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Legacy of bass
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Traces Of One Of The Universe's First Stars Detected
An ancient star in the halo surrounding the Milky Way galaxy appears to contain traces of material released by the death of one of the universe's first stars, a new study reports.
The chemical signature of the ancient star suggests that it incorporated material blasted into space by a supernova explosion that marked the death of a huge star in the early universe — one that may have been 200 times more massive than the sun.
"The impact of very-massive stars and their explosions on subsequent star formation and galaxy formation should be significant," lead author Wako Aoki, of the National Astronomical Observatory of Japan, told Space.com by email. [Top 10 Star Mysteries]
Hidden giants
The first stars in the cosmos, known as Population III stars, formed from the hydrogen and helium that dominated the early universe. Through nuclear fusion, other elements were forged in their hearts. At the end of their lifetimes, supernovas scattered these elements into the space around them, where the material was folded into the next generation of stars.
The universe's first massive stars would have been short-lived, so to determine their composition, scientists must examine the makeup of their offspring — stars that formed from the material distributed by their explosive deaths. While numerical simulations have suggested that at least some of the first stars should have reached enormous proportions, no previous observational evidence had managed to confirm their existence.
Aoki and a team of scientists used the Subaru Telescope in Hawaii to perform follow-up observations of a large sample of low-mass stars with low quantities of what astronomers term "metals" — elements other than hydrogen and helium. They identified SDS J0018-0939, an ancient star only 1,000 light-years from Earth.
"The low abundance of heavy elements suggests that this star is quite old — as old as 13 billion years," Aoki said. (Scientists think the Big Bang that created the universe occurred approximately 13.8 billion years ago.) [5 Weird Facts About the Big Bang]
The chemical composition of SDS J0018-0939 suggests it gobbled up the material blown off of a single massive ancient star, rather than several smaller bodies. If multiple supernovas had provided the material that constructed the star, the "peculiar abundance ratios" in its interior would have been erased, Aoki said.
Volker Bromm of the University of Texas, Austin agrees, saying that SDS J0018 likely evolved from the material from a single star, which could have been more than 200 times as massive as the sun.
Bromm, who has performed theoretical studies on the properties of the first generation of stars and their supernova explosions, did not participate in the new study. He authored a corresponding "News & Views" article that appeared with the research online today (Aug. 21) in the journal Science.
Signs of low-mass first-generation stars have appeared to be more plentiful in their descendants, which contain large amounts of carbon and other light elements, but until these results, scientists had detected no traces of their very massive siblings. The scarcity suggested that low-mass stars were more numerous in the early universe.
"We have come to understand that the first stars had a range of masses, from a few solar masses, all the way up to 100 solar masses, or even more," Bromm told Space.com via email. "The typical, or average, mass is predicted to be somewhere close to a few tens of solar masses.".
Searching for the first generation
Massive stars burn through their material far faster than their lower-mass relations. Therefore, no high-mass stars should exist today. But Aoki suggested that smaller ones could still be visible.
"In the Milky Way, low-mass Population III stars, which have sufficiently long lifetimes, can be found if they have formed at all," he said.
Such stars would be difficult to detect. According to Bromm, their radiation would have been shifted by the expanding universe into the near-infrared wavelength, which requires sensitive space-based detectors.
"This is one of the main targets for [NASA's] James Webb Space Telescope (JWST), planned for launch in 2018," Bromm said.
More massive stars, such as the one that preceded SDS J10018, would be short-lived, so scientists would have to search back to the early universe. Because distance and time are related — observing a star that is 13 billion years old requires looking out a distance of 13 billion light-years — the search would require a massive and extraordinarily sensitive telescope, such as the upcoming Thirty-Meter Telescope and the Giant Magellan Telescope.
In addition to detecting early stars, JWST should also be able to detect the supernovas that mark the end of their lifetimes, Bromm said.
Detecting the material left behind would be more difficult. Due to their low content of heavy metals, early supermassive stars experienced a different type of supernova than stars do today. Those huge stars that undergo the standard core collapse supernova explosion would leave behind enormous black holes that could have formed the seeds of the supermassive black holes that lie at the centers of galaxies. These black holes, along with the neutron stars that could have also formed, would be a challenge to detect.
Aoki expects to continue detailed studies of the evolution and explosion of extremely massive stars.
Five-step guide to diversification
One of the principle tenets of spreading risk in your portfolio is to diversify your investments. Diversification is the process of investing in areas that have little or no relation to each other. This is called a low correlation.
You can also invest in assets that have a negative correlation. This means that the assets will move in opposite directions to each other.
Diversifying your assets helps spread risk because you're lessening the potential for losses. If you had all of your money invested in one asset, sector, or region and it began to drop in value, your investments would suffer.
By investing in assets that aren’t related to each other, while one part of your investment portfolio is falling in value, the others aren’t going the same way. Some assets will actually go up in value when others decrease.
You can diversify through investing in different markets, countries, companies and asset type.
Diversification is an essential part of building your investment portfolio. It can give you peace of mind that your investments will sustain in adverse market conditions and cushion losses. But it will not lessen all types of risk.
Diversification helps lessen what’s known as unsystematic risk, like drops in the value of certain investment sectors, regions or asset types in general. But there are some events and risks that diversification cannot help with, or systemic risks. These include interest rates, inflation, wars and recession. This is important to remember when building your portfolio.
Here are the five main ways you can diversify your portfolio:
Step 1: Assets
Having a mix off different asset types will spread risk because their movements are either unrelated or inversely related to each other. It’s the old adage of not putting all your eggs in one basket.
Probably the best example of this is shares, or equities, and bonds. Equities are riskier than bonds, and can provide growth in your portfolio, but, traditionally, when the value of shares begins to fall bonds begin to rise, and vice versa.
Therefore, if you mix your portfolio between equities and bonds, you're spreading the risk as when one drops the other will rise to cushion your losses. Other asset types, like property and commodities, move independently of each other and investment in these areas can spread further.
Step 2: Sector
Say you held shares in a UK bank in 2006. This investment may have been very rewarding, so you decide to buy more shares in other banks. When the credit crunch hit the following year sparking the banking crisis, the value of your shares in this sector (financials) would have tumbled.
Once you've decided on the assets you want in your portfolio, you can diversify further by investing in different sectors, preferably those that aren’t related to each other.
If the healthcare sector takes a downturn, this will not necessarily have an impact on the precious metals sector. This helps to make sure your portfolio is protected from dips in certain industries.
Step 3: Geography
Investing in different regions and countries can reduce the impact of stock market movements. This means you're not just affected by the economic conditions of one country and one government’s fiscal policies.
Many markets are not correlated with each other - if the Asian Pacific stock markets perform poorly, it doesn’t necessarily mean that the UK’s market will be negatively affected. By investing in different regions and areas, you're spreading the risk that comes from the markets.
However, you need to be aware that diversifying in different geographical regions can add extra risk to your investment.
Developed markets like the UK and US are not as volatile as some of those in the Far East, Middle East or Africa. Investing abroad can help you diversify, but you need to be comfortable with the levels of risk that come with them.
Step 4: Company
Don’t just invest in one company. It might hit bad times or even go bust. Spread your investments across a range of different companies.
The same can be said for bonds and property. One of the best ways to do this is via a collective investment scheme. They will invest in a basket of different shares, bonds, properties or currencies to spread risk around. In the case of equities, this might 40 to 60 shares in one country, stock market or sector.
With a bond fund, you might be invested in 200 different bonds. This will be much more cost effective than recreating it on your own and help diversify your portfolio.
Step 5: Beware of over diversification
Holding too many assets might be more detrimental to your portfolio than good. If you over diversify, you might not end up losing much money, but you may be holding back your capacity for growth as you’ll have such small proportions of your money in different investments to see much in the way of positive results.
It’s usually recommended that you hold up to 15-20 investments (be it shares, bonds or funds) as a maximum.
Lump sum or regular savings?
So you’ve figured out what you want your money to do, how long you want to invest for and how much you can afford to invest. But how you actually pay money into your investments could have a significant impact on the returns you receive.
The two main ways of investing your money is either as a lump sum (all of your savings are invested immediately) or through regular investment (typically through monthly contributions).
How you invest might depend on your circumstances and the affordability of investment, but also your attitude to risk.
If, for example, you're comfortable with risk and have conviction in your choices of investment, you may want to invest a lump sum.
However, if you don’t have enough put aside (most investment funds, for example, have a minimum lump sum investment of £1,000) or are cautious about piling everything in, you might prefer to drip feed your money on a regular basis.
Lump sum or regular – which is best?
Say you have £10,000 to invest. If you invest all of it straight into the stock market, your full amount of capital has the greatest potential for growth, as it’s immediately fully exposed to the market. The assets within which you invest, be it shares, bonds or units (in a unit trust), are bought at the same price and you can benefit from any price increases straight away.
If you drip feed your £10,000 investment on a regular basis, only some of your money will be earning investment returns in the early months and you won't get the access to the total growth you would if you were fully invested.
The potential downside of this is that you’re exposed to potential downward fluctuations in the market. So, if you invested all of your money in the FTSE 100 (the stock market index that tracks share performance of the top 100 companies in the UK), for example, and it dropped by 20%, your investment would follow suit.
Staying invested in the stock market over a long period gives you the opportunity for your money to recover – but this could take a long time and requires a lot of nerve and patience on your part as an investor.
You also have to think about market timing – are you investing at a peak or at a low? This can be hard for even professional investors to judge.
A way to steer around the fluctuations in price of markets or assets is to invest on a regular basis. This is technically known as ‘pound cost averaging.’
Pound cost averaging explained
This is the process of regularly investing the same amount, usually on a monthly basis, to smooth out the highs and lows of the market within which you’re invested. It’s also extremely useful as a means of tipping your toe in the water and monitoring your investments on a monthly basis if you’re a beginner or simply don't have an up front lump sum to invest.
The effect of pound cost averaging is that you're buying assets at different prices on a regular basis, rather than buying at just one price. And while riding out the movements of the market, you could also end up better off than if you invested with a lump sum.
Let’s look at this in practice. If you invested a £10,000 lump sum and bought shares valued at £10 each, you'd have 1,000 shares. Now, if you bought £500 worth of shares per month over 18 months (amounting to £10,000 overall all), you would buy 50 shares in the first month.
But if the share price went down to £9.50 in the second month, you'd be able to buy 52 shares, as the shares are at a lower price. Therefore, rather than your full £10,000 investment being affected by the drop in share price, only a small proportion of your money drops in value. After 18 months of movement in the share price, it might end back on £10.
If you invested with a lump sum, you'd still have the same amount of money and the same number of shares. But by regularly investing, you may end up with more shares and, consequently, some growth of your capital, despite the share price ending up the same as when you invested and investing the same amount.
However, it’s important to remember that you may not necessarily benefit this way using pound cost averaging. One potential downside of this is that if your investments continuously grow, you'll be missing out on some of that growth as not all of your money has been invested over the whole period.
In fact, data from the Association of Investment Companies (AIC) shows that over the very long term (20 years), a lump sum investment of £12,000 has returned £86,000, while a £50 a month investment over the same period as returned £31,000. But if you’re nervous about the markets, or in a particularly volatile market, regular investment can help smooth out the market risk.
Combining the two
If you're confident in investing a lump sum in a particular asset or market, you could split some of your money between a full investment and regular contributions. If you decide to do this, make sure that the money you are holding back for regular investments is working as hard as possible for you in the mean time by keeping it a high-interest savings account that allows you to make regular withdrawals. You can find a Best Rate savings account using Which?’s unique Savings Booster tool.
Five tips to getting started as an investor
Through investment, you have a much greater potential for growth than by leaving your money in a savings account.
In the current economic climate, with interest rates so low and inflation rising, you could be losing out by keeping your money in a savings account because inflation is beating the return on interest rates and, therefore, the real spending power of your money is less.
Investment can enable you to match or even beat inflation and help you reach your long term financial goals. But it’s important to understand that in order to do this, you are introducing the risk of loss to your money.
When you invest, you encounter what is known as a risk/return pay off. Traditionally, the greater the risk you take with your money, the greater the potential for growth.
But with this comes an increased chance of losing your money. Before even considering investing your money, you need to be fully comfortable with introducing the potential for loss.
No investment is risk free and if you simply can’t reconcile that there are no guarantees with investment and that you could, potentially, lose some of your money, you are not ready to become an investor.
When making financial decisions, it’s important to consider the five steps below before you do anything with your money.
1) What are your financial goals?
Set a clear goal of what you want to achieve by investing. Are you just looking to grow your money? Are you looking to provide an income? Is there a set amount that you want your money to grow by or a minimum income that you need to be provided by your investments?
Having an idea of these will help you to decide how much risk you need to take to reach your goals. You may not have a particular reason to invest or it might be open ended, but try to ascertain exactly what you want your money to do.
2) What’s your time frame?
Once you know what your goals are, work out how long you need to achieve them. This will give you a clear idea of the kind of rates of return that you’ll need from your investments and whether or not your goals are realistic.
Factors like your age and health are important to consider. If you have short-term goals (less than five years) you should stick to cash savings. A Best Rate cash Isa is perfect for this but don’t invest – if your investment falls you might not have time to recover your losses before you need the money. Check out how to find the best cash Isa,
Medium (five to 10 years) and long-term goals (10 years or more) are appropriate for investment, but some investments become less appropriate the older you get. You have less time for your money to recover if it falls in value and, if you’re retired, your capacity to earn is diminished.
3) Understand your attitude to risk
Understanding the risks you'll encounter through investment and how much risk you think you're willing to take could have an impact on the length of time you want to invest and, indeed, your financial goals.
If you want your money to grow significantly over a shorter time period, you may have to invest in riskier assets to achieve that growth – but if the potential downsides are too much, you may have to realign your goals. Read our guide to understanding investment risk to learn more about your attitude to risk.
4) How much can you afford to invest?
Be realistic about how much you can afford to invest. Assess all of your liabilities, like debts, insurance premiums, pension contributions, savings and living costs, to see how much spare cash you have to invest.
Remember that investment is long term and you should avoid having to access the money you're investing, as it may not reach its full potential if you do.
5) Seek financial advice
Only those who have knowledge of the markets and strong financial sense should really be managing their investments on their own.
By seeking financial advice, you'll be able to talk through all the points raised above and ensure that your investments are tailored exactly to your needs. Read our guide to choosing a financial adviser for the best ways to get investment advice.
Are you ready to invest?
Taking the decision to begin investing your money is a big step. Many of you are doing so in order to increase the capital value of your money or to get an income and maintain the level of your savings.
Investment means introducing risk to your money. This is not necessarily a bad thing, as increased risk can help you grow your cash. But, conversely, there is the possibility that you could lose some, or all, of your money.
There are four key activities that you must undertake before considering investing your money:
1) Sort out your debt
It's imperative to ensure that your debts are under control before considering investment. Debt is generally much more expensive to service than the returns you'll get from investments and large debt repayments may stop you from reaching your financial goals.
Additionally, if you do lose money by investing, you risk defaulting on your debt repayments. Focus on reducing debt to levels that you're comfortable to manage or, ideally, pay off all debt before investing. Read our guide to dealing with debt for more information.
2) Get protected
Make sure your finances are protected if you cannot work due to illness for an extended period of time. Check your sick pay scheme at work to see how long you would be covered for and consider taking out income protection insurance if you are self employed.
Other insurance, like critical illness cover if you become seriously ill, could also be an option if you have a mortgage or dependents, although this can be expensive.
In addition to this, life insurance is an essential item you need to take out before thinking of investment, especially if you have a family. Your work may offer a death in service benefit, but consider an additional policy, in case you change jobs or are out of work.
Find out more in our guide How to buy life insurance.
3) Think about retirement
One of the biggest problems in the UK is that people are not saving enough for their retirement. Relying on the state to provide a pension for you in older age may not be enough to maintain the lifestyle you have now or leave you comfortable in retirement.
It's vital that you start saving for your later years as early as possible. Make sure you're contributing to your employee pension scheme or a private pension before investing any spare cash – pension savers benefit from employer contributions and generous tax breaks.
4) Make sure you’ve got savings
Have you got spare cash to fall back on? Before introducing risk to your money, you need some core savings as an emergency fund for those unseen events.
The generally accepted rule is to have three months' salary in savings before you invest. And make sure that these savings are in a high-rate savings account, by using our unique Which? Savings Booster tool.
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