Icarus - The Farthest Normal Star Detected So Far

As you may or may not have heard in the science news, a blue giant star was detected by the Hubble Space Telescope (HST) and it has set the record for the detection of the most distant non-supernova star (by a factor of about 100).

The star was 9.3 billion light years from Earth when the light was emitted. Due to the expansion of the Universe it is now about 14 billion light years from us.

The star is so distant that it would normally not be detectable except for two fortunate coincidences.

The light of this star was magnified by the gravitational lensing effect of a galaxy cluster (called called MACS J1149+2223) that lies in between Earth and that star. This lensing effect magnified the star by a factor of about 600. Even that alone is still not enough to make it detectable.

The light was further magnified by the gravitational microlensing of an intervening star with an estimated mass of about 3 Suns. This microlensing effect further magnified that distant star by another factor of about 4 giving a total magnification of more than 2000.

Closing Words

The microlensing effect is a transient phenomenon. This means that it is a temporary effect as the microlensing star will soon be moving out of alignment and the additional magnifying effect will disappear.

It is hoped that this transient magnification effect will be something that the James Webb Space Telescope can take advantage of when it is finally launched (hopefully in May 2020).

If true, the Icarus Star will not be the only instance of this incredible coincidence and it could give astronomers the capability to detect and measure individual stars from the early Universe.

It is interesting to think that the gravitational lensing for this star has in effect made both the galaxy cluster and the intervening star a part of the optical system of the Hubble Space Telescope.

It is also interesting to note the the Icarus Star, being a blue super giant, did not live long as these types of large stars have lifetimes that are measured in millions of years and not billions of years. It was likely a cinder long before the light even reached the first lensing galaxy galaxy cluster.

So it took the birth life and death of this very ancient and very distant star plus the amazing coincidental alignment of a galaxy cluster and a microlensing star to direct enough photons to the Earth for the HST to detect it.

This chain of events made that photo which you can see above which in turn has launched a thousand articles including this blog post.

Thank you for reading my post.

Post Sources

Icarus Star Reference
Gravitational Lensing Reference
Gravitational Microlensing Reference
Hubble Space Telecscope Reference
James Webb Space Telescope Reference
Blue Giant Stars Reference