by Ann » Thu Apr 12, 2018 9:41 am
rj rl wrote: ↑Thu Apr 12, 2018 7:55 am
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
[quote="rj rl" post_id=281460 time=1523519723 user_id=141155]
[quote=Tszabeau post_id=281420 time=1523447655]
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?
[/quote]
I too have this question. How come one particular star was magnified?
[/quote]
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