JohnD wrote: ↑Wed Apr 11, 2018 5:31 pm
Neufer calculates that this star is (was?) 14.523 Gigalight years away.
It is 14.5 Gly distant.
It was 5.8 Gly distant from our point in space when the currently observed light was produced.
It took that light 9.5 Gyr to travel between the two points, because the Universe was expanding between them.
What's the range in estimates of the Age of the Universe? About 14 Billion years?
13.8±0.02 Gyr is the most used value. But the value does depend upon the model under consideration.
So, it happened 9.5 Gyr ago (in our point in space relative time).
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Posted: Thu Apr 12, 2018 7:55 am
by rj rl
Tszabeau wrote: ↑Wed Apr 11, 2018 11:54 am
If this is not a nova... why can we see the star but not the galaxy that it is in or, are my eyes just failing?
I too have this question. How come one particular star was magnified?
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Tszabeau wrote: ↑Wed Apr 11, 2018 11:54 am
If this is not a nova... why can we see the star but not the galaxy that it is in or, are my eyes just failing?
I too have this question. How come one particular star was magnified?
The way I understand it, this was a case of "microlensing". The particular star was aligned, for a very short time, with a small mass concentration in the foreground. (Or rather, the star, the lensing mass concentration and the Earth were briefly lined up.) If a new picture was taken of this area, the star would probably not be seen, because the alignment of the star, the lensing object and the Earth would not be good enough any more. The line of sight between the Earth, the lensing mass concentration and the faraway star would be "broken".
Why wasn't the rest of the galaxy seen, although this particular star was "lensed into Hubble visibility"? Probably because the lensing object was too small to lens anything but the star in question, or because the star, Icarus, was by far the brightest object in its own vicinity. There might have been other stars nearby, but they may have been too faint to show up, even though they were lensed.
The lensed star could be a runaway star, so that there were no other bright stars around it.
Ann
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Posted: Thu Apr 12, 2018 12:49 pm
by Berder
Tszabeau wrote: ↑Wed Apr 11, 2018 11:54 am
If this is not a nova... why can we see the star but not the galaxy that it is in or, are my eyes just failing?
Think of it as a really strong magnifying glass panning over an object. You only see a tiny volume that's in focus. Space is mostly empty, even in galaxies, so the chances of having a star in the path at the right distance are very slim. We should just keep watching that spot, maybe it will pass over a galactic center or globular cluster, that would be spectacular.
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Justamaybe wrote: ↑Wed Apr 11, 2018 5:04 pm
Why all the excitement? "Was this flash the farthest star yet seen? An unexpected flash of light noticed fortuitously on Hubble Space Telescope images may prove to be not only ..."
It's all just a possibility right now .. but the way things go, by tomorrow the weight of opinion will prevail and the 'maybe' will have been removed .. while the proof is yet to be spoken of.
There is no such thing as proof in science. It isn't something that scientists look for.
AHA!!! So the world JUST A MAY BE FLAT!!!!!!!!! (I speaka asa an Italiano.)
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Justamaybe wrote: ↑Wed Apr 11, 2018 5:04 pm
Why all the excitement? "Was this flash the farthest star yet seen? An unexpected flash of light noticed fortuitously on Hubble Space Telescope images may prove to be not only ..."
It's all just a possibility right now .. but the way things go, by tomorrow the weight of opinion will prevail and the 'maybe' will have been removed .. while the proof is yet to be spoken of.
There is no such thing as proof in science. It isn't something that scientists look for.
AHA!!! So the world JUST A MAY BE FLAT!!!!!!!!! (I speaka asa an Italiano.)
The shape of the world isn't a scientific theory, but a scientific observation. We may misinterpret observations, of course, although I think the conclusion we arrive at when observing the shape of the Earth is reasonably solid.
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
There is no such thing as proof in science. It isn't something that scientists look for.
AHA!!! So the world JUST A MAY BE FLAT!!!!!!!!! (I speaka asa an Italiano.)
The shape of the world isn't a scientific theory, but a scientific observation. We may misinterpret observations, of course, although I think the conclusion we arrive at when observing the shape of the Earth is reasonably solid.
So you trust in someone else's observations. Someone else's images. Okay. But I saw it for myself .. my spirit was lifted out of my sleep to someplace between the earth and moon .. I was turned around, and saw the earth as a near-sphere. That's how I know it's not flat. Though you can't explain my experience through science, it is direct, personal proof.
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Tszabeau wrote: ↑Wed Apr 11, 2018 11:54 am
If this is not a nova... why can we see the star but not the galaxy that it is in or, are my eyes just failing?
Think of it as a really strong magnifying glass panning over an object. You only see a tiny volume that's in focus. Space is mostly empty, even in galaxies, so the chances of having a star in the path at the right distance are very slim. We should just keep watching that spot, maybe it will pass over a galactic center or globular cluster, that would be spectacular.