Bismillah. More from Katie Paterson. I’m delighted that a brief conversation about supernovae 1-2 years ago at ROG led to an astronomical art display at the Tate.

Katie says:

I went on to contact and then work with Supernova Hunters all over the world, like you suggested. Particularly Prof Richard Ellis, then at Oxford, now Caltech.

It resulted in a huge map of ‘All the Dead Stars’ in the Universe – that was shown at Tate Britain early this year:

http://www.katiepaterson.org/deadstars/view.html

A whole 27,000 of them! (Gamma ray bursts, white dwarves, supernova type 1a,b etc)

Just look at him. As majestic as the Milky Way.

Holy Moley did I cry with joy when I learned this. Our friends at Hulu have put up all thirteen episodes of Carl Sagan’s magnum opus, Cosmos. If you’re unfamiliar with Cosmos, it’s an awesome series. Sagan explores a different topic each episode, outlining a particular feature of our wonderful universe with his characteristic awe and infectious enthusiasm. Stars, galaxies, the formation of the Earth? The origins of the elements, the subtleties of star death? You’ll find it here! I whole heartedly recommend you watch every single episode. Dang, it’s just so cool!
Go now! Go and be entertained and educated!

-Neil

M1, the Crab Nebula, the remnant of a star that exploded almost 1000 years ago. The heavy elements in the universe--including the ones in our bodies--were created and dispersed by exploding stars.

I know that the molecules in my body are traceable to phenomena in the cosmos. That makes me want to grab people in the street and say, “Have you heard this!?”
- Neil DeGrasse Tyson

Photo from APOD.

This spectacular image of a jet of gas and dust in the constellation Carina was just released by the Hubble team.

Is it Christmas already? Hubble has recovered from a May 2009 service mission and its attendant scientists have released new data and images. Go check it out on the Hubble website, here.

The goal of the May 2009 mission was “to replenish the ‘tool kit’ of Hubble instruments,” drastically increasing its capabilities. The images it produces from here on out will be clearer and more precise than any before. It will also be able to see further into space than any other telescope – scientists on the Hubble team hope to capture images of objects 13 billion light years away. If it accomplishes this, we humans will be getting a glimpse of the universe as it existed moments after its birth. Well, hundreds of millions of years hardly constitute “moments,” but still. It’s really impressive. I’m going to stop now and give you some pictures to stare at. Check out the link above for more.

This is NGC 6302, an incredible supernova blast remnant. The originating star is at the center of the object, obscured by a ring of dark dust. Though the image is static, do not forget that the gas pictured is rushing away from its parent star at extreme speeds!

Next!

Beautiful barred spiral galaxy NGC 6217.

One more, home court advantage.

A brand spanking new picture of our solar system's largest planet. Hubble has produced the highest resolution picture of the planet ever. Note the black spot at the bottom right. This scar is the result of a recent impact by what was probably a comet. It is roughly the size of the Pacific Ocean.

What are you waiting for?? Go look at those pictures!!!

-Neil

I have found videos to be some of the best ways to get ideas across in terms of visualizing data or complex ideas. Wired published the best Science Visualizations Videos of 2009 and some are very very cool.My favorite is the explosion of type Ia supernova. Dang…. awesome stuff!

più che il titolo di un post scientifico sembra il titolo di un romanzo di agatha christie: riusciranno i nostri eroi a trovare l’energia oscura? prima domanda: ma cos’è l’energia oscura? orsù dunque, diciamolo (anzi dicetevelo): nessuno ha davvero capito cos’è l’energia oscura. o meglio (n.d.r vedo già drizzarsi le orecchie dei precisini): sappiamo che c’è, ne abbiamo visto gli effetti, ma è il grande mistero della fisica moderna. l’universo sembra espandersi in maniera accelerata. olè.

chiaro è che per misurare con precisione la d.e (n.d.r meglio nota anche come quintessenza…che nome…) è necessario quindi misurare con precisione anche le distanze, e, sopratutto, se il valore di d.e è variabile in rapporto al tempo. fino ad ora erano sempre arrivate in aiuto le supernovae 1a (n.d.r grandi stelle che muoiono in maniera esplosiva) utilizzate come candele standard, e, perciò, anche come parametri di distanza. beh, daniel kasen, un postdoc dell’università californiana di santa cruz, pensa che sia importante capire anche il modo in cui esplodono.

mi spiego meglio. utilizzando modelli in due dimensioni, le esplosioni sembrano essere tutte uguali ed uniformi. guardate con modelli in tre dimensioni invece no, e sembrano essere, appunto, disuniformi. secondo kasen questa disuniformità potrebbe essere dovuta alla d.e (n.d.r un pò tira di qua ed un pò tira di là), e scoprire un “parametro di disuniformità” potrebbe essere utile per calcolare anche se la d.e è costante o variabile, appunto, nel tempo.

i vecchi metodi son sempre i migliori…

The Hubble Space Telescope. It's a telescope, in space, named after a guy called Hubble. What more do you need to know?

Did you know that the Hubble Space Telescope is awesome? Probably. But did you know you have access to a huge gallery of amazing images taken with everyone’s favorite orbiting telescope? Maybe not! Well now you do! Go here for a hugenormous gallery of stellar photographs of celestial bodies that are truly out of this world. Check below the break for a sampling.

Here’s a few that I like.

The Sombrero Galaxy:

The Sombrero Galaxy, aka NGC 4594, is a spiral galaxy viewed edge-on. The mighty mass of material swirls about a central, supermassive black hole.

The Mice:

The Mice, named for their tails of stars and dust, are a pair of galaxies that seem to have collided. Material from one is drawn off by the other. Some day in the long, dark, future, these two galaxies will be one.

And finally, the Cat’s Eye Nebula, which to me looks very little like a cat’s eye:

The Cat's Eye Nebula lies 3300 light-years from Earth and was formed when the star at the center periodically ejected layers of hot gas. I also periodically eject hot gas, but the results are never quite as beautiful.

That’s just a small sample of the wonders to be found! Hubble is really wonderful, because not only does it bring in a tremendous wealth of valuable scientific data, but it also helps us to see and appreciate the beautiful and incredible place we live in. How can anyone react with anything other than awe and stupefaction when they realize the universe is populated with such objects? So go now, click and be amazed at the bounty of beautiful things in our dear universe!

-Neil

Update:
Aw, jeez, the Hubble is so great. I have more for you.

The Pillars of Creation in the Eagle Nebula. You're looking at massive spire-like clouds of interstellar gas and dust. Places like this are where interstellar gas and dust has come together in sufficient quantities to create new stars.

This is the Black Eye Galaxy. It has an outer ring of material that spins the opposite direction of all the rest of the matter in the galaxy. This material is thought to be the result of an ancient galactic collision.

This is a ring of dust swirling around a black hole.

The Carina Nebula.

The galaxy Centaurus A.

The Horsehead Nebula. I personally think it looks more like a roaring lion.

Cloud of expelled material surrounding super giant V838 Monocerotis.

Our very own Jupiter.

Closeup of Jupiter's clouds.

An aurora on Saturn.

Finally, the Hubble Ultra Deep Field. Take a good hard look at this and really think about it. The narrator describes this picture as “the most important image ever taken.” I don’t think this is an overstatement.

Well, I hope you enjoyed this as much as I have. It makes one feel blessed to think that we live in the time when humanity first opened its eyes to the vastness and beauty of the cosmos.

The Crab Nebula, the remains of a supernova which exploded in 1054 AD. This picture was taken by the Hubble Space Telescope.

You are a star.

I am too.  Every single one of us is.  Every single living thing on Earth- not to mention the Earth itself- is made from materials forged in the furnace of a red super-giant star that lived more than four and a half billion years ago.

When the Universe was formed in the Big Bang, the only elements produced were hydrogen and helium.  Yet all around us we see a world made from heavier elements.  Iron and silicon are in the rocks, calcium is in our bones, oxygen is in the air and the water, and carbon is the basis for every single life-form on the face of this pale blue dot we call a planet.  None of these were produced in the Big Bang; they were produced much later, in the centers of red super-giant stars.

All stars, regardless of size or color, spend the majority of their lives powered by hydrogen fusion.  This is when atoms of hydrogen are combined to form atoms of helium, releasing energy in the process.  It takes enormous temperatures and pressures for this process to happen (a thermonuclear bomb, which uses the same principle, requires a regular nuclear bomb to set it off), so fusion only occurs in the hottest, densest part of a star- the very center.  The rest is just dead weight.

An average star, like our sun.

Eventually, the core of the star runs out of fuel.  There is not enough hydrogen left in the center to fuse into helium, so fusion temporarily shuts down.  This causes two things to happen: the dead weight part of the star expands to hundreds of times its previous size, absolutely obliterating any planets which are unlucky enough to get too close (this is how the Earth will be destroyed, in about five billion years), while the core collapses to a fraction of its former size, causing a drastic increase in both heat and pressure.  Eventually the heat and pressure in the core get high enough to ignite the next level of fusion, helium into carbon.  The heat released by this fusion increases the temperature of the bottom layer of the dead weight hydrogen gas until it gets hot enough to begin fusing into helium.  The star then has a core of helium-to-carbon fusion surrounded by a shell of hydrogen-to-helium fusion, surrounded by a lot of dead weight hydrogen.  This is called a red giant.

A Red Giant Star. Our sun will end its life as one of these.

For stars that started out small, this is where life ends.  They don’t have the heft to get their cores up to the next level of fusion.  But for one of the big boys – a star that started out at least eight or nine times as massive as the sun- this is just the beginning.  A large star goes beyond being a red giant to become a red super-giant star.  It gets its core so hot and pressurized that it can fuse carbon with hydrogen or helium to make nitrogen or oxygen.  Then it fuses carbon with oxygen to make silicon.  Once it has done that, the super-giant is free to make all sorts of different fusions, and it ends up producing all the elements on the periodic table which are lighter than iron.  After that, fusion no longer releases any energy.  Once it reaches iron, the super-giant is finished.  It put up a gallant fight; it hung on to the very end.  But its life is finally over.

A Red Super Giant Star. This diagram is simplified. The interior of a super giant star is chaotic and difficult to predict.

The death-throes of a red super-giant are awesome to behold.  After years of violent instability, the core collapses into a neutron star or a black hole.  This releases a great deal of gravitational potential energy,* igniting one last round of explosive fusion and sending the rest of the star careening out into space.  The super-giant absolutely obliterates itself in a massive, planet-shattering detonation called a supernova.  This explosion is so powerful that for a few weeks, a star going supernova can outshine an entire galaxy. That means that a single star produces more light than the roughly 200,000,000,000 stars in an average galaxy. In all the chaos of this cosmic cataclysm, unprofitable forms of fusion can occur, creating elements heavier than iron.  The gold in your wedding-ring and the copper wires in your computer were both formed in the death throes of a great cosmic giant.

Supernova N63A in the Large Magellanic Cloud. This picture was also taken with the Hubble Space Telescope.

From the ashes, new life is born.  The debris spewed into interstellar space by the supernova is chock full of heavy elements.  There is carbon and oxygen, silicon and iron, and even rarities like copper, gold and uranium.  These elements mix into the interstellar gas, enriching it.  And as the aftershocks of the supernova begin to cool, this gas begins to clump.  Some of these clumps collapse into discs, and from these discs new solar systems are born.  From the silicon and iron blasted forth by the supernova, planets form.  And, if one of those planets is just the right distance from its sun, then from the carbon and nitrogen and oxygen fused in the core of the red super-giant, life may form.  Four and a half billion years ago, the new planet was Earth, and our bacterial ancestors were the new life.  Like roses rising from a grave, each and every one of us owes our existence to the death of a super-giant, the greatest of stars.  As Carl Sagan would say, we are all starstuff.

-Mike

*Gravitational potential energy is the energy you get when matter falls from a high elevation to a low elevation.  It is this energy which does the damage when you drop an anvil on someone’s head.

Das ganze basiert auf Folge 402, wenn ihr also net gespoilert werden möchtet, lasst eure Finger davon! Ist jedenfalls verdammt cool

53 million years ago a massive star in the galaxy NGC 4088 lost its battle with gravity and collapsed upon itself. The resulting collapse increases the temperature and pressure near the center of the star until a massive rebound, or explosion, occurs. This explosion which destroys most of the star is visible to us as a supernova. Though the supernova occurred 53 million years ago, it took the light from that explosion 53 million years to reach Earth which is why we are only seeing it now.

The supernova has been designated SN2009dd and was discovered by 2 independent teams of Italian astronomers. On the night of 2009 April 13, Giancarlo Cortini (Preparrio, Italy), Alessandro Dimai (Cortina d’Ampezzo, Italy) and Elisa Londero (Gemona, Italy) found imaged the supernova. Cortini was the 1st to notice the “super new star”. After a preliminary note was posted, Dimai and Londero found the object in images they took as part of their CROSS survey for new supernovae.

BVR image of SN2009dd in the galaxy NGC 4088. Images taken by Carl Hergenrother with the U of Arizona Kuiper 1.54-m telescope on 2009 May 28.

The above image is a composite of images taken in B (blue), V (yellow) and R (red) filters with the University of Arizona’s Kuiper 1.54-meter telescope on Mount Bigelow. I don’t usually observe supernova (mainly comets and asteroids) but I was helping a friend who was planning a program to observe supernova. Since SN2009dd was the most picturesque one currently observable, it made a great target. The supernova is the star very close to the center of the galaxy. The 2 yellow arrows point at the location of the supernova.

The galaxy (NGC 4088) the supernova is located in is located in the constellation of Ursa Major, the same constellation that contains the Big Dipper. The galaxy is magnitude ~11.2 which makes it a tough target for telescope users unless you have either a large scope or live at a very dark location. The supernova itself peaked at magnitude 13.5 in early April. By the time of my observations on May 28, it had only dimmed slightly to about magnitude ~13.8.

An unusually shaped supernova remnant observed in the Small Magellanic Cloud is likely the remains of an exploded white dwarf.

More?

Yesterday was the occasion of the Annual Ball of the Cardiff  University School of Physics & Astronomy’s Student Society Chaos held in the Cardiff Arms Suite of the Millennium Stadium. I had reservations about going because things like this always make me feel very old, but having been persuaded I was determined to have a good time. It turned out to be very enjoyable, so much so that I ended up moving on with some others to a nightclub to continue the party into the small hours. I think I kept up with the youngsters quite well, although I was well and truly knackered when I got home.

I’m also glad I didn’t disgrace myself too much, or if I did I don’t remember…

There was about a hundred people at the Chaos Ball, the vast majority of them students in the department. Not many staff members went along, although those that did all seemed to have a good time. These social events are quite tricky to pull off for a number of reasons. One is that there’s an inevitable “distance” between students and staff, not just in terms of age but also in the sense that the staff have positions of responsibility for the students. Students are not children, of course, so we’re not legally  in loco parentis, but something of that kind of relationship is definitely there. Although it doesn’t stop either side letting their hair down once in a while, I always find there’s a little bit of tension especially if the revels get a bit out of hand.

To help occasions like this I think it’s the responsibility of the staff members present to drink heavily in order to put the students at ease. United by a common bond of inebriation, the staff-student divide crumbles and a good time is had by all.

A couple of other incidents that happened this week serve to illustrate related issues. On Thursday we had to evacuate the building because the fire alarm went off. It turned out that some work being done on the roof had triggered a smoke detector. Although it wasn’t a real emergency, four fire engines arrived and we all stood outside for the best part of an hour while they figured out what had happened and, curiously, how to switch the alarm off.

The fire alarm had gone off, the fire brigade had turned out, but there was no fire to be seen. I joked that the only possible explanation of this state of affairs was that there must be a dark fire…

Standing outside, staff and students chatted casually while waiting to be let back into the building. It was sunny, which added to the conviviality. I realised, though, that I’d  never really spoken to many of my students like that before, i.e. outside the lecture  or tutorial. I see the same faces in my lectures day in, day out but all I do is talk to them about physics. I don’t know them at all. It’s strange.

The other thing was yesterday morning where I was giving one of my first year lectures on Astrophysical Concepts, a course which I really enjoy teaching. The topic was supernovae and it’s a lecture which I always end by doing an impersonation of a supernova explosion. If you want to see it, you’ll have to sign up for the course.

I was doing my PhD in 1987 when a supernova (SN1987A) went off in the Large Magellanic Cloud. It was  a hot topic for a while and I mentioned in my talk. I started to say “Some of you will remember…” then I suddenly realised to my horror that in 1987  nobody in my class had yet been born…

Light from Type I supernovae is used as a standard for distances

Researchers have come up with a theory for how stars can end in a spectacular so-called Type Ia supernova in less than 100 million years.

While such early-stage supernovae are well-known, theory has been unable to explain them.

The secret, the researchers say, is that white dwarf stars steal mass from nearby “helium stars” until they have enough mass to initiate a supernova.

The research appears in Monthly Notices of the Royal Astronomical Society.

The new theory concerns white dwarf stars, the dense remains of stars like the Sun that have fused their hydrogen into helium and then the helium into carbon and oxygen.

Existing theory held that these carbon/oxygen white dwarves can gather up further mass from nearby companion stars.

When they reach a critical mass, about 40% more than the Sun, they can undergo further fusion. In just a few seconds, the white dwarf’s carbon is fused into heavier elements in a runaway process that releases huge amounts of energy into the cosmos: a supernova.

Too fast

Because the process happens with a known brightness, such supernovae have been used by astronomers as a standard for distances.

However, the theory held that the mass-accreting process would take more than 100 million years to occur. However, observations have it that about half of the Type Ia supernovae observed occur in less than that amount of time.

Bo Wang and colleagues of the National Astronomical Observatories at the Chinese Academy of Sciences investigated the problem, performing calculations based on 2600 relatively nearby white dwarf/companion star pairs.

They found that if the companion star was a so-called helium star – which had fused all its hydrogen to form a helium core – then the white dwarf could steal away mass more quickly, leading to a supernova event in less than 100 million years.

“Before this investigation, there was no model which could produce a large population of such young Type Ia supernovae, and no knowledge of a way to produce such numbers,” study co-author Xuefei Chen told BBC News.

Dr Chen said that the theft of mass from helium stars is likely to produce most of the “young” Type Ia supernovae that we observe, if not all of them.

“A significant population of young Type Ia supernovae may have an effect on models of galactic chemical evolution, since they would return large amounts of iron to the interstellar medium much earlier than previously thought,” Dr Chen added.

“It may also have an impact on cosmology, as they are used as cosmological distance indicators.”

The team now plans to study the extremely high-velocity helium stars that would be the remnants of such supernovae.

While such fast-moving stars have been spotted before, their speed was attributed to gravitational interactions, rather than supernovae. Those remnants may now serve as proof of the team’s theory.

__________

Full article and photo: http://news.bbc.co.uk/2/hi/science/nature/7996852.stm

Supernovae, suatu ledakan dasyat dan sangat kuat yang terjadi pada bintang-bintang di akhir hidupnya, mungkin merupakan jawaban dari misteri yang usianya sudah 10 miliar tahun: asal-usul debu kosmis!

Para astronom telah sejak lama meyakini bahwa debu ruang angkasa terbentuk dalam suatu proses yang relatif dingin, yakni dari sebuah bintang yang terbakar perlahan dan debu-debunya diterbangkan angin. Partikel-partikel hasil kebakaran itu lepas secara sangat pelan, sampai suatu ketika memenuhi ruang angkasa menjadi kabut yang sering disebut sebagai nebula. Karena gaya tarik menarik, partikel nebula itu akhirnya menyatu dan menjadi planet.

Namun minggu lalu para astronom dari Inggris dan Wales mengungkapkan penemuan baru. Mereka mengamati bahwa beberapa supernovae melepaskan debu sekaligus dalam jumlah banyak, bukan perlahan-lahan seperti yang diperkirakan selama ini. Hal itu menimbulkan dugaan yang menyatakan dari situlah sebagian besar debu kosmis di jagad raya berasal.

Teori Baru

Dugaan yang sekaligus menjadi teori terbaru mengenai asal-usul debu kosmis itu ditemukan setelah Dr Loretta Dunne, seorang astronom dari Universitas Cardiff, dan rekan-rekannya di Royal Observatory, Edinburgh, memanfaatkan kamera revolusioner yang disebut SCUBA. SCUBA adalah kamera sangat kuat yang mampu mendeteksi panjang gelombang sub-milimeter (antara 0,1 – 1 milimeter). Dengan kamera ini, debu kosmis yang sehalus asap rokok pun bisa dilihat.

“Debu-debu itu bersinar dalam panjang gelombang sub-milimeter. Anda dapat menangkap gambarnya menggunakan kamera khusus ini dan melihat cahayanya,” jelas Dunne.

Tim peneliti memanfaatkan SCUBA untuk mengamati debu-debu yang merupakan sisa-sisa supernova Cassiopeia A, bintang yang 30 kali lebih besar dari matahari dan berjarak 11.000 tahun cahaya dari Bumi. Satu tahun cahaya adalah sekitar 10 triliun kilometer jarak tempuh cahaya dalam satu tahun.

Pada akhir hidup Cassiopeia A, debu-debu hasil ledakannya telah menyebar ke angkasa luar dengan kecepatan 10.000 kilometer per detik selama 300 tahun. Dalam foto-foto yang diambil menggunakan teleskop-teleskop raksasa, kumpulan debu supernovae itu menghasilkan gambar kabut kebiruan yang sangat indah.

Supernovae

Apakah supernovae itu? Seperti sudah disebut di atas, supernovae adalah ledakan maha dasyat dari sebuah bintang pada akhir hidupnya. Dalam ledakan tersebut, sebuah supernova dapat melepaskan lebih banyak energi dibanding energi yang dihasilkan matahari selama 9 miliar tahun umurnya. Selain menghasilkan debu yang terdiri dari karbon dan silikat, ledakan juga menyemburkan oksigen ke ruang angkasa.

Haley Morgan, mahasiswa di Universitas Cardiff, menjelaskan, “Beberapa supernovae adalah akhir dari bintang yang hidup singkat dan mati muda. Bintang-bintang ini beberapa kali lebih besar dari matahari, dan mereka terbakar ribuan kali lebih cepat, yakni hanya dalam waktu beberapa juta tahun.”

Penghasil Debu Kosmis

Sebenarnya sejak semula para astronom sudah menduga supernovae menghasilkan debu kosmis. Namun pengamatan sebelumnya hanya menemukan sedikit saja debu pada peristiwa ledakan itu. Nah, pada kasus Cassiopeia A, ledakan itu menghasilkan debu kosmis dalam jumlah besar, ribuan kali lebih besar dibanding yang pernah dideteksi sebelumnya.

“Bila semua supernovae menghasilkan debu sebanyak yang terlihat pada Cassiopeia A, maka produsen utama debu kosmis bisa dipastikan dalah supernovae, bukan debu bintang yang diterbangkan angin secara perlahan di galaksi,” tandas Dunne, yang menulis penemuan ini di journal Nature.

Karena supernovae berevolusi lebih cepat dari bintang biasa, maka planet-planet di jagad ini kemungkinan besar terbentuk oleh debunya. “Debu kosmis yang ada sekitar 10 miliar tahun lalu atau lebih itu hanya bisa berasal dari supernovae,” tandas Dunne. “Dan bila itu benar, maka Bumi yang kita injak saat ini merupakan sisa dari sebuah supernovae.” (Rtr/sciencedaily/wsn)

(sumber diambil dari kompas.com)

Objects in space rarely look the same in different wavelengths.

Here 3C58 changes quite dramatically moving from soft to hard x-rays and in radio.

Overlaying the x-ray on to of the visible gives and idea of the different scales of the object.

Finally, putting them all together gives an ‘artists rendering’ idea of how it might appear if we could see all of those images at once.

This entry is in specific response to the “Where Have All the Remnants Gone?” article from Creation Science Evangelism, though it is espoused in other creation literature.

There is a young-Earth creationism argument that goes as follows:  Stars that are much more massive than the Sun end their lives by exploding their outer layers into space in a process called a “supernova.”  These outer layers of stellar debris are heated and lit up by the energy from the supernova event.  The claim then goes that there is a certain expected rate of these (this particular article claims 1 every 25 years in our Milky Way galaxy).  Then, if you take the number of observed remnants (around 200) and multiply by the rate of occurrence, you get an age of our galaxy of around 5000 years.

Seems pretty bad for a 13.7-billion-year-old Universe, right?  Well sure it does when you’re fed half-truths.

The real story is a little more complicated, though I’m going to work a little backwards through this problem.  First, almost no astronomer says that a supernova should occur in our galaxy once every 25 years.  Rather, the canonical number is about 1 every 100 years (in fact, this was featured in an episode of Star Trek Voyager, “The Q and the Gray”).  Revisions over the past few years have pinned it down more at once every 50 years.

So now, if we do straight multiplication, we have about 50 * 200 = 10,000 years.  Isn’t that exactly what creationists say (more or less) the age of the Universe should be?  Yep, but there’s more.

We cannot observe supernova remnants across our entire galaxy – basically nebulae.  Supernova events we can see across the visible universe, but the actual gaseous remnants are much fainter because they are more diffuse.  Because of dust and gas in the way, we cannot see all the objects in our own Galaxy.  Probably the farthest we can see into the galaxy is maybe to a distance of 10,000 light-years.  The galaxy is about 100,000 light-years across.  Doing a simple calculation of the area of a disk 10,000 light-years vs. 100,000 light-years yields an area of our galaxy about 100 times larger that we can NOT survey for supernova remnants vs. what we can.

So now, we need to multiply our 10,000 years by 100, giving us 1,000,000 years for the age of the galaxy.

The next part is that supernova remnants don’t just form out of nothing, they form from the explosions of dying stars.  The stars that live and die the fastest still take about 10,000,000 years before they “go nova” and release a cloud of debris that will later become what we observe.  That’s pretty much the minimum time a star can “live” during the current epoch of the Universe.  Only after that will we see a supernova form.

So, add that to our estimate of the age by the number of stars and we have 11,000,000 years, or 11 million years for the age of the galaxy.  You should note at this point I’ve been saying “age of the galaxy.”  That’s because this would only be used to date our galaxy, not the Universe as a whole.  So you need to add in the time for galaxy formation … which is still a number that’s hotly debated, but no respected astronomer will say happens instantaneously

BUT, there’s another complication to this situation which shows why this apparent “method” for dating our galaxy isn’t valid:  Supernova remnants fade!  They only are visible for a few tens of thousands of years.  What does this mean for our estimate of 1,000,000 years for the age of our galaxy?  Well, by the time the “oldest” supernova is fading, we starting to observe supernova 200!  We should only expect to see in the neighborhood of a few hundred supernova remnants in our vicinity, regardless of how old our galaxy actually is.

This month’s public meeting featured a talk by world renowned supernovae hunter Tom Boles, who took us through the methods, motivations and rewards of his work at his Coddenham Observatory where he patrols the night sky detecting, imaging & reporting supernovae – the luminous explosions of aging massive stars. Tom is one of the leading amateurs in the world for supernova detection, having discovered over 100 such events.

The Society also had on display it’s new Lottery funded telescopes:

Public meeting attendees with the new telescopes and Tom Boles (far right)

From KurzweilAI.net — This Live Science article opines we exist in an abnormal bubble of space-time that explains away dark energy.

Do We Live in a Giant Cosmic Bubble?

Live Science, Sep. 30, 2008 Earth may be trapped in an abnormal bubble of space-time that is particularly void of matter, which could account for the apparent acceleration of the universe’s expansion, not dark energy. Matter warps space-time. Light travelling from supernovae outside our bubble would appear dimmer, because the light would diverge more than we would expect once it got inside our void. Oxford researchers Pedro G. Ferreira and Kate Land say that the upcoming Joint Dark Energy Mission, planned by NASA and the U.S. Department of Energy to launch in 2014 or 2015, may be able to distinguish between dark energy and the void. The satellite aims to measure the expansion of the universe precisely by observing about 2,300 supernovae. They suggest that by looking at a large number of supernovae in a certain region of the universe, they should be able to tell whether the objects are really accelerating away, or if their light is merely being distorted in a void.   Read Original Article>>

Was just on a lecture on supernovae.

One could ask why, really. I mean, I think it’s interesting and all that, but I’m supposed to be having vacation! Which would include a whole lot of no-school-things.

But I was there, and it was interesting. Sure, my days as a physicist (and we’re not talking any high-level stuff, here) are about three years gone so I didn’t quite get all the formulas. But the rest was interesting. Most of it wasn’t new since I’ve been reading books on the subject, but this way is more interesting than books. To have someone who is really into it tell you about it. Plus, I needed this. Some variation is always welcome. After all, a day at school isn’t that bad.

Quick facts:

• A supernova is when a white-dwarf star starts to collect dust from it’s surroundings, finally resulting in a thermonuclear explosion when it reaches a critical mass.
• A supernova emits the same amount of light as an entire galaxy.
• The critical mass is constant, making all supernovae emit the same (or at least similar) data which scientists are able to compare to each other. The differences measured can be used to calculate the distance to the supernovae.

The lecture, held by Michael Smith, Colorado State University, was also on the mysterious dark energy. I won’t go into it, partially because it is really hard to understand it, but he concluded it all with saying that probably the Universe isn’t mostly composed of dark energy (as the theory proposes) but rather space-time. Funny. Kind of like dismissing his own work. But I guess that’s the spirit of a true scientist.

- Quiquid latine dictum sit altum viditur.