New Technique Finds Farthest Supernovae
Written by Nancy Atkinson
This artist’s impression of a supernova shows the layers of gas ejected prior to the final deathly explosion of a massive star. Credit: NASA/Swift/Skyworks Digital/Dana Berry
Two of the farthest supernovae ever detected have been found by using a new technique that could help find other dying stars at the edge of the universe. The two cosmic blasts occurred 11 billion years ago. The next-farthest large supernova known occurred about 6 billion years ago. Jeff Cooke from the University of California Irvine said this new method has the potential to allow astronomers to study some of the very first supernovae and will advance the understanding of how galaxies form, how they change over time and how Earth came to be.
A supernova occurs when a massive star (more than eight times the mass of the sun) dies in a powerful, bright explosion. Cooke studies larger stars (50 to 100 times the mass of the sun) that blow part of their mass into their surroundings before they die. When they finally explode, the nearby matter glows brightly for years.
Typically, cosmologists find supernovae by comparing pictures taken at different times of the same swath of sky and looking for changes. Any new light could indicate a supernova.
Cooke built upon this idea. He blended pictures taken over the course of a year, then compared them with image compilations from other years.
"If you stack all of those images into one big pile, then you can reach deeper and see fainter objects," Cooke said. "It's like in photography when you open the shutter for a long time. You'll collect more light with a longer exposure."
This image shows the host galaxy containing one of the newly discovered supernovae. Comparing the images shows how the galaxy visibly brightens in 2004 and then returns to normal. This suggested that in 2003 the supernova was not detected; it appeared in 2004 and was beginning to fade in 2005. The last frame subtracts the images from the years that the supernova was not detected as well as the galaxy’s light to reveal only the supernova. Credit: Jeff Cooke/CFHT
This image shows the host galaxy containing one of the newly discovered supernovae. Comparing the images shows how the galaxy visibly brightens in 2004 and then returns to normal. This suggested that in 2003 the supernova was not detected; it appeared in 2004 and was beginning to fade in 2005. The last frame subtracts the images from the years that the supernova was not detected as well as the galaxy’s light to reveal only the supernova. Credit: Jeff Cooke/CFHT
Doing this with images from the Cooke found four objects that appeared to be supernovae. He used a Keck telescope to look more closely at the spectrum of light each object emitted and confirmed they were indeed supernovae.
"The universe is about 13.7 billion years old, so really we are seeing some of the first stars ever formed," Cooke said.
Cooke's paper is published in the journal Nature on July 9.
Source: UC-Irvine
Filed under: Astronomy
Tags: SupernovaeRelated stories on Universe Today
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July 8th, 2009 at 11:01 am
Two questions come to mind: 1) Exactly what type of supernova were observed (Type Ia, Ib, type II, etc.)? 2) I was taught in college that the first stars to form were massive Pop III stars that rapidly went supernovae, enriching the IGM. To my knowledge, no Pop III stars have been detected to date. Are they referring to early Pop II stars? Also, is there any word of the type of galaxies these SNe occurred in?
July 8th, 2009 at 8:04 pm
PopIII stars exist more theoretically. They probably existed in some form, but in what way is not entirely clear, from what I understand. These stars would be all hydrogen, which has a near zero opacity. This means the stars do not scatter photons well in their interiors. The 1% or so of non-hydrogen material in the sun is what scattered the first photons produced in the early sun, as with other stars. This means they may not have been stable stars as we normally think of them. If fusion got going in them most of the photons just escaped directly without heating the material up. These stars might have just collapsed continually into a direct runaway supernova.
From what I understand these PopIII stars were peculiar beasts. Given the need for early nucleosythesis they or related objects had to exist.
At 11 By ago this object probably has z ~ 6 and is some time after the reionization phase of the unvierse. PopIII stars are thought to be the source of reionization. So if I had to guess this object is probably not a PopIII star
Lawrence B. Crowell
July 8th, 2009 at 10:40 pm
edge of the KNOWN universe!
edge of the KNOWN UNIVERSE!!!!!
in case you were wondering, yes, i have issues.
July 9th, 2009 at 5:07 am
@ Lawrence B. Crowell, I found some clarification to my first two queries at the Keck website in their press release. The observed SNe were Type IIn. These objects were indeed Pop II stars, but researcher Jeff Cooke is quoted as saying '… while the newly identified explosions may be the farthest of any supernovae type found to date, the innovative method developed to identify the explosions should make it possible to discover even more distant supernovae—possibly even a few of the very first stars to blow themselves apart.'. This would seem to indicate that this method may be suitable to search for signs of these elusive 'peculiar beasts' (Pop III stars).
July 9th, 2009 at 5:10 am
The phrase "edge of the known universe" comes with some qualifications. Of course far beyond the known luminous universe is the CMB region. The CMB wall of opaqueness is back to 380000 years after the big bang, and some 60 billion light years away. The divergence from 13.7 billion years to the big bang is due to frame dragging of particles in the expansion of the universe. Particles out there are not on the same frame bundle as we are on.
After the radiation dominated period of the universe, where the CMB is the remnant of that time, the universe was in a dark age. The occurrence of PopIII stars and supernova resulted in the reionization of the universe. This probably set in around .5 billion years after the big bang. As yet we have a paucity of data on this phase of the universe. These large "super-scopes" being planned might detect objects in the region (time) by tuning into their redshifted photons in the infrared domain.
July 9th, 2009 at 7:08 am
Indeed, as Lawrence B. Crowell points out, Pop III stars are thought to be major players in the reionization phase of our universe around 500 million years after the big bang. What I found interesting in the Keck press release was this statement by Alicia Soderberg: "This new method could not have been published at a better time, explaining that many large survey telescopes, such as the Large Synoptic Survey Telescope, will soon be online to identify thousands of candidate supernovae. Astronomers can then use large eight to ten meter telescopes, such as Keck, to obtain the necessary deep spectra of the supernovae to determine their distance and the abundance of elements that they spew into space after they explode." This technique may also be of use to astronomers studying dark energy, despite their use of Type Ia supernovae as their 'standard candle' (the SNe in this story were identified as Type IIn). A link to the Keck press release can be found here: http://keckobservatory.org/index.php/news/new_method_finds_most_distant_supernovae/ . Btw, the parent galaxy of the SN illustrated in this story appears to be a distant, young 'clump-cluster' galaxy similar to those seen in the Hubble Deep Fields and Ultra Deep Fields (HDF & HUDF).
July 9th, 2009 at 7:24 am
For those readers not familiar with what astronomers call Population I, II & III stars, check out this Wiki link: http://en.wikipedia.org/wiki/Population_III_stars . As noted before, Pop III stars are 'peculiar beasts' indeed
July 9th, 2009 at 9:03 am
Thanks all for explaining the awesomeness and peculiarities of the first star population!
I assume there is no reason to think either way if (also opaque) dark matter was involved in the seeding and dynamics of these first gravitationally assembled objects. Making it even more a mystery, I'm sure.
@ PP:
Edge of the VISIBLE universe – we know, barring validating new mechanisms such as bubble universes AFAIU, that the (indirectly) observable universe is at least 5 times larger than that, thanks to the CMB. Of course, one can always nitpick and discuss the difference between falsifiable knowledge and not-directly-or-at-all-testable learning.
You see, issues are universal in nature.
[Speaking of nitpicking, AFAIU it isn't a space geometric "edge" as much as a space-time geometric "edge-time". Or perhaps a "time-edge", since we are running out of time faster than space going backwards.
Or, more properly and meaningfully perhaps "loosing focus", since the "edge" is really us looking back towards the beginning, every direction we look, with loss of resolving power.
It's a big nit to pick at.]
July 9th, 2009 at 9:19 am
"discuss the difference"
Come to think of it, that difference is probably not applicable to the basic observation here.
AFAIU the universe when it left inflation by these observations must have been at least 5 times larger than the visible one by the standard cosmology (and I bet a lot of similar cosmologies), even if those putative other bubble universes later enchroached on that volume. The observation is more like a test of the hypothesis of flat space, or vice versa.
If so, that discussion should really be more on nitpicking on what we mean by "universe" and discussing if there are multiverses or not.
July 9th, 2009 at 10:46 am
I have a couple of really n00b questions here.
When the article reads " find other dying stars at the edge of the universe." The "edge of the universe" means the observable universe right? There are parts of the universe where we can not detect, right?
My second question is if the universe is believed to be about 13.7 billion years old, what about the region of space that is still expanding? Would the newly created regions of space still be considered 13.7 billion years old?
Thanks in advance for answering rookie questions.
July 9th, 2009 at 3:48 pm
Wow, off topic, but I must comment on the recent improvement in the rational discussion of relevant astrophysical topics here at UT (as some others have already pointed out). Keep it up, I'm learning new facets of my lifelong 'obsession' at a much greater rate than just a few days ago!
July 9th, 2009 at 5:10 pm
spam909 Says:
July 9th, 2009 at 10:46 am
"When the article reads " find other dying stars at the edge of the universe." The "edge of the universe" means the observable universe right? There are parts of the universe where we can not detect, right?"
Nobody is really sure. As far as we can tell, there may be vast areas of the universe beyond the observable region, or there may not be. Our only method of ever finding out will be indirect – if we can confirm certain aspects of, say, some brand of inflationary theory, then we may be able to get some idea of what may be out there based on the other predictions of the theory.
"My second question is if the universe is believed to be about 13.7 billion years old, what about the region of space that is still expanding? Would the newly created regions of space still be considered 13.7 billion years old?"
Have to be careful with wording here, because all of space is still expanding – the whole universe. As the observable universe expands however, it is important to note that no new space is being 'created' – the existing space is simply expanding. Using the old analogy of a loaf of bread in the oven, the loaf expands as the yeast goes to work on it and the bread rises, but there is no new 'bread material' being created per se… In other words, it's not a case of the universe growing larger by creating new space out on the fringes of the observable universe – space itself is literally streching. Hence, any region in the observable universe can be considered to be 13.7 billion years old.
However (and I believe this is what you may be referring to), inflationary theory explains certain facets of our observable universe by invoking a short period of extremely rapid expansion of the universe occurring only moments after the BB. Some inflationary theories propose that this inflation is ongoing – that the universe has 'normal' regions and 'inflating' regions, and that somewhere in the larger universe (far beyond our observable region), inflation is still running riot. In this case, I guess you could say that the age of a given region could be related to how long it has been since the region in question transitioned from inflationary to normal. So in this model of the universe, in the case of our 'region' that transition happened 13.7 billion years ago. Anyway, it's a tough one to wrap one's head around…
July 10th, 2009 at 4:07 pm
The Wiki piece on Pop III stars lists two references that might indicate the presence of these objects. The first, co-authored by Stan Woosley, is largely theoretical, and can be found here: http://arxiv.org/PS_cache/astro-ph/pdf/0107/0107037v2.pdf .
July 10th, 2009 at 4:17 pm
The second Wiki reference to a possible observation of Pop II stars refers to a lensed galaxy in Lynx and can be found here: http://arxiv.org/PS_cache/astro-ph/pdf/0307/0307162v1.pdf . So far, no direct observational proof of Pop III stars, but current theory holds that they must have existed (see Wikipedia link above).
July 12th, 2009 at 1:37 am
i can't help but notice a similarity in writing style amoung a few of the posters above.
is everything here as it seems?
anyhow, my objection is to the certainty that we know where the edge is amoung some members of the cosmology community.
i know, i know, both sides can argue it until we're blue in the face. time will tell. i hope i'm still around when/if it does.
science that deals with matters of such vast and distant scope should always have a respectful asterisk once in a while to remind the reader that it's okay to question cosmologists who make sweeping claims with 100% certainty.
srry for preaching
July 12th, 2009 at 4:49 am
@ Pvt. Pantzov, I certainly find your posts interesting and engaging. These questions on the size of the universe are extremely deep and most profound. I agree with Astrofiend's excellent summary above and note that as he states "nobody is really sure" of the size of the universe. And, like you, I hope I'm still around if/when that question might be answered with a greater degree of certainty