
A Four Planet System in Orbit, Directly Imaged and Remarkable - kilovoltaire
https://astrobiology.nasa.gov/news/a-four-planet-system-in-orbit-directly-imaged-and-remarkable/
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sbierwagen
This article neatly illustrates something I find interesting: the biases of
the various methods of detecting exoplanets.

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

Direct imaging more easily detects massive planets that orbit _far_ away from
their star. Every one of the planets that orbit HR8799 (that we've detected)
are farther out than Saturn, and many times heavier than Jupiter.

On the other hand, the transit and and radial velocity methods work better for
planets that are _closer_ to their star, and with radial planes that are edge
on to us. On the third hand, with the astromery method, it helps for the
orbital plane to be _face_ on to us, so we can detect the wobble in the host
star!

For all these methods, it helps if the star is both small and dim. The only
way we'll find out if Rigel A (~120,000x brighter than Sol) hosts a planet is
if we send a probe there.

~~~
padobson
>On the third hand...

Sounds these biases on exoplanets hit a little too close to home.

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hackuser
If it matters to you, you are not actually seeing the planets in motion:

> Wang said that the animation is based on eight observations of the planets
> since 2009. He then used a motion interpolation algorithm to draw the orbit
> between those points.

I wish NASA was more upfront with the enhancements it adds to media, including
often adding color and, in this case at least, adding motion.

~~~
adewinter
OK, you clearly did not read the article because you are incorrect.

That statement you quote is referring to the still image in the article, below
the video, which is of an entirely different star and system of planets
(Fomahault b).

The video has a time legend /embedded in the movie/, at the bottom of the
frame clearly showing when the observation for each frame of the video was
taken.

NASA was being plenty up front here, I think you maybe just skimmed the
article slightly too quickly.

~~~
greeneggs
No, he is correct. Eight of the frames in the animation are real observations.
Between these eight frames, the other frames are interpolated.

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marcosscriven
Is it correct to say this kind of direct imaging only works if the planets are
large and hot enough to have a significant infrared output of their own,
rather than light reflected from their star?

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HillaryBriss
> HR 8799 is 129 light years away

i know pretty much nothing about astronomy, which is probably why i find it
amazing that this planet-level imagery was collected by an earth-based
telescope. fantastic work.

i can't help but wonder: will we see more imagery/animations of other
exoplanets in the near future or is this just a rarity?

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ianai
Might not be the coolest plateary system we'll ever spot but I'm glad to have
lived to see the first.

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Jun8
Yep, the Warden Diamond has been verified
([https://en.wikipedia.org/wiki/Four_Lords_of_the_Diamond](https://en.wikipedia.org/wiki/Four_Lords_of_the_Diamond))!
Very imaginative and gripping series that I totally recommend.

