...pari päivää sitten. Kyllä loksahtaa leuat auki vielä, kunhan saadaan tutkittua paremmin.
Tässä satunnaisia artikkeleita, elämä on maapallolla hiuskarvan varassa koko ajan.
Supernova poised to go off near Earth
* Supernova "smoking gun" linked to mass extinctions
* Astronomy, Harvard University
* Space Telescope Science Institute
* Harvard Smithsonian Center for Astrophysics
* Supernovae, NASA
A student at Harvard University has stumbled across the terrifying spectacle of a star in our galactic backyard
that is on the brink of exploding in a supernova.
It is so close that if it were to blow up before moving away from us, it could wipe out life on Earth.
Most supernovae occur when large stars run out of fuel and then collapse under their own weight.
As atoms in the star are squeezed together, they rebound outwards, blowing off energy in a dazzling and
dangerous display lasting several weeks.
But this one is different. Called HR 8210, it is a humble white dwarf,
a star that has run out of fuel and should be too small to produce a supernova.
But it may not stay that way. First, it is not alone, but is orbiting a companion star in a typical binary system.
And it is 1.15 times the mass of our Sun, which for a white dwarf is a whopper.
The system was first logged in 1993 but little attention was paid to it.
Then when Harvard student Karin Sandstrom investigated HR 8210 for a college paper this year,
she discovered that it is only just shy of the Chandrasekar limit -
the mass at which it would be big enough to go supernova.
That makes it the best and by far the closest supernova candidate discovered so far.
The crunch will come when HR 8210's companion begins to run out of fuel.
As it expands to form a red giant star, its outer layers will be dumped onto HR 8210,
pushing it over the Chandrasekar limit.
"Our initial idea was that this might happen very soon," says Sandstrom's supervisor Dave Latham.
Too close for comfort.
But do not panic yet. "Very soon" could mean hundreds of millions of years in the future.
And that is just as well, because we are only 150 light years away from HR 8210 at present -
well short of the 160 to 200 light years thought to be the minimum safe distance from a supernova.
If it did let fly, the high-energy electromagnetic radiation and cosmic rays it released
would destroy Earth's ozone layer within minutes, giving life little chance of survival.
This would not be the first time a supernova has changed the course of life on Earth.
In 2001, Jesus Maiz-Apellaniz and colleagues from the Space Telescope Science Institute in Baltimore, Maryland,
found a "smoking gun" supernova remnant, in the group of stars known as the Scorpius- Centaurus association.
The timing of the supernova corresponds to an otherwise mysterious deposit of heavy isotopes in
deep Earth cores and to a mass marine extinction two million years ago.
At the time, Scorpius-Centaurus was around twice as far away from Earth as HR 8210 is now.
Fortunately, it will take time for HR 8210 to accumulate the mass it needs.
Preliminary calculations by Rosanne di Stefano at the Harvard-Smithsonian Center suggest this may take
hundreds of millions of years. By that time it will be much further away, she says, though she still needs
to confirm exactly how far. "I want to be sure I'm right."
But will similar stars threaten us before then?
"The fact that there's such a system so close to us suggests maybe these objects are not so rare," says Latham.
RS Ophiuchi
The recurrent nova RS Ophiuchi has brightened more than 6 magnitudes and is currently
visible to the naked-eye for the first time in 21 years.
http://www.spacedaily.com/reports/Exploding_Star_Within_A_Star_Surprises_Astronomers.html
http://www.space.com/scienceastronomy/supernova_threat_021216.html
It was reported that the star, Sirius, in older times was coppery colored or red. In modern times it's now blue.
In other words if Sirius has indeed gone thru the red giant phase, shed its outter layers, it being 9 light years away
and plenty close to cause some real damage to earth from a supernova, how would we have any warning of it?
Very little. The fact that the shock wave would travel at very fast speeds would mean that the only clue we would have
is that the subject in question suddenly got a lot bigger. When we notice that, we would have about half an hour to an hour
to evacuate Earth to a place where the shock wave would have dissipated enough to not cause any damage.
Problem: no place to live. In which case, it would be easier to just stay on earth and be torn to itty bitty pieces
from the shock wave and get it over with than to try and escape from our own solar system and beyond for safety.
If Sirius blows the shock wave would be at best 80% of the speed of light.
That means when we see the light, sirius being 9 light years away, gives us 20% of 9 Years befor the shock wave gets to us.
Almost two years. And our own star, the Sun, would go nova as a result of the immense shock wave from a star of that size.
Että sellasta.
Tässä satunnaisia artikkeleita, elämä on maapallolla hiuskarvan varassa koko ajan.
Supernova poised to go off near Earth
* Supernova "smoking gun" linked to mass extinctions
* Astronomy, Harvard University
* Space Telescope Science Institute
* Harvard Smithsonian Center for Astrophysics
* Supernovae, NASA
A student at Harvard University has stumbled across the terrifying spectacle of a star in our galactic backyard
that is on the brink of exploding in a supernova.
It is so close that if it were to blow up before moving away from us, it could wipe out life on Earth.
Most supernovae occur when large stars run out of fuel and then collapse under their own weight.
As atoms in the star are squeezed together, they rebound outwards, blowing off energy in a dazzling and
dangerous display lasting several weeks.
But this one is different. Called HR 8210, it is a humble white dwarf,
a star that has run out of fuel and should be too small to produce a supernova.
But it may not stay that way. First, it is not alone, but is orbiting a companion star in a typical binary system.
And it is 1.15 times the mass of our Sun, which for a white dwarf is a whopper.
The system was first logged in 1993 but little attention was paid to it.
Then when Harvard student Karin Sandstrom investigated HR 8210 for a college paper this year,
she discovered that it is only just shy of the Chandrasekar limit -
the mass at which it would be big enough to go supernova.
That makes it the best and by far the closest supernova candidate discovered so far.
The crunch will come when HR 8210's companion begins to run out of fuel.
As it expands to form a red giant star, its outer layers will be dumped onto HR 8210,
pushing it over the Chandrasekar limit.
"Our initial idea was that this might happen very soon," says Sandstrom's supervisor Dave Latham.
Too close for comfort.
But do not panic yet. "Very soon" could mean hundreds of millions of years in the future.
And that is just as well, because we are only 150 light years away from HR 8210 at present -
well short of the 160 to 200 light years thought to be the minimum safe distance from a supernova.
If it did let fly, the high-energy electromagnetic radiation and cosmic rays it released
would destroy Earth's ozone layer within minutes, giving life little chance of survival.
This would not be the first time a supernova has changed the course of life on Earth.
In 2001, Jesus Maiz-Apellaniz and colleagues from the Space Telescope Science Institute in Baltimore, Maryland,
found a "smoking gun" supernova remnant, in the group of stars known as the Scorpius- Centaurus association.
The timing of the supernova corresponds to an otherwise mysterious deposit of heavy isotopes in
deep Earth cores and to a mass marine extinction two million years ago.
At the time, Scorpius-Centaurus was around twice as far away from Earth as HR 8210 is now.
Fortunately, it will take time for HR 8210 to accumulate the mass it needs.
Preliminary calculations by Rosanne di Stefano at the Harvard-Smithsonian Center suggest this may take
hundreds of millions of years. By that time it will be much further away, she says, though she still needs
to confirm exactly how far. "I want to be sure I'm right."
But will similar stars threaten us before then?
"The fact that there's such a system so close to us suggests maybe these objects are not so rare," says Latham.
RS Ophiuchi
The recurrent nova RS Ophiuchi has brightened more than 6 magnitudes and is currently
visible to the naked-eye for the first time in 21 years.
http://www.spacedaily.com/reports/Exploding_Star_Within_A_Star_Surprises_Astronomers.html
http://www.space.com/scienceastronomy/supernova_threat_021216.html
It was reported that the star, Sirius, in older times was coppery colored or red. In modern times it's now blue.
In other words if Sirius has indeed gone thru the red giant phase, shed its outter layers, it being 9 light years away
and plenty close to cause some real damage to earth from a supernova, how would we have any warning of it?
Very little. The fact that the shock wave would travel at very fast speeds would mean that the only clue we would have
is that the subject in question suddenly got a lot bigger. When we notice that, we would have about half an hour to an hour
to evacuate Earth to a place where the shock wave would have dissipated enough to not cause any damage.
Problem: no place to live. In which case, it would be easier to just stay on earth and be torn to itty bitty pieces
from the shock wave and get it over with than to try and escape from our own solar system and beyond for safety.
If Sirius blows the shock wave would be at best 80% of the speed of light.
That means when we see the light, sirius being 9 light years away, gives us 20% of 9 Years befor the shock wave gets to us.
Almost two years. And our own star, the Sun, would go nova as a result of the immense shock wave from a star of that size.
Että sellasta.
Vastaukset 7
Vanhimmat
Kaikkihan on teoreettisesti mahdollista. En kuitenkaan aio asian johdosta yöunia menettää.
teoreettisesti on mahdollista myös se että jotkut menettävät yöunensa asian johdosta.
Heh, jenkit ne osaa dramatisoida kaikkea. "Elämä maapallolla hiuskarvan varassa". Niin tyypillistä sensaatiohakuista tadaa taas kerran. Aina kun ne tekee jotain dokumentteja niin pitää olla hirmu skuupit niissä mukana.
...on varmaan huijausta, kuten sen Plutkonkin olemassaolo!
Kun se on tapahtunu miljardeja vuosia sitten.
On kovin vanhanaikaista uskoa noihin "vanhaa valoa" satuihin. Supernovassa valokin liikkuu sellasella nopeudella että oksat pois.
Miljardeja vuosia, ehe-ehe.
Niin no olis aika itsensä pettämistä kuvitella että maa olis jotenkin erityosasemassa tai erityisen turvallisessa paikassa avaruudessa. Joukkotuhoja on ollut ennenkin eli on täysion varmaa että seuraava tulee ennemmin tai myöhemmin on se sitten supernova, asteroidi, komeetta, auringon valtava purkaus tai valtava gammapurkaus mikä sen aiheuttaa.
Ei tosin yöunia kannata menettää ton takia. jos supernova vielä kärventää maan niin sitä ei kukaan pysty estämään. Sillon ihmiskunnan ainoa toivo on, että alienit on ennen sitä kertonu miten madonreikiä käytetään. Eli kun sitä ei pysty estämään niin turha murehtia, mutta paras silti pyrkiä keksimään keino päästä mahdolisimman kauas täältä ja levittää asutusta muihin aurinkokuntiin niin että jos yksi tuhoutuu ni se ei ole sitte game over.