Sunday, February 20, 2011

Alberta's Oil Sands: A Primer On the Industry and its Impact

I, an Albertan, have a front-row seat to an energy battle that is rapidly reaching epic proportions. During the past year, international interest in the oil sands has exploded and not in a good way. Canada, and specifically Alberta's Oil Sands, did not come out looking very good in both local and international media at the last International Climate Conference in Copenhagen. A media campaign called ReThink Alberta, launched last summer by Corporate Ethics International, an American organization, depicts Northern Alberta's transformation from a beautiful wildlife sanctuary into a dirty wildlife-killing wasteland. You can see the associated video as well as Alberta Environment minister Rob Renner's response here. This group also posted giant billboards of dying birds soaked in oil in many major American cities.

To try to neutralize these horrific images, our premier, Ed Stelmach, launched a political junket in Washington, encouraging Americans in power to realize that our bitumen is there for the offer as an environmentally safe source of energy from a politically friendly neighbour. The BP offshore oil disaster had recently occurred and this helped Alberta sell the oil sands as a safer alternative, but it also brought into focus the general danger of the world relying on oil for energy. Alberta is mired in controversy over our oil sands industry. It is blamed for both global warming and local pollution. Recent deaths of hundreds of migratory birds that landed on poisonous tailings ponds circulated in the media and led several local politicians and environmental protection groups around the world to question how effectively the industry protects wildlife. Some independent researchers are now making it their mission to study the effects of the industry on the ecosystem as well as on the people that live nearby. A Nature of Things Special TV presentation called Tipping point: The Age of the Oil Sands (watch the entire episode here), hosted by scientist and environmental activist, David Suzuki, brought these concerns into focus. Meanwhile the Alberta government has launched a series of advertisement campaigns both in Alberta and internationally to promote efforts made by the oil sands industry to reduce its environmental impact. The oil sands industry is expected to triple by 2015.

Albertans are growing more polarized in their opinions about the oil sands. We are becoming mired down in a media/public relations storm of opinions and pseudofacts at a critical time when we need to, and still have a window of opportunity to, influence the industry's fate: We can

1) embrace the industry wholeheartedly or
2) accept the industry conditionally with strict environmental protection measures in place or
3) pressure the industry to stop the expansion or
4) shut it down entirely.

By "we" I mean the Canadian government, the only body that has the jurisdiction to enforce restrictions, in response to our public pressure (and perhaps the Alberta government as well).

A middle road could be envisioned where the Canadian government and public pressure compel the industry into placing its expansion efforts on hold while it takes an intermediate step of finding and incorporating new technologies that reduce its environmental damage to a level that is agreeable to all parties, including the Albertan public and specifically the people living nearby and downstream of the Athabasca river, who are most affected by the industry, as well as international environmental groups and all levels of government. This step would require a unprecedented level of transparency, coordination of information sharing and cooperation from the industry and the industry must assume the risk that if no acceptable technologies can be found that will mitigate the environmental damage, for example if the tailings ponds cannot be fully reclaimed in a reasonable time period or if the stress on the fresh water systems cannot be reduced to an acceptable limit, then the industry will suffer a severe setback. However, if the industry successfully embraces the environmental challenges brought forth and works hard toward transparency and cooperation then both the public and investors can hail the industry for its forward-thinking and environmentally responsible reputation. There may be a way for the world to use the enormous reserve of oil sands energy for many years to come as we gradually wean ourselves from nonrenewable energy. The expense of oil sands oil, made higher because the environmental technology must be added to the cost, might help drive that ultimate transition. I urge you to keep these possibilities in mind as we explore the details and to determine for yourself which response is the best fit. Or perhaps you will have your own solution not addressed here.

First, both the public and the government (and company shareholders!) need to be properly informed about the science of the oil sands and the science of the environmental mitigation technologies that could be used, such as carbon capture technology, for example.

The Need for Energy

We in the industrialized world have become accustomed to a very high standard of living that consumes a great deal of energy, and countries like India and China, with far greater populations, are quickly evolving toward a similar standard. I, a typical Canadian, consume the energy equivalent of about 8200 kg of oil per year. That's close to about 10 barrels of sweet crude oil. If I multiply that by 34 million people in Canada, we as a country consume 340 million barrels of oil per year personally. We have to add industry and public consumption to this figure so we arrive at a total Canadian consumption of 730 million barrels of oil per year (using 2009 numbers). Alberta has total bitumen-based oil reserves in excess of 170 billion barrels, the second largest reserve in the world after Saudi Arabia, with a current production of over 1 million barrels of oil per day from bitumen reserves.

In reality we don't consume just oil for energy. In Canada, only about 32% of our energy comes from oil. A quarter each comes from natural gas and hydroelectric power, 10% comes from coal and the rest, 8%, comes from nuclear and renewable sources. Click here to see how Canada energy usage compares to the rest of the world. Unlike many other countries, particularly Germany, biofuels, wind and solar energy, are only used marginally in Canada, so far.  However, even countries serious about greening up like Germany have a long way to go to wean themselves from fossil fuels such as oil, coal and natural gas. Renewables account for 6% of Germany's total energy consumption compared to 1% here in Canada.

What Is Wrong with Fossil Fuels?

Fossil fuels provided the energy that made the industrial revolution possible, from coal-fueled steam turbines to the combustion engine. We would not be where we are today without them. But fossil fuels come with problems. They are a finite nonrenewable resource. The earth has only so much stored energy deposited in ancient reservoirs. Perhaps an even more urgent problem with these fuels is that they, as a result of their extraction and refinement as well as eventual combustion, release pollutants into the ecosystem, damaging it and creating health concerns for us. Most importantly of all, fossil fuels are strongly linked to global warming, a global threat not only to our survival but to the survival of all species. This will be discussed in more detail shortly.

The bitumen extracted from the oil sands in northern Alberta is a fossil fuel and it comes with these problems. And, as we will soon explore, bitumen has additional environmental hurdles to overcome as well.

How Do The Oil Sands Stack Up As a Sustainable Energy Source?

With an eye to making a significant shift toward sustainability, we can view the oil sands from a perspective that enables us to question its role in our future energy, rather than blindly accepting this familiar argument:

1) Our society is in danger of collapsing as the world runs out of energy.
2) The world is running out of energy and some of that energy must come from oil.
3) All remaining oil reserves including the oil sands must be exploited.

Can bitumen from the oil sands be incorporated into an energy mix that is sustainable from a long-term perspective?

What Bitumen Is

Bitumen is a naturally occurring mixture of heavy hydrocarbons. Like oil, it was created under great heat and pressure over millions of years from the biomass of ancient algae and other living organisms that once thrived during the cretaceous period, about 70 million years ago. It is, in fact, oil that is in the process of escaping to the Earth's surface and in that process it has been exposed to, and partly degraded by, bacteria.

From Bitumen to Synthetic Oil

The shorter hydrocarbon chains of bitumen were destroyed first as they were exposed to surface bacteria and what remains is a sticky black semisolid that consists of large highly branched hydrocarbon molecules which must be cracked, or broken, into smaller hydrocarbon molecules and then refined into usable synthetic crude oil, which I will refer to as syncrude in this article. Northern Alberta's bitumen, along with substantial natural gas deposits, resides in the Upper Devonian Grosmont formation. This deposit contains an estimated 50 billion cubic metres of heavy crude bitumen.

Bitumen, like all energy sources, can ultimately be traced back to energy from the Sun. During photosynthesis, algae and other plants trap light energy in chemical bonds where it is stored. When ancient plants died, their biomass was slowly converted into crude oil, natural gas and coal, depending on which conditions and geologic processes they underwent. These fossilized organic hydrocarbons contain energy stored in their carbon bonds. When they are burned, a combustion reaction takes place. The carbon bonds are destroyed, releasing water, carbon dioxide and energy. This is where the concern over global warming comes in.

Carbon Dioxide and Global Warming

Carbon in the form of atmospheric carbon dioxide acts as a thermal blanket over the Earth, trapping heat from the Sun inside the atmosphere and warming the planet. There is naturally a certain level of this so-called greenhouse gas and while it has varied naturally over the eons, it tends toward a state of equilibrium in which it varies little over thousands of years. If atmospheric carbon dioxide rises rapidly, however, as it has over the past decade, it not only puts tremendous strain on ecosystems, strains that could lead to potential mass extinctions of species because they cannot adapt fast enough to survive and reproduce, but it rapidly changes the chemistry of the oceans as well, causing, among other things, coral reefs and shellfish shells to dissolve, species which are important ecological anchors to the entire ocean ecosystem. On top of this, vast oceanic ice shelves in Antarctica and terrestrial glaciers all over the world are melting quickly and contributing to rising sea levels. This is already beginning to threaten coastal cities and development around the world. Finally, global warming is destroying the glaciers on which many populations, including ours here in Alberta, rely for fresh water, and contributing to increased drought and flood stress on agriculture around the world. The relationship between carbon dioxide and global warming is explored in depth in my article, "Earth's Atmosphere Part 8 – How To Care For Earth's Atmosphere."

Synthetic petroleum production from bitumen mining is a carbon-positive industry. A great deal of carbon that was once chemically bound up is released into the atmosphere. In order to slow down global warming or perhaps eventually stop it altogether, we need to reduce the world's carbon footprint to zero. Unfortunately, carbon dioxide emissions continue to increase globally. Even if we stopped emitting greenhouse gases today, future climate change is inevitable and we ourselves, will face challenges to our way of life to which we will have to adapt. Ever-increasing worldwide greenhouse gas emissions could lead to run-way global warming, a catastrophic series of possible future scenarios based on climate modeling. It remains a controversial idea despite support by a large consensus of climate researchers.

In an article written for Scientific American in 1998 by Richard George, CEO and director of Suncor Energy Inc., the process by which bitumen is mined and processed into syncrude is introduced. The article also provides an interesting pre-media-storm history of the oil sands that helps to put the industry into perspective. Bitumen must be strip mined, extracted from its sandy aggregate, upgraded into syncrude, and then shipped to refineries which turn it into usable fuels, all of which require energy, much of which comes from natural gas in Alberta. All of this adds to bitumen's carbon footprint, which I have found very difficult to pin down in my research. According to a study referenced in Wikipedia, the bitumen to liquid fuel process generates about 3 times the amount of greenhouse gases per barrel as the production of crude oil, 86 kg CO2 per barrel of oil compared to 29 kg CO2 per barrel, respectively. Alberta's oil sands are becoming Canada's fastest growing source of carbon dioxide emissions according to the World Wildlife Foundation and the Pembina Institute, which give the oil sands a failing grade because the Canadian government has not yet regulated its carbon emissions with any absolute targets.

Future Plans for The Oil Sands

Canadian bitumen is upgraded into syncrude, which can then be refined into gasoline (usually about 50% goes into this), diesel fuel, jet fuel, heating oil and kerosene. Much of the syncrude will ultimately be destined for refineries in the Midwest and the Texas Gulf, which are currently being retrofitted, an investment of $20 billion, to turn syncrude into fuel. Alberta has several upgraders northeast of Edmonton with plans to install a new one, at a cost of $5 billion, with the capacity to process diesel fuel and talks are underway for a future $5 billion refinery in Alberta so that more profits can be kept at home. A $5.5 billion new pipeline is also being considered, called the Northern Gateway Pipeline. Syncrude would be piped to Kitimat, British Columbia where it would be shipped to large and rapidly growing Pacific Rim markets. The proposaI is facing tremendous opposition from First Nations people who own the land it would traverse as well as environmental groups.

A From-Bitumen-to-Cars Business

These future plans are not without controversy. The United States has about 250 million cars on its roads, most of which run on gasoline, and China currently has almost 200 million cars on the road, a number that is rapidly increasing. Until alternatives like electric cars or fuel cell cars are embraced in significant numbers by major car manufacturers and the public, worldwide demand for syncrude will continue to increase, enough to make the planned tripling of operations here in Alberta economically feasible. Business is essentially an amoral operation. Owners and investors understandably place customer and shareholder satisfaction as their bottom line in a free market society like ours. Inadequate limits placed on the industry by both levels of government here as well as a lack of Canadian will to adhere to the international limits of CO2 emissions of the Kyoto protocol and a lack of cooperation by both Canada and the United States with the Copenhagen Climate Council makes me wonder if the Canadian government is taking too much luxury maintaining a laissez faire attitude toward the oil sands industry. As we reap the financial rewards will we be leading the world to environmental disaster? We must remember that we as consumers are complicit in the business of oil.

Efforts to Mitigate Environmental Damage

The oil sands industry in Alberta represents an enormous financial investment, estimated at about $140 billion from 1997 to 2010, made by many international companies as well as the Alberta government. If they were shut down tomorrow, the companies as well as Alberta's, and Canada's economies would be seriously affected. Even so, a few Canadian politicians are beginning to publicly ponder shutting down the oil sands.

Sufficient public pressure might influence the oil companies to invest in and implement environmental controls, and that is already beginning to happen.

Carbon Capture and Storage Plan

The Alberta government just announced that it will go ahead with a carbon capture and storage plan, a $2 billion investment. While this technology could significantly reduce CO2 emissions it will not eliminate them. It will be difficult to implement the technology in a complex system with multiple CO2 emission points and the technology itself is unproven. Carbon capture and storage has become a public relations necessity for the oil sands in an effort to clean up its "dirty oil" image. The federal and provincial governments strongly support the implementation while environmental groups question its actual effectiveness. This technology doesn't address the pollution attributed to the end-stage burning of the fuels. For example, new technologies, traffic management and changes in car use must be explored and applied. In the meantime, it may take a great deal of time to determine the effectiveness of carbon capture technology.

Reclamation of Former Mines and Tailings Ponds

The oil sands are also engaged in reclamation of oil sands land. Syncrude Canada Ltd. has invested $100 million into this effort over the last five years. Gateway Hill, a reclaimed forest in the former west mine area just north of Fort McMurray was recently opened to the public and is the first to receive government reclamation certification.  How effective this reclamation was is a source of controversy. Reclamation of the industry's tailings ponds is also underway and, in fact, Suncor Energy Inc. recently celebrated its first reclamation of a tailings pond into 220 hectares of wetland. Environmentalists as well as First Nations people living downstream are not impressed however. Dr. Lee Foote, a wetlands specialist and an expert on land reclamation at the University of Alberta, questions whether the new wetland is a functioning ecosystem rather than simply an area that has been made to appear alive and green. Other environmental groups agree that it is too soon to call the site reclaimed. Meanwhile, Suncor has been charged with violating storm water management regulations and there is growing concern that chemicals such as toxic and carcinogenic naphthenic acids and heavy metals from old tailings ponds are leaking into the Athabasca river, the major water supply in the area, as well as local water aquifers. The Pembina Institute, an Alberta environmental watchdog, details what is known about which chemicals are in the tailings ponds as well as the enormity of the area the "ponds" entail. The companies involved in the oil sands industry must find ways to address this unacceptable hazard to both the people who rely on the water supply as well as the ecosystem. Last but not least, reports of the deaths of thousands (per annum) of migratory birds that land in the tailings ponds is seriously damaging the industry's reputation both here and abroad. The full impact on the various species involved, some of which are endangered, for example the whopping crane, is not yet known, nor is a workable solution yet available. Both Suncor and Syncrude have said that their deterrent systems were fully functional when migratory birds recently landed during a freezing rainstorm.

As the world's oil reserves dwindle and oil becomes more expensive, revenue from the oil sands will increase. The companies involved could go a long way toward satisfying a jittery public that they are not ruining the Earth by not only devoting more resources to environmental research but forming a cooperative relationship with independent researchers to allow renowned scientists like freshwater expert Dr. David Schindler, full access to the operations to run fully independent testing, and to hear and respond to the research findings in a fully transparent way. I hope for a solution to the oil sands problem that can reach a compromise between the public vilifying the industry and the industry shutting out the public. I think there is a danger of opposing sides digging in and creating a stagnant impasse that jeopardizes the problem-solving process so badly needed.

The business of the oil sands is impressive. A world-class conglomerate of cooperative companies is coming together to create what will be one of the greatest capitalistic enterprises in history. The industry is well aware that its customers are ultimately us, as we all increasingly consume the fuels refined from bitumen to support our industries and lifestyles. I leave it up to you to decide if it is time to venture into the great energy unknown and trade in your current gasoline-powered car for an electric or hydrogen fuel model, for example. Maybe you already have. I ask you where you think the oil sands industry should be heading. Do you agree with what is happening and, if not, do you think public pressure will succeed in forcing the industry to sufficiently green up or will it succeed only in eliciting superficial responses from the industry which ultimately will have little environmental impact and serve to further muddy the waters of information? Can the world afford to wait and see what the full environmental impact of decades of oil sands production and end-use of its products will be, before governments step up and impose restrictions?

The oil sands industry is on the verge of becoming the largest environmental gamble in history. 50 years from now will we be thankful for the affordable fuel we have had access to, secure knowing that the sky didn't fall after all? Will we look back with regret, living in a mortally wounded world and wondering why we didn't do anything to stop it? Will we look back from an entirely new perspective where the economy, industry, infrastructure and our lifestyles adapted to the end of the fossil fuel age?

Added Note:

I recently watched "Earth: The Operator's Manual," a 1-hour special on climate change and sustainable energy that explores in particular our reliance on oil, natural gas and coal and our alternatives, on PBS (premiered in April, 2011). This is is the most scientifically presented well-rounded treatment I've seen and I highly recommend you view it (click to watch the whole episode below) as you consider Earth's complex energy issues.

Tuesday, February 15, 2011

Fracking: Alberta's Imminent Disaster

*This article has been updated. See asterisk at the end of this post.

I recently watched a documentary on CBC News Network called Burning Water (aired in October 2010), about the effects from fracking (hydraulic fracturing) on local well water quality in Alberta. I was deeply disturbed and moved by what I saw and I feel compelled to make an effort here to help educate myself as well as fellow Albertans about this industrial process.

What is fracking?

Alberta (and Saskatchewan) is rich in natural gas. A very large reservoir of this gas is locked up within coal thousands of metres deep underground. It is possible to tap this resource by creating a hydraulic fracture within the shale by pumping very high-pressure fluid into the wellbore. The fluid fractures the coal and rock and creates a large surface area in which the gas can permeate out and be captured. The fluid used is mostly fresh water but it also contains a small percentage of chemicals and it is these chemicals that are creating a major controversy both here and in many areas in the United States where the process is also used to extract gas. There is growing evidence that these chemicals can find their way into local water aquifers and contaminate local water supplies.

Most people in the industry claim that fracking has very little potential to contaminate water aquifers because most aquifers are much less deep than the areas in which the fracking is done. In the United States, a study done by the Environmental Protection Agency in 2004 revealed that there is some uncertainty about how fracturing fluid migrates through rocks, and how the seismic activity, which accompanies such drilling, may affect this migration. An act called the FRAC Act was introduced in the U.S. in 2009 in an attempt to force the fracking industry to reveal exactly what is in their fracking fluids. The industry is currently resisting this bill because it considers the recipes for these fluids to be trade secrets.

There has been no investigation into the potential pollution of aquifers by fracking in Canada.

Why is fracking dangerous?

According to two studies done by the U.S. Department of Energy and the Ground Water Protection Council, chemicals used in fracking may include kerosene, benzene, toluene, xylene and formaldahyde. These chemicals, most of which are solvents, may be used either directly in fracking fluid or in other parts of the job.

Some of these chemicals are extremely dangerous even in very low concentrations in water. Benzene is a carcinogen, toluene and xylene are neurotoxins and formaldehyde is both a toxin and a possible carcinogen.

The Burning Water documentary I watched concentrated on a farming family living near Rosebud in southern Alberta. Encana, Canada's largest gas company, had recently begun drilling several fracking wells under and near their farm and they soon discovered that their well water was causing chemical-like burns on their skin. Their water had always contained some natural methane gas but now it was so saturated with it that it could be lit on fire. They took aquifer samples to independent water testing services and found the presence of both toluene and benzene, two highly toxic chemicals that are not found naturally.

Importantly, they also contacted the company Encana itself, Alberta Environment and the Alberta Research Council and all three determined that the effects the family observed were unrelated to the fracking activity. The family, as well as others nearby, and families on farms near Edmonton as well have had to either haul in water or abandon their farms because the aquifers their wells draw from are contaminated.

What can we do?

I have not found any Canadian documented harmful effects to people or farm animals that are directly tied to fracking activity. But I did find a transcript of an interesting interview conducted with Dr. Theo Colborn by an advocacy group in the U.S. called Democracy Now, which highlights some of the potential toxic effects of the chemicals used in fracking (

I am deeply concerned that the Alberta government is unwilling to test for possible effects on our water quality caused by the fracking wells that are now scattered all over our province and it is unwilling to inform Albertans of what it might already know. In the meantime we must ask ourselves if we are willing to wait until the health effects of some of these toxic chemicals becomes clear. When it does become clear, how difficult will it be to remove them from Alberta's water supply even after they have been banned from industrial use?

New York State has banned all fracking activity because legislators there are worried that the water supply of New York City could become irreversibly contaminated. Citizen's groups all over the U.S. as well as in British Columbia have spoken up and banned this activity near their homes.

I think we Albertans need to consider whether we are willing to risk our water supply for the sake of increased provincial gas revenue.

To help you make an informed decision for yourself I recommend two documentaries: Joel Fox’s documentary, Gasland, and Burning Water, a documentary produced for CBC's Passionate Eye series. If you simply enter "fracking" into Google, you will find a wealth of controversy over this industrial process.

Finally, if you are living near any fracking wells and you are concerned about your water quality please take a water sample and have it tested by an independent water-testing lab (University of Alberta or University of Calgary for example).

Write letters to the editor of your local newspaper. Talk to your neighbours. Write a blog.

*Has the fracked gas business bubble already burst? Check out this fascinating New York Times article published June 24, 2011. 

Monday, February 7, 2011

Stellar Objects Part 1: Introduction To Stars

Stellar Objects Part 1: Introduction To Stars

How did the universe come to be filled with stars? What are they made of and why are there so many kinds of them? How are they born and how do they die?

What is a star?

A star is a ball of mostly hydrogen and helium with enough mass that it can sustain nuclear fusion in its core. Our Sun is a star but stars come in a wide range of colours and vary a great deal in mass. The least massive possible star is about 80 times the mass of Jupiter. This is the theoretical minimum mass a star can have and still support fusion in its core. The most massive star possible is not really known but most physicists now peg it at about 250 times the Sun's mass. An example is the star, R136a1, its discovery published in July 2010. Tremendously massive stars like this one shed enormous amounts of energy and mass through a continuous stellar wind. They last only a few million years before exiting brilliantly as powerful supernovas. These stars are known as Wolf-Rayet stars. They far surpass what is called the Eddington limit. This limit is likely reached at around 120 solar masses, as which point a star starts to eject its envelope through intense solar wind because its outward radiation pressure exceeds the force of gravitational attraction. Radiation pressure is negative (outward) pressure resulting from the radiation of electrons, protons and other high-energy particles from the star. Solar wind is an example. This is why these huge stars blow off energy and mass at a very fast rate.

The longest-lived stars are the smallest ones. These are red dwarfs. They consume very small amounts of matter, put out very little energy over time and can live for up to 10 trillion years. That's far older than the universe is itself, which is about 14 billion years old. These are the most common stars in the universe today. 85% of the stars in the Milky Way are red dwarfs

This is an artist's conception of what a red dwarf might look like close up.

Star Birth

These are star-forming pillars of hydrogen gas and dust within the Eagle Nebula, as seen by the Hubble Space Telescope.

This region is also called the Pillars of Creation. It is the beginning of an immense star nursery. Small dark areas imbedded in the pillars are believed to be baby stars called protostars. There are countless numbers of these nurseries scattered throughout the universe. It is bittersweet to know that we are observing something that is probably already gone. The nebula is 7000 light years away from us and scientists have recent evidence that a supernova exploded nearby about 6000 years ago, destroying the pillars. We will not see the new shape of this nebula for another millennium.

How to Make a Star

Step one: wait. 75% of the matter in the universe is hydrogen and 23% is helium. These elements came from the Big Bang.  A nebular cloud of elemental gas and dust must wait, perhaps for millions of years, until a gravitational disturbance passes through it to turn on the process of star formation. This disturbance can be, for example, a passing star or a shock wave from an exploding star. In a pre-star environment, the disturbance might even be the result of a phase transition or the ionizing influence of primordial black holes. Once the disturbance occurs, matter begins to swirl and ripple and this sets off the process of accretion. This means that a locally dense region of gas and dust gravitationally attracts more and more gas and dust to itself. This will only occur if the cloud has sufficient mass. The gas and dust molecules in it have energy of their own that resists collapse and this energy must be overcome by the gravitational pull of the cloud. In other words the cloud must have a critical mass, about 80 times Jupiter's mass, before it can overcome the energy of the dust and gas particles as they randomly collide and bounce off each other, creating a negative pressure that resists gravitational attraction. If the critical mass is not reached, the cloud continues to swirl and clump but the clumps won't be permanent. They'll dissolve and reform over and over again. When critical mass is reached, the infalling material brings with it the sum of the angular momentum* of each its particles and this force begins to organize it into a disc than begins to rotate faster and faster as it continues to feed on surrounding material. This accretion disc stage can last for up to 10 million years, accumulating on average about 10-8 solar masses per year.

* Every subatomic particle, every atom, and in fact, every rotating object has angular momentum.

Step two: let gravity do its work. Eventually, clumps of gas and dust grow bigger and together into one clump. When this clump reaches a high enough density it will stop losing heat to the surrounding nebula. This occurs because as its density increases, particles become closer and closer together and eventually they can exchange heat with each other and conserve energy compared to the looser arrangement of particles that surrounds them, which are too far apart to exchange heat (these begin to act like a Thermos container). Before the cloud begins to collapse, it may be very cold. The heat it acquires comes from gravitational potential energy. The collapsing material also becomes optically thick. This occurs when atoms become so energetic they ionize and the disc becomes full of freely scattering electrons. These free electrons collide into photons and prevent them from radiating away. It also means that gravitational potential energy can no longer be radiated away. This prevents any further cooling of the condensing gasses and their temperature now begins to spike rapidly. The gas falling toward the opaque center creates its own shock waves that further heat the core.

The clump is now called a protostar, shown here in this artist's rendering.

It has reached a state of hydrostatic equilibrium, in which internal pressure counteracts the force of gravity. When the accretion process is complete, the star is called a pre-main sequence star. It is a true star, when, at about 10 million K*, hydrogen begins to fuse in its core, igniting a fusion chain reaction and the star begins to shine. Solar wind quickly disperses the remaining dust and gas in its vicinity. This scenario is well documented for low mass stars, including the Sun. For stars larger than 8 solar masses the mechanism of star formation is not well understood but it occurs on a much faster timeline.

*K or Kelvins, the SI base unit of temperature, is used by astrophysicists. For example, absolute zero (0 K), the point at which all motion, even that of electrons, stops, is equivalent to -273°C.

An example of a very massive star is Eta Carinae; it is visible as a bright white spot in the center of the nebula shown here. It is thought to be more than 100 times the mass of the Sun.

It produces more than 1 million times the light of the Sun and it is quite rare. Only a dozen or so exist in the Milky Way.

Very low mass protostars become brown dwarfs. These are tiny stars, which are not technically stars, between 1/18 and 1/00 of one solar mass. They are no longer surrounded by their parent nebula but they are not hot enough to initiate fusion. The physical characteristics of these oddball "failed stars" fall somewhere between stars and giant gas planets.

This is an artist's rendering of a brown dwarf.

What did the first stars look like?

The fist stars in the universe turned on about 200 million years after the Big Bang and ushered in billions of years of intense stellar formation.

This is a simulated NASA image of what the first stars may have looked like within what are called faint blue galaxies. These first galaxies underwent large bursts of star formation resulting in blue light from young extremely massive stars.

Even at about 3-5 billion years old, the universe was a different star formation environment than it is today. Typical galaxies had up to 10 times more molecular gas than they do today and the rate of star formation was, as a result, up to 10 times higher then. These early stars accreted from gases that contained very few elements heavier than lithium-7 (for our purposes we call all these heavier elements "metals" as the astronomers do, not to be confused with actual metals) so very old stars are expected to contain no metals and yet all stars observed, some of them being very old, do. These stars are observed when they were young in their lifecycle so they could not have created their own metals through nucleogenesis (this process will be discussed later in this article). One explanation for this puzzle is that while only metal-free stars formed first, these stars were likely several hundred solar masses, far larger than what could form today. Physicists think this is because they had practically no elements heavier than hydrogen and helium. Heavier elements catalyze hydrogen fusion reactions, increasing a star's heat and therefore outward radiant pressure. These stars, in contrast, were able to amass much more gas before exceeding their Eddington limit. With such high inner densities of hydrogen, they lived very short lives and blew up spectacularly, blowing the first 26 elements up to iron, created inside them in the process of nucleogenesis, far into the galaxies in which they formed, thus relatively quickly seeding the early universe with metals. None of these very first stars have been observed but there is an active hunt for them within the oldest most distant galaxies. Another possible source for the metals observed in stars is black holes created by even more massive earliest stars. Instead of exploding into supernovae these truly enormous stars collapsed into black holes, and all their matter, including metals, eventually sprayed from their relativistic jets throughout the universe. The oldest observed stars have very low metallicities and subsequent generations of stars became more metal-enriched as the gas clouds from which they formed contained more and more metal-rich dust.

This is an image of globular cluster M 80, about 28,000 light years away. The densely packed metal-poor stars in this cluster are believed to be almost as old as the universe itself.

Our Sun

Our Sun is a young star. It contains a high metal content and it is these metal-rich stars that are most likely to have planetary systems formed from the accretion of metals.

The Sun is a main sequence star. This means that it is part of a sequence of stars on a graph on which surface temperature and brightness are plotted against each other, called a Hertzsprung–Russell diagram. Main sequence stars like the Sun are undergoing fusion of hydrogen into helium and are in hydrostatic equilibrium (compression due to gravity is balanced by outward pressure). The Sun is about halfway through its main sequence evolution. Stars as small as the Sun are essentially a proton-proton chain reaction contained by gravity. Higher mass main sequence stars undergo a different fusion reaction called the CNO (carbon-nitrogen-oxygen) cycle because they reach a higher core temperature.

This is a portrait of the Sun taken by Nasa's Solar Dynamics Observatory.

Three quarters of the Sun's mass is hydrogen and most of the rest consists of helium. Just 2% of its mass consists of heavier elements such as oxygen, carbon and iron. It makes up 99.8% of the total mass of the solar system. Within its core about 500 million tons of hydrogen are fused into helium every second at a rate of about 9 x 1037 fusion reactions per second. The fusion rate of the core maintains a state of equilibrium. If fusion increases, the core heats up and expands. If the core expands, the fusion rate slows. It's a density-dependent reaction. This proton-proton fusion reaction releases 0.7% of the fused mass as energy, resulting in a total energy output of about 4 x 1026 watts per second, as neutrinos and solar radiation.

Researchers have attempted to control the fusion process for over 50 years. It would be the answer to the world's energy crisis. Nuclear fusion, not to be confused with nuclear fission, the process undertaken within nuclear reactors, comes with some very difficult practical problems. First it takes a tremendous amount of input energy to get (positively charged and therefore repulsive) nuclei to fuse, even small hydrogen nuclei, because of the enormous electromagnetic repulsive force between them. If they are accelerated to very high speeds and energies, the attractive nuclear strong force can be sufficient to achieve fusion. Very powerful accelerators are required to achieve this. The beauty of nuclear fusion is that is has an energy density (energy produced per unit mass) many times greater than even nuclear fission does. However, even if powerful accelerators become cost effective, there are other barriers to overcome. One problem is once a self-sustaining reaction is achieved how do you contain it? Gravitational, magnetic and inertial containment are three options currently being investigated.

The Sun has the same chemical composition as the interstellar medium from which it formed almost 5 billion years ago. Its metallic portion (2% of its mass) was created within stars, which had since exploded as supernovae through the process of nucleogenesis. The entire solar system began with the gravitational collapse within a cloud of mostly molecular hydrogen.

This is a molecular cloud, similar to the one from which the solar system formed. It's a star nursery broken off of the Carina Nebula about 8000 light years away from us. The bright pinkish spots are new stars, which will "boil away" the surrounding gas and destroy this cloud within a few million years.

Most of the collapsing cloud formed the Sun while the rest contributed to an orbiting protoplanetary disc. It is from this disc that the planets, moons, asteroids and comets formed.

This is an artist's rendering of what a protoplanetary disk might look like.

The Sun will continue to fuse hydrogen into helium until almost all of its hydrogen is used up, in another 5 billion years.

The Sun isn't massive enough to explode into a supernova at that time. Instead, it will expand into a red giant. Its core will be full of inactive helium. Because nuclear fusion will no longer exert outward pressure, the core will begin to collapse under its own gravity. This will heat a shell outside the core where some hydrogen remains. Nuclear fusion will continue for a while longer within this shell as it balloons and the Sun expands, pushing the planets outward. The expansion will spread the heat over a much larger surface area so the surface cools and that is why the Sun will look red. The collapsing core will continue to heat up because of increasing pressure as helium accumulates. Mercury, Venus and likely Earth will be incinerated. Eventually it will ignite helium fusion in what is called a triple alpha process. At around 100 million K, 3 helium nuclei fuse into one carbon-12 nucleus. Some oxygen will also be produced. Larger stars at this point would repeat the fusion cycle, fusing heavier and heavier elements in successive phases but the Sun will never fuse carbon. It will instead end its life in what is called a helium flash. Its core will continue to grow hotter until runaway fusion of helium occurs. At this point, in a matter of seconds, up to 80% of the helium in the core will fuse into carbon and release an incredible amount of energy. A planetary nebula will be blasted out into space leaving behind a carbon-oxygen white dwarf. The dwarf's reduced mass will weaken its gravitational pull on the remaining planets, now frozen, and eventually they may be lured away by other stellar bodies that pass nearby.

A white dwarf is mostly made up of electron-degenerate matter. It is so dense that instead of ordinary atoms with electrons occupying stable orbitals, it consists of a collection of carbon and oxygen nuclei floating in a sea of loose electrons. White dwarfs are luminous not because they are generating any energy but because they have trapped huge amounts of it. Normal matter exerts pressure when it is heated but electron-degenerate matter cannot. It becomes super-compressed with nuclei pushed right up against one another, resulting in an extremely hot dense "solid." For stars the mass of the Sun, what is known as degeneracy pressure resists further collapse of matter. When stars larger than about 4 to 8 times the mass of the Sun collapse, atoms can collapse into each other even further creating a neutron star, which is itself supported by neutron degeneracy pressure. When very massive stars collapse, even neutron degeneracy pressure may fail to support the atoms and the matter then collapses completely into a black hole. The white dwarf that is left over from the helium flash will be about half the mass of the Sun and only slightly larger than the Earth. It will have a very thin atmosphere of purely hydrogen or helium surrounding a crystalline lattice of carbon and oxygen, almost like an impossibly dense diamond. And it will initially be very hot, over 100,000 K. White dwarfs are extremely stable once they are formed. It will take many billions of years to cool and eventually transform into a black dwarf. The only way a white dwarf can lose energy to cool off is through the process of proton decay, in which energy is radiated away through gamma ray photons. Protons are very stable, having a half-life of 7 x 1033 years so this process is extremely slow. In fact no black dwarfs have ever been detected because the calculated time required for a white dwarf to cool into a black dwarf is longer than the age of the universe. As a black dwarf it will stop shining all together.

A Special Section on Nucleogenesis

I have mentioned that the Sun will never create any element larger than carbon, except for small amount of oxygen. It will create these elements when three helium atoms fuse into one carbon atom and four helium atoms fuse into one oxygen atom. This will begin to happen after the helium flash, mentioned earlier. Larger stars can compress their cores enough to fuse higher elements. At a core temperature of about 600 million K, carbon atoms can fuse into oxygen, neon, sodium and magnesium. At 1 billion K, oxygen atoms can fuse into silicon and the elements from magnesium to silver on the periodic table. These atoms can in turn fuse into elements as massive as iron. Stellar fusion (nucleogenesis) stops at iron because fusing atoms larger than iron requires more energy than it releases. Fusion can produce energy only as long as the sum of the masses of the new nuclei is less than that of the original nuclei. When iron nuclei (26 protons and 30 neutrons) begin to fuse with other nuclei the resulting nuclei have more mass, the process consumes more energy than it produces and the process stops. An iron core then begins to form inside the star.

How are elements heavier than iron created? There are two processes, one slow and one very fast. Over time, free neutrons occasionally slam into atomic nuclei. When they do so, they decay into protons and release an electron. Adding a proton creates the next element on the periodic table. Massive stars last long enough to allow this process to happen and they make atoms as large as bismuth (83 protons) as they do so. Atoms larger than bismuth can only be created in a Type II supernova. Successive fusion reactions within a large star leave an iron core. Eventually this core reaches what is called Chandrasekhar mass, which is about 1.4 solar masses. At this point, not even electron degeneracy pressure can hold it up. It collapses pushing protons and electrons together to form neutrons and neutrinos. Neutrinos do not normally interact with matter but at this density they exert a tremendous outward pressure. Even so, the core continues to collapse and approach neutron degeneracy. The outer layers crash inward and rebound, creating a neutrino outburst and a shock wave, and when they do so, they trigger an enormously powerful Type II supernova explosion.

Twenty years ago, astronomers witnessed one of the brightest stellar explosions in more than 400 years. The supernova SN 1987A exploded with the power of 100 million Suns. This NASA image shows its shock wave, visible as a glowing pink ring of gases.

This explosion, which occurs within a timescale of milliseconds and creates an initial temperature as high as 100 billion K, creates a tremendous number of neutrons, and these neutrons slam into atomic nuclei, resulting in all the elements heavier than bismuth, including all of the radioactive elements, and blasts them far into space.

All the metals within stars, planets and asteroids, all the metal-containing interstellar dust, originally came from the initial fusion of hydrogen and helium. You would expect a decreasing abundance of elements corresponding to the frequency of various fusion reactions within the universe and roughly equivalent to increasing mass, and this is generally the case. The heavier "metal" elements are far more rare than the lighter ones - only 2% of the Milky Way disc is composed of metallic matter by mass. The metallicity of a stellar object can be used to determine past stellar activity within its region of space.

You might be wondering why the nucleogenesis of metals didn't occur just after the Big Bang when nucleons formed. Temperatures were more than hot enough then, just under 2 trillion K. Actually, fusion would have continued then just as it does in large stars and in supernovae if the universe hadn't very quickly entered a period of extremely rapid expansion in which density and temperature dropped below what would be required to sustain fusion. That is why the first baryonic matter (to be distinguished from dark matter) in the universe consisted almost entirely of hydrogen and helium, and no elements heavier than beryllium existed before the first stars approached the ends of their lives.

I leave you now with NASA's star gallery. Click on an image to learn about the story behind it. Such fascinating and beautiful objects stars are!

Next up: Neutron Stars.

Sunday, February 6, 2011

Stellar Objects Part 2: Neutron Stars

Stellar Objects Part 2: Neutron Stars

A neutron star is a supernova remnant of degenerate matter so dense that it represents matter at the limit of physical laws, atoms balanced at the cusp of total annihilation, a black hole.

A neutron star is a stellar remnant from a supernova explosion. The tiny white dot indicated by the arrow in the photograph shown below represents the first neutron star directly observed in visible light. Neutron stars comprise the densest form of matter known to exist. Matter denser than this collapses into a black hole.

About 2000 known neutron stars populate the Milky Way and the Magellanic Clouds. The closest one, shown here, is 424 light years away from us.

There are various classifications of neutron stars, generally according to what kinds of energy they emit. When these stars are very young, they rapidly pulse radio or X-rays. These pulses are believed to be caused by particles accelerating near the star's magnetic poles. The mechanism for these pulses is not well understood but the beams are coherent and synchronized to the rotation of the star, although the magnetic and rotational axes are not aligned, so the beams sweep around as the star rotates like the spotlight of a lighthouse. Neutron stars that emit these pulses are called pulsars. The rotation of pulsars very gradually slows down over time and the pulses eventually die out because magnetic torque acts against the spin. Pulsar radiation is not generally dangerous to life on Earth. Possible exceptions are neutron stars that may be soft gamma ray repeaters. However, magnetars, which are discussed in a different article, are more commonly associated with soft gamma ray emission. Gamma rays are very energetic photons and a nearby gamma ray burst directed at Earth from a supernova, for example, could cause a mass extinction. Soft gamma rays are slightly less energetic but harmful nonetheless. A gamma ray burst could alternatively come from the merging of two neutron stars or a neutron star and a black hole.

Sometimes a neutron star will experience a glitch in which its rotation momentarily speeds up. This may be caused by transitions in the vortices in its neutron superfluid core into a lower energy state. What results is a star quake.

This is an artist's concept of a 2004 neutron star quake that flared so brightly it momentarily blinded all X-ray satellites in orbit. Some neutron stars aren't isolated but instead are part of a binary system. A neutron star's accretion from its companion star or from gases near a black hole may also affect its rotation and its fate.

How Neutron Stars Form

Stars that are about 4 to 10 solar masses have cores that are hot and dense enough to fuse elements up to iron. Fusion (nucleogenesis) stops at iron because fusing atoms larger than iron requires more energy than it releases. Fusion can produce energy only as long as the sum of the masses of the new nuclei is less than that of the original nuclei. When iron nuclei (26 protons and 30 neutrons) begin to fuse with other nuclei the resulting nuclei have more mass, the process consumes more energy than it produces, and the process stops. An iron core then begins to form inside the star.

Eventually this core reaches what is called Chandrasekhar mass, which is about 1.4 solar masses (this explains why all neutron stars are about the same mass). At this point, not even electron degeneracy pressure can hold it up. It collapses, pushing protons and electrons together to form neutrons and neutrinos. Neutrinos do not normally interact with matter but at this density they exert a tremendous outward pressure. Even so, the core continues to collapse under its own gravity and approach neutron degeneracy (discussed in the next paragraph). The outer layers crash inward and rebound, creating a neutrino outburst and a shock wave, and when they do so, they trigger an enormously powerful supernova explosion.

What remains is a stellar remnant composed almost entirely of neutrons. This extremely hot neutron star is supported against further collapse by neutron degeneracy pressure. This pressure results when neutrons become so tightly packed together they occupy all the lowest possible energy states with some neutrons left over that must then occupy higher energy states. These high-energy neutrons create the outward directed degeneracy pressure. This is a quantum mechanical effect and as a result it is insensitive to temperature. That means that the neutrons stay packed together even as the neutron star cools off, as it eventually does, through neutrino radiation.

A neutron stars packs a mass of between 1.4 and 2 solar masses into a sphere about 20 km in radius. A 1 cm cube of neutron star would weigh as much as a mountain. These stars have been observed in supernova remnants and in binary systems. Four of them are thought to have planets. As a general rule, stars that are between 0.5 and 4 solar masses eventually mature into black dwarfs. More massive stars, between 4 and 10 solar masses, mature into neutron stars and very massive stars, more than 10 solar masses mature into black holes. Neutron stars retain most of their angular momentum. This means that because they are only a small fraction of their parent star's radius, they have extremely high rotational speeds, somewhere between ¼ millisecond to 30 seconds per revolution. These stars, due to their density, also have extreme surface gravity, up to 7 x 1012 m/s2, compared to Earth's 9.98 m/s2. If an object fell from a height of 1 meter onto the surface of a neutron star it would take 1 microsecond to land and it would be landing at a velocity of 7 million km/h! The gravity on a neutron star's surface results in an escape velocity of 100,000 km/s, about 1/3 the speed of light. The extreme gravitational field around a neutron star acts as a gravitational lens, bending radiation that passes through it. This means that distant objects behind neutron stars become visible.

Mysterious Innards

Neutron stars are very hot when they form, about 1012 K, but they cool rapidly through neutrino radiation, to about 106 K in a few years. As they cool they are thought to form layers and as you explore deeper within these layers, the kinds of matter you might encounter are, well, are just plain bizarre. Remember, neutron stars are made of the densest matter possible. In fact, physicists are beginning to wonder if the name "neutron" is itself a misnomer because they think that in the center of neutron stars the neutrons themselves may be squished down into more exotic types of matter. Some recent computer models have suggested that these stellar corpses may be filled with free quarks, the constituents of neutrons, or even hyperons or kaon condensates.* The October 2010 discovery of a neutron star called J1614-2230 located 4000 light years away not only has broken the record for mass, 2 times solar mass, but it deals a death blow to many proposed models for the kind of matter that makes up a neutron star. Free quarks, kaons and hyperons are out. A neutron star composed of any of these materials would collapse to form a black hole before it could reach 2 times solar mass. What a neutron star is actually made of remains a mystery.

*Under normal conditions all quarks are bound up in atoms as neutrons or protons. Free quarks do not exist except under extraordinary heat and pressure in the form of quark-gluon plasma. Hyperons, like neutrons and protons, are made of three quarks, but the quarks that make them up are of a different kind.  Kaons are particles called mesons that consist of two quarks. Both Kaons and hyperons contain strange quarks. These particles constitute what is called strange matter. When neutrons are compressed beyond a certain limit they dissociate into strange matter quarks. These strange matter quarks in turn transform into a bound state called a strangelet, composed of roughly equal numbers of up, down and strange quarks. Such a state could be as small as the mass of a hydrogen nucleus or as large as meters across and these strangelets are believed to be what make up something very exotic called quark stars or strange stars as they are sometimes called (these stars are discussed in more detail in another article). Normally, strange quarks are unstable and don't exist for long, but in large numbers in neutrons, for example, they may represent the lowest possible energy state. Having three kinds of quarks allows them to be packed in together more efficiently. If this strange matter hypothesis is correct, it could have some potentially dire consequences. For example, if a strangelet came into contact with an ordinary atomic nucleus in a clump of matter on Earth, it would convert that matter into strange matter. By doing so it would release energy, producing a larger more stable strangelet, and this process would continue until all nuclei in all the matter in Earth were converted. Earth would as a result be converted into a hot large clump of strange matter. Not to worry though, about the only way this matter would come into contact with Earth would be if a quark star slammed into it, very unlikely, and we would have bigger worries at that point. If a strangelet hit a neutron star it would theoretically convert it into a quark star or strange star. The strange matter hypothesis is unproven. One nagging question is why aren't all neutron stars strange stars, since strange matter seems to represent a lower energy state. There is an ongoing effort to determine whether the surfaces of known neutron stars consist of strange matter or nuclear matter. The phenomenon of X-ray bursts is well explained in terms of nuclear matter and seismic vibrations of magnetars (see the article on magnetars) also support nuclear matter.

I recommend Dr. Coleman Miller's Neutron Star page as a fun read.  Some of his information is based on his own personal speculations but he backs everything up with scientific argument and some very helpful diagrams.

An Exciting Update

University of Alberta astronomer Craig Heinke and his colleagues have just increased our understanding of the physical nature of the matter inside neutron stars, as described in a February 2011 Edmonton Journal article, specifically how matter behaves inside the core of the neutron star, Cassiopeia A, a remnant from a supernova that exploded 11,000 light years away in the Milky Way.

This is a false colour image of Cassiopeia A, using the Hubble and Spritzer telescopes as well as the Chandra X-ray observatory.

They found direct evidence that the core contains a frictionless superfluid (a fluid that flows with absolutely no friction) that seems to defy gravity, as well as a superconductor (a material through which electrons can flow without losing any energy along the way). They have been observing the neutron star's surface temperature (it's about 2 million °C) for 10 years and have found that only a superfluid core could explain its rapid rate of cooling, of about 4% per year.  The only superfluids observed on Earth are extremely cold, just above absolute zero. And superconductors are observed here only when temepratures drop below - 100 °C. Evidence of superfluid and superconducting hot matter inside neutron stars will hopefully spark a new wave of theoretical research supported by computer modelling as we try to probe further into the workings of matter that is squeezed to its absolute limit, and perhaps, beyond.

Sept 19, 2014 addition: A new 5-minute video just released by Kurzgesagt (which means "in a nutshell" in German) explains neutron stars in a fun and very clear (and accurate!) way. It's an excellent watch:

Next up: Quark Stars.