Don't give up on Planet Nine yet: Hubble 'scope finds just such a world a mere 336 light-years away The Hubble Space Telescope has spied a previously unknown exoplanet with similar properties as our Solar System's hypothetical object Planet Nine. This newly spotted body is living on the outskirts of another solar system 336 light-years away. Astronomers have not yet glimpsed Planet Nine after it was predicted that the …
What I find amazing is that we can find a planet in a system 336 light years away but we cant find something 5-10 times the mass of Earth in our own back yard, I mean it's probably only between 37 and 75 billion miles away, although it might be a bit cold and dark.
I don't think that's surprising: there are a huge number of stars to look at while there is only one Sun and a lot of the exoplanets we find are not really very like planets in the Solar system (Jupiter-mass objects in well sub-Mercury orbits, say); and finally Planet 9 is very likely not there at all – if there was good evidence for it we'd know where to look.
Well, this planet is ~3500 times more massive than earth, and is presumably around the diameter of Jupiter. Planet 9 is expect to be 5-10 the mass of the earth.
And while not quite heavy enough to ignite deuterium, this planet should still be bubbling like a witch's cauldron, which helps when you're looking in the near infrared. Whereas our planet 9 is probably icy and, if so, may be covered in soot.
Moreover we found this planet by looking in on another system. The region of interest was maybe a hundred milliarcseconds in diameter. We're trying to find planet 9 by looking out from our solar solar across the whole fucking sky.
But, apart from all that, I don't see why we haven't found planet 9 every bit as easily...
It tends to be easier to spot things when looking in from the outside than from the inside looking out. When it comes to planets, it's the difference between looking at a star and seeing a small wobble, and looking at the entire sphere of empty space surrounding us and hoping to see something tiny, dark, and barely moving. If you're looking at a forest from a nearby hillside, it's relatively easy to spot an extra tree growing a bit of a distance from most of the rest. If you're in the middle of the forest, it's pretty tricky to figure out where all the trees are.
"...it is hard to see how it can be known to have cleared the neighborhood around its orbit..."
Well, it's Marie Kondo moments are what suggests there might be a Planet 9. (Also, it's pretty steeply inclined so it won't have to do much cleaning.)
But clearing out an orbit amounts to a mass limit without anybody having to say exactly what mass a planet has to have. (Remember Pluto is less than a fifth of the mass of the moon.) A super-earth is going to make the grade.
Maybe cooler, but how much heat does our planets core generate? And we're just a little kitty planet compared to that one...
I think this discovery is a good example of how human science works, we've seen something interesting and we're thinking about what happened, and how it might have happened. And one day maybe we will know.
Jovian planets can generate a lot of heat. Jupiter emits significantly more energy than it receives from the some; this is powered by the planet's contraction (as I recall, it's diameter shrinks by about 1 cm per century). Certainly a Jovian or super-Jovian planet in the sort of a highly distant orbit proposed for Planet 9 would probably have the same characteristics and should stand out to a good IR telescope, if only we knew in which direction to point it!
"...super-Jovian planet in the sort of a highly distant orbit proposed for Planet 9..."
It's HD 106906 b that is eleven Jovian masses - bordering on brown dwarf.
Our proposed planet 9 is a super-earth - thought to be 5-10 times the mass of the earth. That's what makes it especially fascinating - we'll get to see a super-earth close up. The first question being whether it's gaseous or rocky.
As I said in another comment: such an object would definitely be detectable by gravitational microlensing, if you knew where to look for it.
Very light black holes like this are assumed to be primordial – to be a direct result of the big bang – as you say, if they exist. I think the general assumption is that they don't exist in significant numbers, but everyone wants to be wrong of course.
Planet-mass black holes definitely would have enough gravity to be detectable by lensing (technically microlensing) events. Light BHs like this are (or were) one of the candidates for dark matter, and one of the ways they have been largely ruled out is by surveys looking for microlensing events, and finding there are not nearly enough of them for such objects to make up a significant fraction of dark matter.
Even more astonishingly we have used microlensing events to detect exoplanets, which are, well, planet-mass objects.
Billiards with gravity :0)
Nudged back by a passing star seems to be a very tight set of circumstances where the passing star effectively imparts a 180 degree about turn.
My thinking is that after formation some planets will eventually come into close enough proximity to result in collisions or major orbital changes. Any planets gaining enough velocity from such an encounter has the possibility of escaping the local stars gravity well, so it follows that they can also be captured if they intersect* with another solar systems gravity well and there must be a lot of cold dark planets whizzing through the void.
It feels to me more likely that the vast majority of eccentric orbit results from either purely internal dynamics or being captured by another star entirely.
* A narrow band between falling into the star or another course change into the void for another bite at getting captured.
LISTER: Let me get this straight. Is she doing what I think she's doing?
CAT: Why? What DO you think she's doing?
LISTER: Playing pool with planets.
RIMMER: Is that possible?
LISTER: Well, it's not going to work. It's completely insane. It's
whacko. It's noodle-doodle.
CAT: I'm with you, buddy.
LISTER: No, not the idea, the shot. There's not enough side.
RIMMER: "Side?"
LISTER: Yeah, side-spin. It's a complete mis-cue.
RIMMER: What are you drivelling about, Lister? We're talking about a
computer with an IQ in excess of twelve thousand.
LISTER: Doesn't mean she can play pool. I can. Trust me. I know
whereof I speak. Aigburth Arms on a Friday night. They used to call
me Dave "Cinzano Bianco" Lister 'cause once I was on the table, you
couldn't get rid of me. This pool arm is as sound as a dollarpound,
and I promise you that shot _will not come off_. She's topped it,
that's what she's done, she's topped it! It's a felt-ripper! That
planet is off the table and into somebody's pint of beer.
RIMMER: We are talking about the trigonomics of four-dimensional space,
you simple-minded gimboid! We are not talking about some seedy game of
pool in a backstreet Scouse drinking pit.
LISTER: It's the same principle.
RIMMER: Of course it isn't!
LISTER: Rimmer, I promise you, THAT is a complete mis-cue. I say we
chuck Holly's coordinates in the bin and let ME take the shot.
RIMMER: Well, I say we put it to the vote. On one hand, we have a
computer, with an IQ in excess of twelve thousand, who has a total
grasp of astrophysics. And on the other hand, we have Lister, who, and
let's be fair to him, is a complete gimp. To whom do we entrust our
lives, the safety of this vessel and the future of everything? If it's
a tie, we go with Holly. What's your vote, Lister?
LISTER: Well, I vote for Dave "Cinzano Bianco" Lister.
RIMMER: One-nil to Listypoos. I vote for Holly. Cat?
CAT: Well, I agree with you, buddy. But I'm voting for Doodoo Breath.
The thing is, even though you're right, I could not bring myself to
vote for someone with your dress sense. I couldn't put my cross next
to the Bri-nylon party.
RIMMER: Down to you, Kryten.
KRYTEN: Well, I agree it's insane and suicidal, Sir, but I'm afraid I
have to side with the human.
LISTER: Brutal!
RIMMER: You're voting for El Dirtball?
KRYTEN: It's in my programming, Sir. A living human outranks a hologram.
I'm sorry.
LISTER: Three-one to me! Let's do it!
RIMMER: Congratulations, Kryten. Your vote has just killed everyone.
CAT: Will you relax? I've seen Gerbil-Face play down in the Recreation
Room. He's a diva! He can knock those striped balls around the table
all night long, and I tell you what, I have never once seen him lose a
single ball down one of those holes!
This was talked about here I think. If it's a small BH they expect to see accretion events as there's enough crud in the outer solar system that there should be some and they'd be fairly bright. I think it may depend on them being able to get enough time to do the survey. One nice thing (and I think the real reason for wanting to do the survey), is that by looking for accretion events they can place an upper bound on the number of primordial BHs in the Sun's neighbourhood, and this bound is lower than the one we have for such objects already. So if we assume the Sun's neighbourhood is not weird, this would be a new upper bound on the number of primordial BHs which exist, and hence on how much dark matter might be primordial BHs. I think everyone is expecting there not to be any, but if there were it would be cool as fuck.
Nice thing about the Vera Rubin telescope is that it will image the entire southern sky every night for 10 years. The computing infrastructure will then be able to automatically find anything new or moving in the solar system from the 20TB of nightly images from the 3200 megapixel camera. Unfortunately there could be a Starlink satellite in nearly every image it takes.
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