Starship Asterisk*

Posted: **Fri Jan 24, 2014 9:25 pm**

Some galaxies, like Andromeda, are obnoxiously close when you're using a telescope like Hubble. It's good if you want to study the individual stars but it's really hard to get an overall picture of a galaxy that close. M82 takes about 4 Hubble frames to fit into a single image. It's close enough to study individual stars and globular clusters but far enough to easily create a mosaic of the entire galaxy, too. It seems ideally suited for some observations, including this supernova.

Posted: **Fri Jan 24, 2014 10:39 pm**

geckzilla wrote:
[M82] seems ideally suited for some observations, including this supernova.

Except for the possible galactic schmutz in the way.

Posted: **Fri Jan 24, 2014 10:56 pm**

...Which is ubiquitous and something astronomers are used to dealing with?

Posted: **Fri Jan 24, 2014 11:08 pm**

I spent a while looking at M82 Wednesday night. It appeared as a small streak of fuzz at 113x in my 127mm schmidt cassegrain. No evidence of a supernova. I'll keep looking. Next weekend I'll take the 204 mm SCT to a dark location, and may have better luck.

On the question of M82's distance, and whether it's really far or very close -- one of the most satisfying things about astronomy, for me, has been learning the distances to different objects, and getting a sense of scale. I find the speed of light to be the best metric. The Moon is really close at less than two light seconds. The Sun, eight light minutes. Neptune, the farthest (non-dwarf) planet in our solar system, four light hours. The nearest star, four light years. Most of the stars we can see with our unaided eyes, tens to hundreds of light years, with a few exceptionally bright stars visible to the naked eye across thousands of light years. The center of our galaxy, about 25,000 light years. The whole Milky Way galaxy, 100,000 light years across. Andromeda, the nearest galaxy as big as our own, 2.5 million light years away. The closest groups of galaxies outside our local group, around 10 or 12 million light years. The center of the nearest big cluster of galaxies, in Virgo, 50 million light years. The brightest quasar, 2.4 billion light years distant, although now distances are starting to get complicated by the expansion of the universe. The theoretical edge of the observable universe, maybe 46 billion light years, although as physical constants and cosmological theories are refined this could change next week.

So is 12 million light years far away compared to the 100,000 light year diameter of our solar system, relatively close compared to Virgo cluster galaxies four times as far away, or a neighboring dust speck in the 92 billion light year wide expanse of the universe potentially perceptible to us today? You tell me.

Posted: **Fri Jan 24, 2014 11:15 pm**

Anthony, i think you told yourself pretty good, although i am wondering how our solar system got so BIG all of a sudden.

Posted: **Fri Jan 24, 2014 11:21 pm**

Beyond wrote:Anthony, i think you told yourself pretty good, although i am wondering how our solar system got so BIG all of a sudden.

Inflation 2.0. Guess you missed it.

Posted: **Fri Jan 24, 2014 11:22 pm**

Chris Peterson wrote:
Nitpicker wrote:On the other hand, the vast majority of apparently bright objects we see in the night sky (with just our eyes, binoculars, or a small telescope) are within the Milky Way, more than 100 times closer than M82.
True, but who cares about the Milky Way? Get rid of it completely, and the Universe would never notice the difference.

If I had to choose between getting rid of our galaxy or M82, I'd pick M82. Call me biased, but I really do care about the Milky Way more than any other galaxy. I am relatively comfortable with galactic scales, but much less so with the scales affected by the metric expansion of space. It is not that I'm sceptical at all, just a bit dim.

Posted: **Fri Jan 24, 2014 11:24 pm**

Beyond wrote:Anthony, i think you told yourself pretty good, although i am wondering how our solar system got so BIG all of a sudden.

Thanks Beyond. I would imagine that you're used to thinking about distances, and further distances ... .

By the way, I wonder if having a Type IA supernova so close by will allow astronomers to further refine our understanding of these supernovae and perhaps revise the distances that have been calculated using them as "standard candles." Hmm, an exploding cigar as a standard candle -- I can't wait for Art's next contribution to our high-minded symposium.

Posted: **Fri Jan 24, 2014 11:36 pm**

geckzilla wrote:Wait, Rob. Where are you trying to go in 20 years at .999999999999 c?

Remember, I'd get to M82 in 20 of my years in the ship, but back here on Earth, you stick-in-the-muds will experience about 12 million years. If M82 turns out to be boring, I'll come back in another 20 years (ignoring the humungous accelerations and decelerations involved, just to keep things simple) and we can all catch up on who won all the Super Bowls I missed. Then I'll sit down to watch Super Bowl 24002014. (I leave as a challenge for the reader converting that to Roman Numerals.)

Rob

Posted: **Fri Jan 24, 2014 11:41 pm**

Nitpicker wrote:
Chris Peterson wrote:
Nitpicker wrote:On the other hand, the vast majority of apparently bright objects we see in the night sky (with just our eyes, binoculars, or a small telescope) are within the Milky Way, more than 100 times closer than M82.
True, but who cares about the Milky Way? Get rid of it completely, and the Universe would never notice the difference.
If I had to choose between getting rid of our galaxy or M82, I'd pick M82. Call me biased, but I really do care about the Milky Way more than any other galaxy. I am relatively comfortable with galactic scales, but much less so with the scales affected by the metric expansion of space. It is not that I'm sceptical at all, just a bit dim.

I'd miss the things like planetary nebulas which we can only study up close and from within our own galaxy. I am curious about what kind of things are on the other side of the bulge, though.

rstevenson wrote:
geckzilla wrote:Wait, Rob. Where are you trying to go in 20 years at .999999999999 c?
Remember, I'd get to M82 in 20 of my years in the ship, but back here on Earth, you stick-in-the-muds will experience about 12 million years. If M82 turns out to be boring, I'll come back in another 20 years (ignoring the humungous accelerations and decelerations involved, just to keep things simple) and we can all catch up on who won all the Super Bowls I missed. Then I'll sit down to watch Super Bowl 24002014. (I leave as a challenge for the reader converting that to Roman Numerals.)

Time dilation. How does it even work?

Posted: **Fri Jan 24, 2014 11:45 pm**

geckzilla wrote:Time dilation. How does it even work?

I recommend one of two approaches. Either don't think about it at all, or think about it quite hard. It's casual thinking about things like that which will mess you up.

Posted: **Sat Jan 25, 2014 12:03 am**

Chris Peterson wrote:
geckzilla wrote:Time dilation. How does it even work?
I recommend one of two approaches. Either don't think about it at all, or think about it quite hard. It's casual thinking about things like that which will mess you up.

The only reason I'm thinking about it all is that this semester I'm taking Intro to Modern Physics. So I kinda have to think about it, for a while at least. (In class we're conveniently ignoring what would happen to my spaceship and me if I ran into a cloud of gas and dust at such a speed.)

Rob

Posted: **Sat Jan 25, 2014 12:07 am**

geckzilla wrote:
Time dilation. How does it even work?

Relativity + constant speed of light

http://www.kcvs.ca/site/projects/specialRelativity.html wrote:
[url=http://www.kcvs.ca/site/projects/specialRelativity.html][b][color=#0000FF][size=200]Photon Clock[/size][/color][/b][/url]

Posted: **Sat Jan 25, 2014 10:27 am**

rstevenson wrote:Remember, I'd get to M82 in 20 of my years in the ship, but back here on Earth, you stick-in-the-muds will experience about 12 million years. If M82 turns out to be boring, I'll come back in another 20 years (ignoring the humungous accelerations and decelerations involved, just to keep things simple) and we can all catch up on who won all the Super Bowls I missed. Then I'll sit down to watch Super Bowl 24002014. (I leave as a challenge for the reader converting that to Roman Numerals.)

Rob

I just had a vision of the Super Bowl of the distant future being played by robots (perhaps also with an alternative, lingerie-clad league). It would therefore be in hexadecimal: Super Bowl 16E3DDE.

Posted: **Sat Jan 25, 2014 1:44 pm**

"M82 is a mere 12 million light-years away (so the supernova explosion did happen 12 million years ago, that light just now reaching Earth)". OK that's not even in a backyard in galactic time/distance away, but it's still mind-boggling (well it is to me!).

I wonder what will happen to 'light' already moving when (if?) the Universe collapses back (opposite of a Big Bang). Sorry if I am being very unscientific as my mind is just wandering (and wondering) but can a collapse be faster than the speed of light and if so what will happen to the light.

Posted: **Sat Jan 25, 2014 3:45 pm**

DavidLeodis wrote:"M82 is a mere 12 million light-years away (so the supernova explosion did happen 12 million years ago, that light just now reaching Earth)". OK that's not even in a backyard in galactic time/distance away, but it's still mind-boggling (well it is to me!).

I wonder what will happen to 'light' already moving when (if?) the Universe collapses back (opposite of a Big Bang). Sorry if I am being very unscientific as my mind is just wandering (and wondering) but can a collapse be faster than the speed of light and if so what will happen to the light.

The currently accepted cosmological orthodoxy is that our universe will never collapse. It does not contain enough matter for gravity to overcome the "dark energy" that seems to be causing the accelerating expansion of space. Everything is expected to eventually dissipate into cold dark nothingness over the next gagillion years. The people who understand this stuff are very confident of this model. Their forebears, however, have been equally certain of other models. We'll have to wait and see.

Posted: **Sat Jan 25, 2014 3:49 pm**

Anthony Barreiro wrote:We'll have to wait and see.

The evidence for continued expansion is very strong. However, we should know by simple direct observation within a few quadrillion years, so lets keep this thread open.

Posted: **Sat Jan 25, 2014 4:16 pm**

Chris Peterson wrote:
The evidence for continued expansion is very strong. However, we should know by simple direct observation within a few quadrillion years, so lets keep this thread open.

Won't dark energy do that for us

Posted: **Sat Jan 25, 2014 4:17 pm**

Anthony Barreiro wrote:
DavidLeodis wrote:"M82 is a mere 12 million light-years away (so the supernova explosion did happen 12 million years ago, that light just now reaching Earth)". OK that's not even in a backyard in galactic time/distance away, but it's still mind-boggling (well it is to me!).

I wonder what will happen to 'light' already moving when (if?) the Universe collapses back (opposite of a Big Bang). Sorry if I am being very unscientific as my mind is just wandering (and wondering) but can a collapse be faster than the speed of light and if so what will happen to the light.
The currently accepted cosmological orthodoxy is that our universe will never collapse. It does not contain enough matter for gravity to overcome the "dark energy" that seems to be causing the accelerating expansion of space. Everything is expected to eventually dissipate into cold dark nothingness over the next gagillion years. The people who understand this stuff are very confident of this model. Their forebears, however, have been equally certain of other models. We'll have to wait and see.

For a long time I was truly scared that the universe was going to collapse. Not in my lifetime, obviously, but I was very scared that that it would happen some time, and I was particularly terrified that there might already be minuscule signs that the contraction (which would eventually lead to the collapse) had already started. So whenever I got the chance to talk to a professional astronomer, I asked him (there was rarely a "her") how we would know if the universe had already "stalled" and was preparing for a collapse. The astronomers always shook their heads and told me that they didn't know. But once I read an article, probably in Sky &Telescope, which said that the first signs of a universal contraction would be seen at intermediate distances. Close by we would see nothing, and at really large distances there would also be nothing to see. As to why that should be so, I don't remember. (Obviously that article was written before the acceleration of the universe was discovered.)

What would happen to light if the universe was to collapse, though? To me the answer seems obvious. The light from every part of the universe would be blueshifted, wouldn't it? The more the universe contracted, the more blueshifted light would become. A contracting universe should be ever more brilliantly bright, and at a certain point in time the collapsing universe should be filled with intensely "hard" gamma rays.

Ann

Posted: **Sat Jan 25, 2014 4:18 pm**

neufer wrote:
Chris Peterson wrote:
The evidence for continued expansion is very strong. However, we should know by simple direct observation within a few quadrillion years, so lets keep this thread open.
Won't dark energy do that for us

Probably!!!

Ann

Posted: **Sat Jan 25, 2014 4:30 pm**

geckzilla wrote:
neufer wrote:
geckzilla wrote:
[M82] seems ideally suited for some observations, including this supernova.
Except for the possible galactic schmutz in the way.
...Which is ubiquitous and something astronomers are used to dealing with?

http://www.slate.com/blogs/bad_astronomy/2009/05/27/m82_stifles_a_cosmic_belch.html wrote:
[b][color=#0000FF][size=200]SN 2008iz in M82[/size][/color][/b]
M82 stifles a cosmic belch
By Phil Plait, 2009/05/27

<<M82 is a weird galaxy. Deep images of it show vast amounts of gas obviously screaming out from it, as if the galaxy itself is exploding. For a long time it was thought that exploding stars were driving the gas out of the galaxy, but now we know that M82 is a starburst galaxy, where huge numbers of stars are being born. There are so many young, hot, massive stars being made that their fierce stellar winds are driving out the material seen. But those kinds of stars are exactly the types that live short furious lives, dying after only a few million years in titanic supernovae explosions. And now, astronomers are reporting that one has been seen... but the thing is, it can't be seen.

OK, here's the deal. Newly formed stars produce a lot of dust, complex molecules that are really good at absorbing visible light. M82 is lousy with new stars, so it's choked with that dust, which blocks the visible light coming from the galaxy's heart. However, infrared and radio light can go right through the dust. So the newly discovered supernova [SN 2008iz] was seen using radio telescopes; it's completely invisible in visible light. M82 is close, only 12 million light years away; if it weren't for all that dust the supernova would have been visible in binoculars!

The supernova, called SN2008iz, was only just discovered. It was seen in some older data from last year, but is not seen in data taken before then. The size of the object -- 20 light days, about 500 billion km, or very roughly 50 times the size of our solar system -- is pretty good evidence of it being the expanding debris from an exploding star, and the circular shape is also pretty conclusive; that's just what you expect from an expanding shell of gas. By combining the power of several radio telescopes, astronomers can see this object in some detail, even though from our distance it looks very small. Better yet, as the debris grows larger we can watch it expand, giving information on the energy of the explosion and what sort of material surrounds it as well, just as we did for a supernova that happened in 1987.

Supernovae create the heavy elements in the Universe, including iron and calcium which are in our bones and blood. I think that's enough to make them worthy of study all by itself... but they are also just so freakin' cool. Unimaginably, impossibly violent explosions due to a star ending its life not with a whimper but with a bang that can outshine entire galaxies... and even that mighty light can be hidden, shrouded by the expulsions of stars just being born. I'd say it's ironic, but since iron is actually involved that seems somehow wrong. Still. It's cool. And that's ironic too.>>

Posted: **Sat Jan 25, 2014 6:13 pm**

Thanks all for your very interesting and thought provoking replies to my wonderings about the collapse of the Universe. As to a blue shifted Universe then I hope Ann that there is some Rhythm and Blues playing, though perhaps it will just be a period when we will all feel very down in the blues. A bit

for that but still

ing.

Posted: **Sat Jan 25, 2014 7:10 pm**

Chris Peterson wrote: The evidence for continued expansion is very strong. However, we should know by simple direct observation within a few quadrillion years, so lets keep this thread open.

Given that the universe is currently understood to be less than 14 billion years old, and we don't have a clue what 69.3% of the stuff in the universe ("dark energy") is, I don't see how one could be at all confident predicting what's going to happen when the universe is millions of times older. If there were cosmologists somewhere in the universe more than five billion years ago, when the universe was smaller and denser and the expansion of the universe is believed to have been decelerating, they would have been entirely correct to extrapolate to exactly the sort of big crunch that gives Ann the heebie-jeebies. Who knows what our inconceivably remote future may hold?

In any event, I'm happy to live in universe during this epoch, when there are so many lovely stars to be seen, and there are sentient beings who can relate supernovae, dusty starburst galaxies, Alfred E. Newman, and Fidel Castro.

Posted: **Sat Jan 25, 2014 7:24 pm**

Anthony Barreiro wrote:Given that the universe is currently understood to be less than 14 billion years old, and we don't have a clue what 69.3% of the stuff in the universe ("dark energy") is, I don't see how one could be at all confident predicting what's going to happen when the universe is millions of times older.

I don't agree. If we have a solid theory of cosmology, it may be entirely reasonable to predict what's going to happen in the distant future with a fair degree of confidence.

If there were cosmologists somewhere in the universe more than five billion years ago, when the universe was smaller and denser and the expansion of the universe is believed to have been decelerating, they would have been entirely correct to extrapolate to exactly the sort of big crunch that gives Ann the heebie-jeebies.

This depends on their understanding of cosmology. Suggestions of something like dark energy showed up in our theories before it was observed. While our primary observational evidence lies in the increasing expansion rate of the Universe, that's not to say that other ideas, and other observations might not lead to the same conclusion. So cosmologists five billion years ago could well have predicted that the Universe would one day be dominated by dark energy and start expanding at a faster rate, despite their inability to observe that.

Who knows what our inconceivably remote future may hold?

"Know"? Well, nobody. But make some well reasoned predictions with a fair degree of confidence? Modern cosmology. Despite our personal cognitive biases, there's nothing to suggest that there's any such thing as an inconceivable future when viewed critically.

Posted: **Sat Jan 25, 2014 8:24 pm**

Chris Peterson wrote:
Anthony Barreiro wrote:
Given that the universe is currently understood to be less than 14 billion years old, and we don't have a clue what 69.3% of the stuff in the universe ("dark energy") is, I don't see how one could be at all confident predicting what's going to happen when the universe is millions of times older.
We're pretty sure now that the universe will keep expanding
but we don't know if the "Big Rip" will occur:
http://en.wikipedia.org/wiki/Big_Rip wrote:
[img3="The Phantom is the 21st in a line of crimefighters that originated in 1536,
when the father of British sailor Christopher Walker was killed during a
pirate attack. Swearing an oath on the skull of his father's murderer to
fight evil, Christopher started the legacy of the Phantom that would be
passed from father to son, leaving people to give the mysterious figure
nicknames such as "The Ghost Who Walks", "The Man Who Cannot Die"
and "Guardian of the Eastern Dark", believing him to be immortal."]http://upload.wikimedia.org/wikipedia/e ... omics2.jpg[/img3]
<<The Big Rip is a cosmological hypothesis first published in 2003, about the ultimate fate of the universe, in which the matter of the universe, from stars and galaxies to atoms and subatomic particles, is progressively torn apart by the expansion of the universe at a certain time in the future. According to the hypothesis, the scale factor of the universe and with it all distances in the universe will become infinite at a finite time in the future.

The hypothesis relies crucially on the type of dark energy in the universe. The key value is the equation of state parameter w, the ratio between the dark energy pressure and its energy density. At w < −1, the universe will eventually be pulled apart. Such energy is called phantom energy, an extreme form of quintessence. A universe dominated by phantom energy expands at an ever increasing rate. However, this implies that the size of the observable universe is continually shrinking; the distance to the edge of the observable universe which is moving away at the speed of light from any point moves ever closer. When the size of the observable universe becomes smaller than any particular structure, no interaction by any of the fundamental forces (gravitational, electromagnetic, weak, or strong) can occur between the most remote parts of the structure. When these interactions become impossible, the structure is "ripped apart". The model implies that after a finite time there will be a final singularity, called the "Big Rip", in which all distances diverge to infinite values.

According to the latest cosmological data available, the uncertainties are still too large to discriminate among the three cases w < −1, w = −1, and w > −1.>>

Starship Asterisk*

APOD: Bright Supernova in M82 (2014 Jan 24)

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SN(2008)iz up schmutz

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