Cidersomerset
7th November 2014, 22:03
http://news.sciencemag.org/sites/all/themes/news_interim/img/logo-science-aaas.svg
Rogue stars outside galaxies may be everywhere
http://news.sciencemag.org/sites/default/files/styles/thumb_article_l/public/sn-galaxies.jpg
NASA/ESA/Hubble Heritage Team
Do merging galaxies, like this pair called Arp 142, spew stars out into intergalactic space?
Daniel is a deputy news editor for Science.
Email Daniel
By Daniel Clery 6 November 2014 4:45 pm 1 Comment
You’ve heard of rogue planets, floating through the universe untethered to any solar
system. Now meet rogue stars, which drift through space with no galaxy to call home. A
new study has come to the startling conclusion that as many as half of all stars in the
universe may be rogue, having been ejected from their birthplaces by galaxy collisions
or mergers.
http://news.sciencemag.org/space/2014/11/rogue-stars-outside-galaxies-may-be-everywhere
=====================================================
http://static.bbci.co.uk/frameworks/barlesque/2.75.0/desktop/3.5/img/blq-blocks_grey_alpha.png
6 November 2014 Last updated at 20:02
Background light suggests many stars 'outside galaxies'By Jonathan Webb
Science reporter, BBC News
http://news.bbcimg.co.uk/media/images/78801000/jpg/_78801540_c0115179-colliding_galaxies,_space_telescope_image-spl.jpg
colliding galaxies Collisions and mergers can strip stars out of galaxies
A new study of the universe's background light has suggested that as many as half its
stars might be hidden in the space between galaxies.
Measurements were made by two cameras sent beyond the atmosphere on a rocket.
After subtracting all the interference from dust and galaxies, the leftover light has
ripples in it, which the study's authors ascribe to lone stars, flung out during galactic collisions.
Other scientists believe it comes from whole galaxies that are very distant.
The new results are published in the journal Science.
Jet Propulsion Laboratory
Prof Jamie Bock from Nasa's Jet Propulsion Laboratory, one of the report's authors,
described the extragalactic background light (EBL) as "kind of a cosmic glow".
"It's very faint - but basically the spaces between the stars and galaxies aren't
dark. And this is the total light made by stars and galaxies during cosmic history,"
Prof Bock told the BBC.
Earlier measurements from rockets and satellites had shown that there was more
fluctuation in this background than the sum total of known galaxies could explain.
At least two proposals were made to account for the extra light: it might come from
very early, distant galaxies that formed when the universe was much younger, or it
might come from stray stars outside galactic boundaries.
Prof Bock's team set out to study the EBL in detail, in terms of its colour and its
distribution, to try and settle the debate.
http://news.bbcimg.co.uk/media/images/78801000/jpg/_78801545_4.jpg
CIBER rocket The cameras were taken to sub-orbital space on a sounding rocket
Checking it twice
Two rocket flights were used to collect the data, in 2010 and 2012, as part of an
experiment dubbed CIBER: the cosmic infrared background experiment.
On each 10-minute flight, a 10m (30ft) sounding rocket travelled briefly beyond the
Earth's atmosphere and two infra-red cameras took wide-angle images of the sky.
Doing the measurements twice allowed the researchers to rule out fluctuations
coming from the dust within our own solar system.
"[On the second flight] we're looking through a completely different patch of the
solar system, and we see the same signal," Prof Bock explained.
"It's been really nice to have multiple flights, so we can do all these checks."
Once all the non-background light, such as galaxies themselves, was discarded
- "you kind of surgically remove them" from the images, Prof Bock said - the team
was left with a clean picture of the EBL.
University of Oxford
The brightness and the blueness of the light in that picture, they claim, support the
idea that it comes from stars stripped of their galaxies.
"It's inconsistent with [the light coming from] the very first galaxies, because it
would look a lot redder," Prof Bock said.
The report also says there is so much light in the recordings that there might be
just as many stars outside galaxies as inside them.
"Astronomers know this stripping happens, but we're saying it's much more
prevalent."
'Perfectly possible'
Other researchers are less certain of the data's implications.
Jo Dunkley, a professor of astrophysics at the University of Oxford, said she did not
think the evidence for vast numbers of lonely stars was compelling - "though it
would obviously be really interesting if it were".
"This is a big question in astronomers' minds, because we can't assign all the light
we see to galaxies we know," Prof Dunkley told BBC News. "So where is all the rest
of it coming from?"
She said that the work represented "a really nice measurement" and agreed that
the reported background light probably could not have come from the very earliest
galaxies - but argued that there is much still to know about those galaxies, and the
ones that followed soon after.
"There's so many galaxies out there, very faint galaxies, very far away, and I don't
we've got a full census of those yet."
http://news.bbcimg.co.uk/media/images/78801000/jpg/_78801543_c0224706-zodiacal_light-spl.jpg
zodiacal light To measure EBL, things like zodiacal light (caused by dust in our solar
system) must first be substracted Prof Steve Eales, an astronomer at Cardiff
University, was also cautious about the findings.
"When you see a result like this, you never say 'well yes that's obviously right'," he said.
Prof Eales said the JPL team's interpretation - and their conclusion about
extragalactic stars - was "perfectly possible" but that corroborating evidence would
be needed.
If so many stars exist outside galaxies, he explained, you might expect to find more
examples in between the galaxies closer to our own.
"But the problem is, once single stars move away, they're very hard to see.
"There's nothing to rule out the possibility but there's probably no other evidence
yet that they exist."
Prof Bock acknowledged that his findings would probably not meet with universal
acclaim.
"We have to hear how other people react to it," he said.
http://www.bbc.co.uk/news/science-environment-29917082
=====================================================
http://www.scientificamerican.com/sciam/includes/themes/sciam/images/logo.jpg
Half of Stars Lurk Outside Galaxies
A rocket experiment has captured the glow attributed to renegade stars in intergalactic space
November 7, 2014 |By Alexandra Witze and Nature magazine
http://www.scientificamerican.com/sciam/cache/file/0B46B455-8A77-477F-84698F697B3FB093_article.jpg
Collisions between galaxies can kick stars out into intergalactic space.
Credit: NASA ESA/Hubble SM4 ERO Team
Astronomers have spotted a faint cosmic glow, unseen until now, that may come from
stars that float adrift between galaxies. The discovery suggests that as many as half of
all stars in the Universe lurk outside galactic boundaries.
“There might be people living out there, out in the middle of cold dark space, that don't
have a Milky Way,” says Harvey Moseley, an astrophysicist at NASA's Goddard Space
Flight Center in Greenbelt, Maryland.
The stars were probably tossed there when galaxies collided. A team led by
astrophysicist Michael Zemcov, of the California Institute of Technology (Caltech) in
Pasadena, reports the discovery in the November 7 issue of Science.
http://www.scientificamerican.com/article/half-of-stars-lurk-outside-galaxies/
Rogue stars outside galaxies may be everywhere
http://news.sciencemag.org/sites/default/files/styles/thumb_article_l/public/sn-galaxies.jpg
NASA/ESA/Hubble Heritage Team
Do merging galaxies, like this pair called Arp 142, spew stars out into intergalactic space?
Daniel is a deputy news editor for Science.
Email Daniel
By Daniel Clery 6 November 2014 4:45 pm 1 Comment
You’ve heard of rogue planets, floating through the universe untethered to any solar
system. Now meet rogue stars, which drift through space with no galaxy to call home. A
new study has come to the startling conclusion that as many as half of all stars in the
universe may be rogue, having been ejected from their birthplaces by galaxy collisions
or mergers.
http://news.sciencemag.org/space/2014/11/rogue-stars-outside-galaxies-may-be-everywhere
=====================================================
http://static.bbci.co.uk/frameworks/barlesque/2.75.0/desktop/3.5/img/blq-blocks_grey_alpha.png
6 November 2014 Last updated at 20:02
Background light suggests many stars 'outside galaxies'By Jonathan Webb
Science reporter, BBC News
http://news.bbcimg.co.uk/media/images/78801000/jpg/_78801540_c0115179-colliding_galaxies,_space_telescope_image-spl.jpg
colliding galaxies Collisions and mergers can strip stars out of galaxies
A new study of the universe's background light has suggested that as many as half its
stars might be hidden in the space between galaxies.
Measurements were made by two cameras sent beyond the atmosphere on a rocket.
After subtracting all the interference from dust and galaxies, the leftover light has
ripples in it, which the study's authors ascribe to lone stars, flung out during galactic collisions.
Other scientists believe it comes from whole galaxies that are very distant.
The new results are published in the journal Science.
Jet Propulsion Laboratory
Prof Jamie Bock from Nasa's Jet Propulsion Laboratory, one of the report's authors,
described the extragalactic background light (EBL) as "kind of a cosmic glow".
"It's very faint - but basically the spaces between the stars and galaxies aren't
dark. And this is the total light made by stars and galaxies during cosmic history,"
Prof Bock told the BBC.
Earlier measurements from rockets and satellites had shown that there was more
fluctuation in this background than the sum total of known galaxies could explain.
At least two proposals were made to account for the extra light: it might come from
very early, distant galaxies that formed when the universe was much younger, or it
might come from stray stars outside galactic boundaries.
Prof Bock's team set out to study the EBL in detail, in terms of its colour and its
distribution, to try and settle the debate.
http://news.bbcimg.co.uk/media/images/78801000/jpg/_78801545_4.jpg
CIBER rocket The cameras were taken to sub-orbital space on a sounding rocket
Checking it twice
Two rocket flights were used to collect the data, in 2010 and 2012, as part of an
experiment dubbed CIBER: the cosmic infrared background experiment.
On each 10-minute flight, a 10m (30ft) sounding rocket travelled briefly beyond the
Earth's atmosphere and two infra-red cameras took wide-angle images of the sky.
Doing the measurements twice allowed the researchers to rule out fluctuations
coming from the dust within our own solar system.
"[On the second flight] we're looking through a completely different patch of the
solar system, and we see the same signal," Prof Bock explained.
"It's been really nice to have multiple flights, so we can do all these checks."
Once all the non-background light, such as galaxies themselves, was discarded
- "you kind of surgically remove them" from the images, Prof Bock said - the team
was left with a clean picture of the EBL.
University of Oxford
The brightness and the blueness of the light in that picture, they claim, support the
idea that it comes from stars stripped of their galaxies.
"It's inconsistent with [the light coming from] the very first galaxies, because it
would look a lot redder," Prof Bock said.
The report also says there is so much light in the recordings that there might be
just as many stars outside galaxies as inside them.
"Astronomers know this stripping happens, but we're saying it's much more
prevalent."
'Perfectly possible'
Other researchers are less certain of the data's implications.
Jo Dunkley, a professor of astrophysics at the University of Oxford, said she did not
think the evidence for vast numbers of lonely stars was compelling - "though it
would obviously be really interesting if it were".
"This is a big question in astronomers' minds, because we can't assign all the light
we see to galaxies we know," Prof Dunkley told BBC News. "So where is all the rest
of it coming from?"
She said that the work represented "a really nice measurement" and agreed that
the reported background light probably could not have come from the very earliest
galaxies - but argued that there is much still to know about those galaxies, and the
ones that followed soon after.
"There's so many galaxies out there, very faint galaxies, very far away, and I don't
we've got a full census of those yet."
http://news.bbcimg.co.uk/media/images/78801000/jpg/_78801543_c0224706-zodiacal_light-spl.jpg
zodiacal light To measure EBL, things like zodiacal light (caused by dust in our solar
system) must first be substracted Prof Steve Eales, an astronomer at Cardiff
University, was also cautious about the findings.
"When you see a result like this, you never say 'well yes that's obviously right'," he said.
Prof Eales said the JPL team's interpretation - and their conclusion about
extragalactic stars - was "perfectly possible" but that corroborating evidence would
be needed.
If so many stars exist outside galaxies, he explained, you might expect to find more
examples in between the galaxies closer to our own.
"But the problem is, once single stars move away, they're very hard to see.
"There's nothing to rule out the possibility but there's probably no other evidence
yet that they exist."
Prof Bock acknowledged that his findings would probably not meet with universal
acclaim.
"We have to hear how other people react to it," he said.
http://www.bbc.co.uk/news/science-environment-29917082
=====================================================
http://www.scientificamerican.com/sciam/includes/themes/sciam/images/logo.jpg
Half of Stars Lurk Outside Galaxies
A rocket experiment has captured the glow attributed to renegade stars in intergalactic space
November 7, 2014 |By Alexandra Witze and Nature magazine
http://www.scientificamerican.com/sciam/cache/file/0B46B455-8A77-477F-84698F697B3FB093_article.jpg
Collisions between galaxies can kick stars out into intergalactic space.
Credit: NASA ESA/Hubble SM4 ERO Team
Astronomers have spotted a faint cosmic glow, unseen until now, that may come from
stars that float adrift between galaxies. The discovery suggests that as many as half of
all stars in the Universe lurk outside galactic boundaries.
“There might be people living out there, out in the middle of cold dark space, that don't
have a Milky Way,” says Harvey Moseley, an astrophysicist at NASA's Goddard Space
Flight Center in Greenbelt, Maryland.
The stars were probably tossed there when galaxies collided. A team led by
astrophysicist Michael Zemcov, of the California Institute of Technology (Caltech) in
Pasadena, reports the discovery in the November 7 issue of Science.
http://www.scientificamerican.com/article/half-of-stars-lurk-outside-galaxies/