Archive for the ‘Interesting Sites’ Category

More Planets Could Harbour Life

Posted: September 11, 2012 in Interesting Sites

 

 

More planets could harbour life….

 

By Jonathan Ball BBC News

 

Exoplanet   ESO/L. Calçada Scientists should not exclude planets that reside in colder regions

 

 

New computer models suggest there could be many more habitable planets out there than previously thought.

 

Scientists have developed models to help them identify planets in far-away solar systems that are capable of supporting life.

 

Estimates of habitable planet numbers have been based on the likelihood of them having surface water.

 

But a new model allows scientists to identify planets with underground water kept liquid by planetary heat.

 

The research was presented at the British Science Festival in Aberdeen.

 

Water is fundamental for life as we know it.

 

Planets too close to their sun lose surface water to the atmosphere through evaporation.

 

Surface water on planets located in the more frigid distant reaches from their sun is locked away as ice.

 

The dogma was, for water to exist in its life-giving liquid form, a planet had to be the right distance from its sun – in the habitable zone.

 

As Sean McMahon, the PhD student from Aberdeen University who is carrying out the work explained: “It’s the idea of a range of distances from a star within which the surface of an Earth-like planet is not too hot or too cold for water to be liquid.

 

“So traditionally people have said that if a planet is in this Goldilocks zone – not too hot and not too cold – then it can have liquid water on its surface and be a habitable planet”

 

But researchers are starting to think that the Goldilocks theory is far too simple.

 

Continue reading the main story

Planetary heat

Infographic

• A planet is warmed by two sources of heat – solar energy and internal heat

• The further away a planet is from its sun the less energy it receives and surface water freezes

• As the distance increases underground water also starts to freeze

• But if the planet is large enough and produces enough internal heat, it could still contain deep reservoirs of liquid water capable of supporting life, no matter how far away from the sun

 

Planets can receive two sources of heat – heat direct from the star and heat generated deep inside the planet.

 

As you descend through the crust of the Earth, the temperature gets higher and higher. Even when the surface is frozen, water can exist below ground.

 

Immense quantities of water in fact – teeming with primitive life.

 

As Prof John Parnell, also from Aberdeen University, who is leading the study, said: “There is a significant habitat for microorganisms below the surface of the Earth, extending down several kilometres.

 

“And some workers believe that the bulk of life on Earth could even reside in this deep biosphere.”

 

So the Aberdeen team are developing models to predict which far-flung planets might harbour underground reservoirs of liquid water with the possibility of alien life.

 

Explaining their rationale, Mr McMahon said: “If you take into account the possibility of deep biospheres, then you have a problem reconciling that with the idea of a narrow habitable zone defined only by conditions at the surface.”

 

As you move away from the star the amount of heat a planet receives from the star decreases and the surface water freezes – but any water held deep inside will stay liquid if the internal heat is high enough – and that water could support life.

 

Even a planet so far from the star that it receives almost no solar heat could still maintain underground liquid water.

 

According to Mr McMahon, “There will be several times more [habitable] planets”.

 

 

 

 

Wise telescope data
Wise has been able to see objects not visible to past science instruments

A space telescope has added to its list of spectacular finds, spotting millions of supermassive black holes and blisteringly hot, “extreme” galaxies.

The finds, by US space agency Nasa’s Wide-Field Infrared Survey Explorer (Wise), once lay obscured behind dust.

But Wise can see in wavelengths correlated with heat, seeing for the first time some of the brightest objects in the Universe.

The haul will help astronomers work out how galaxies and black holes form.

It is known that most large galaxies host black holes at their centres, sometimes feeding on nearby gas, dust and stars and sometimes spraying out enough energy to halt star formation altogether.

How the two evolve together has remained a mystery, and the Wise data are already yielding some surprises.

Wise gives astronomers what is currently a unique view on the cosmos, looking at wavelengths of light far beyond those we can see but giving information that we cannot get from wavelengths we can.

Continue reading the main story

Black holes

Artist's depiction of black hole
  • These are regions of space where gravity is so powerful that not even light can escape
  • One way they can form is when huge stars collapse in on themselves
  • So-called supermassive black holes sit at the centres of galaxies, including the Milky Way

Among its other discoveries, in 2011 Wise spotted in a “Trojan” asteroid ahead of the Earth in its orbit.

But with the latest results, Wise has come into its own as an unparalleled black hole hunter.

“We’ve got the black holes cornered,” said Daniel Stern of Nasa’s Jet Propulsion Laboratory (JPL), lead author of one of the three studies presented on Wednesday.

Dr Stern and his colleagues used the Nuclear Spectroscopic Telescope Array (Nustar) space telescope to examine the X-rays coming out of the black hole candidates spotted by Wise, presenting their findings in a paper to appear in Astrophysical Journal.

“Wise is finding them across the full sky, while Nustar is giving us an entirely new look at their high-energy X-ray light and learning what makes them tick,” he said.

The other two studies presented – one already published in Astrophysical journal and another yet to appear – focussed on extremely hot, bright galaxies that have until now remained hidden: hot dust-obscured galaxies, or hot-Dogs.

There are so far about 1,000 candidate galaxies, some of which can out-shine our Sun by a factor of 100 trillion.

“These dusty, cataclysmically forming galaxies are so rare Wise had to scan the entire sky to find them,” said Peter Eisenhardt of JPL, lead author of the paper describing Wise’s first hot-Dog find.

“We are also seeing evidence that these record-setters may have formed their black holes before the bulk of their stars. The ‘eggs’ may have come before the ‘chickens’.”

The data from the Wise mission are made publicly available so that scientists outside the collaboration can also carry out their own studies, so the future will hold a wealth of studies from these extreme and otherwise hidden corners of the Universe.

Nasa sky probe sends back images
Trojan rock seen in Earth’s orbit
Huge cloud heading for black hole

A space telescope has added to its list of spectacular finds, spotting millions of supermassive black holes and blisteringly hot, “extreme” galaxies.

The finds, by US space agency Nasa’s Wide-Field Infrared Survey Explorer (Wise), once lay obscured behind dust.

But Wise can see in wavelengths correlated with heat, seeing for the first time some of the brightest objects in the Universe.

The haul will help astronomers work out how galaxies and black holes form.

It is known that most large galaxies host black holes at their centres, sometimes feeding on nearby gas, dust and stars and sometimes spraying out enough energy to halt star formation altogether.

How the two evolve together has remained a mystery, and the Wise data are already yielding some surprises.

Wise gives astronomers what is currently a unique view on the cosmos, looking at wavelengths of light far beyond those we can see but giving information that we cannot get from wavelengths we can.
Continue reading the main story
Black holes
Artist’s depiction of black hole

These are regions of space where gravity is so powerful that not even light can escape
One way they can form is when huge stars collapse in on themselves
So-called supermassive black holes sit at the centres of galaxies, including the Milky Way

Brian Cox on what happens near black holes

Among its other discoveries, in 2011 Wise spotted in a “Trojan” asteroid ahead of the Earth in its orbit.

But with the latest results, Wise has come into its own as an unparalleled black hole hunter.

“We’ve got the black holes cornered,” said Daniel Stern of Nasa’s Jet Propulsion Laboratory (JPL), lead author of one of the three studies presented on Wednesday.

Dr Stern and his colleagues used the Nuclear Spectroscopic Telescope Array (Nustar) space telescope to examine the X-rays coming out of the black hole candidates spotted by Wise, presenting their findings in a paper to appear in Astrophysical Journal.

“Wise is finding them across the full sky, while Nustar is giving us an entirely new look at their high-energy X-ray light and learning what makes them tick,” he said.

The other two studies presented – one already published in Astrophysical journal and another yet to appear – focussed on extremely hot, bright galaxies that have until now remained hidden: hot dust-obscured galaxies, or hot-Dogs.

There are so far about 1,000 candidate galaxies, some of which can out-shine our Sun by a factor of 100 trillion.

“These dusty, cataclysmically forming galaxies are so rare Wise had to scan the entire sky to find them,” said Peter Eisenhardt of JPL, lead author of the paper describing Wise’s first hot-Dog find.

“We are also seeing evidence that these record-setters may have formed their black holes before the bulk of their stars. The ‘eggs’ may have come before the ‘chickens’.”

The data from the Wise mission are made publicly available so that scientists outside the collaboration can also carry out their own studies, so the future will hold a wealth of studies from these extreme and otherwise hidden corners of the Universe.