High School First Interstellar Asteroid Found

[CygnusX-1]

A minor note: Wikipedia is incorrect - surprise, surprise! - about Haumea's density.

It is actually about 1.9 grams per cubic centimeter, nearly the same as Pluto's. See Ken Croswell and Nature.

 

[OmCheeto]

A minor note: Wikipedia is incorrect - surprise, surprise! - about Haumea's density.

It is actually about 1.9 grams per cubic centimeter, nearly the same as Pluto's. See Ken Croswell and Nature.

Oops!
I should have checked further.

wiki, regarding Haumea's density, in the side-bar:

Mean density

2.6 g/cm³[9][13]
1.885–1.757 g/cm³[8]​

My bad.

 

[OmCheeto]

ps. Any spiritual Ferengis, in the future, who should spot an extrastellaroid, with a 2:1 ratio, should shell out the money to catch it.

kg/m^3 Name
18,950 Uranium
19,320 Gold
19,350 Tungsten
19,840 Plutonium
20,200 Neptunium
21,040 Rhenium
21,450 Platinum
22,400 Iridium
22,600 Osmium

pps. You do the maths... (≈7 billion kg of gold plated latinum!)

 

[DaveC426913]

If it is stationary relative to our Solar Sysyem, it won't be approaching us so we would never observe it going through the SS.

Agree. The point is that its motion is a red herring to NR's argument (as I see it). It just confuses the issue of what he's trying to ask, which is about being bound to some star.
The object is not g-bound to Sol; is it possible it's not (and never was) g-bound to any other star system?
(Of course, it is g-bound to the Milky Way)

 

[rootone]

Of course, it is g-bound to the Milky Way)

Finding an intergalactic asteroid really would be very impressive.

 

[Ernest S Walton]

Finding an intergalactic asteroid really would be very impressive.

Presumably they are much more numerous than their interstellar cousins, considering galactic evolution is orders of magnitude more chaotic than mere stellar dynamics.

 

[stefan r]

Presumably they are much more numerous than their interstellar cousins, considering galactic evolution is orders of magnitude more chaotic than mere stellar dynamics.

Why are we presuming that? For an asteroid to escape the milky way from the solar system it would need to gain several hundred km/sec.

Is there any reason to believe population 2 or population 3 stars form a lot of asteroids?

 

[Ernest S Walton]

Why are we presuming that? For an asteroid to escape the milky way from the solar system it would need to gain several hundred km/sec.

Is there any reason to believe population 2 or population 3 stars form a lot of asteroids?

We see numerous examples of galactic mergers or large galaxies sucking material from their companions (M51 and NGC 5195 eg). I'm assuming these processes result in the transfer of quadrillions of asteroids, comets and other debris.

 

[OmCheeto]

... All I can say is that the universe gave us a great homework problem.
...

Ehr mehr gerd...
This is so much fun.

Given the wiki-posted range of interstellar Hydrogen density, and the possible time range this object has been traveling, I come up with a range of energies colliding with interstellar hydrogen of:

1. enough to cook a piece of toast, 0.03 kwh (given the minimums of 250,000 years & 0.4 mg of Hydrogen), to
2. 16 trillion kwh (13 billion years & 190 billion kg of Hydrogen)​

 

[snorkack]

Presumably they are much more numerous than their interstellar cousins, considering galactic evolution is orders of magnitude more chaotic than mere stellar dynamics.

Look at the stars. Extragalactic stars exist, but are less common than stars in galaxies.

 

[Ernest S Walton]

Look at the stars. Extragalactic stars exist, but are less common than stars in galaxies.

It is estimated that the current Solar System represents 2% of the mass of the original nebular cloud. The vast majority of asteroids are traveling through free space, not in orbit around a star.

 

[mfb]

... and most of them will still be in the galaxy. Their dynamics will be similar to the motion of stars.

Most of the initial mass of the gas cloud was hydrogen and helium, by the way, the fraction that stayed here doesn't tell you anything about solid objects.

 

[OmCheeto]

Yay!
For days I've been trying to figure out where this stick came from.
Fortunately, my Sol to Galactic coordinate transformation skills are nil, so I didn't even start on any calculations.
But it appears the smarties have been trying, and there seems to be a lot of head scratching going on:

NEWS
ASTRONOMY,PLANETARY SCIENCE
We still don’t know where the first interstellar asteroid came from
Clues from ‘Oumuamua’s speed and trajectory lead to answers all over the sky map
BY LISA GROSSMAN 11:38AM, DECEMBER 1, 2017​

So I don't feel so stupid.

 

[Al_]

Does it need a solar system to form an asteroid?

Not sure about the average asteroid. Maybe the definition matters here.
But this one, well, it's long and thin, so it is not formed by accretion. Which leaves collision. Two planets, or planetoids, or moons, or such an object and a pretty large asteroid collided. Now, maybe Oort cloud or interstellar objects sometimes collide, but interstellar space is so very huge that such collisions will be very rare. Far more likely to happen in the more crowded space a round a star. Hence, a solar system.

 

[Al_]

The object is not g-bound to Sol

Chasing it down with a rocket would require huge delta vee. But .. what about a rotating space tether? If we saw another one coming in, and had time to set it up, how long & strong would a tether have to be to have a tip velocity of say, 70km/sec? Is that even possible?

Erm, I answered my own question. Surprisingly, the max velocity does not increase with tether length. https://en.wikipedia.org/wiki/Space_tether#Practical_materials 2 or 3 km/sec is the best we can hope for.

 

[DrStupid]

Two planets, or planetoids, or moons, or such an object and a pretty large asteroid collided.

Yes, that's quite clear. But does the formation of such objects require a cloud with sufficient mass to form a star and not just planets? The paucity of small stars compared to the expected numbers (e.g. according to a Pareto distribution) suggests such a lower limit. But I didn't found corresponding sources.

 

[Al_]

Yes, that's quite clear. But does the formation of such objects require a cloud with sufficient mass to form a star and not just planets? The paucity of small stars compared to the expected numbers (e.g. according to a Pareto distribution) suggests such a lower limit. But I didn't found corresponding sources.

I see. Doh.
But, thinking about it, not unrelated is the question of how did it get up to 26km/sec? Was it due to the speed of the source objects relative to us as they dive toward a star, or just relative to us as they go their own way along between the stars? I suppose a star's involvement makes it more likely, and a big star more so? Look at it another way - if a cloud of dust formed a planet or two, without a star, why would a piece come flying at us so fast, unless the original cloud was going fast. Has it already done some flybys of stars, and completely lost all relation to it's cloud?

 

[snorkack]

I see. Doh.
But, thinking about it, not unrelated is the question of how did it get up to 26km/sec? Was it due to the speed of the source objects relative to us as they dive toward a star, or just relative to us as they go their own way along between the stars?

Relative to Sun. Which is moving at 20 km/s relative to local standard of rest.

What were the relative directions? What was the speed of Oumuamua relative to local standard of rest?

 

[DrStupid]

how did it get up to 26km/sec?

Speed is relative. It could ask how we got up so fast. Such a relative speed is not unusual in interstellar space.

 

[mfb]

20 km/s is a typical relative speed of stars. 26 km/s is nothing special.

But it appears the smarties have been trying, and there seems to be a lot of head scratching going on:

Well, there is a reasonable accuracy for the direction it came from, but finding a specific system is much harder as there is no obvious nearby star in that direction.

 

[CWatters]

Sorry if already mentioned but apparently oumuamua is getting faster...

https://www.standard.co.uk/news/int...leaving-nasa-scientists-baffled-a3875736.html

 

[stefan r]

Sorry if already mentioned but apparently oumuamua is getting faster...

https://www.standard.co.uk/news/int...leaving-nasa-scientists-baffled-a3875736.html

Did they report the delta-v?

 

[mfb]

He said: “This additional subtle force on ′Oumuamua likely is caused by jets of gaseous material expelled from its surface,”

“This same kind of outgassing affects the motion of many comets in our solar system.”

The original source

The observed accleration peaks at a few times 10^-6 m/s², or 30 m/s over one year. As its passage was faster, the total delta_v is smaller but an exact number needs an integral.

 

[DaveC426913]

It seems our little asteroid friend is actually a comet, venting gas.

 

[stefan r]

It seems our little asteroid friend is actually a comet, venting gas.

I thought you had to see the gas/dust in order for it to be called a comet. It should be called a "solar thermal rocket".

 

[rootone]

It just fired up the low tech impulse motors
the AI is now going to head to next the next interesting destination.
Only some curious white noise around the star Sol.

 

[at94official]

I had loads of fun this morning figuring out where the "25 km/s" number came from.
I think I did my maths correctly, as I came up with a figure of 25.7 km/sec.

Another number I came up with was, that if it was from Vega, it would have taken 580,000,000 years to travel that distance.
Though, as indicated by another of your simulations, Vega was probably nowhere near where it came from, that far back.
(Our galaxy looks like a busy airport when you look at it in 1000years/increment timescales. Freakin' stars flying everywhere!)

ps. Any idea who runs "projectpluto.com"? They seem to know what they are talking about:"Pseudo-MPEC" for A/2017 U1

[edit: millions of millions sounded too much like Sagan]

How did you figure all out of this? With my knowledge, solar systems move uniquely towards the center of our Galaxy, there's no way Vega is in there, from the direction of the Asteroid. Is it?

My knowledge in Astronomy is very little, I would love your direct and simple explanation.

Thanks,
Austin

 

[davenn]

With my knowledge, solar systems move uniquely towards the center of our Galaxy,

the solar system is orbiting the core of the Milky Way, as in the same ways the Earth orbits the Sun

 

[at94official]

the solar system is orbiting the core of the Milky Way, as in the same ways the Earth orbits the Sun

Right, and we can't go back from the same spot, ever. Right?

 

[davenn]

Right, and we can't go back from the same spot, ever. Right?

probably not exactly the same spot, but after one full orbit around the outer rim of the galaxy,
the solar system will be in a reasonably similar location ( one full orbit takes around 250 million years, from memory)