Friday, November 16, 2007
Pareidolia: part n + 8
Over at Stupid Evil Bastard, Les lets us know about a new pancake with a mysterious image in it. Apparently, the woman who made the pancake thinks it's Jesus and Mary. But we all know that's wrong. It's quite obviously the Flying Spaghetti Monster. She was touched by his noodly appendage and was too blind to see it. No beer volcano for her!
Labels:
pareidolia,
Pastafarianism
Exorcism kills again
It seems that another woman has died due to a failed exorcism in New Zeland in which she had syringes suck into her eyes and was forced to drink excessive amounts of water. Did New Zeland not take the lesson from people here in the US when a woman died of water poisoning in a contest?
To make things worse, the same treatment was also forced upon a 14 year old. Furthermore, the police weren't called until l8 hours after the woman died. If someone stops breathing, I would think you would call for help immediately, unless your ability to think has been impaired. What were they expecting? A magical resurrection like Jesus?
To make things worse, the same treatment was also forced upon a 14 year old. Furthermore, the police weren't called until l8 hours after the woman died. If someone stops breathing, I would think you would call for help immediately, unless your ability to think has been impaired. What were they expecting? A magical resurrection like Jesus?
Thursday, November 15, 2007
Finding New Stuff with Big Sky Surveys
One of the coolest things about astronomy is that we live in a universe. A big universe. And that means that there's a lot of fun stuff to find out there. It's like a never ending easter egg hunt. Unfortunately, these eggs don't contain chocolate. But they do glow in the dark, so that's pretty cool.
What's especially amazing sometimes, is that we are still trying to catalog our own galactic back yard. Phil Plait at Bad Astronomy addressed the reason for this (transcript), namely that things are pretty darn faint. So, even in our own galaxy, we can't really see terribly far.
Break out the telescopes, and many more things become visible. But then you start to run into some other problems. First off, we live in a spiral galaxy. Spiral galaxies are partially known for having large amounts of dust and gas. So it's a lot like trying to look around in a fog bank. You can't see too far. Another problem is that the further away things are, the smaller they are in angular size. So even if something is relatively bright, you might not even notice it in all the clutter.
Historically, new objects were discovered just wandering around the sky with telescopes and documenting anything that was suspicious. This was the foundation for the famous Messier Catalog. Now, serendipitous discoveries along those lines don't happen too often, although, they occasionally still do.
Today, instead of wandering aimlessly across the sky, new discoveries are often the result of computer controlled survey missions. Sometimes the astronomers know what they're looking for. Other times, new discoveries are simply a byproduct of other data taking. An example of the latter is the numerous comets discovered by the SOHO mission which has discovered over 1,300 comets (including it's first perioditic comet recently).
Another example is the Sloan Digital Sky Survey (SDSS), which slowly scans the sky, taking high resolution images with its 120 megapixel camera. Sloshing through this data, a group from the Max Plank Institute with Cambridge astronomers have discovered 2 new globular clusters in our galaxy (Kopsov, 2007). To do this, a computer program mapped the stars imaged in the survey and looked for places where there were spikes in the density of them. But a jump in the density of stars alone doesn't tell astronomers what the object is.
Since not only our universe is big, but we also live in a pretty good sized galaxy, our galaxy gets to be a bit of a bully. This means we cannibalize dwarf galaxies. So when we look around some of the overdensities can also be the result of these tiny doomed galaxies.
So how can we tell the difference? One of the main ways is to look at their HR diagrams. If it's a cluster, all stars will have formed at the same time, and thus, you should see something resembling an isochrone. If it's a galaxy, then stars would have formed at largely different times and there should be no distinct turn off. Since the color-magnitude diagrams (CMDs, essentially an HR diagram) show distint main sequence turn offs, the possibility that these are distinct galaxies can be ruled out.
Now that we know that these are clusters, what can we say about them. One of the first things that the paper notes is that these clusters are faint. Each is estimated to have a total surface brightness of -2 to -1 magnitudes (remember, in the magnitude system, bigger numbers are fainter. Thus, a -20m object is brighter than a -15m object. Similarly, a 1m object is brighter than a 2m object.) To date, the faintest globular clusters ever found had magnitudes of roughly -1.6.
Additionally, these two new clusters are way out there in the halo of the galaxy. Finding faint galaxies that far out hints that there may be a lot more of these bitty guys out there that have yet to be discovered. So why are they so puny while most of the inner globulars are nice and big?
It looks like these clusters are falling apart due to the tidal stripping that keeps coming up in my posts. This would suggest that in the past, there were even more of these and they were bigger. But fear not creationists. The current estimated lifetime for clusters with this density is about 8 billion years. So the evaporating comet nonsense doesn't work for these objects either.
But globular clusters aren't the only objects lurking in our galaxy that are yet to be discovered. In another paper from the same ApJ issue discusses some more findings from another sky survey. This one was looking for planetary nebulae (Cohen, 2007). These guys don't last all that long before they spread out and blend back into the interstellar medium. But since they're the result of low mass stars ending their lives and there's a good number of stars doing that, there should be a pretty good number out there.
However, since these form from dying stars, we should expect more where there are stars, namely, in the disk of the galaxy. So unlike globular cluster hunting, we have to look close to the galactic plane. Unfortunately, this means there's going to be a lot of extra dust and gas in the way hiding them.
The Macquarie-AAO-Strasbourg Hα PN project (MASH) again uses sky surveys to look for these objects. Instead of looking for density spikes, they look for objects with emission due to hydrogen and then compare the brightness of that in the mid-infrared part of the spectrum, to the brightness in the radio as well as differences in spectra to distinguish the objects from other objects that may masquerade as planetary nebulae (such as HII regions).
So far, this study has found 905 new objects that are likely to be planetary nebulae in our own galaxy! This has increased the known number by ~60%. Wow! This paper alone added an additional 58 to that list. Many of these new nebulae are quite evolved and starting to diffuse back into the interstellar medium, so having this large collection of additional objects will allow us to put new constraints on these objects and figure out how they evolve.
Another thing this survey gives us is a lot of new PNe morphologies to study. Ideally, they should all be nice and symmetrical (since stars are round and all). But the universe is never idea (*sigh*). Stellar rotation, magnetic fields, asymmetrical releases, companion stars and all sorts of nasty things whip planetary nebulae into odd shapes. There's so many ways to do things that it's hard to untangle them all and hopefully, having more to study will untangle the mess. Roughly 28% of these new PNe are bipolar which is a pretty significant number.
So now we've seen two examples of how large sky surveys are uncovering scores of new objects that can help us learn about the universe we live in. Nice little benefit of these things that is, but there's also a downside. Having gigantic surveys like this generates loads of data. Way more than astronomers can possibly sort through. That's why we've been seeing projects that are starting to put some of the grunt work in the hands of passionate amateurs. Hopefully we'll develop more sophisticated ways of handling the terrabytes of data that can be generated in a single night of observation.
Koposov, S., de Jong, J.T., Belokurov, V., Rix, H., Zucker, D.B., Evans, N.W., Gilmore, G., Irwin, M.J., Bell, E.F. (2007). The Discovery of Two Extremely Low Luminosity Milky Way Globular Clusters. The Astrophysical Journal, 669(1), 337-342. DOI: 10.1086/521422
Cohen, M., Parker, Q.A., Green, A.J., Murphy, T., Miszalski, B., Frew, D.J., Meade, M.R., Babler, B., Indebetouw, R., Whitney, B.A., Watson, C., Churchwell, E.B., Watson, D.F. (2007). . The Astrophysical Journal, 669(1), 343-362. DOI: 10.1086/521427
What's especially amazing sometimes, is that we are still trying to catalog our own galactic back yard. Phil Plait at Bad Astronomy addressed the reason for this (transcript), namely that things are pretty darn faint. So, even in our own galaxy, we can't really see terribly far.
Break out the telescopes, and many more things become visible. But then you start to run into some other problems. First off, we live in a spiral galaxy. Spiral galaxies are partially known for having large amounts of dust and gas. So it's a lot like trying to look around in a fog bank. You can't see too far. Another problem is that the further away things are, the smaller they are in angular size. So even if something is relatively bright, you might not even notice it in all the clutter.
Historically, new objects were discovered just wandering around the sky with telescopes and documenting anything that was suspicious. This was the foundation for the famous Messier Catalog. Now, serendipitous discoveries along those lines don't happen too often, although, they occasionally still do.
Today, instead of wandering aimlessly across the sky, new discoveries are often the result of computer controlled survey missions. Sometimes the astronomers know what they're looking for. Other times, new discoveries are simply a byproduct of other data taking. An example of the latter is the numerous comets discovered by the SOHO mission which has discovered over 1,300 comets (including it's first perioditic comet recently).
Another example is the Sloan Digital Sky Survey (SDSS), which slowly scans the sky, taking high resolution images with its 120 megapixel camera. Sloshing through this data, a group from the Max Plank Institute with Cambridge astronomers have discovered 2 new globular clusters in our galaxy (Kopsov, 2007). To do this, a computer program mapped the stars imaged in the survey and looked for places where there were spikes in the density of them. But a jump in the density of stars alone doesn't tell astronomers what the object is.
Since not only our universe is big, but we also live in a pretty good sized galaxy, our galaxy gets to be a bit of a bully. This means we cannibalize dwarf galaxies. So when we look around some of the overdensities can also be the result of these tiny doomed galaxies.
So how can we tell the difference? One of the main ways is to look at their HR diagrams. If it's a cluster, all stars will have formed at the same time, and thus, you should see something resembling an isochrone. If it's a galaxy, then stars would have formed at largely different times and there should be no distinct turn off. Since the color-magnitude diagrams (CMDs, essentially an HR diagram) show distint main sequence turn offs, the possibility that these are distinct galaxies can be ruled out.
Now that we know that these are clusters, what can we say about them. One of the first things that the paper notes is that these clusters are faint. Each is estimated to have a total surface brightness of -2 to -1 magnitudes (remember, in the magnitude system, bigger numbers are fainter. Thus, a -20m object is brighter than a -15m object. Similarly, a 1m object is brighter than a 2m object.) To date, the faintest globular clusters ever found had magnitudes of roughly -1.6.
Additionally, these two new clusters are way out there in the halo of the galaxy. Finding faint galaxies that far out hints that there may be a lot more of these bitty guys out there that have yet to be discovered. So why are they so puny while most of the inner globulars are nice and big?
It looks like these clusters are falling apart due to the tidal stripping that keeps coming up in my posts. This would suggest that in the past, there were even more of these and they were bigger. But fear not creationists. The current estimated lifetime for clusters with this density is about 8 billion years. So the evaporating comet nonsense doesn't work for these objects either.
But globular clusters aren't the only objects lurking in our galaxy that are yet to be discovered. In another paper from the same ApJ issue discusses some more findings from another sky survey. This one was looking for planetary nebulae (Cohen, 2007). These guys don't last all that long before they spread out and blend back into the interstellar medium. But since they're the result of low mass stars ending their lives and there's a good number of stars doing that, there should be a pretty good number out there.
However, since these form from dying stars, we should expect more where there are stars, namely, in the disk of the galaxy. So unlike globular cluster hunting, we have to look close to the galactic plane. Unfortunately, this means there's going to be a lot of extra dust and gas in the way hiding them.
The Macquarie-AAO-Strasbourg Hα PN project (MASH) again uses sky surveys to look for these objects. Instead of looking for density spikes, they look for objects with emission due to hydrogen and then compare the brightness of that in the mid-infrared part of the spectrum, to the brightness in the radio as well as differences in spectra to distinguish the objects from other objects that may masquerade as planetary nebulae (such as HII regions).
So far, this study has found 905 new objects that are likely to be planetary nebulae in our own galaxy! This has increased the known number by ~60%. Wow! This paper alone added an additional 58 to that list. Many of these new nebulae are quite evolved and starting to diffuse back into the interstellar medium, so having this large collection of additional objects will allow us to put new constraints on these objects and figure out how they evolve.
Another thing this survey gives us is a lot of new PNe morphologies to study. Ideally, they should all be nice and symmetrical (since stars are round and all). But the universe is never idea (*sigh*). Stellar rotation, magnetic fields, asymmetrical releases, companion stars and all sorts of nasty things whip planetary nebulae into odd shapes. There's so many ways to do things that it's hard to untangle them all and hopefully, having more to study will untangle the mess. Roughly 28% of these new PNe are bipolar which is a pretty significant number.
So now we've seen two examples of how large sky surveys are uncovering scores of new objects that can help us learn about the universe we live in. Nice little benefit of these things that is, but there's also a downside. Having gigantic surveys like this generates loads of data. Way more than astronomers can possibly sort through. That's why we've been seeing projects that are starting to put some of the grunt work in the hands of passionate amateurs. Hopefully we'll develop more sophisticated ways of handling the terrabytes of data that can be generated in a single night of observation.
Koposov, S., de Jong, J.T., Belokurov, V., Rix, H., Zucker, D.B., Evans, N.W., Gilmore, G., Irwin, M.J., Bell, E.F. (2007). The Discovery of Two Extremely Low Luminosity Milky Way Globular Clusters. The Astrophysical Journal, 669(1), 337-342. DOI: 10.1086/521422
Cohen, M., Parker, Q.A., Green, A.J., Murphy, T., Miszalski, B., Frew, D.J., Meade, M.R., Babler, B., Indebetouw, R., Whitney, B.A., Watson, C., Churchwell, E.B., Watson, D.F. (2007). . The Astrophysical Journal, 669(1), 343-362. DOI: 10.1086/521427
Labels:
astronomy,
bpr3,
clusters,
journal summaries,
planetary nebulae
Wednesday, November 14, 2007
DI in the Whaaaaambulance
In a blog post far far away...
I wrote a list of talking points for making a pro-ID/Creationist arguments.
The first point under the section about defining Intelligent Design read:
Remember to as vague as possible. Do not mention what ID actually says about common descent or age of the earth so that fundamentalists won't get offended and will continue giving you funding. Additionally, not adequately explaining yourself will give you the ability to dismiss critics later by insisting that they just don't understand Intelligent Design.The list was based largely on a flopped presentation Dembski had given at KU but also drew from several years of watching other ID proponents presentations and observing their responses to criticism.
But it seems that the Discovery Institute is showing just how true it is in response to PBS's Judgement Day: Intelligent Design on Trial. Crowther claims that the show misrepresented ID. Yet this documentary wasn't their words. It was straight from the mouths of the ID proponents themselves!
- We had Buckingham and Bosnell being open and honest that they were Young Earth Creationists and they wanted it in the classroom in any way they thought it could fit in (and then perjuring themselves as to where the books had come from).
- We had Behe and Minnich define ID for us and be so utterly vague about it that Behe had to admit that astrology would be science.
- We had the DI's touted textbook, Of Pandas and People being caught in the act of giving the facelift to Creationism (and even leaving us transitional fossils to demonstrate it.
- We had the DI's own Wedge Document in which they clearly state their objective as "nothing less than the overthrow of materialism and its cultural legacies".
- We had repeated quotes from Phillip Johnson, the founder of your own movement, admitting that, "Our strategy has been to change the subject a bit, so that we can get the issue of intelligent design, which really means the reality of God, before the academic world and into the schools."
These aren't our words here Disco boys. They're the words of people on your side.
In my last post, I wrote about how Behe and other ID proponents have failed to learn an important childhood lesson, namely, that if you act like a fool, you're going to get made fun of and you have no one to blame but yourself. Now, we catch them in their immaturity in yet another way: Adults know how to take responsibility for their own actions. Even Richard Thompson from the Thomas Moore Law Center admitted it was a "fair trial". But it seems that the Discovery Institute won't admit that they need to take responsibility for their actions and that they were beat in a fair fight. Instead, all we get is spin, spin, spin, rationalization, spin, spin.
Perhaps one day, creationists can all grow up.
Karma's a Bitch
One of my earliest posts in this blog, was a commentary on one of the fundamental points most of us learned in elementary school: If you want respect, earn it. The gist of that blog was that if you repeatedly reject the option to earn some respect and instead act like a fool, then you deserve to be ridiculed.
Unfortunately, this lesson is one that Behe, like so many other creationists, seems to have never learned. Instead, they continue to make a mockery of the very foundation of science, making grand claims that go unsupported, offering up untestable hypothesies, fallacies of bifurcation, maintaining willful ignorance and downright lying. Of course, Behe keeps up this fine tradition.
So when ERV decided to take on his nonsense and give Behe the well earned ribbing he's earned. But maybe Behe's finally learned the lesson that is even obvious to most children. So he posts an announcement saying he's going to rebut the letters directed towards him. It's a grand flourish and I was sincerely hoping that Behe was setting up for something big and would actually, I don't know, address the arguments?
So what's the first thing he says?
"Whhhhhhaaaaaaah. I'm being made fun of."
That's right. Behe plays the victim card and claims that he's the victim of an ad hominem attack. But he wasn't. For a real ad hominem, it requires that the offender substitute an argument with a mocking. This is not the case. Rather, the argument was supplemented with a mocking that matched the mockery Behe and his fellows make of science.
But after that, is Behe finally ready to grow up? I'm not going to pretend I understand the technical exchange any more than Behe would be able to follow articles in the Astrophysical Journal (although Behe's buddy Dembski apparently knows everything about everything), but there's a few keys phrases that are amazingly typical of creationists trying to worm their way out of being confronted with evidence.
#1) "It is not clear to me why you call that Smith’s "core argument."" - Translation: I don't get it because I'm too busy repeating my claims ad nauseum to actually read anything. Careful Behe. You let that pesky reality pile up on you too long and it will bite you in the ass like it did on the stand at Dover.
#2) "...as her own citations show" - Translation: ...as her own citations show if you ignore everything except that introductory sentence used as a literary device, disregard all the evidence that supports her and buy into my quote mining bullshit. FTK might consider out of context quotes as indicative of "an open issue", but those of us that keep reading to discover the issue is well on the way towards a resolution don't buy into such sleazy tricks.
#3) "I think this is a trivial biochemical change..." - Call it trivial and ignore it. Or if "trivial" isn't your cup of tea, you can always call it pathetic.
I'll wait for a layman's version of the technical bits, but right now, it's looking pretty clear that Behe is just up to the same old nonsense: Flaunt, cry, obfuscate. Someone let me know when the reruns are over and something new is on.
Meanwhile, Behe has the audacity to say, "One of the very basic prerequisites for education is to be able to engage in civil discourse...".
Guess what Behe, so is actually backing up your arguments without lying.
Unfortunately, this lesson is one that Behe, like so many other creationists, seems to have never learned. Instead, they continue to make a mockery of the very foundation of science, making grand claims that go unsupported, offering up untestable hypothesies, fallacies of bifurcation, maintaining willful ignorance and downright lying. Of course, Behe keeps up this fine tradition.
So when ERV decided to take on his nonsense and give Behe the well earned ribbing he's earned. But maybe Behe's finally learned the lesson that is even obvious to most children. So he posts an announcement saying he's going to rebut the letters directed towards him. It's a grand flourish and I was sincerely hoping that Behe was setting up for something big and would actually, I don't know, address the arguments?
So what's the first thing he says?
"Whhhhhhaaaaaaah. I'm being made fun of."
That's right. Behe plays the victim card and claims that he's the victim of an ad hominem attack. But he wasn't. For a real ad hominem, it requires that the offender substitute an argument with a mocking. This is not the case. Rather, the argument was supplemented with a mocking that matched the mockery Behe and his fellows make of science.
But after that, is Behe finally ready to grow up? I'm not going to pretend I understand the technical exchange any more than Behe would be able to follow articles in the Astrophysical Journal (although Behe's buddy Dembski apparently knows everything about everything), but there's a few keys phrases that are amazingly typical of creationists trying to worm their way out of being confronted with evidence.
#1) "It is not clear to me why you call that Smith’s "core argument."" - Translation: I don't get it because I'm too busy repeating my claims ad nauseum to actually read anything. Careful Behe. You let that pesky reality pile up on you too long and it will bite you in the ass like it did on the stand at Dover.
#2) "...as her own citations show" - Translation: ...as her own citations show if you ignore everything except that introductory sentence used as a literary device, disregard all the evidence that supports her and buy into my quote mining bullshit. FTK might consider out of context quotes as indicative of "an open issue", but those of us that keep reading to discover the issue is well on the way towards a resolution don't buy into such sleazy tricks.
#3) "I think this is a trivial biochemical change..." - Call it trivial and ignore it. Or if "trivial" isn't your cup of tea, you can always call it pathetic.
I'll wait for a layman's version of the technical bits, but right now, it's looking pretty clear that Behe is just up to the same old nonsense: Flaunt, cry, obfuscate. Someone let me know when the reruns are over and something new is on.
Meanwhile, Behe has the audacity to say, "One of the very basic prerequisites for education is to be able to engage in civil discourse...".
Guess what Behe, so is actually backing up your arguments without lying.
The M81 Group
As I've mentioned before, M82 is one of my favorite galaxies. It's an exciting galaxy that had a collision with its neighbor M81, which is also chewing on NGC 3077, a while back. The results of this are having all sorts of exciting effects not only on M82, but also in the resulting mess from the collision.
These galaxies look like they're quite independent, but when astronomers Yun, Ho, and Lo started mapping atomic hydrogen in 1994, it turned out there were large bridges of gas between the galaxies. This sort of thing happens when galaxies interact due to tidal forces; the galaxies get stretched because the end closer to the other galaxy is being pulled on more than the far end. This is very well illustrated by galaxies that are very obviously interacting, such as the Mice or the Antennae. We can even find these long stretched out tails around our own galaxy where we've torn apart dwarf galaxies that have gotten too close.
But not to be content with just saying that the galaxies were related, astronomers went so far as to actually model the system and try to recreate the observed structure! This isn't an easy task with even two galaxies, but here we have three that are interacting. In this image, you can see just how closely their result matches with the actual observed morphology. The overall shapes, the angles, the relative sizes all match with amazing precision. Pretty nifty.
Meanwhile, tidal tails aren't just pretty. Clumps can form in them, containing thousands of times the mass of the sun worth of raw materials. In some of these knots, large numbers of young, blue stars have been discovered, suggesting that they can form new dwarf galaxies (Markova, 2002, Ciardullo, 2004). But this high rate of new star formation isn't limited to the tidal tails. M82 is undergoing such high star formation that it's blowing the galaxy apart.
I've talked a bit about how galactic interactions form new clusters, but M82 has them aplenty! Of the 650 clusters found in M82 by Chavez et al., 400 of them are in the area where starburst is no longer occurring, but that still leaves 250 brand new clusters in the area where the highest amount of star formation is taking place. And these clusters are massive.
Although these newly formed clusters have a distinct difference from what are typically considered to be globular clusters, it's possible that they may be the precursor to globular clusters. To determine this, the group is looking at how well such clusters can survive aging. To make it, clusters need to be able to survive three main processes.
The first is the pressure from early supernovae when the massive stars die. This is nicknamed the "infant mortality" stage and it lasts about 107 years. Next up is mass loss from stars decreasing the overall mass of the cluster and allowing it to drift apart. Another factor of 10 longer and if the cluster's still there, it should be OK. Last up are multibody interactions. There's two main forms to this. One is something I've discussed previously: tidal stripping. Just like the interaction of the galaxies in this association can draw out tidal tails, the same happens to clusters as they orbit the galaxy. As they get drawn out, the cluster disperses. The other is gravitational interactions within the cluster itself. Some stars will pass too close to another star and get a gravitational slingshot out of the cluster, again adding to loss. But if the cluster can make it past all these hurdles, and become a "relaxed system," it should be relatively stable.
The ones that survive become full fledged adult clusters, either globular or open depending on the number of stars. The question is whether or not these supermassive star clusters in M82 will survive to adulthood. Fortunately for the clusters in M82, they've already hit the 107 year mark, so many are well on their way. Based on their masses and sizes, the group expects that many of these clusters should survive to become brand new globular clusters.
And of course, where there's new stars, there's massive stars. And massive stars live fast, die young, and go out with a bang. More accurately, they go supernova. And as I've mentioned before, supernovae help seed the universe with heavy elements. Interestingly enough, the ratio of Silicon and Sulfur to that of Oxygen is unusually high. Too high, it seems, for the typical run of the mill supernovae to account for it. Thus, Umeda et al. (2002), have suggested that a good number of these massive stars were so massive, that they didn't end in just regular supernovae, but rather as the even more powerful hypernovae, which have a different metal output. Given that the lifetimes of these massive stars are nearly identical (~107 years) to the time that the rapid star formation occurred, this would seem like a plausible scenario since it would otherwise be a surprising coincidence.
It should go without saying that these huge supernovae are putting out some pretty intense stellar winds, which are whipping up the remaining gas, making huge bubbles. One group thinks that the shock front may be the cause of compact radio sources. The other leading hypothesis is that supernova remnants themselves may be the source.
Radio isn't the only non-visual regime in which there's some activity though. M82 is also highly active in the X-ray due to some supermassive black holes that are enjoying a feeding frenzy with all the activity. But black holes aren't something I've been much into, so I won't bother going into any detail on the current work.
Regardless, M82 and the rest of the M81 group is a pretty exciting set of galaxies in which a lot of fundamental astronomy is happening.
Yun, S., Ho, P.T.P., Lo, K.Y., Nature, 2002, 372, 530.
Makarova, L. N., et al., 2002, A&A, 396, 473.
Mayya. Y.D., et al. 2007, arXiv:0710.2145v1.
Hideyuki, U., et al., 2002, ApJ, 578, 855.
These galaxies look like they're quite independent, but when astronomers Yun, Ho, and Lo started mapping atomic hydrogen in 1994, it turned out there were large bridges of gas between the galaxies. This sort of thing happens when galaxies interact due to tidal forces; the galaxies get stretched because the end closer to the other galaxy is being pulled on more than the far end. This is very well illustrated by galaxies that are very obviously interacting, such as the Mice or the Antennae. We can even find these long stretched out tails around our own galaxy where we've torn apart dwarf galaxies that have gotten too close.
But not to be content with just saying that the galaxies were related, astronomers went so far as to actually model the system and try to recreate the observed structure! This isn't an easy task with even two galaxies, but here we have three that are interacting. In this image, you can see just how closely their result matches with the actual observed morphology. The overall shapes, the angles, the relative sizes all match with amazing precision. Pretty nifty.
Meanwhile, tidal tails aren't just pretty. Clumps can form in them, containing thousands of times the mass of the sun worth of raw materials. In some of these knots, large numbers of young, blue stars have been discovered, suggesting that they can form new dwarf galaxies (Markova, 2002, Ciardullo, 2004). But this high rate of new star formation isn't limited to the tidal tails. M82 is undergoing such high star formation that it's blowing the galaxy apart.
I've talked a bit about how galactic interactions form new clusters, but M82 has them aplenty! Of the 650 clusters found in M82 by Chavez et al., 400 of them are in the area where starburst is no longer occurring, but that still leaves 250 brand new clusters in the area where the highest amount of star formation is taking place. And these clusters are massive.
Although these newly formed clusters have a distinct difference from what are typically considered to be globular clusters, it's possible that they may be the precursor to globular clusters. To determine this, the group is looking at how well such clusters can survive aging. To make it, clusters need to be able to survive three main processes.
The first is the pressure from early supernovae when the massive stars die. This is nicknamed the "infant mortality" stage and it lasts about 107 years. Next up is mass loss from stars decreasing the overall mass of the cluster and allowing it to drift apart. Another factor of 10 longer and if the cluster's still there, it should be OK. Last up are multibody interactions. There's two main forms to this. One is something I've discussed previously: tidal stripping. Just like the interaction of the galaxies in this association can draw out tidal tails, the same happens to clusters as they orbit the galaxy. As they get drawn out, the cluster disperses. The other is gravitational interactions within the cluster itself. Some stars will pass too close to another star and get a gravitational slingshot out of the cluster, again adding to loss. But if the cluster can make it past all these hurdles, and become a "relaxed system," it should be relatively stable.
The ones that survive become full fledged adult clusters, either globular or open depending on the number of stars. The question is whether or not these supermassive star clusters in M82 will survive to adulthood. Fortunately for the clusters in M82, they've already hit the 107 year mark, so many are well on their way. Based on their masses and sizes, the group expects that many of these clusters should survive to become brand new globular clusters.
And of course, where there's new stars, there's massive stars. And massive stars live fast, die young, and go out with a bang. More accurately, they go supernova. And as I've mentioned before, supernovae help seed the universe with heavy elements. Interestingly enough, the ratio of Silicon and Sulfur to that of Oxygen is unusually high. Too high, it seems, for the typical run of the mill supernovae to account for it. Thus, Umeda et al. (2002), have suggested that a good number of these massive stars were so massive, that they didn't end in just regular supernovae, but rather as the even more powerful hypernovae, which have a different metal output. Given that the lifetimes of these massive stars are nearly identical (~107 years) to the time that the rapid star formation occurred, this would seem like a plausible scenario since it would otherwise be a surprising coincidence.
It should go without saying that these huge supernovae are putting out some pretty intense stellar winds, which are whipping up the remaining gas, making huge bubbles. One group thinks that the shock front may be the cause of compact radio sources. The other leading hypothesis is that supernova remnants themselves may be the source.
Radio isn't the only non-visual regime in which there's some activity though. M82 is also highly active in the X-ray due to some supermassive black holes that are enjoying a feeding frenzy with all the activity. But black holes aren't something I've been much into, so I won't bother going into any detail on the current work.
Regardless, M82 and the rest of the M81 group is a pretty exciting set of galaxies in which a lot of fundamental astronomy is happening.
Yun, S., Ho, P.T.P., Lo, K.Y., Nature, 2002, 372, 530.
Makarova, L. N., et al., 2002, A&A, 396, 473.
Mayya. Y.D., et al. 2007, arXiv:0710.2145v1.
Hideyuki, U., et al., 2002, ApJ, 578, 855.
Saturday, November 10, 2007
Why I'm Happy To Be An Atheist
Being an atheist isn't all gloom and doom. I'm not angry all the time. There's actually a lot to be happy about.
One of the problems I have with the theist mindset (which is especially prevalent among the creationists) is that it looks for the easy answers out. "Why bother with thousands of journal articles when can have all my answers packaged in one book?" it asks.
With atheism, you don't get any prepackaged answers. Science has become the default explanation, but unlike theists, those answers had to be worked for, instead of just having them handed down from on high. This alone doesn't mean they're any better any more than building your home yourself is any better than buying one.
But from these conclusions, we can instill messages. Fellow SOMA member Chuck Lunney put it,
As my mother will tell you, it's made me fiercely independent. I'm not one to ask for favors or hand me downs lightly. Struggling to overcome my own problems has made me explore the limits of who I am and what I am capable of.
This mindset has given me a consistent, logical approach to problem solving that extends just beyond examination of physical realities. The same methodology can also be used in the interpersonal relationships I share with friends. Spending the time to investigate emotions and the connections I share with others has lead to some very deep and amazing friendships that I cannot even fathom experiencing with a mindset that promotes blind acceptance and shallow thought.
Another advantage to this mindset is that it avoids hasty and irrational decisions. Every time I've heard about people being taken in by the silly Nigerian Email scam, it's always someone taking a "something for nothing" offer on blind faith. In several instances, victims have thought God was telling them to help this person (and help themselves). This is not to say that atheists are immune to such scams, but having a mindset that requires actually holding answers up to some sort of scrutiny greatly decreases the chances of getting taken in by frauds.
Another one of the things I'm quite happy about is that I have a general optimistic view of humanity. Unlike religion, which tells us that humans are all awful sinners and deserve eternal damnation unless they accept the particular deity of choice, atheism carries no such inherent emotional baggage. We're free to actually make informed decisions on one another. As I already noted, this doesn't mean we trust anyone willy nilly, but it does allow for optimistic skepticism.
Lastly, I'm glad for my time. Not just that I get to sleep in on Sunday mornings, but that I get to actually live my life without absurd notions about what I have to do or not do to to ensure eternal life. It's freeing to know that my time is my own and that, when I do give it, it's because I do so knowing I care about friends and humanity, and not because I'm trying to earn karma points for the afterlife. I have my life, and I'm not about to waste it in prayer, or kissingGod's Hank's ass, or mumbling worthless incantations.
I'm going to live it fully; Without reservations, self loathing, blindness, or any of the other nonsense that comes with the theistic mindset. This is what the atheist mindset gives us: Life.
And that's precious.
One of the problems I have with the theist mindset (which is especially prevalent among the creationists) is that it looks for the easy answers out. "Why bother with thousands of journal articles when can have all my answers packaged in one book?" it asks.
With atheism, you don't get any prepackaged answers. Science has become the default explanation, but unlike theists, those answers had to be worked for, instead of just having them handed down from on high. This alone doesn't mean they're any better any more than building your home yourself is any better than buying one.
But from these conclusions, we can instill messages. Fellow SOMA member Chuck Lunney put it,
Rather than being created apart and unique from the rest of the living biosphere, accepting the fact that humans are part of and intimately connected to the universe makes me care intensely about every little thing that exists.But it's not necessarily the answers and the messages we instill from them that are what it's all about. It's also the process of getting there. The idea of not taking the easy answers and taking things for granted that comes from the atheist mindset is something that has greatly influenced me as a person.
As my mother will tell you, it's made me fiercely independent. I'm not one to ask for favors or hand me downs lightly. Struggling to overcome my own problems has made me explore the limits of who I am and what I am capable of.
This mindset has given me a consistent, logical approach to problem solving that extends just beyond examination of physical realities. The same methodology can also be used in the interpersonal relationships I share with friends. Spending the time to investigate emotions and the connections I share with others has lead to some very deep and amazing friendships that I cannot even fathom experiencing with a mindset that promotes blind acceptance and shallow thought.
Another advantage to this mindset is that it avoids hasty and irrational decisions. Every time I've heard about people being taken in by the silly Nigerian Email scam, it's always someone taking a "something for nothing" offer on blind faith. In several instances, victims have thought God was telling them to help this person (and help themselves). This is not to say that atheists are immune to such scams, but having a mindset that requires actually holding answers up to some sort of scrutiny greatly decreases the chances of getting taken in by frauds.
Another one of the things I'm quite happy about is that I have a general optimistic view of humanity. Unlike religion, which tells us that humans are all awful sinners and deserve eternal damnation unless they accept the particular deity of choice, atheism carries no such inherent emotional baggage. We're free to actually make informed decisions on one another. As I already noted, this doesn't mean we trust anyone willy nilly, but it does allow for optimistic skepticism.
Lastly, I'm glad for my time. Not just that I get to sleep in on Sunday mornings, but that I get to actually live my life without absurd notions about what I have to do or not do to to ensure eternal life. It's freeing to know that my time is my own and that, when I do give it, it's because I do so knowing I care about friends and humanity, and not because I'm trying to earn karma points for the afterlife. I have my life, and I'm not about to waste it in prayer, or kissing
I'm going to live it fully; Without reservations, self loathing, blindness, or any of the other nonsense that comes with the theistic mindset. This is what the atheist mindset gives us: Life.
And that's precious.
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atheism
Friday, November 09, 2007
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