
The farthest star - yitchelle
http://www.syfy.com/syfywire/the-farthest-star
======
kirykl
Amazing to me is the causal influence this star has on the Earth from 9
billion light years away. Physically the influence is zero, but the meaning
humans are able to give it, makes it huge.

~~~
changoplatanero
It caused you to physically move your fingers and type that comment.

~~~
trypt
That's a cool observation. You could then forget about this whole event and
remember it again at the age of 90 and write another comment saying "I
remember back when this was discovered"

Human bodies are very chaotic in their responses to stimuli due to the ability
to react to old old memories...

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xenophonf
This line from the article is wrong:

> Over nine billion light-years away.

With a redshift of z=1.49, the light from SN Refsdal was emitted 9.34 billion
years ago, but the proper distance at the current time (a/k/a the co-moving
distance) is 14.4 Gly due to the metric expansion of space:

[https://en.wikipedia.org/wiki/SN_Refsdal](https://en.wikipedia.org/wiki/SN_Refsdal)

Here's the paper announcing the discovery:

[https://arxiv.org/pdf/1706.10279.pdf](https://arxiv.org/pdf/1706.10279.pdf)

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chiefofgxbxl
An amazing discovery. If we can see things that far away, it's a wonder what
we'll discover when we keep improving telescopes, introducing new telescopes
(e.g. Webb space telescope), and even build devices on other celestial bodies!
I'm looking forward to a permanent telescope on the far side of the moon where
Earthly signals are no distraction.

As for the article, it was distracting by the poor writing style (emphasis
mine). It's frustrating to hear people say "like" and "literally" all the time
in speech, but far worse to see it in written pieces:

\- "...point source ( _literally_ , a dot of light)"

\- "...galaxy, a star, you, me — bends space, _literally_ warps it"

\- "...too faint to see. _Like_ , hundreds of times too faint"

~~~
curtis
It's a blog post rather than a proper article. And it's by Phil Plait (AKA
"The Bad Astronomer") who has been writing with a similar tone for over a
decade now.

~~~
function_seven
I didn't notice the author, thanks for pointing out. I remember passing the
time between college classes reading Bad Astonomy in the computer lab. In
1997. Over a decade for sure...

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pmoriarty
Here's a nice size comparison of objects in the universe.[1] According to that
video (and a Wikipedia article on it[2]), the observable universe is 93
billion light years in diameter.

Yet the "farthest star" article says the farthest star is only 9 billion light
years away, which is ten times closer than the diameter of the observable
universe.

[1] -
[https://www.youtube.com/watch?v=4S69zZwYrx0](https://www.youtube.com/watch?v=4S69zZwYrx0)

[2] -
[https://en.wikipedia.org/wiki/Observable_universe](https://en.wikipedia.org/wiki/Observable_universe)

~~~
morganvachon
> _Yet the "farthest star" article says the farthest star is only 9 billion
> light years away_

I think you completely misread the article. This is the farthest star _we 've
been able to observe directly at its normal luminescence_, as in, not a
supernova. Granted, it is due to gravitational lensing.

The article never says this is the farthest star that exists, simply the
farthest (by far) that we've been able to directly observe.

~~~
euyyn
What are the farthest stars we've been able to detect?

~~~
morganvachon
The farthest directly observed objects are galaxies and quasars, to about 13
billion light years from us. We have indirect evidence of individual stars
that far out, but prior to this discovery the farthest directly observed
star[1] (SDSS J1229+1122) was 55 million light years away, so this is quite a
leap.

[1] [http://www.skyandtelescope.com/astronomy-news/the-most-
dista...](http://www.skyandtelescope.com/astronomy-news/the-most-distant-star-
everseen/)

------
tekkk
I started to wonder how on earth it's possible we can see it if the amount of
photons is still the same right? Well before I decided to blurt my
unproductive comment here on HN I researched this article on Quora
[https://www.quora.com/If-photons-have-no-mass-then-how-
does-...](https://www.quora.com/If-photons-have-no-mass-then-how-does-
gravitational-lensing-occur) which says that gravity increases the photons
energy, frequency and speed(I thought they travel at the constant speed of
light?) as they travel through space allowing those faint objects to be still
visible here on near-Earth space.

Yet if the amount of photons that travel is the same with a gravitional lense
or not I'd argue that the information to see a lot of other distant and faint
objects exists as well. We just need better instruments to detect them. And
probably there is a threshold after which the photon's energy become so small
that it regresses into a background noise. Well kinda obvious now that I wrote
it down.

~~~
DiThi
I think lensing implies we're receiving more photons that would otherwise be
scattered elsewhere.

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mozumder
> Once they found it in the 2016 images, the astronomers found it in other
> data as well. The apparent brightness of the star changed over time in the
> images. While a blue supergiant can change its brightness, it’s more likely
> LS1 is moving as it orbits the center of its own galaxy, and as it does so
> the effects of the gravitational lens change.

Can gravitational lensing really affect the brightness of an star traveling
around a galaxy within a few months timespan?

~~~
ISL
It doesn't affect the star, but it might influence the _image_ of a star
through the very imperfect lens formed by the foreground mass distribution.

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d_theorist
"This is incredible: Due to a quirk of cosmic geometry, astronomers have
detected the light from the farthest individual star ever seen."

That is perhaps the _least_ incredible thing I have ever heard. In fact, it's
very nearly a tautology.

The overall writing style of this article is very poor and distracting.

~~~
Tepix
Your quote is incomplete, the next two sentences are an important part of it:

" How far away is it?

Over nine billion light-years away."

To see the light of a star that far away is indeed "incredible" as in "so
extraordinary as to seem impossible".

The following paragraphs then explain why it appears to be legit (" Then I
read the paper, played with the math a little, and, sure enough, this appears
legit.").

