Planet Nine race, how is it going?

[nikkkom]

Pardon this possibly information-free post...

Since Mike Brown published his papers on the possibility of ~10 Mearth mass body beyond ~200 AU, and it was discussed a lot, I imagine now there is sort of a quiet race among astronomers in TNO field to find this thing.

IIUC, Mike has his own team in this race which netted many (most?) of recent large TNO discoveries.

One thing which would happen if Mike's team would have a preliminary detection candidate of P9, is Mike would stop talking about his P9 work. Discussing not-yet verified object would only reveal it to the "competition"; but talking about his P9 papers as if he still has no hint of discovery would be misleading on the verge of lying...

Well. The last post on www.findplanetnine.com from Batygin (Mike's co-author) which was specifically discussing P9 matters is from Since October 10, 2017. There were many posts before that in 2017, but since then, only one additional post, from an undergrad, not a core member of the team.

Maybe Mike found something!

 

[unusually_wrong]

I highly doubt there will be a planet 9 since there are requirements (set by IAU) and most are not met.

 

[fizzy]

That's a good point about the rules which demoted Pluto. But if P9 does not comply how will they class it ? At 10 Earth masses it can hardly be called a dwarf planet.

 

[nikkkom]

I personally will avoid any discussions about whether it should be "officially called a planet" or not. Not interesting.

 

[Eric Bretschneider]

I think a discussion on "officially called a planet" would have some merit. I think the members of the IAU didn't spend enough time thinking about the ramifications of their definition.

"Planet 9" if found would most likely not be an "official planet" even if it were 10 Earth masses - its orbit would be too large and the orbital velocity too low for it to have any reasonable chance of clearing its neighborhood. There is a mass relationship with the orbital radius. Move the Earth to the orbit of Neptune and its no longer a planet.

If a planet is ejected from its solar system it would no longer be a planet - it would not be in orbit around a star and by default it would not have been able to clear its neighborhood.

 

[fizzy]

10 EM does seem rather small, does that mean it is likely an ejected inner planet; a captured object or a comet ? What other categories are possible?

 

[unusually_wrong]

Move the Earth to the orbit of Neptune and its no longer a planet.

Agreed. The composition of the planet would be entirely wrong for the location.

If a planet is ejected from its solar system it would no longer be a planet - it would not be in orbit around a star and by default it would not have been able to clear its neighborhood.

Indeed. It would simply be a "planet" sized object.

 

[nikkkom]

I think a discussion on "officially called a planet" would have some merit.

How about it having some merit in a different thread?

 

[fizzy]

Sorry, it has somewhat diverged from your original.

"but talking about his P9 papers as if he still has no hint of discovery would be misleading on the verge of lying..."

well, without getting into second guessing why someone is or isn't talking, a simple reason is that there is only so long it makes sense to talk about a hypothesis without further input. He got quite a lot of attention to his work but until something happens there's not a lot more to say.

I would also think that once they are looking in the right direction they will see it. They will not need nine months to be sure.

It's a bit like evidence of collusion, you know whether you have found something or not.

 

[nikkkom]

"but talking about his P9 papers as if he still has no hint of discovery would be misleading on the verge of lying..."

well, without getting into second guessing why someone is or isn't talking, a simple reason is that there is only so long it makes sense to talk about a hypothesis without further input. He got quite a lot of attention to his work but until something happens there's not a lot more to say.

I would also think that once they are looking in the right direction they will see it. They will not need nine months to be sure.

I would be very happy if someone more knowledgeable chimes in on this...

From what I understand, at >200 AU distances from the Sun, detections quickly become harder (the reflected light intensity falls as d^4... ugh). If the body is currently closer to the aphelion (which is statistically more likely), it will not exactly stand out even in a Subaru image.

Also, you'd need about a year to get good parallax and thus, good distance measurement. Having just, say, two photos a month apart will not be enough to discriminate this body from background stars. You need a longer baseline.

So, if P9 hunters today would have two photos ~9 months apart with some tentative near-limit detections, can they confirm them using narrow-angle imaging? Well, narrow-angle image would only give you a better SNR, it will not give you a better parallax. You need to wait another several months, preferably about a year.

 

[russ_watters]

How about it having some merit in a different thread?

That thread is here:
https://www.physicsforums.com/threa...ficially-called-a-planet.952860/#post-6037455

And @Eric Bretschneider I made similar points in it.