washington nasa observe cosmic explosion GammaRB (28Mar2008)

sinpix · Post by **sinpix** » Wed Mar 26, 2008 12:48 am

powerful enought to be detect by eyes on earth and product 7.5 Milliards years (half visible univers) anybody get more information about this light heart...sebas! on of my girl friend had a paranoia trans, before mailing me the information from yahoo actuality and so forth, schizophrenia and cosmic phenomenon in relation or a thru paranormal appartement.

William Roeder · Post by **William Roeder** » Wed Mar 26, 2008 2:49 am

Wat U talk'n 'bout Willas?

Indigo_Sunrise · Post by **Indigo_Sunrise** » Wed Mar 26, 2008 2:43 pm

HEY! - This poster and 'neufer' should be able to communicate with each other perfectly!!!!

bystander · Post by **bystander** » Wed Mar 26, 2008 3:02 pm

Nah

While some of neufer's posts leave you wondering "Whaaaaaa

", they are at least intelligible. I even enjoy them. Sinpix has yet to post anything intelligible, let alone enjoyable.

Arramon · Post by **Arramon** » Wed Mar 26, 2008 4:55 pm

I believe he's referring to the gamma ray burst that was visible to the naked eye...
http://www.eurekalert.org/pub_releases/ ... 032008.php

=b

hehehhehe...... willis.

bystander · Post by **bystander** » Wed Mar 26, 2008 5:05 pm

Yes, You are probably right. I saw that one, too.

HEAPOW: Home of the Whopper? (2008 March 24)
NASA Satellite Detects Naked-Eye Explosion Halfway Across Universe

But how you got that from what was said escapes me.

Arramon · Post by **Arramon** » Wed Mar 26, 2008 5:16 pm

Looks like alot of the stars in this image are really old ones... from the hue of their color...? Or is it that they are hotter? Or a specific filter they are using... =/

*wallpapers it*

kovil · Post by **kovil** » Wed Mar 26, 2008 10:16 pm

Just the Facts, Jack. Spare us your BBT fantasy's.

NASA satellite detects record gamma ray burst explosion.

"This burst was a whopper," said Swift

The burst was detected at 2:12 a.m. EDT, March 19, and pinpointed the coordinates in the constellation Boötes.

Swift's other two instruments, the X-ray Telescope and the Ultraviolet/Optical Telescope, also observed brilliant afterglows. Several ground-based telescopes saw the afterglow brighten to visual magnitudes between 5 and 6 in the logarithmic magnitude scale used by astronomers. The brighter an object is, the lower its magnitude number. From a dark location in the countryside, people with normal vision can see stars slightly fainter than magnitude 6. That means the afterglow would have been dim, but visible to the naked eye.

In any kind of city, forget about it, plus you'd have to know exactly_where to look.

Later that evening, the Very Large Telescope in Chile and the Hobby-Eberly Telescope in Texas measured the burst's redshift at 0.94. A redshift is a measure of the distance to an object. A redshift of 0.94 translates into a distance of 7.5 billion light years, meaning the explosion took place 7.5 billion years ago, a time when the universe was less than half its current age and Earth had yet to form. This is more than halfway across the visible universe.

The problem in determining distance by redshift alone, is that redshift is not caused by recessional velocity alone, and the so called Cosmological Constant of Expansion of the Universe is incorrect. So a 0.94 redshift does not translate into a 7.5 Gly distance automatically, to the dismay and detriment of Mainstream Astrophysics calculators.

sinpix translator;
Milliards = billion light years
His girlfriend in France has a fear of sending him an email, as the USGovt records and searches for signs of terrorists on all electronic communications coming into this country. She doesn't need the false attention.

Arramon · Post by **Arramon** » Wed Mar 26, 2008 10:43 pm

Jack???? *looks around*

iamlucky13 · Post by **iamlucky13** » Wed Mar 26, 2008 11:56 pm

kovil wrote:In any kind of city, forget about it, plus you'd have to know exactly_where to look.

Not just where to look, but when to look. From what I've read it sounds like it peaked a little brighter than magnitude 6, but faded within a few hours. It probably looked a lot more impressive in gamma and xrays than secondary visible light.

JohnD · Post by **JohnD** » Fri Mar 28, 2008 9:29 am

Animation of visible burst from website of Polish "Pi of the Sky" team:
http://grb.fuw.edu.pl/pi/ot/grb080319b/normal.html

John

rstevenson · Post by **rstevenson** » Fri Mar 28, 2008 1:31 pm

Hello,

I'm particularly interested in the size of the explosion. It's described as "over 2.5 million times more luminous than the brightest known supernova". Is that big enough to be a galaxy buster? Or is the average distance between stars still too big for any kind of chain reaction, even with that scale of explosion? And how large a star was it to create such a vast explosion?

TIA

Rob

henk21cm · Post by **henk21cm** » Fri Mar 28, 2008 6:09 pm

rstevenson wrote:I'm particularly interested in the size of the explosion. Or is the average distance between stars still too big for any kind of chain reaction, even with that scale of explosion? And how large a star was it to create such a vast explosion?

Rob,

As a rule of thumb: the larger the length scale of an explosion, the longer the time scale of an explosion.

The Polish site reports a graph of a fading glow with a characteristic time scale of a minute. Applying the rule of thumb, the size of the explosion should be roughly a light minute. The sun is 8 light minutes away from the earth.

Thought experiment: suppose a part of a star explodes. The light of the star starts its journey to earth. The explosion trigger a second explosion in slightly more distant part of the star. Light of the first explosion travels away from earth, triggers the explosion and the light of the second explosion starts its journey towards earth. Since this light had to go forth and back, it reaches earth slightly later. The length of the explosion pulse is extended. The wider the pulse, the more distant parts of the explosion there are, the larger the exploding parts are.

For a whole galaxy to explode, the duration of the explosion must be many thousands of years.

The flaw in this reasoning is that a galaxy is not a continuum, but it is build of discrete objects. Each of these objects may explode, giving rise to enhanced discrete amounts of light, originating from individual starts within a galaxy.

Hope this helps.
Henk

iamlucky13 · Post by **iamlucky13** » Fri Mar 28, 2008 6:13 pm

The distance between stars would still be too high to "destroy" a galaxy. I don't know if the energy levels might blow away significant amounts of material from a nearby star such that it could disrupt fusion, but it wouldn't surprise in the case of a binary system.

No one actually knows for sure what causes gamma ray bursts. This is not necessarily the same as a supernova. There are actually two types of GRB's: long and short. The long GRB's probably are giant stars (100 or more times the mass of our sun) collapsing into black holes at the end of the life in an event that is basically a large supernova, or hypernova. These typically occur in regions of recent star growth, where such stars are likely to form.

The short type of GRB's are what the event we're talking about was. These are rarer and typically more distant. It sounds to me like the leading theory is they're caused by the merger of two neutron stars, or a neutron star and a black hole.

rstevenson · Post by **rstevenson** » Fri Mar 28, 2008 6:19 pm

Thanks to both of you for that clarification.

I gather from this that there is no direct (or at least, no obvious to me) correlation between the degree of luminosity (2.5 million times a large supernova) and the actual "bang" or shockwave that might be emitted.

[a few minutes later]
Prompted by your answers, I've just been to Wikipedia reading about Gamma Ray Bursts. Very interesting indeed.

Let's hope we never get a real close look at one in action.

Rob

Wagon25 · Post by **Wagon25** » Fri Mar 28, 2008 9:41 pm

Astronomy isn't my field, but I noticed in the caption of this 3/28 post it referred to this gamma-ray burst as being "halfway across the universe." I had serious questions about whether it could be known to be halfway across the universe, and whether or not the size of the universe could even be calculated. If so, what this area called that is "outside" the universe?
I noticed in a post someone used the phrase "visible universe." If that's what was actually meant, there seems to be a huge (literally infinite) difference between the terms "universe" and "visible universe". I guess it's possible the word "visible" was accidentally left out?

BMAONE23 · Post by **BMAONE23** » Sat Mar 29, 2008 4:15 pm

Lets not forget though that the lesser and farther away GRB's also occured billions of years ago (the latest one in particular) when the observed universe was only about half of its currently believed age.

BMAONE23 · Post by **BMAONE23** » Sat Mar 29, 2008 4:18 pm

We may need to alter the term "Visible Universe" and refer to the universe as "Obeservable Universe" as we can also see in un-visible light

bystander · Post by **bystander** » Mon Mar 31, 2008 12:42 pm

APOD: Across the Universe (2008 March 28)

iamlucky13 · Post by **iamlucky13** » Mon Mar 31, 2008 7:27 pm

rstevenson wrote:Thanks to both of you for that clarification.

I gather from this that there is no direct (or at least, no obvious to me) correlation between the degree of luminosity (2.5 million times a large supernova) and the actual "bang" or shockwave that might be emitted.

I'm not quite sure I understand the question, but I'll give it a shot.

A shockwave occurs when a disturbance propogates through a medium (like interstellar gas or a planetary nebula) at high speed. So the shockwave effects depend more or less on the presence and density of matter external to the original explosion.

The brightness is dependant upon the energy of the explosion.

In this case, there is a relation. Gamma ray bursts are normally so energetic that they flash almost entirely in the gamma ray range of the electromagnetic spectrum. This event was visible at much lower frequencies including visible light, however, because some interstellar medium was present to absorb the gamma rays then re-emit the energy at a lower frequency.

This absorption of the explosive energy would have resulted in a shock wave, but that isn't what was seen.

Hmmm...I don't think that fully answered the question, but hopefully it helps.

bystander · Post by **bystander** » Mon Mar 31, 2008 7:40 pm

Wagon25 wrote:Astronomy isn't my field, but I noticed in the caption of this 3/28 post it referred to this gamma-ray burst as being "halfway across the universe." I had serious questions about whether it could be known to be halfway across the universe, and whether or not the size of the universe could even be calculated. If so, what this area called that is "outside" the universe?
I noticed in a post someone used the phrase "visible universe." If that's what was actually meant, there seems to be a huge (literally infinite) difference between the terms "universe" and "visible universe". I guess it's possible the word "visible" was accidentally left out?

APOD: Across the Universe (2008 March 28)

The Universe is thought to be 13.7 billion years old. So something 7.5 bly away is over halfway across the universe. The earliest light we could see couldn't have been emitted before the beginning of time.

For a BBT discussion in layman terms on the size of the universe, see http://en.wikipedia.org/wiki/Observable_universe

Starship Asterisk*