Explanation: 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 an unusual gravitational lensing event but also an image of a normal star 100 times farther away than any star previously imaged individually. The featured image shows the galaxy cluster on the left complete with many yellowish galaxies, while on the right is an expanded square where a source appeared in 2016 that was not evident in 2011. The spectrum and variability of this source are strangely unlike a supernova, but rather appear more consistent with a normal blue supergiant star magnified by about a factor of 2000 by a confluence of aligned gravitational lenses. Dubbed Icarus, the source is in a galaxy well behind the galaxy cluster and far across the universe -- at redshift 1.5. If the lens interpretation is correct and Icarus is not an exploding star, further observations of it and other similarly magnified stars could give information about the stellar and dark matter content in the galaxy cluster and the universe.
The star, MACS J1149+2223 Lensed Star 1 (more simply known as “Icarus”) was about 9 billion light years away when it emitted the light now reaching Earth.
Ann
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Posted: Wed Apr 11, 2018 11:33 am
by orin stepanek
Nice catch by the Hubble!
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Posted: Wed Apr 11, 2018 11:54 am
by Tszabeau
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?
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Posted: Wed Apr 11, 2018 1:09 pm
by Sa Ji Tario
Look at the link "... gravitational lens aligned ..." and the same image appears, commenting on another topic
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
It is now 13.698 Gyr since the Big Bang. The age at redshift z = 1.5 was 4.226 Gyr. The light travel time was 9.472 Gyr. The comoving radial distance, is 14.523 Gly.
The star, MACS J1149+2223 Lensed Star 1 (more simply known as “Icarus”) was about 9 billion light years away when it emitted the light now reaching Earth.
Well...not exactly:
The current comoving distance between the Earth and the remains of Icarus is 14.523 Gly..
But the Universe has expanded (1+z) = 2.5 times since Icarus emitted the light we currently see.
Hence, when Icarus emitted that light it was 5.8 Gly (=14.523 Gly/2.5) away from the Milky Way.
<<The universe is way, way bigger than you can probably comprehend. And because of this astronomical (sorry) size, it can take a really long time for light to reach Earth from the cosmic wilderness. Even traveling at its immense speeds, by the time light from this distant star reached Earth, 9 billion years had passed. When Icarus released the photons currently hitting the Hubble’s cameras, Earth hadn’t even formed yet — it would be another 4.4 billion years before our solar system even began to coalesce from the dust of the universe. Such distant views of the universe are helping astronomers learn about what the universe was like before our time, even giving us glimpses back to the moments after the Big Bang.>>
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Posted: Wed Apr 11, 2018 4:38 pm
by bystander
Sa Ji Tario wrote: ↑Wed Apr 11, 2018 1:09 pm
Look at the link "... gravitational lens aligned ..." and the same image appears, commenting on another topic
This link is to the multiple images of the supernova Refsdal (see discussions here and here) lensed by the same galaxy cluster, MACS J1149+2223. That image is from 2015. Later subsequent appearances of Refsdal were predicted and imaged, also in 2015. Icarus was discovered in an image from 2016.
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Posted: Wed Apr 11, 2018 5:04 pm
by Justamaybe
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.
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Posted: Wed Apr 11, 2018 5:09 pm
by Chris Peterson
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.
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.
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Posted: Wed Apr 11, 2018 5:31 pm
by JohnD
Neufer calculates that this star is (was?) 14.523 Gigalight years away.
What's the range in estimates of the Age of the Universe? About 14 Billion years?
But the First Stars are said to have shone when it was about 100 million years old, ), 0.1 of a Billion, but we were tod those had been seen ten years ago. What makes this earlier?
JOhn
PS in the time I took to write that, neufer posted again - and this site asked me if I wnated to review my draft post in the elight of his! WHAT a good idea! Full marks, Asterisk!
PPS your embedded video didn't run, neufer, so I've let my post run.
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Posted: Wed Apr 11, 2018 5:38 pm
by Chris Peterson
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.
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Posted: Wed Apr 11, 2018 7:00 pm
by RJN
moontrail wrote: ↑Wed Apr 11, 2018 10:58 am
In the explanation given I miss the info about how far it`s supossed to be.
The word redshift is linked. Please follow the link get the distance in other units! I see this type of hyperlink one of the main utilities of hypertext writing in general -- by linking a word, the hypertext-writer has less of a need to explain that word and can exercise better brevity.
- RJN
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Posted: Wed Apr 11, 2018 10:28 pm
by ta152h0
Was this a " lucky shot " ?
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Posted: Thu Apr 12, 2018 12:12 am
by neufer
ta152h0 wrote: ↑Wed Apr 11, 2018 10:28 pm
Was this a " lucky shot " ?
A Fortuitous Flash Photobomb for the Farthest Star.
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Posted: Thu Apr 12, 2018 12:15 am
by Craig Willford
I am just staggered that they can get a spectrum from such a tiny dot of light in a field full of sources of light AND with undoubtedly such a miniscule AMOUNT of light!
Does Hubble have variable sized masks to allow only the selected source of light through to a spectroscope?
Astronomy sure has advanced since I was a kid! Wow.
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Posted: Thu Apr 12, 2018 1:46 am
by neufer
Craig Willford wrote: ↑Thu Apr 12, 2018 12:15 am
I am just staggered that they can get a spectrum from such a tiny dot of light in a field full of sources of light AND with undoubtedly such a miniscule AMOUNT of light!
Does Hubble have variable sized masks to allow only the selected source of light through to a spectroscope?
Whatever the mask used at least it can be used twice and then
a subtraction applied thanks to the temporary nature of the source.
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Posted: Thu Apr 12, 2018 5:01 am
by alter-ego
Chris Peterson wrote: ↑Wed Apr 11, 2018 5:38 pm
...
It was 5.8 Gly distant from our point in space when the currently observed light was produced.
...
That's right, and assuming a long lived star (not if it's a blue super giant), the star's redshift from our position in space was ~2.3 when the currently observed light was emitted.
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Chris Peterson wrote: ↑Wed Apr 11, 2018 5:38 pm
...
It was 5.8 Gly distant from our point in space when the currently observed light was produced.
...
That's right, and assuming a long lived star (not if it's a blue super giant), the star's redshift from our position in space was ~2.3 when the currently observed light was emitted.
You want to try rephrasing that
Re: APOD: Fortuitous Flash Candidate for the... (2018 Apr 11)
Chris Peterson wrote: ↑Wed Apr 11, 2018 5:38 pm
...
It was 5.8 Gly distant from our point in space when the currently observed light was produced.
...
That's right, and assuming a long lived star (not if it's a blue super giant), the star's redshift from our position in space was ~2.3 when the currently observed light was emitted.
You want to try rephrasing that
An observer in our galaxy when the Universe was ~4.3Gyr old, would measure that star's redshift to be ~2.3. (As seen today at z = 1.5, 4.3Gyr was when light from that star was emitted.)
Fortuitous Flash Candidate for the Farthest Star Yet Seen
You want to try rephrasing that 
