Advance in astronomy 'can help find other worlds'

The pull of gravity on a distant star can now be measured more accurately, shedding light on other worlds, say astronomers.

The method makes it possible to study even the faintest of stars.

"Our technique can tell you how big and bright is the star, and if a planet around it is the right size and temperature to have water oceans, and maybe life," said Prof Jaymie Matthews.

The findings appear in the journal, Science Advances.

Surface gravity is the intensity of the force that pulls everything on the surface of a star or celestial body towards the centre.

It is usually calculated by measuring a star's light or brightness - but this only works well for the closest, brightest stars.

A team led by Thomas Kallinger of the University of Vienna used data from theKepler space telescope - which is searching for other worlds like the Earth - to show that variations in the brightness of distant stars can give more accurate measurements of surface gravity.

The timescale of turbulence and vibration at a star's surface, based on its brightness variations, tells you its surface gravity, say the researchers.

Future space missions will hunt for planets around distant stars that might be capable of harbouring liquid water oceans and perhaps life.

The method can be applied to data from these searches to help understand the nature of stars like our Sun and to help find other planets like our Earth, says Dr Kallinger.

Earth-sized world

Since surface gravity depends on the star's mass and radius, the method should also help astronomers work out the masses and sizes of distant stars - and any planets circulating around them.

"If you don't know the star, you don't know the planet," said co-researcher Prof Matthews of the University of British Columbia, Canada.

"The size of an exoplanet is measured relative to the size of its parent star.

"If you find a planet around a star that you think is Sun-like but is actually a giant, you may have fooled yourself into thinking you've found a habitable Earth-sized world. "

UK Iraq veterans 'may face prosecution'

UK soldiers who fought in the Iraq War may face prosecution for war crimes, according to the head of a unit investigating alleged abuses.

Mark Warwick said there were "lots of significant cases" and that discussions would be held over whether they met a war crimes threshold.

Lawyers are continuing to refer alleged abuse cases by soldiers to the Iraq Historic Allegations Team (IHAT).

The Ministry of Defence said it took such allegations "extremely seriously".

Two public inquiries have already looked at claims against UK troops in Iraq.

Mr Warwick, the former police detective in charge of IHAT, told the Independentthe allegations being investigated included ones of murder.

He added: "Over the next 12 to 18 months, we will review all the caseload to better understand the picture and then I think we can say whether 2019 seems realistic."

The inquiry has considered at least 1,515 possible victims, of whom 280 are alleged to have been unlawfully killed.

'Wholly unacceptable'

He said: "We would look at the credibility of the allegation in the first instance and, when we've looked at a lot of these extra cases coming to us, some of them are duplicates of cases, some of them we've already identified as part of our own investigation process, and some are multiple allegations, where we would investigate as a single allegation."

IHAT's budget of £57.2m runs until the end of 2019 - 16 years after the invasion of Iraq began in 2003.

BBC political correspondent Chris Mason said Mr Warwick's comments may have been a response to an interview by Michael Fallon in the Telegraph.

In it, the defence secretary said soldiers were inhibited on the battlefield because they feared "ambulance-chasing British law firms" would haul them in front of the courts on their return.

Carla Ferstman, director of the human rights charity Redress, also told the newspaper that the "incredibly slow pace" of IHAT's investigations was "wholly unacceptable".

He added: "Things seem to still be moving at a snail's pace. We call upon the government to ensure IHAT can, and does, do what it was set up to do, and to do it now. This cannot be a whitewash."

Colonel Richard Kemp, a former army commander in Afghanistan, agreed that the investigation needed to be completed urgently, but said it was "inconceivable" that that number of allegations against British troops could be legitimate.

"Of course one has to be concerned about these allegations, but the number, the sheer number, thousands of allegations made against British soldiers in Iraq, I just cannot believe that any significant number of them can be valid," he told BBC Radio 4's Today programme.

'Corporate failure'

A spokeswoman for the Ministry of Defence said most members of the armed forces behaved correctly.

She added: "The vast majority of UK service personnel deployed on military operations conduct themselves professionally and in accordance with the law.

"Where there is sufficient evidence, members of HM Forces can be prosecuted. It is estimated that the Ihat's work will take until the end of 2019."

An inquiry into claims of abuse by UK troops in Iraq highlighted the death of 26-year-old hotel worker Baha Mousa, who died in UK military custody in September 2003.

It concluded in September 2011, with inquiry chairman Sir William Gage blaming "corporate failure" at the Ministry of Defence for the use of banned interrogation methods in Iraq.

The Al-Sweady Inquiry, set up in 2009, followed allegations made in judicial review proceedings at the High Court that the human rights of several Iraqis were abused by British troops in the aftermath of a firefight with insurgents near the town of Majar al Kabir.

Inquiry chairman Sir Thayne Forbes said allegations that troops murdered and mutilated Iraqis in custody were "wholly without foundation". But he did conclude that some of the detention techniques had amounted to mistreatment.