Zoom in on New, Stunning Image of the Carina Nebula

Color composite image of the Carina Nebula. Credit: ESO

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In today’s 365 Days of Astronomy podcast, two astronomers from the University of Minnesota discuss Eta Carina, a relatively close enigmatic star in the Carina Nebula. In a sense of great timing, new images also released today from the ESO (European Organisation for Astronomical Research in the Southern Hemisphere) reveal amazing detail in the intricate structures of the Carina Nebula, one of the largest and brightest nebulae in the sky. In addition to the gorgeous picture above, enjoy a pan-able image and a video that zooms in on this nebula (also known as NGC 3372), where strong winds and powerful radiation from an armada of massive stars are creating havoc in the large cloud of dust and gas from which the stars were born.

The Carina Nebula is located about 7,500 light-years away in the constellation of the same name (Carina; the Keel). Spanning about 100 light-years, it is four times larger than the famous Orion Nebula and far brighter. It is an intensive star-forming region with dark lanes of cool dust splitting up the glowing nebula gas that surrounds its many clusters of stars.

The glow of the Carina Nebula comes mainly from hot hydrogen basking in the strong radiation of monster baby stars. The interaction between the hydrogen and the ultraviolet light results in its characteristic red and purple color. The immense nebula contains over a dozen stars with at least 50 to 100 times the mass of our Sun. Such stars have a very short lifespan, a few million years at most, the blink of an eye compared with the Sun’s expected lifetime of ten billion years.

One of the Universe’s most impressive stars, Eta Carinae, is found in the nebula. It is one of the most massive stars in our Milky Way, over 100 times the mass of the Sun and about four million times brighter, making it the most luminous star known. Eta Carinae is highly unstable, and prone to violent outbursts, “In the 1840’s it blew up, and for about ten years it was one of the brightest stars in the sky,” said Dr. Kris Davidson in today’s 365 Days of Astronomy Podcast, hosted by Michael Koppelman of Slacker Astronomy. “But it’s almost a thousand times farther away than the brightest star in the sky Sirius, which means the amount of light coming out was really prodigious. After awhile it faded, now we see a nebula blowing out, expanding around it. Clearly its the ejecta the from the star. We can now ‘weigh’ the ejecta, and it is about 10 times the mass of the sun. That’s just the ejecta, the material the star lost about 160 years ago…. We have no right to have such a rare object that close!”

The large and beautiful image displays the full variety of this impressive skyscape, spattered with clusters of young stars, large nebulae of dust and gas, dust pillars, globules, and adorned by one of the Universe’s most impressive binary stars. It was produced by combining exposures through six different filters from the Wide Field Imager (WFI), attached to the 2.2 m ESO/MPG telescope at ESO’s La Silla Observatory, in Chile.

Source: ESO, 365 Days of Astronomy

IYA 2009 – Brian Sheen Reports on “Canoe Africa”

IYA 2009 - Canoe Africa

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Back in September of last year, UT reported on one of our intrepid readers who was about to embark on a most ambitious journey to promote the International Year of Astronomy in “Canoe Africa“. For those of you who follow BBC SW Spotlight or Radio Cornwall, you might already know about Brian Sheen’s African astronomy education adventures – but he’s taken this special opportunity to share his story with Universe Today. Grab a paddle and let’s ride…

Brian Sheen
Brian Sheen
“The expedition to the River Niger was part of Roseland Observatory’s contribution to IYA. The plan was to canoe the river taking the story of astronomy to some of the remotest countries in Africa with me. We flew into Sierra Leone (10 degrees north and 10 degrees west) in the beginning of November as soon as possible. We drew breath when we looked into the night sky. We knew, of course, that the lack of light pollution would give us a great view denied to us in Europe and also much of America. Also many of the constellations familiar us in the north would be below the horizon – Polaris was lost in the murk and Ursa Major invisible. However, the compensation was many more constellations in the south never seen at home in Cornwall, UK.

09africa4Lecturing opportunities at the local colleges and universities were organised by our hosts the Scouts of Sierra Leone. We were able to use the solar scope PST to good effect and the meteorite samples – thanks Tammy – were studied with enthusiasm. During the evening sessions the Sky Scout was extremely useful giving those who had looked up and wondered the answer to at least some of their questions. Away from the kit I was asked some very searching questions – many philosophical. One of the centres we worked with was developing a UV water treatment that was actually free to use. Well or river water was placed in plastic soft drink bottles (label removed) and then laid down in the Sun and let the UV emissions do the rest. The organisers we interested to learn that at sunspot minimum solar UV levels were about 50% of a few years before.

09africa5After our shakedown period we crossed the border into Guinea and on to the headwaters of the Niger at Faranah. We were hosted by the local Scouts, who had arranged for a boat builder to build a plank canoe (a modern version of the dugout) to our specification. This is a type of canoe used throughout Guinea by local fishermen. The canoe was built in only four days and we were off into the remotest part of the journey an almost uninhabited region which would take 10 days to paddle with no opportunity to buy food or other supplies. Some nights camping out we could see meteors reasonably often – too many to be sporadics and wrong time for a major shower. Checking with David Levy’s book “Guide to Observing Meteor Showers” it seems likely that I was seeing the minor shower – Nu Orionids peaking Nov 28th.

09africa2The biggest threat, apart from the mosquitoes, came from the big beast of the jungle the hippo. We saw one in the river and tiptoed past him and camped a few miles down stream. It was one those places where it was possible to sleep with out a mosquito net or tent. Looking south we were able to see Orion rise on his back stand up and lie down in the west. As it was dark I had a go at counting the stars inside the square of Orion I reached 30 excluding the Belt and Sword. This gives visible stars down to magnitude 6. Beats counting sheep! Then we heard the unmistakeable sound of a hippo grunting in the river just 20 metres away! We were possibly camping on his get out point! A couple more logs on the fire kept him at bay and eventually he moved back up stream.

sheen_hippo_416In the morning we set off again and the river was pretty easy to paddle until the canoe came to an abrupt halt. Geoff at the stern of the craft flew into the air Mike at the bow shouted hippo and we all ended up in the river. A 3 ton Bull Hippo had hit us like a submarine launched missile. As we are all lifeguards we swam the canoe to side and emptied out. It was too badly damaged to go on so we were forced to walk out of the jungle through razor edged elephant grass considered impenetrable by many. After five days we reached a small village and safety. At many times I felt that we were caught in a 19th century “ripping yarn for boys”. The jungle was very uneven with deep run off channels hidden by the grass. We all fell more than once, however we never even opened a Band Aid in the whole time we were in West Africa.

African_Venus_Occultation:_Paul_Hughes
African_Venus_Occultation:_Paul_Hughes

We actually missed one event I had been looking forward to, the occultation of Venus by the Moon, however we felt that saving our lives was even more important! Meanwhile back at the Observatory Paul Hughes took an excellent set of images. The Americans will have to wait until 22nd April for their opportunity to witness this for themselves. (While looking into Elephant Grass I found that it could be used as a bio-fuel so perhaps it has uses after all.) The movements of Jupiter, Venus and the Moon provided good teaching material. As the days went by Jupiter moved further and further towards the west at a given time. It was also moving from west to east against the background stars. Venus on the other hand was climbing in the night sky. Eventually it was over taken by the Moon, the occultation, proving that the Moon too moves from west to east but at a faster rate than the planets. Perhaps the most spectacular view was of the Orion complex containing Betelgeuse, Rigel, Aldabran, Capella, Castor, Pollux, Procyon, Sirius, Canopus and Achernar. Most we can see from the UK but in Africa these stars were much higher and appear much brighter in dark skies.

09africa3Although the European population in Sierra Leone and Guinea is tiny we were given a tremendous welcome from the local people and Scouts everywhere we went. There is a real hunger for knowledge, at the moment they “look up perfect silence at the stars” to quote Walt Whitman and wonder. Astronomers with a good knowledge of Africa could find an open-ended opportunity. In the future, we have a promise made to Bamako University in Mali to meet, and the river between there and Timbuktu runs through the very interesting inland delta also the Dogon people claim special insights into astronomy. Would I go back to the incident site? A filmed reconstruction would be good – any offers? For more information and images check out Roseland Observatory and follow the links.” — Reporting for Universe Today, Brian Sheen, Roseland Observatory, RAS Education Focus Group.

iya_logo_smallBrian is back home safe again in Cornwall, perhaps no worse for the wear, but definately more full of IYA 2009 adventure and spirit than most of us will ever hope to achieve this year. (For a charming insight on their hippo adventure, be sure to listen to the BBC Audio Interview). The team hopes to revisit the area again next year and we wish them the best. For now, hats off to Brian Sheen and his excellent astronomy outreach work!

Nearest Stars

Toliman
Artist impression of Alpha Centauri

Look up into the night sky and you’ll see stars dozens and even hundreds of light-years away. It’s hard to know where are the closest and which are the most distant stars because the brightest stars can be seen far away. Astronomers have measured the distance to most of the stars you can see with your unaided eye to determine which are the nearest stars.

Here is a list of the 20 closest star systems and their distance in light-years. Some of these have multiple stars, but they’re part of the same system.

  1. Alpha Centauri – 4.2
  2. Barnard’s Star – 5.9
  3. Wolf 359 – 7.8
  4. Lalande 21185 – 8.3
  5. Sirius – 8.6
  6. Luyten 726-8 – 8.7
  7. Ross 154 – 9.7
  8. Ross 248 – 10.3
  9. Epsilon Eridani – 10.5
  10. Lacaille 9352 – 10.7
  11. Ross 128 – 10.9
  12. EZ Aquarii – 11.3
  13. Procyon – 11.4
  14. 61 Cygni – 11.4
  15. Struve 2398 – 11.5
  16. Groombridge 34 – 11.6
  17. Epison Indi – 11.8
  18. Dx Carncri – 11.8
  19. Tau Ceti – 11.9
  20. GJ 106 – 11.9

So how do astronomers measure the distance to stars? They use a technique called parallax. Do a little experiment here. Hold one of your arms out at length and put your thumb up so that it’s beside some distant reference object. Now take turns opening and closing each eye. Notice how your thumb seems to jump back and forth as you switch eyes? That’s the parallax method.

To measure the distance to stars, you measure the angle to a star when the Earth is one side of its orbit; say in the summer. Then you wait 6 month, until the Earth has moved to the opposite side of its orbit, and then measure the angle to the star compared to some distant reference object. If the star is close, the angle will be measurable, and the distance can be calculated.

You can only really measure the distance to the nearest stars this way. This technique only works to about 100 light-years.

We have written many articles about stars here on Universe Today. Here’s an article about how new stars were discovered using the parallax method, and a newly discovered star that could be the third closest.

If you’d like more information on stars, check out Hubblesite’s News Releases about Stars, and here’s the stars and galaxies homepage.

We have recorded several episodes of Astronomy Cast about stars. Here are two that you might find helpful: Episode 12: Where Do Baby Stars Come From, and Episode 13: Where Do Stars Go When they Die?

Two Satellites Collide in Earth Orbit

An iridium satellite flar as seen from the ISS. Credit: Don Pettit, NASA

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A commercial Iridium communications satellite collided with a Russian satellite or satellite fragment, on Tuesday, creating a cloud of wreckage in low-Earth orbit, according to CBS News. A source quoted in the article said U.S. Space Command is tracking about 280 pieces of debris, most of it from a non-operational Russian satellite. It appears the International Space Station is not currently threatened by the debris, but it’s not yet clear whether the debris poses a risk to any other satellites in similar orbits. Iridium operates a constellation of approximately 66 satellites, along with orbital spares, to support satellite telephone operations around the world.

Neither NASA or Iridium Satellite LLC has officially released any information about the collision, and a spokesman for U.S. Space Command was not aware of the incident. But one NASA manager who asked not to be named, seemed to confirm the collision and said, “Everybody is saying the risk (of further collisions) is minimal to NASA assets.”
UPDATE: The Spaceflightnow.com article has been updated with quotes from a statement by Iridium and U.S. Strategic Command, that confirm the collision took place.

In an article on Spaceflightnow.com, Nicholas Johnson, NASA’s chief scientist for orbital debris at the Johnson Space Center in Houston, confirmed the collision. “They collided at an altitude of 790 kilometers (491 miles) over northern Siberia Tuesday about noon Washington time,” said “The U.S. space surveillance network detected a large number of debris from both objects.”

Iridium Satellite System.  Credit: Spaceflightnow.com
Iridium Satellite System. Credit: Spaceflightnow.com

The Iridium spacecraft are in orbits tilted 86.4 degrees to the equator at an altitude of about 485 miles while the ISS orbits Earth at an altitude of about 215 miles in an orbit tilted 51.6 degrees to the equator. Other civilian science satellites operate in polar orbits similar to Iridium’s and presumably could face an increased risk as a result of the collision.

Johnson said the collision is unprecedented. “Nothing to this extent (has happened before),” he said. “We’ve had three other accidental collisions between what we call catalog objects, but they were all much smaller than this and always a moderate sized objects and a very small object. And these are two relatively big objects. So this is a first, unfortunately.”

Sources: CBS News, Spaceflightnow.com

List of Stars

Most stars have scientific names, but some have common names that have been passed down through history. Some astronomers use the scientific name, while others use the common name. Here’s a list of the brightest stars in the sky:

  1. Sirius
  2. Canopus
  3. Arcturus
  4. Alpha Centauri A
  5. Vega
  6. Rigel
  7. Procyon
  8. Achernar
  9. Betelgeuse
  10. Hadar (Agena)
  11. Capella A
  12. Altair
  13. Aldebaran
  14. Capella B
  15. Spica
  16. Antares
  17. Pollux
  18. Fomalhaut
  19. Deneb
  20. Mimosa

Of course, this is just a tiny list of stars. There are some enormous lists of stars out there. One of the most comprehensive is the SIMBAD database. This is an online database that contains 4.3 million objects. NASA has an even larger database of extragalactic objects that contains 163 million objects.

Here’s a good list of all the named stars in alphabetical order.

We have written many articles about stars here on Universe Today. Here’s an article about the biggest star in the Universe, and here’s an article that describes how massive stars form.

If you’d like more information on stars, check out Hubblesite’s News Releases about Stars, and here’s the stars and galaxies homepage.

We have recorded several episodes of Astronomy Cast about stars. Here are two that you might find helpful: Episode 12: Where Do Baby Stars Come From, and Episode 13: Where Do Stars Go When they Die?

This Week’s Where In The Universe Challenge

Its time once again for another Where In The Universe Challenge. The goal of this challenge is to test your skills and knowledge of the cosmos. Guess where in the Universe this image is from, and give yourself extra points if you can guess which spacecraft is responsible for the image. Post your guess in the comment section (no links to hints please!) and check back tomorrow for the answer. Good luck!

UPDATE (2/14) The answer has now been posted below!

Did you recognize this intriguing globular cluster of stars? Just kidding! — it’s actually the constellation of city lights surrounding London, England, here on planet Earth, as recorded with a digital camera by astronaut Don Pettit from the International Space Station. Taken in February 2003, north is toward the top and slightly left in this nighttime view. The encircling “London Orbital” highway by-pass, the M25 , is easiest to pick out south of the city. Even farther south are the lights of Gatwick airport and just inside the western (left hand) stretch of the Orbital is Heathrow. The darkened Thames river estuary fans out to the city’s east. In particular, two small “dark nebulae” – Hyde Park and Regents Park – stand out slightly west of the densely packed lights at the city’s core.

The crew of the International Space Station acquired this image shortly after 7:22 p.m. local time on the evening of February 4, 2003. Either thin, low clouds or perhaps fog is evident in the fuzzy character of patterns for some of the surrounding smaller cities while that of the warmer urban center is still clear and sharp.

For more info on this image see here and here.

Check back next week for another WITU Challenge (and sorry for the delay in posting the answer this week!)

Stellar Jets are Born Knotted

Herbig Haro object HH47 (a stellar jet), observed with the Hubble Space Telescope

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Some of the most beautiful structures observed in the Universe are the intricate jets of supersonic material speeding away from accreting stars, such as young proto-stars and stellar mass black holes. These jets are composed of highly collimated gas, rapidly accelerated and ejected from circumstellar accretion disks. The in-falling gas from the disks, usually feeding the black hole or hungry young star, is somehow redirected and blown into the interstellar medium (ISM).

Much work is being done to understand how accretion disk material is turned into a rapid outflow, forming an often knotted, clumpy cloud of outflowing gas. The general idea was that the stellar jet is ejected in a steady flow (like a fire hose), only for it to interact with the surrounding ISM, breaking up as it does so. However, a unique collaboration between plasma physicists, astronomers and computational scientists may have uncovered the true nature behind these knotted structures. They didn’t become knotted, they were born that way

The predominant theory says that jets are essentially fire hoses that shoot out matter in a steady stream, and the stream breaks up as it collides with gas and dust in space—but that doesn’t appear to be so after all,” said Adam Frank, professor of astrophysics at the University of Rochester, and co-author of the recent publication. According to Frank, the exciting results uncovered by the international collaboration suggest that far from being a steady stream of gas being ejected from the circumstellar accretion disk, the jets are “fired out more like bullets or buckshot.” It is therefore little wonder that the vast stellar jets appear twisted, knotted and highly structured.

A member of the collaboration, Professor Sergey Lebedev and his team at the Imperial College London, made an attempt to replicate the physics of a star in the laboratory, and the experiment matched the known physics of stellar jets very well. The pioneering work by Lebedev is being lauded a possibly the “best” astrophysical experiment that’s ever been carried out.

Using an aluminium disk, Lebedev applied a high-powered pulse of energy to it. Within the first few billionths of a second, the aluminium began to evaporate, generating a small cloud of plasma. This plasma became an accretion disk analogue, a microscopic equivalent of the plasma being dragged into a proto-star. In the centre of the disk, the aluminium had eroded completely, creating a hole. Through this hole, a magnetic field, being applied below the disk, could penetrate through.

It would appear that the dynamics of the magnetic field interacting with the plasma accurately depicts the observed characteristics of extended stellar jets. At first, the magnetic field pushes the plasma aside around the disk’s hole, but its structure evolves by creating a bubble, then twisting and warping, forming a knot in the plasma jet. Then, a very important event occurs; the initial magnetic “bubble” pinches off and is propelled away. Another magnetic bubble forms to continue the process all over again. These dynamic processes cause packets of plasma to be released in bursts and not in the steady, classical “fire hose” manner.

We can see these beautiful jets in space, but we have no way to see what the magnetic fields look like,” says Frank. “I can’t go out and stick probes in a star, but here we can get some idea—and it looks like the field is a weird, tangled mess.”

By shrinking this cosmic phenomenon into a laboratory experiment, the investigators have shed some light on the possible mechanism driving the structure of stellar jets. It appears that magnetic processes, not ISM interactions, shape the knotted structure of stellar jets when they born, not after they have evolved.

Source: EurekAlert

What is the Light From Stars?

Star classifications. Image credit: Kieff

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Look into the night sky and you’ll see stars in all directions shining and twinkling in the dark. But what is the light that we’re seeing, and how does it get all the way from the distant stars to here?

All stars are just vast balls of hot plasma. They’re made up of mostly hydrogen and helium, with trace amounts of other elements. Mutual gravity holds the star together, and compresses it inward. Without some kind of force pushing back, stars would just compress themselves down to the size of the Earth, or even smaller.

But as a star gets smaller, the gravitational friction causes it to heat up in its core. When the core of the star reaches about 15 million Kelvin, hydrogen fusion can begin. In this process, atoms of hydrogen are crushed together through a multi-stage process to form helium. This reaction is exothermic, which means that it gives more energy than it gives off. A star like the Sun is releasing 3.86 x 1026 joules of gamma radiation every second.

These photons of energy are trapped inside the star and have to get out. Over a journey that can take more than 100,000 years, the photons are continuously emitted and then absorbed by atoms in the Sun. Each of these jumps can cause the photon to lose energy. When they finally reach the surface of the star, they’ve lost a tremendous amount of energy, and have fallen from high energy gamma rays down to visible wavelengths.

And then, the photons are released from the surface of the star, and free to cross the vacuum of space. Unless they encounter anything, they’ll keep traveling in a straight line for millions, billions and even trillions of years. When you step outside and look at a star that could be a few hundred light-years away, your eyes are the first things the photons have bumped into since they left the surface of the star!

We have written many articles about stars here on Universe Today. Here’s an article about the biggest star in the Universe, and here’s an article about how many stars there are in the Milky Way.

If you’d like more information on stars, check out Hubblesite’s News Releases about Stars, and here’s the stars and galaxies homepage.

We have recorded several episodes of Astronomy Cast about stars. Here are two that you might find helpful: Episode 12: Where Do Baby Stars Come From, and Episode 13: Where Do Stars Go When they Die?

References:
http://www.jet.efda.org/fusion-basics/what-is-fusion/
http://www.ips.gov.au/Category/Educational/The%20Sun%20and%20Solar%20Activity/General%20Info/Solar_Constant.pdf

Hypergiant Stars

Eta Carinae Credit: Gemini Observatory artwork by Lynette Cook

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The vast majority of stars out there are tiny red dwarfs, then come the solar mass stars like our Sun. There are giant stars and even supergiant stars. But the biggest stars out there are the monstrous hypergiant stars, which pump out millions of times more energy than the Sun. So just how big and powerful are hypergiant stars?

First, let’s take a look at a regular star like our Sun. Our Sun is the baseline, with 1 solar mass, and 1 solar diameter. It puts out 1 solar amount of luminosity. An example giant star would be Rigel, with 17 times the mass of the Sun. It’s putting out about 66,000 times as much energy as the Sun, and it’s estimated to have 62 times the radius of the Sun.

Next, let’s go bigger and look at a supergiant star: Betelgeuse. This familiar star is located in the constellation Orion, and has 20 times the mass of the Sun (1 solar mass = the mass of the Sun). Betelgeuse is estimated to be 1000 times the size of the Sun, and puts out 135,000 times as much energy.

Those stars are nothing compared to hypergiant stars. An example of a red hypergiant star is VY Canis Majoris, which measures 1,500 times the size of the Sun.

The true monsters of the Universe are the blue hypergiant stars, like Eta Carinae. It has 150 times the mass of the Sun, and measure up to 180 times the size of the Sun. Eta Carinae is putting out 4 million times as much energy as the Sun! Of course, Eta Carinae is a “live fast, die young” kind of star. It’s probably only been around for 3 million years or so, and astronomers think it’ll detonate as a supernova within 100,000 years.

We have written many articles about stars here on Universe Today. Here’s an article about the biggest star in the Universe, and here’s an article about Eta Carinae, which is expected to blow up any time now.

If you’d like more information on stars, check out Hubblesite’s News Releases about Stars, and here’s the stars and galaxies homepage.

We have recorded several episodes of Astronomy Cast about stars. Here are two that you might find helpful: Episode 12: Where Do Baby Stars Come From, and Episode 13: Where Do Stars Go When they Die?

References:
http://en.wikipedia.org/wiki/VY_Canis_Majoris
http://en.wikipedia.org/wiki/Rigel
http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970616b.html
http://seds.org/messier/xtra/ngc/etacar.html

Cosmologists Look Back to Cosmic Dawn

The Universe 590 million years after the Big Bang. Credit: Alvaro Orsi, Institute for Computational Cosmology, Durham University.

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What did the Universe look like early in its history, only 500 million years after the Big Bang? Currently, we have no way of actually “looking” back that far with our telescopes, but cosmologists from Durham University in the UK have used a computer simulation to predict how the very early Universe would have appeared. The images portray the “Cosmic Dawn,” and calculate the formation of the first big galaxies. The simulation also attempts to discern the role that dark matter played in galaxy formation. “We are effectively looking back in time and by doing so we hope to learn how galaxies like our own were made and to understand more about dark matter,” said Alvaro Orsi, lead author of the study from Durham University’s Institute for Computational Cosmology (ICC). “The presence of dark matter is the key to building galaxies – without dark matter we wouldn’t be here today.”

In the images produced by the computer simulation, the green swirls represent dark matter, which the scientists say is an essential ingredient in galaxy formation, while the circles show the star formation rate in galaxies. The different color circles represent the varying luminosity of star formation with yellow being brightest. The top image portrays the Universe as it was 590 million years after the Big Bang, and the image below shows the Universe 1 billion years after the Big Bang, as star formation rates begin to ramp up.

The Universe 1 billion years after the Big Bang. Credit: Alvaro Orsi, Institute for Computational Cosmology, Durham University.
The Universe 1 billion years after the Big Bang. Credit: Alvaro Orsi, Institute for Computational Cosmology, Durham University.

The very first galaxies were created from the debris of massive stars which died explosively shortly after the beginning of the Universe. The Durham calculation predicts where these galaxies appear and how they evolve to the present day, over 13 billion years later. Although the galaxies today are bigger, they are not forming stars as quickly now as they were in the past. “Our research predicts which galaxies are growing through the formation of stars at different times in the history of the Universe and how these relate to the dark matter,” said co-author Dr. Carlton Baugh. “We give the computer what we think is the recipe for galaxy formation and we see what is produced which is then tested against observations of real galaxies.”

The massive simulation shows how structures grow in dark matter with a model showing how normal matter, such as gas, behaves to predict how galaxies grow. Gas feels the pull of gravity from dark matter and is heated up before cooling by releasing radiation and turning into stars. The simulation images show which galaxies are forming stars most vigorously at a given time. The image below shows the Universe 1.9 billion years after the Big Bang, a very active time of star formations in galaxies.

The Universe 1.9 billion years after the Big Bang.  Credit: Alvaro Orsi, Institute for Computational Cosmology, Durham University.
The Universe 1.9 billion years after the Big Bang. Credit: Alvaro Orsi, Institute for Computational Cosmology, Durham University.

The calculations of the Durham team, supported by scientists at the Universidad Catolica in Santiago, Chile, can be tested against new observations reaching back to early stages in the history of the Universe almost one billion years after the Big Bang. Professor Keith Mason, Chief Executive of the Science and Technology Facilities Council, said: “Computational cosmology plays an important part in our understanding of the Universe. Not only do these simulations allow us to look back in time to the early Universe but they complement the work and observations of our astronomers.”

This image shows the Universe today, 13.6 billion years after the Big Bang. Galaxies are not forming stars as quickly now as they were in the past.

The Universe today.  Credit: Alvaro Orsi, Institute for Computational Cosmology, Durham University.
The Universe today. Credit: Alvaro Orsi, Institute for Computational Cosmology, Durham University.

The team hopes that further study and simulations of effects of dark matter on galaxies will help astronomers learn more about what this ubiquitous substance is.

Source: Science and Technology Facilities Council

Institute for Computational Cosmology, Durham University
Department of Physics, Durham University