Does Planet Nine really exist?

[Admin]

For the past few years, the possibility of a new (and big!) planet hanging around in the far outer solar system has tantalized scientists and the public alike. Is "Planet Nine" out there or not?

Does Planet Nine really exist? : Read more

 

[rod]

As this report stated "But in the years since the claim of a ninth planet made headlines, astronomers haven't snagged a picture of it. Which isn't too worrisome, at least not yet: if Planet Nine exists, it is very small (relatively) and very far away, making it hard to spot."

Other past reports show planet nine could be some 10 earth masses and orbit about 600 AU from the Sun. That suggest a period close to 14700 years, https://www.sciencedaily.com/releases/2016/10/161019173023.htm

"Brown and Batygin's discovery of evidence that the Sun is orbited by an as-yet-unseen planet that is about 10 times the size of Earth with an orbit that is about 20 times farther from the Sun on average than Neptune's changes the physics."

It seems continued searches come up short confirming planet nine is out there and that is how good astronomy measurements and testing work.

 

[Helio]

It seems continued searches come up short confirming planet nine is out there and that is how good astronomy measurements and testing work.

Yes. I would have liked to have seen something about the IR surveys. It was noted in the past, likely more than a year ago, that the IR surveys would have recorded such a large object, which would be glowing in IR. But, there was the chance that if the galactic plane happened to be in the background then it might go undetected. Are there any updates on this IR story?

 

[rod]

Helio, planet nine surveys are reported but results are not confirmed. https://astronomy.com/magazine/2020/01/in-pursuit-of-planet-nine, https://ui.adsabs.harvard.edu/abs/2019PhR...805....1B/abstract
https://www.foxnews.com/science/planet-9-already-found-study

Planet nine models I read about range quite a bit, e.g. 5 to 15 earth masses, distances 400 to 800 AU, eccentricity ranging 0.2 to 0.5, etc. Nothing conclusive I see, even at the NASA ADS site, https://ui.adsabs.harvard.edu/

 

[rod]

FYI, according to wikpedia, planet nine if it exists could be fainter than apparent magnitude +22, really faint target , https://en.wikipedia.org/wiki/Planet_Nine

 

[rod]

FYI. I did a MS SQL query of exoplanets using this site, http://exoplanet.eu/ searching for 5 to 15 earth masses. 156 reported. The min semi-major axis is 0.0116 and max is 4 AU from the host star. Nothing like the searches for planet nine claims in solar system some 400 to 800 AU from the Sun.

 

[Helio]

FYI. I did a MS SQL query of exoplanets using this site, http://exoplanet.eu/ searching for 5 to 15 earth masses. 156 reported. The min semi-major axis is 0.0116 and max is 4 AU from the host star. Nothing like the searches for planet nine claims in solar system some 400 to 800 AU from the Sun.

Yes, but that's would I would expect even if most every star has one of those. The transit method requires it to be in the plane of our view, but only closer objects will actually be seen to block starlight. A tiny fraction of a degree from our plane of view will make it unobservable. Worse yet is how long we would have to wait for it to cross the disk.

Given this orbital period issue, the Doppler approach hasn't a chance either, and I doubt direct imaging would work since it would have very little illumination.

[I should have a little time soon to crunch some magnitude values.]

 

[Helio]

FYI, according to wikpedia, planet nine if it exists could be fainter than apparent magnitude +22, really faint target , https://en.wikipedia.org/wiki/Planet_Nine

That looks about right. I used 600 AU, 25,000km R (ice planet), 50% albedo (Geo) and got 20.6 ap. mag.

The HST can see to about 31 ap. mag., JWST should be able to reach to about 34.

 

[rod]

FYI, here is a more detailed report on Planet Nine (P9) apparent magnitude calculations, the arxiv report is attached. https://ui.adsabs.harvard.edu/abs/2017Icar..282...19M/abstract "The magnitudes of P9 estimated in this study are given in Tables 10 – 12 where the planets Neptune, Jupiter and Pluto, respectively, are used for brightness models as described in the following paragraphs. In each case though the radius of P9 is scaled to 3.66 RE."

The tables present a detailed view with V band magnitudes 21 to 22 or so and different distances from 1 AU to 1120 AU or perihelion distance. I like the space.com report wrap up, "What's more, it's hard to square the existence of a ninth planet with the formation of the solar system as we currently understand it. Astronomers can, of course, work to fold in a ninth planet (say, by arguing that it's an ejected failed core of a planet or a captured rogue exoplanet), but the more complicated the scenario gets, the harder it is to swallow.

Without a smoking-gun picture of the planet, the astronomical community isn't going to be fully swayed by the wayward motion of a handful of iceballs in the outer solar system. So for now the search for a new planet continues."

 

[Helio]

Interesting paper. Thanks Rod.

When I thought about it, their 3.66 Re for No. 9 estimate is kinda amusing for an object that may not even exist. It reminds me of the Beatles White album played backwards where we can hear "number nine" clearly, but it was never there. I hope the planet can be found.