In the article they say that these planets are young and hot and they detected them in infrared by blocking light from the host star using special device. We would easily detect such super-massive hot planet at 300 AU in the solar system, but there is no reason for them to exist here since solar system is much older.
Just to emphasize one point you made: It appears the first companion planet (160 AU) was originally detected using direct imaging last year (preprint [1] is dated Dec 2019, see sec. 4 for methods).
And I guess the second one was announced in OP, making it a multi-planet system.
The point of this comment is to note that these 2 planets were originally detected by direct imaging, not by other techniques.
I was thinking that in out case hot or cold is not the main issue, but the area where to look.
If you look at a star 300 light years away, you just have to search a couple of pixels away from the star.
But if you searched for such a planet at 300 AU from out Sun, you would have a massive amount of space to search throug -- like a massive cilindrical wall of space around the Sun(if it was not exactly on our plane around the Sun).
But in anycase, I was wondering if we had such a planet in our solar system, but obviously cold by now, could we detect it?
Now, 300 AU is far away, but then, 14 times the mass of jupiter is heavy. But I'm not knowledged enough to do the math here.
On a 2nd thought, maybe not. How long would a year be for a planet that far outside? Maybe several hundred years? We'd need to be in the right window of time to spectate such effects in first place.
To be equivalent to the gravitational impact of Neptune the mass would have to be about 70,000 times the mass of Neptune. This is more equivalent to trying to find Planet Nine [0], which, although was also “discovered” through gravitational effects, those effects are much subtler and the planet might not exist and if it does, hasn’t been found.
Your comment jogged my memory. Ulysses, a cleverly-named solar-polar mission, used a deployment from the Shuttle, and a gravity assist from Jupiter, to reach an inclination of 80 degrees.
> Because direct injection into a solar polar orbit from the Earth is not feasible, a gravity-assist is required to achieve a high-inclination orbit. As a result, Ulysses was launched at high speed towards Jupiter in October 1990, after being carried into low-Earth orbit by the space shuttle Discovery. Following the fly-by of Jupiter in February 1992 /3/, the spacecraft is now travelling in an elliptical, Sun-centred orbit inclined at 80.2 degrees to the solar equator.
