Amazing answers to your curious questions

Just how big can stars get?

In 2005, studies conducted by NASA using the Hubble Space Telescope showed astronomers that stars have an upper limit of about 150 times the mass of the Sun. Hubble was used to measure stars in the Arches Cluster, which is the densest group of stars found in the Milky Way and is about 25,000 light years away.

Expecting to find as many as 30 stars with masses up to 1,000 times the Sun’s mass, astronomers were surprised to find that the largest ones were only about 130 solar masses. One theory is that the intense radiation from large stars blows them apart – if a star is 100 times the solar mass, that means it burns about a million times brighter than the Sun. However, the star R136a1 was found in 2010 in the R136 star cluster, around 163,000 light years away, which was 250 times the mass and 5 million times brighter than our Sun. So while we’re still unsure exactly what the upper limit is, there’s little doubt that there is one.

HOW DOES ANTI-VIRUS SOFTWARE WORK?

Anti-virus programs typically employ two methods to detect and eradicate their digital nemesis. The first is to check known virus signatures against a database, engineering a fix that directly matches the bug. Most anti-viral software relies on this method, drawing on the internet for its effectiveness by constantly updating the ‘wild list’ of known viruses, allowing patches to be developed and downloaded into your anti-virus database to keep it up to date.

The second method is simply to think like the virus coders, looking out for weaknesses in existing programs and then staking them out. Working closely with software manufacturers, anti-virus software coders can detect when a known program is behaving strangely, alerting everyone to a potential threat before developing an antidote.

WHAT ARE ROOT CANALS?

Although they seem pretty solid, our teeth are hollow inside, all the way to the roots. The core is filled with nerves, blood vessels and a connective tissue called dental pulp. In the actual tooth, this space is known as the coronal chamber, but when you get down to the roots they’re called canals. The blood vessels run through the centres like graphite in a pencil. A ‘root canal’ is also used to describe a dental procedure in which the pulp and other tissues are removed and replaced with a filler. This is usually done when the tooth is severely infected: while considered ‘dead’, the tooth can at least be preserved.