All Things Space / Science / Technology

Neat. Scary... but neat.

Astronomers solve mystery of the universe’s missing stars

There are not enough stars in the universe and now astronomers think they know why.

Using the Hubble space telescope, they have discovered a distant galaxy in which star formation is itself driving the raw materials for more stars out into space at two million miles per hour – and in the process slowing future star production.

They believe the discovery could explain why the number of stars in space is lower than expected.

The astronomer Carl Sagan memorably said there were more stars in the universe than grains of sand on all the beaches in the world. That estimate has been refined more recently to 10 stars for every grain – or roughly one hundred thousand million million million, or 100 sextillion, stars. Yet not even this vast figure is enough for modern astronomers.

“We’ve known for about 10-15 years that there are not as many stars in the universe as we expect,” says Dr James Geach, of the University of Hertfordshire.

Stars form when clouds of gas are pulled together by the force of gravity. But computer simulations of this process always overestimate the number of stars that astronomers can observe. There should be double or even triple the number of stars in the night sky.

Now, Geach and his colleagues think they have discovered what astronomers have been missing.

They have found a distant galaxy known as a starburst 10bn light years away that is furiously forming stars at 260 times the rate of our own Milky Way. The torrents of radiation created by the celestial newborns are driving out the remaining gas. As this raw material is blasted away into deep space, the rate of formation will slow and eventually come to a halt.

“We are witnessing the aggressive termination of star formation,” said Geach.

The more stars that form, the more pressure their starlight creates, driving out more gas and preventing rapid star formation.

This is the first time this process has been seen driven solely by the action of star formation itself. Usually it is associated with the action of an active black hole at the centre of a galaxy. However, there is no signature of an active black hole in this galaxy. The study is published in the journal Nature.

In the nearby universe, many galaxies have stopped forming stars altogether. “Something must have cleared the gas out of these galaxies,” said Philip Best, professor of extragalactic astronomy at the University of Edinburgh, who was not involved in the study.

It is not just individual stars that can fall victim to this process. In its most extreme form, astronomers think that it could even blow small galaxies apart, explaining why there are ten to a hundred times fewer dwarf galaxies than expected.

Geach says his team’s observation, published in the journal Nature, is “an important new clue in our understanding of the evolution of galaxies”.

www.theguardian.com/science/2014/dec/03/astronomers-mystery-universe-missing-stars?CMP=share_btn_tw

No skimming this time, Knerys.

Hey I don't skim! I started reading and kept getting interrupted by work things and it was becoming a losing battle. So I saved it for later.

I have nothing to prove to you. 

     

"the phases of Jibbs' untimely demise"

Two planets as big as Earth ‘could be on edge of solar system’

Scientists say belt of space rocks known as ‘extreme trans-Neptunian objects’ appear to be influenced by gravitational pull

At least two as-yet undiscovered planets as big as Earth or larger may be hiding in the outer fringes of the solar system, scientists believe.

The secret worlds are thought to exist beyond the orbits of Neptune, the furthest true planet from the Sun, and the even more distant tiny “dwarf planet” Pluto.

The evidence comes from observations of a belt of space rocks known as “extreme trans-Neptunian objects” (Etnos).

Orbiting the Sun beyond Neptune, Etnos should be distributed randomly with paths that have certain defined characteristics. But a dozen of the bodies have completely unexpected orbital values consistent with them being influenced by the gravitational pull of something unseen.

Spanish lead scientist Professor Carlos de la Fuente Marcos, from the Complutense University of Madrid, quoted by the Spanish scientific news service, Sinc, said: “This excess of objects with unexpected orbital parameters makes us believe that some invisible forces are altering the distribution of the orbital elements of the Etno, and we consider that the most probable explanation is that other unknown planets exist beyond Neptune and Pluto.

“The exact number is uncertain, given that the data that we have is limited, but our calculations suggest that there are at least two planets, and probably more, within the confines of our solar system.”

Astronomers have spent decades debating whether a hidden planet beyond Pluto remained undiscovered.

The new research, published in the journal Monthly Notices of the Royal Astronomical Society Letters, is based on analysis of an effect called the “Kozai mechanism”, by which a large body disturbs the orbit of a smaller and more distant object.

The scientists wrote: “In this scenario, a population of stable asteroids may be shepherded by a distant, undiscovered planet larger than the Earth …”

One problem is that the theory goes against predictions of computer simulations of the formation of the solar system, which state there are no other planets moving in circular orbits beyond Neptune. But the recent discovery of a planet-forming disk of dust and gas more than 100 astronomical units (AU) from the star HL Tauri suggests planets can form long distances away from the centre of a solar system.

An astronomical unit, the distance between the Earth and the Sun, is the equivalent of 93 million miles.

More results based on a larger sample of Etno objects are due to be published in the coming months.

“If it is confirmed, our results may be truly revolutionary for astronomy,” said Prof De La Fuente Marcos.

www.theguardian.com/science/2015/jan/18/two-undiscovered-planets-earth-solar-system