the mass of a star that could form a white dwarf and that this is approximately 1.4 times the mass of our sun. Beyond this limit, the collapsing star will form a neutron star or even a black hole, from which no light or matter will escape.

Some white dwarfs, however, exist as one partner of a binary - two stars in relatively close proximity and in orbit about each other. The high density of the white dwarf and the associated gravitational pull results in the accretion of material from its neighbour and, although starting out below the Chandrasekhar limit of 1.4 solar masses, the point in time eventually comes when this limit is reached. At this point a runaway reaction is triggered, resulting in the explosion that we see as a type Ia supernova. As the mass of the star is known, so is the amount of energy released and hence the luminosity. The peculiar process of the explosion also results in the unique absence of hydrogen which provides the identifier. We therefore have a type of "standard candle" with which we can make measurements of distances to the galaxies that contain them.

Studies, in the late 1990s, of large numbers of galaxies, already establised as being distant, have resulted in the observation of type Ia supernovae and thence the calculation of distances. So far, using this method, it has been estimated that the most distant objects in the observed Universe are around 12 billion years old. This, however, is in conflict with estimates for the age of the Universe, of 15 to 18 billion years, drawn from other methods and has given rise to fresh consideration of ideas originally proposed by Albert Einstein in 1915.

Einstein’s Universe, as described by his theories of gravity and general relativity, was static. There was no provision for the expansion that we now believe, and Einstein accepted, to be present. This apparent anomoly lead Einstein to introduce the "cosmological constant" which inferred the presence of forces which repel between all bodies in the Universe. The new data from the supernovae lent credance to this part of Einstein’s theory and much of the puzzle, which had eluded cosmologists for decades, seemed to be falling into place. Not only was the size and age of the Universe now known, but it was also predicted that the expansion is increasing and that, with all parts of the Universe accelerating away from each other, there would be no violent end, or "big crunch". Instead the Universe would gradually thin out, with galaxies and clusters of galaxies becoming more and more isolated, into a kind of dismal, uninteresting perpetuity.

Just as the apparent properties of type Ia supernovae were allowing cosmologists to make parts of the jigsaw fit together, new data regarding these "standard candles" has upset the whole picture. Within the last few years, more detailed studies of supernovae have shown that there is a significant difference in the time taken for luminosities to "peak" when comparing nearby type Ia’s with those in more distant galaxies. Respectively, these average 20 and 17.5 days and this fact has given rise to theories regarding possible differences in the processes which form the supernovae. Maybe the process required to cause a type Ia supernova was different when the Universe was young, as demonstrated by the distant variants, to what it is in the more recent events.

It is believed that the fusion process in the type Ia supernova produces radioactive nickel from a combination of oxygen and carbon and that this begins when the white dwarf draws gas from its neighbour (possibly a red giant) until reaching the 1.4 solar mass limit, when it "ignites". The luminosity is attributed to the radioactive nickel as it decays. However, it is possible that there is considerable variability in the "burning front" of this process as it penetrates through to the star’s surface and that this, in turn, affects the luminosity. The theory holds that, if the "burning front" moves slowly, the luminosity can be reduced by a factor of 10 with corresponding increases in a more rapid system.

Maybe the more distant supernovae have different rates of fusion and do not bear the same standard brightness as previously thought. Alternatively, it may be that some explode prematurely before reaching the 1.4 solar mass limit. Another possible reason to doubt the reliability of data from type Ia studies is the inadequacies of the methodology. Studies of nearer supernovae have largely been done with photographic plates whereas, for those more distant, electronic detectors have been used. The tendency for photographic emulsion to become overexposed due to the intensity of light near the centre of a galaxy, may have lead to some unwitting selection bias in the studied supernovae and, if there is a chance that those on the edge of a galaxy behave differently to those at its centre, more reason for doubt could be present.

One reasonable conclusion is that the type Ia supernova is not the reliable "standard candle" that we thought and that theories of an accelerating universe may be premature. Fortunately there is other emerging evidence regarding the age, size and possible fate of the Universe and cosmologists look, among other places, towards the study of the background microwave radiation and the quest for knowledge of the "dark matter" for new clues. Meanwhile the study of type Ia supernovae continues as an important topic in its own right, regardless of any notion of cosmological "standard candles".

References :-

Books.

Before the Beginning, M. Rees, Simon & Schuster.

Images of the Universe, Ed. C. Stott; Supernovae, P.Murdin, Cambridge University Press.

Stars and Planets, I. Ridpath, Dorling Kindersley.

Oxford Dictionary of Astronomy, I. Ridpath, Oxford University Press.

Galaxies: structure and evolution, R.J. Tayler, Cambridge University Press.

Visions of Heaven, T. Wilkie & M. Rosselli, Hodder & Stoughton.

Articles.

Scientific American, Oct. 99 pg. 18, G. Musser.

Astronomy, Nov.99 pg. 24, R. Graham.

Astronomy Now, Oct. 99 pg. 8 & 9, C. Kitchen.

Astronomy Now, Nov. 99 pg 5. P. Bond.

Nature, 16 Sept. 99 pg. 252, I. Zehavi & A. Dekel.

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Once upon a time there was an interstellar cloud who wanted to be a star.
So he went along to the office and said, "Can I be a star please?".

"Can I just check your parameters, sir?" said the girl at the desk.

"Temperature?" "100K"

"Density?" "I’m afraid I don’t know."
So she weighed him - only 13 solar masses, not very big - and she measured his diameter - 10pc; so she could calculate his density.
"What sort of hydrogen are you? - neutral atomic? OK, so you’re about two million atoms per cubic metre; that seems reasonable. Any rotation? - no. Any significant magnetic fields? - no, good," she said.

So she put all the figures into her spread-sheet, and she said, "I’m sorry, sir - for your temperature and density, the Jeans mass is about 2500 solar masses, so at 13 solar masses you’re nowhere near massive enough to start contracting and become a star."

"Isn’t there anything can I do about it?" he asked. 
"You could try lowering your temperature a bit," she suggested, and she showed him a diagram of how the Jeans mass depends on temperature and number density.  (This is just a rough version.)

She checked: he’d expanded from 10pc diameter to 100pc.
"Well, that changes your density," she said.
So she put in the new diameter, and his density was down to only about 2000 atoms per cubic metre;  and the Jeans mass went up again, to 85 solar masses - not as high as it was before, but still well out of his reach.

"So I can’t be a star?" he said. "I mean, I can’t get any colder!"
"No," she said, "but perhaps you could go back to the way you were, and instead of worrying about your temperature, see if you can get your density up instead.  Try to contract a bit."
So off he went, and he came back saying, "I must be really dense now - look how small I’ve got!"
He’d shrunk from 10pc to only 0.1pc.
"Wow - that should make a difference," she said, and she worked out his number density as 2x10¹² atoms per cubic metre.
"Great, your Jeans mass is now just 2.5 solar masses again, and you’re 13 solar masses, so yes, you can become a star! - assuming all your other parameters are still the same?"
"Well, I have heated up a bit...."  he admitted.

She checked, and his temperature had shot way up - from a hundred K to a million K!
"Oh dear," she said, and she ran the calculations again - the Jeans mass was now 2½  million solar masses.
"Just a minute," she said suddenly, "You said you were neutral hydrogen, but I don’t think you can be now, can you? - not at that temperature!"
"No, I think I’m totally ionised now. Hey, so I’ve got twice as many particles!"
"Yes," she said, "but it also reduces your average particle mass. Let me see. No, it makes matters worse."
The Jeans mass was now three times greater - even further out of his reach.

"So I can’t ever be a star," he said.
"Look," she said (she really did want to help him), "I tell you what your problem is: you’re adiabatic, that’s what you are. You expand, you cool down; you contract, you heat up. You just keep moving backwards and forwards on this same line.

"You can't ever be a star unless you can manage to cool down and contract at the same time."
"But how can I do that?"
"You need to start interacting with your environment a bit. Look, go back to the way you were, and start contracting, but this time, instead of letting yourself heat up, try radiating a bit - throw some of your heat away into space, no-one will notice. And that’ll bring your Jeans mass down - honest!"

So he tried it:  he started to contract, and as soon as he began to get hot, he waited until he could radiate away the heat, and then he contracted some more.  And it worked: he finally got his Jeans mass down below his actual mass, and he did become a star. And he lived happily - not for ever after, but for about 20 million years, which is not far off.

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An Interesting Theory ?

A while ago I talked about one of my heroes, Fred Hoyle. He was always an "unconventional figure" (awkward so-and-so) who finally upset just about everyone in the scientific community with his pet theory about the origin of life, no less.

This theory is called "panspermia". It has been around a long time, but had been totally rejected, certainly since the 19^th century, as being too far-fetched. There were other reasons too, not all of them scientific, which will become apparent.

The following has been mostly transcribed from a website about Cosmic Ancestry; I found it pretty readable, I hope you do too.

Recently, panspermia has been incorporated into a wider theory known as Cosmic Ancestry, which is a new theory pertaining to evolution and the origin of life on Earth. It holds that life on Earth was seeded from space, and that life's evolution to higher forms depends on genetic programs that come from space. (It accepts the Darwinian account of evolution that does not require new genetic programs.) It is a wholly scientific, testable theory for which evidence is accumulating.

First, a bit of history. Panspermia — literally, "seeds everywhere" was originally advocated by the Greek philosopher Anaxagoras, who influenced Socrates. However, Aristotle's theory of spontaneous generation, e.g mice appearing from dirt, came to be preferred by science for more than two thousand years. Then on April 9, 1864, French chemist Louis Pasteur announced his great experiment disproving spontaneous generation as it was then held to occur. In the 1870s, British physicist Lord Kelvin and German physicist Hermann von Helmholtz reinforced Pasteur and argued that life could come from space. And in the first decade of the 1900s, Swedish chemist and Nobel laureate Svante Arrhenius theorized that bacterial spores propelled through space by light pressure were the seeds of life on Earth.

But in the 1920s, Russian biochemist Alexander Oparin and English geneticist J.B.S. Haldane, writing independently, revived the doctrine of spontaneous generation in a more sophisticated form. In the new version, the spontaneous generation of life no longer happens on Earth, takes too long to observe in a laboratory, and has left no clues about its occurrence. Supporting this theory, in 1953, American chemists Stanley Miller and Harold Urey showed that some amino acids can be chemically produced from ammonia and methane. That experiment is now famous, and the Oparin - Haldane theory still prevails today.

Starting in the 1970s, Fred Hoyle and Chandra Wickramasinghe rekindled interest in panspermia. By careful spectroscopic observation and analysis of light from distant stars they found new evidence, traces of life, in the intervening dust. They also proposed that comets, which are largely made of water-ice, carry bacterial life across galaxies and protect it from radiation damage along the way. One aspect of this research program, that interstellar dust and comets contain organic compounds, has been pursued by others as well. It is now universally accepted that space contains the "ingredients" of life. This development could be the first hint of a huge change in ideas. But mainstream science has not accepted the hard core of modern panspermia, that whole cells seeded life on Earth.

Hoyle and Wickramasinghe also broadened or generalized panspermia to include a new understanding of evolution. While accepting the fact that life on Earth evolved over the course of about four billion years, they say that the genetic programs for higher evolution cannot be explained by random mutation and recombination among genes for single-celled organisms, even in that long a time: the programs must come from somewhere beyond Earth. In a nutshell, their theory holds that all of life comes from space. It incorporates the original panspermia in the same way that General Relativity incorporates Special Relativity.

Meanwhile on a different track, in the early 1970s, British chemist and inventor James Lovelock proposed a theory, called Gaia, that life controls Earth's environment to make it suitable for life. However, seen from a Darwinian perspective, the Gaia theory looks teleological - somebody made it happen. It is hard to imagine how purposeful Gaian processes that take millions of years could be discovered by trial and error. In response to such criticism, Lovelock has retreated slightly from some of his earlier bold claims for Gaia. Here we endorse Lovelock's theory at its original strength. We propose that Gaian processes are not blindly found and peculiar to Earth, but are pre-existent and universal — life from space brings Gaian processes with it. It may be that Gaian processes are necessary for higher forms of life to emerge and succeed on any planet.

The union of Lovelock's Gaia with Hoyle and Wickramasinghe's expanded theory of panspermia is known as Cosmic Ancestry. This account of evolution and the origin of life on Earth is profoundly different from the prevailing scientific idea — the theory challenges not merely the answers but the questions that are popular today. Cosmic Ancestry implies, we find, that life can only descend from ancestors that were at least as highly evolved as itself. And it means that there can be no origin of life from nonliving matter in the finite past. Without supernatural intervention, therefore, it is concluded that life must have always existed. Although these conclusions cut across the boundaries between science, philosophy, and religion, there is much good evidence in their support. In fact, new data that support many aspects of Cosmic Ancestry are coming in rapidly. These since 1995 :-

Bacteria can survive without any metabolism for at least 25 million years; probably they are immortal. Bacteria found that can survive radiation much stronger than any that Earth has ever experienced.

Fossilized evidence of ancient life in meteorites from Mars & elsewhere. Geneticists showed evidence that many genes are much older than the fossil record would indicate.

NASA officially recognized the possibility that life on Earth comes from space. Stardust mission announced the detection of very large organic molecules in space.

Geneticists reported evidence that the evolutionary step from chimps to humans was assisted by viruses.

Cosmic ancestry Would also explain one or two other things; evolution seems to have occurred in a very "lumpy" way - sudden changes, not the smooth development from species to species as predicted by Darwinism. Also, the maths. of random selection doesn’t make sense, particularly when you try to produce DNA from it’s raw materials. Incidentally, lentils have the basic gene sequence for haemoglobin locked up in their DNA - why would that be? Blood’s no use to a lentil! (Blood out of a stone, maybe …)

The case for Cosmic Ancestry is not yet proven, of course. At this point the best reason to notice it is that sustained evolutionary progress and the origin of life on Earth are not satisfactorily accounted for by Darwinism.

References:

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For those interested in purchasing a telescope there are a couple of good suppliers in the area :-

Green Witch,

Unit 6, Dry Drayton Industries, Scotland Road, Dry Drayton, Cambridge, CB3 8AT

Tel: 01954-211288

Mention Stour Astronomical Society

Sneezums,

10 Cornhill,Bury St. Edmunds, Suffolk,

IP33 1BH

Tel: 01284-755210

ALSO – for CCD and related products

Ian King Imaging

41 Blackberry Way

Paddock Wood

Kent, TN12 6BP

Tel: 01892-834004

5% Discount for SAS Members

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PPARC

NASA

Jet Propulsion Laboratory

European Space Agency

Institute of Astronomy

Mullard Radio Astronomy Laboratory

Jodrell Bank

Royal Observatory, Greenwich

European Southern Observatory

National Space Centre

TheSociety for Popular Astronomy

"Dark Matter and Dark Energy"

Dr. Kevin Marshall

"Variable Stars"

Dr. Kevin Marshall

"Wide Field CCD Imaging"

Ian King

"The Lunar Landscape"

Dr. Kevin Marshall

"The Sun’s Power Source"

Dr. Kevin Marshall

Members Talk Evening

Star Party, Quiz & Bar-B-Q

"Giant Gas Planets"

Dr. Kevin Marshall

"Is the Universe Flat ?"

Dr. Kevin Marshall

"Messier Objects"

Dr. Kevin Marshall

"A Tour of Orion"

Dr. Kevin Marshall

At each meeting an illustrated talk will be given either by Dr. Kevin Marshall or by a guest speaker.

The Society was founded in 2003 to provide a focal point for amateur astronomers of all levels of interest and ability to meet and share their enjoyment of the night skies. It is anticipated that members will be drawn from nearby towns and villages in the Stour Valley area.

Observation will be possible on clear dark nights and members are invited to bring telescopes or binoculars when weather conditions permit.

We very much welcome new members to the Stour Astronomical Society. Membership is £12.00 per year.

The membership year runs from 1^st April and fees depend upon date of joining as follows :-

Date of Joining Fee

April - June £12.00

July – September £9.00

October – December £6.00

January – March £3.00

Visitors & Members’ Guests are also very welcome - £1.50 per evening.

"Dark Matters" is the newsletter of the Stour Astronomical Society (S.A.S.).

Our web site is :-

Secretary – Geoff Burling

01787-281584

Chairman – Kevin Marshall

01787-249534

Webmaster – Chris Strellis

01787-277155

Telescope – Chris Strellis

01787-277155

Librarian – Richard Davy

01787-280209

Treasurer – Colleen Sarratt

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Located at a distance of about 45 million light-years in the southern constellation Fornax (the Furnace), NGC 1097 is a relatively bright, barred spiral galaxy of type SBb, seen face-on. At magnitude 9.5, and thus just 25 times fainter than the faintest object that can be seen with the unaided eye, it appears in small telescopes as a bright, circular disc.

ESO PR Photo 35d/04, taken on the night of December 9 to 10, 2004 with the VIsible Multi-Object Spectrograph ("VIMOS"), a four-channel multiobject spectrograph and imager attached to the 8.2-m VLT Melipal telescope, shows that the real structure is much more complicated. NGC 1097 is indeed a most interesting object in many respects.

As this striking image reveals, NGC 1097 presents a centre that consists of a broken ring of bright knots surrounding the galaxy's nucleus. The sizes of these knots - presumably gigantic bubbles of hydrogen atoms having lost one electron (HII regions) through the intense radiation from luminous massive stars - range from roughly 750 to 2000 light-years. The presence of these knots suggests that an energetic burst of star formation has recently occurred.

NGC 1097 is also known as an example of the so-called LINER (Low-

Ionization Nuclear Emission Region Galaxies) class. Objects of this type are believed to be low-luminosity examples of Active Galactic Nuclei (AGN), whose emission is thought to arise from matter (gas and stars) falling into oblivion in a central black hole.

There is indeed much evidence that a supermassive black hole is located at the very centre of NGC 1097, with a mass of several tens of million times the mass of the Sun. This is at least ten times more massive than the central black hole in our own Milky Way.

However, NGC 1097 possesses a comparatively faint nucleus only, and the black hole in its centre must be on a very strict "diet": only a small amount of gas and stars is apparently being swallowed by the black hole at any given moment.

As can be clearly seen in the upper part of the photo, NGC 1097 also has a small galaxy companion; it is designated NGC 1097A and is located about 42,000 light-years away from the centre of NGC 1097. This peculiar elliptical galaxy is 25 times fainter than its big brother and has a "box-like" shape, not unlike NGC 6771, the smallest of the three galaxies that make up the famous Devil's Mask.

Image overleaf……………………………………

This unique and beautiful image was obtained with the Very Large Telescope at the ESO Paranal Observatory, Chile.

The ESO Very Large Telescope consists of four 8-meter telescopes which can work independently or in combined mode. In this latter mode the VLT provides the total light collecting power of a 16 meter single telescope, making it the largest optical telescope in the world. The four 8-m telescopes supplemented with 3 auxilliary 1 m telescopes may also be used in interferometric mode providing high angular resolution imaging. The useful wavelength range extends from the near UV up to 25 microns in the infrared.

The Paranal Observatory is located on Cerro Paranal in the Atacama Desert, northern Chile. Science operation with the first unit telscope (UT1) commenced in 1999. Full operations of all telescopes is expected shortly.

The second galaxy, also imaged by the VLT, is another spiral, the beautiful multi-armed NGC 7424 that is seen almost directly face-on. Located at a distance of roughly 40 million light-years in the constellation Grus (the Crane), this galaxy was discovered by Sir John Herschel while observing at the Cape of Good Hope.

This other example of a "grand design" galaxy is classified as "SAB(rs)cd" [2], meaning that it is intermediate between normal spirals (SA) and strongly barred galaxies (SB) and that it has rather open arms with a small central region. It also shows many ionised regions as well as clusters of young and massive stars. Ten young massive star clusters can be identified whose size span the range from 1 to 200 light-years. The galaxy itself is roughly 100,000 light-years across, that is, quite similar in size to our own Milky Way galaxy.

Because of its low surface brightness, this galaxy also demands dark skies and a clear night to be observed in this impressive detail. When viewed in a small telescope, it appears as a large elliptical haze with no trace of the many beautiful filamentary arms with a multitude of branches revealed in this striking VLT image. Note also the very bright and prominent bar in the middle.

Image overleaf………………………………………