The thought that Eta Carinae, a star at least 100 times more massive than the Sun, is a ticking time bomb seems to infuse much of the coverage about the huge supernova recently observed by the Chandra X-ray Observatory. And you can see why. Big explosions are marketable, which is why it sometimes seems that one way to categorize many of today’s movies is by how many cars were blown up during the making of them. When you’re talking about something a hundred times larger than the typical supernova, you’re going to get attention. What if a star 100 times the size of the Sun — or larger — goes off in our neighborhood?
Adding to the comparison is the fact that the supernova, known as SN 2006gy, seems to have expelled a large amount of material before the catastrophe. Eta Carina also shows signs of expelling mass, and it’s 7500 light years away, vs. the 240 million light years of SN 2006gy. Close enough to cause us problems? I don’t know the answer, but it does seem clear that one result would be spectacular visual effects. “Eta Carinae’s explosion could be the best star-show in the history of modern civilization,” says Mario Livio (Space Telescope Science Institute).
Image: According to observations by NASA’s Chandra X-ray Observatory and ground-based optical telescopes, the supernova SN 2006gy is the brightest and most energetic stellar explosion ever recorded and may be a long-sought new type of explosion. This is an artist’s illustration that shows what SN 2006gy may have looked like if viewed at a close distance. Credit: NASA/CXC/M.Weiss; X-ray: NASA/CXC/UC Berkeley/N.Smith et al.; IR: Lick/UC Berkeley/J.Bloom & C.Hansen.
What I find interesting is the mechanism that may be at work in such giant stars, for it’s believed that explosions like these were far more common in the early universe. Instead of the core being crushed under its own gravity to become a black hole (with the outer layers blown off as the visible supernova), supernovae like SN 2006gy may be the result of intense gamma ray radiation producing particle/anti-particle pairs, creating an energy drop that causes swift and violent stellar collapse. That, in turn, would trigger thermonuclear reactions fueling the explosion.
The consequences for the local environment are huge, since a mammoth explosion spreads elements cooked inside the star out into the cosmos, while a black hole seals some of this material off forever. Is SN 2006gy an example of this new kind of explosion? Whatever the case, it took seventy days to reach full brightness, and eight months later it remains as bright as a typical supernova at its peak. “Of all exploding stars ever observed, this was the king,” says Alex Filippenko (Lick Observatory).
Results are slated for The Astrophysical Journal. Then again, you may want to revisit Richard Cowper’s 1974 novel The Twilight of Briareus, a personal favorite whose author’s real name was John Middleton Murry, Jr. (I have all kinds of things to say about Murry himself — he was the son of the well known British writer and critic — but that’s a task for another time). In the novel, a nearby supernova blows in the constellation Briareus. Here’s the protagonist, a teacher in the local school, viewing it:
It was as if a hundred filmy scarves of pastel gauze had been suspended from the zenith to curtain off the whole of the northern sky; frail webs of pendant iridescence — pink and blue and green and yellow — which seemed to wave in slow motion like ghostly battle banners. The sight simply beggared description; it was unearthly. Next day I set it as a subject for a poem and one of the bright specks in the third form came up with — “slow waving fronds of winter weed. In rainbow rippling tropic seas” — which caught a faint fragrance of the magic but that’s about all.
Talk about visual effects! But as they unfold, the Earth is being bathed in a shower of particles that changes everything and produces an unforgetable kind of mutation. This guy could flat out write — I wonder if any of you share my enthusiasm for Murry’s work, which ranged from straightforward Ballard-era British disaster fiction to memorable fantasy, with interesting stops in between. The Twilight of Briareus is a wonderful book to return to, even if Eta Carinae isn’t likely to supply us with a modern day equivalent of the supernova in question.
I read a few things from different sources over the years about a safe distance for a planet’s biosphere, in case of a ‘typical’ supernova explosion. Very tentatively, distances of 10, 20, 30 ly have been mentioned. Even if we take the highest, 7500 ly is very much more than a safe distance.
Anyway, I also read that the nearest star massive enough to potentially become a supernova is over 300 ly away.
In the galactic HZ the risk of supernovas (supernovae?) seems to be very small, much smaller than often formerly mentioned, i.e. hardly a serious risk for (by far) most living planets in the course of their biological evolution.
Any comments?
To elaborate a bit and putting it in perspective: in comparison with more imminent geological and astronomical phenomena, such as supervolcano eruptions, meteorite impacts and a new ice age, the risk of a supernova explosion pales.
Hi All
The mutational angle of that novel’s story reminds me of a more serious proposal for the role of cosmic forces in human evolution. Andrew Collins is a writer of various occult books, but over the last decade he has examined recent prehistory with some pretty well-researched and not-so-sensationalist works. His most recent and most interesting is “The Cygnus Mystery” which examines the peculiar cosmic rays (dubbed “cygnets”) thrown at us stochastically by Cygnus X-3 and the rather remarkable change in human behaviour around 15,000 years ago.
Ronald, my only reservation is simply the size of the supernova in question, and Eta Carinae’s own huge mass. If this work really does point to a different category of supernova explosion, I wonder if the same thinking that applies to ‘conventional’ supernovae applies in terms of safe distance. But you’re right — most astronomers I’m seeing cited on this seem to agree that if Eta Carinae were to go supernova, it would be much to far away to pose a problem.
And yes, I’m far more concerned about asteroid impacts than Eta Carinae!
Adam, sounds a bit like Arthur Clarke, as far as extraterrestrial influences waking up (or creating) neural change. I assume that what Collins is getting at is the sudden move to neolithic cultural patterns, including farming. I’ve never heard of ‘cygnets’ — what are these emissions?
Ronald,
The risks to life of Supernovae vs Meteors, Volcanoes and Ice ages are different.
The latter threaten life a single planet only,and may be “frequent” in terms of the life of a planet (we’ve had multiple ice ages). Supernovae potentially could
sterilise a very large volume of space, wiping out many planets; hypothesised Huge Gamma ray events even more so.
It took 4 Gyrs for complex life to appear on Earth. A large supernova in our Galaxy every 2-3 billion years, wiping 1000 light year radius, and complex life becomes impossible, These are rare events, but rare enough ?
Quite agree about Cowper–very effective writer. Dead now, methinks.
Yes, Cowper died not too long ago.
Hmm — he died five years ago (4/29/2002). Longer than I thought.
OK, thanks for the reaction;
some data from Wikipedia concerning the danger from supernovae, hypernovae.
“Recent estimates predict that a Type II supernova would have to be closer than eight parsecs (26 light-years) to destroy half of the Earth’s ozone layer”.
“The nearest supernova candidate is IK Pegasi (HR 8210), located at a distance of only 150 light-years (…) a Type Ia supernova”.
It also mentions that the energy released in a typical supernova explosion would be 10^44 Joule.
In a hypernova explosion the amount of energy released is about 100 times greater: 10^46 Joule.
The greatest danger of a hypernova is the fact that they are probably the source of gamma ray bursts. These could be dangerous up to several hundred ly away.
However, these hypernovae and related GRB seem to be very rare: “Comparative work in 2006 on galaxies in which GRBs have occurred suggests that metal-poor galaxies are the most likely candidates. The likelihood of the metal-rich Milky Way galaxy hosting a GRB was estimated at less than 0.15%, significantly reducing the likelihood that a burst has caused mass extinction events on this planet “.
Eta Carinae is mentioned is (one of) the closest potential candidate(s).
Another encouraging thing: the fact that “metal-poor galaxies are the most likely candidates”. In other words, the galaxies that are most suitable for (terrestrial) planet building (the metal-rich ones, such as our MW and Andromeda) are at the same time those with the least hypernovae/GRB.
In addition to a galactic HZ this seems to suggest something like a “habitable galaxy”. Sorry, I get a bit carried away now, but creation seems to work in such a way, that certain galaxies are made for planets and life.
Hi Paul
“Cygnets” are big, neutral particles spat out by Cygnus X-3 and many would like to know just what they are.
I’m kind of annoyed that Andrew’s book isn’t getting a release here in Oz – probably too cerebral for the New Age book-shelf his stuff usually gets misfiled on. Speculative ancient history maybe, but no more so than Graham Hancock or Robert Bauval.
Off topic, but kind of interesting – Frank Tipler’s latest book has been out since March, “The Physics of Christianity”, to mixed reviews. I just learnt about it from an email from Kevin Kelly, who is currently reading it. As expected from his various writings on the web – now handily available on his webpage – Tipler uses his Singularity theorems and Omega Point Theory to make a case for Christianity being “scientific”. I’ll say more on my blog, so I don’t drag this even more off topic…
http://crowlspace.com/
Mr Cowper is not on Amazon for some reason. I have a book of short stories in paperback which I found in a second hand book shop in Belfast. I am not prepared to sell it as the book is for my kids.
Stevie, I imagine most of Cowper’s work is out of print, but a second hand store may well have him. He’s worth the hunt, in any case, and I liked what you said about your copy of his short stories being for your kids. I think you’ll find his novels equally rewarding.
I remember the relevance of Tipler’s new book now – he claims that a hypernova in the Andromeda Galaxy was probably the Star of Bethlehem. Now there’s a story in that I’m sure…
“Twilight of Briareus” is one of my favourite books. It seems to be one of the forgotten masterpieces of sci-fi. It made me want to read Cowper’s other works, but the only book of his available in the New York Public Library was “Clone”, which I was supremely disappointed with. I’ve just started reading the short story “Piper at the Gates of Dawn” which I have in a compilation of Fantasy & Science Fiction stories, and that seems pretty good so far. Hopefully “Clone” was just the exception, and I’ve found a new favourite author.
Ah, another Cowper enthusiast! After ‘Piper,’ you might want to sample one of the short story collections, like Out Where the Big Ships Go. How the man could write…
New Risk to Earth Found in Supernova Explosions
By Laura Kinoshita
Special to LiveScience
posted: 08 January 2008
06:27 am ET
An explosive star within our galaxy is showing signs of an
impending eruption, at least in a cosmic time frame, and
has for quite some time. From 1838 to 1858, the star called
Eta Carinae brightened to rival the light of Sirius, the brightest
star in the sky, and then faded to a dim star. Since 1940 it
has been brightening again, and scientists think Eta Carinae
will detonate in 10,000 to 20,000 years.
Fortunately, Eta Carinae is far away, at least 7,500 light-
years from Earth. If it explodes, most of its energy will be
scattered or absorbed in the vast emptiness of space. It also
happens to be tilted about 45 degrees from the line of sight
to Earth, so any type of gamma-ray burst, a high-energy
outburst expected with this star’s eventual eruption, would
miss the Earth. Cosmic rays would be diffused by magnetic
fields, and most of the damaging light would not affect life
on Earth.
In general, threats to life on Earth from supernovae are
extremely small, for all except the nearest explosions — those
30 light-years away or closer.
But what if a supernova were 100 times brighter than usual?
Would there be any risk to life on Earth then?
Astronomers found such a record-breaking supernova last
year, SN 2006gy.
Full article here:
http://www.space.com/scienceastronomy/080108-eta-carinae.html
The Early Spectra of Eta Carinae 1892 to 1941 and the Onset of Its High Excitation Emission Spectrum
Authors: Roberta M. Humphreys, Kris Davidson, Michael Koppleman
(Submitted on 18 Jan 2008)
Abstract: The observed behavior of eta Car from 1860 to 1940 has not been considered in most recent accounts, nor has it been explained in any quantitative model. We have used modern digital processing techniques to examine Harvard objective-prism spectra made from 1892 to 1941.
Relatively high-excitation He I 4471 and [Fe III] 4658 emission, conspicuous today, were weak and perhaps absent throughout those years. Feast et al. noted this qualitative fact for other pre-1920 spectra, but we quantify it and extend it to a time only three years before Gaviola’s first observations of the high-excitation features. Evidently the supply of helium-ionizing photons(lambda less than 504A) grew rapidly between 1941 and 1944.
The apparent scarcity of such far-UV radiation before 1944 is difficult to explain in models that employ a hot massive secondary star, because no feasible dense wind or obscuration by dust would have hidden the photoionization caused by the proposed companion during most of its orbital period. We also discuss the qualitative near-constancy of the spectrum from 1900 to 1940, and eta Car’s photometric and spectroscopic transition between 1940 and 1953.
Comments: 41 pages, 12 figures
Subjects: Astrophysics (astro-ph)
Cite as: arXiv:0801.2967v1 [astro-ph]
Submission history
From: Roberta Humphreys [view email]
[v1] Fri, 18 Jan 2008 20:39:49 GMT (1348kb)
http://arxiv.org/abs/0801.2967
Possible Implications of Mass Accretion in Eta Carinae
Authors: Amit Kashi, Noam Soker (Technion, Israel)
(Submitted on 1 Feb 2008)
Abstract: We apply the previously suggested accretion model for the behavior of the super-massive binary system Eta Carinae close to periastron passages. In that model it is assumed that for ~10 week near periastron passages one star is accreting mass from the slow dense wind blown by the other star. We find that the secondary, the less massive star, accretes ~2×10^{-6}Mo. This mass posses enough angular momentum to form a disk, or a belt, around the secondary. The viscous time is too long for the establishment of equilibrium, and the belt must be dissipated as its mass is being blown in the reestablished secondary wind. This processes requires about half a year, which we identify with the recovery phase of Eta Car.
We show that radiation pressure, termed radiative braking, cannot prevent accretion. In addition to using the commonly assumed binary model for Eta Car, we also examine alternative models where the stellar masses are larger, and/or the less massive secondary blows the slow dense wind, while the primary blows the tenuous fast wind and accretes mass for ~10 week near periastron passages. We end by some predictions for the next event (January-March 2009).
Comments: Submitted to new Astronomy
Subjects: Astrophysics (astro-ph)
Cite as: arXiv:0802.0167v1 [astro-ph]
Submission history
From: Noam Soker [view email]
[v1] Fri, 1 Feb 2008 17:14:06 GMT (264kb)
http://arxiv.org/abs/0802.0167
ESA’s Integral has made the first unambiguous discovery
of high-energy X-rays coming from a rare massive star at
our cosmic doorstep, Eta Carinae. It is one of the most
violent places in the galaxy, producing vast winds of
electrically-charged particles colliding at speeds of
thousands of kilometres per second.
More at:
http://www.esa.int/esaSC/SEMIQPVHJCF_index_0.html
An Aboriginal Australian Record of the Great Eruption of Eta Carinae
Authors: Duane W. Hamacher, David J. Frew
(Submitted on 22 Oct 2010)
Abstract: We present evidence that the Boorong Aboriginal people of northwestern Victoria observed the Great Eruption of Eta ({\eta}) Carinae in the nineteenth century and incorporated the event into their oral traditions.
We identify this star, as well as others not specifically identified by name, using descriptive material presented in the 1858 paper by William Edward Stanbridge in conjunction with early southern star catalogues.
This identification of a transient astronomical event supports the assertion that Aboriginal oral traditions are dynamic and evolving, and not static. This is the only definitive indigenous record of {\eta} Carinae’s outburst identified in the literature to date.
Comments: Accepted in the Journal for Astronomical History & Heritage, Volume 13, Issue 3 (November, 2010). 9 Figures, 4 Tables
Subjects: History of Physics (physics.hist-ph); Solar and Stellar Astrophysics (astro-ph.SR); Physics and Society (physics.soc-ph)
Cite as: arXiv:1010.4610v1 [physics.hist-ph]
Submission history
From: Duane Hamacher [view email]
[v1] Fri, 22 Oct 2010 04:18:34 GMT (3803kb)
http://arxiv.org/abs/1010.4610