Interstellar Asteroid 1I/2017 U1 'Oumuamua

[bystander]

First Interstellar Immigrant Discovered in the Solar System
Royal Astronomical Society | 2018 May 21

Images of 2015 BZ509 obtained at the Large Binocular Telescope Observatory (LBTO)
that established its retrograde co-orbital nature. The bright stars and the asteroid
(circled in yellow) appear black and the sky white in this negative image.
(Credit: C. Veillet / LBTO)

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A new study has discovered the first known permanent immigrant to our Solar System. The asteroid, currently nestling in Jupiter’s orbit, is the first known asteroid to have been captured from another star system. ...

The object known as ‘Oumuamua was the last interstellar interloper to hit the headlines in 2017. However it was just a tourist passing through, whereas this former exo-asteroid – given the catchy name (514107) 2015 BZ509 – is a long-term resident.

All of the planets in our Solar System, and the vast majority of other objects as well, travel around the Sun in the same direction. However 2015 BZ509 is different – it moves in the opposite direction in what is known as a ‘retrograde’ orbit.

“How the asteroid came to move in this way while sharing Jupiter’s orbit has until now been a mystery,” explains Dr Fathi Namouni, lead author of the study. “If 2015 BZ509 were a native of our system, it should have had the same original direction as all of the other planets and asteroids, inherited from the cloud of gas and dust that formed them.”

However the team ran simulations to trace the location of 2015 BZ509 right back to the birth of our Solar System, 4.5 billion years ago when the era of planet formation ended. These show that 2015 BZ509 has always moved in this way, and so could not have been there originally and must have been captured from another system. ...

An Interstellar Origin for Jupiter's Retrograde Co-Orbital Asteroid - F. Namouni, M.H.M. Morais

• Monthly Notices of the RAS: Letters 477(1):L117 (June 2018) DOI: 10.1093/mnrasl/sly057
  arXiv.org > astro-ph > arXiv:1805.09013 > 23 May 2018

viewtopic.php?t=37020

[neufer]

<<2015 BZ509 is an asteroid in a resonant, co-orbital motion with Jupiter. Its orbit is retrograde, which is opposite to the direction of most other bodies in the Solar System. It was discovered on 26 November 2014, by astronomers of the Pan-STARRS survey at Haleakala Observatory on the island of Hawaii, United States. It is the first example of a retrograde co-orbital asteroid with any of the planets. It is thought to be an interstellar asteroid captured 4.5 billion years ago into an orbit around the Sun.
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As of February 2017 its period was 11.65 years and its orbit had an eccentricity of 0.38 and an inclination of 163 degrees. Its period is close to the 11.86-year period of Jupiter. During one Jovian year, Jupiter moves 360° around the sun whereas 2015 BZ509 moves 366.3° in the opposite direction. The eccentricity of its orbit allows it to alternately pass inside and outside of Jupiter's orbit at its closest approaches of 176 million kilometers. Each time it passes near Jupiter its orbital elements, including its period, are slightly altered. Over thousands of years the angle between the position of the asteroid and its perihelion minus the angle between Jupiter and the asteroid's perihelion tends to oscillate around zero with a period of about 660 years and an amplitude of about 125°, although sometimes this difference slips by a whole 360°.

The adjunct diagram shows one complete orbit of asteroid 2015 BZ509 in a frame of reference rotating with Jupiter. The view is from the north looking south onto the Solar System. The dot in the middle is the Sun and the green circle is the orbit of Earth. The black circle shows the size of the orbit of Jupiter but in this frame of reference Jupiter (the red dot) stays almost stationary at the point on the circle directly to the right of the sun. The orbit of this asteroid is shown in blue when it is above the plane of the orbit of Jupiter, and it is shown in magenta when it is below the plane of the orbit of Jupiter.
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The second diagram shows one complete orbit of asteroid 2015 BZ509 in a frame of reference rotating with Jupiter. The view is from side looking into the Solar System. The Sun is the yellow disk in the middle. The plane of the orbit of Jupiter is shown in black, but in this frame of reference Jupiter (the red dot) stays at the right end of the black line. The orbit of this asteroid is shown in blue when it is above (north of) the plane of the orbit of Jupiter, and it is shown in magenta when it is below (south of) the plane of the orbit of Jupiter.

Perturbations from Jupiter maintain the stability of this orbit over millions of years. Simulations show that it has been in its co-orbital relation with Jupiter for at least a million years and will continue for at least another million years. It is somewhat of a mystery how this asteroid (or comet) got into this orbit, but it is thought that at some time in the distant past it was put into an orbit resembling its present orbit by an interaction with Saturn, and then its orbit was perturbed into the state it is in today. Likewise, in the far future it may eventually get close enough to Saturn to be expelled from its present co-orbital relation with Jupiter.

A statistical search for stable orbits shows that asteroid (514107) 2015 BZ509 has been in its current orbital state since the formation of the Solar System, yet it has a retrograde orbit. This suggests that it was captured from the interstellar medium about 4.5 billion years ago. The hypothesis was published 21 May 2018. If confirmed, it would have implications on current theories such as the detailed timing and mechanics of planet formation, and the delivery of water and organic molecules to Earth.>>

[neufer]

Click to play embedded YouTube video.

[neufer]

Click to play embedded YouTube video.

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<<Captain Peter “Wrongway” Peachfuzz made his debut in Jet Fuel Formula, the first Rocky & Bullwinkle story arc, originally broadcast late 1959 and early 1960. (The captain was named for Rocky and Bullwinkle producer Peter Piech.) According to the narration of Jet Fuel Formula, Peachfuzz was, from his youngest days, an incompetent sailor. As a child, even his toy boats sank. At the age of 18 he joined the Navy. He was awarded numerous medals, all of which were donated by the enemy. Sailing the wrong way through the Panama Canal and becoming the only captain of an icebreaker in the South Seas earned him the nickname "Wrongway." After receiving a large inheritance from an aunt, he purchased and took command of the S.S. Andalusia. His crew considered mutiny but decided rather to install a dummy control room, so that Peachfuzz would think he was in command, while the crew actually controlled the ship from another location. Unfortunately, Peachfuzz took a wrong turn and wound up in the real control room.

In Upsidaisium, it is revealed that Peachfuzz eventually sailed his ship up Wall Street, whereupon the S.S. Andalusia was given a permanent street address: 17½ Wall Street. In an effort to get rid of him, his board of directors arranged for him to get a government job counting penguin eggs (Q.2) because "we couldn't find any place further away." However, the secretary, a niece of the captain, mistyped the order and as a result Peachfuzz is made head of G.2, the main spy agency (Government Intelligence System). As "the muddle-headed head" of G.2, Peachfuzz demonstrates more examples of his usual incompetence when he tries to confiscate telephone books (because they list his name and telephone number) and sets up dozens of pairs of spies (who only spy on each other); likewise in Greenpernt Oogle, it is revealed that, having attacked the Supreme Court Building, he is reassigned to the one place felt fit for a man who is wrong all the time: the Weather Bureau. For a time he replaced the Greenpernt Oogle as the chief adviser for New Greenpernt, with the instructions to do the opposite of what he said.>>

[BDanielMayfield]

A statistical search for stable orbits shows that asteroid (514107) 2015 BZ509 has been in its current orbital state since the formation of the Solar System, yet it has a retrograde orbit. This suggests that it was captured from the interstellar medium about 4.5 billion years ago. The hypothesis was published 21 May 2018. If confirmed, it would have implications on current theories such as the detailed timing and mechanics of planet formation, and the delivery of water and organic molecules to Earth.

Well, possibly so, but this remains an unproven hypothesis. Reading the very next sentence in the same wiki article ...

Others suggest that 2015 BZ509 originated in the Oort cloud or that it acquired a retrograde orbit due to interactions with Planet Nine, and that it is a short term resident of its current resonance.

What made me take notice of this to dig a little deeper was the curious dual claims that it is both from beyond our solar system and that it has been here for almost the entire lifetime of our system. I thought, 'if it's really interstellar, couldn't it have been captured at any time since our system's formation?'

Bruce

[neufer]

'if it's really interstellar, couldn't it have been captured at any time since our system's formation?'

The probability of it being interstellar goes up the longer it can be demonstrated as being in a stable orbit
...especially if that time goes back to when the Sun was surrounded by its birth siblings.

[BDanielMayfield]

'if it's really interstellar, couldn't it have been captured at any time since our system's formation?'

The probability of it being interstellar goes up the longer it can be demonstrated as being in a stable orbit
...especially if that time goes back to when the Sun was surrounded by its birth siblings.

Yeah, that makes sense. The thought that the odds of interaction between systems would have been much higher back when the Sun was still part of an open cluster had occurred to me too ..., but this idea hardly proves beyond reasonable doubt that it's interstellar. Therefore I think the claim is questionable. Perhaps likely, but still speculative. Claiming that this is a definitive discovery of an interstellar origin for this body is going too far I think.

Bruce

[Chris Peterson]

'if it's really interstellar, couldn't it have been captured at any time since our system's formation?'

The probability of it being interstellar goes up the longer it can be demonstrated as being in a stable orbit
...especially if that time goes back to when the Sun was surrounded by its birth siblings.

Yeah, that makes sense. The thought that the odds of interaction between systems would have been much higher back when the Sun was still part of an open cluster had occurred to me too ..., but this idea hardly proves beyond reasonable doubt that it's interstellar. Therefore I think the claim is questionable. Perhaps likely, but still speculative. Claiming that this is a definitive discovery of an interstellar origin for this body is going too far I think.

I don't think anybody is making such a claim. The only thing that is certain to a high degree of confidence is that it's been in its current orbit for about a million years. Beyond that, the discussion becomes statistical in nature.

[BDanielMayfield]

Claiming that this is a definitive discovery of an interstellar origin for this body is going too far I think.

I don't think anybody is making such a claim. The only thing that is certain to a high degree of confidence is that it's been in its current orbit for about a million years. Beyond that, the discussion becomes statistical in nature.

The bold title of the RAS article and its first statements make this claim. They do declare:

First interstellar immigrant discovered in the Solar System

Last Updated on Tuesday, 22 May 2018 15:38
Published on Monday, 21 May 2018 12:00
A new study has discovered the first known permanent immigrant to our Solar System. The asteroid, currently nestling in Jupiter’s orbit, is the first known asteroid to have been captured from another star system.

That's a confident claim of discovery.

Bruce

[Chris Peterson]

Claiming that this is a definitive discovery of an interstellar origin for this body is going too far I think.

I don't think anybody is making such a claim. The only thing that is certain to a high degree of confidence is that it's been in its current orbit for about a million years. Beyond that, the discussion becomes statistical in nature.

The bold title of the RAS article and its first statements make this claim. They do declare:

First interstellar immigrant discovered in the Solar System

Last Updated on Tuesday, 22 May 2018 15:38
Published on Monday, 21 May 2018 12:00
A new study has discovered the first known permanent immigrant to our Solar System. The asteroid, currently nestling in Jupiter’s orbit, is the first known asteroid to have been captured from another star system.

That's a confident claim of discovery.

I always ignore what press releases say. They don't typically reflect what the scientists themselves say, as you can see if you go to the actual sources.

[neufer]

The bold title of the RAS article and its first statements make this claim. They do declare:

First interstellar immigrant discovered in the Solar System

A new study has discovered the first known permanent immigrant to our Solar System. The asteroid, currently nestling in Jupiter’s orbit, is the first known asteroid to have been captured from another star system.

That's a confident claim of discovery.

I always ignore what press releases say.

But NASA will need to know if it will be required to separate Bee Zee from
its parent bodies (i.e., Jupiter & Sol) and 'put into foster care or whatever'.

[bystander]

Hubble/VLT See 'Oumuamua Getting a Boost
ESA Hubble | ESO VLT | Science Release | 2018 Jun 27

Artist impression of 'Oumuamua - Credit: ESA/Hubble, NASA, ESO, M. Kornmesser

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New results indicate interstellar nomad `Oumuamua is a comet

`Oumuamua, the first interstellar object discovered in the Solar System, is moving away from the Sun faster than expected. This anomalous behaviour was detected using the NASA/ESA Hubble Space Telescope in cooperation with ground-based telescopes. The new results suggest that `Oumuamua is most likely a comet and not an asteroid. The discovery appears in the journal Nature.

`Oumuamua — the first interstellar object discovered within our Solar System — has been the subject of intense scrutiny since its discovery in October 2017 [1]. Now, by combining data from the NASA/ESA Hubble Space Telescope, the Canada-France-Hawaii Telescope, ESO’s Very Large Telescope and the Gemini South Telescope, an international team of astronomers has found that the object is moving faster than predicted. The measured gain in speed is tiny and `Oumuamua is still slowing down because of the pull of the Sun — just not as fast as predicted by celestial mechanics.

The team, led by Marco Micheli (European Space Agency) explored several scenarios to explain the faster-than-predicted speed of this peculiar interstellar visitor. The most likely explanation is that `Oumuamua is venting material from its surface due to solar heating — a behaviour known as outgassing [2]. The thrust from this ejected material is thought to provide the small but steady push that is sending `Oumuamua hurtling out of the Solar System faster than expected — as of 1 June, it is travelling with about 114 000 kilometres per hour. ...

Our Solar System's First Known Interstellar Object Gets Unexpected Speed Boost
NASA | STScI | HubbleSite | 2018Jun 27

Interstellar Asteroid Is Really a Comet
ESA Space Science | 2018 Jun 27

Is ʻOumuamua Really a Comet?
Canada-France-Hawaii Telescope | 2018 Jun 27

Is the Interstellar Asteroid Really a Comet?
Institute for Astronomy | University of Hawaii | 2018 Jun 27

Mysterious Interstellar Visitor Is a Comet — Not an Asteroid
Nature News | 2018 Jun 27

Non-Gravitational Acceleration in the Trajectory of 1I/2017 U1 (‘Oumuamua) - Marco Micheli et al

• Nature (online 27 Jun 2018) DOI: 10.1038/s41586-018-0254-4 (preprint)

[neufer]

Click to play embedded YouTube video.

[BDanielMayfield]

So then since this object is now shown to be a comet, is the elongated shape easier or harder to explain?

As comets go 'Oumuamua is extremely weak in activity level. That suggests to me that it may have made a great many close passes by the star/stars of its origin system.

Bruce

[Chris Peterson]

So then since this object is now shown to be a comet, is the elongated shape easier or harder to explain?

As comets go 'Oumuamua is extremely weak in activity level. That suggests to me that it may have made a great many close passes by the star/stars of its origin system.

Well, we don't have a clear distinction between comets and asteroids. There's a gray zone of overlap- comet-like asteroids and asteroid-like comets. Presumably there are different populations of objects defined by their formation environment, not just two. When they call this object a "comet" all they're saying is that it's outgassing volatiles. But asteroids might do that, too. In fact, we might expect that of very young asteroids. So this could be an asteroid-like body that was ejected from its stellar system very early, or a comet-like body that was ejected much later, after losing most of its volatiles.

[BDanielMayfield]

So then since this object is now shown to be a comet, is the elongated shape easier or harder to explain?

As comets go 'Oumuamua is extremely weak in activity level. That suggests to me that it may have made a great many close passes by the star/stars of its origin system.

Well, we don't have a clear distinction between comets and asteroids. There's a gray zone of overlap- comet-like asteroids and asteroid-like comets. Presumably there are different populations of objects defined by their formation environment, not just two. When they call this object a "comet" all they're saying is that it's outgassing volatiles. But asteroids might do that, too. In fact, we might expect that of very young asteroids. So this could be an asteroid-like body that was ejected from its stellar system very early, or a comet-like body that was ejected much later, after losing most of its volatiles.

Thanks. Good answer.

[starbrush]

I get the idea that outgassing could change 'Oumuamua's velocity; but I understand that the object is tumbling. Therefore how would any outgassing have a useful constant direction? Could the outgassing be so rapidly responsive e.g. to the Sun's heat that it still manages to outgas preferentially on its sunward side? At the moment my mental image is of a slow motion firecracker with no constant outflow!

[neufer]

ʻOumuamua's hyperbolic trajectory over the Solar System

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I get the idea that outgassing could change 'Oumuamua's velocity; but I understand that the object is tumbling. Therefore how would any outgassing have a useful constant direction? Could the outgassing be so rapidly responsive e.g. to the Sun's heat that it still manages to outgas preferentially on its sunward side? At the moment my mental image is of a slow motion firecracker with no constant outflow!

ʻOumuamua's hyperbolic trajectory left it moving on an exiting trajectory that is almost perpendicular to it's entering trajectory. Assuming that it is basically rotating around its minor axis it is likely that that fixed axis was pointing in the general direction of toward or away from the Sun either on its inward trajectory or (more likely) its outward trajectory.

[Chris Peterson]

I get the idea that outgassing could change 'Oumuamua's velocity; but I understand that the object is tumbling. Therefore how would any outgassing have a useful constant direction? Could the outgassing be so rapidly responsive e.g. to the Sun's heat that it still manages to outgas preferentially on its sunward side? At the moment my mental image is of a slow motion firecracker with no constant outflow!

Tumbling doesn't mean some kind of random rotational movement, it simply means rotating on two axes. So unless the outgassing was perfectly isotropic (which is unlikely), there's still be a net thrust vector and consequent deviation from a purely ballistic orbit.

[starbrush]

These are helpful, thanks to both. I guess observers will always be on the lookout for variations in rotation as well.

[Chris Peterson]

I get the idea that outgassing could change 'Oumuamua's velocity; but I understand that the object is tumbling. Therefore how would any outgassing have a useful constant direction? Could the outgassing be so rapidly responsive e.g. to the Sun's heat that it still manages to outgas preferentially on its sunward side? At the moment my mental image is of a slow motion firecracker with no constant outflow!

Tumbling doesn't mean some kind of random rotational movement, it simply means rotating on two axes. So unless the outgassing was perfectly isotropic (which is unlikely), there's still going to be a net thrust vector and consequent deviation from a purely ballistic orbit.

[bystander]

Tracking the Interstellar Object 'Oumuamua to Its Home
Max Planck Institute for Astronomy | 2018 Sep 25

A team of astronomers led by Coryn Bailer-Jones of the Max Planck Institute for Astronomy has tracked the interstellar object ‘Oumuamua to several possible home stars. The object was discovered in late 2017 – this was the first time astronomers have been able to observe an astronomical object from another star system visiting our own Solar System. Bailer-Jones and his colleagues used data from the ESA astrometry satellite Gaia to find four plausible stars where ‘Oumuamua could have begun its long journey, more than a million years ago. ...

Plausible home stars of the interstellar object 'Oumuamua found in Gaia DR2 ~ C.A.L. Bailer-Jones et al

• arXiv.org > astro-ph > arXiv:1809.09009 > 24 Sep 2018

[rstevenson]

Tracking the Interstellar Object 'Oumuamua to Its Home
Max Planck Institute for Astronomy | 2018 Sep 25

A team of astronomers led by Coryn Bailer-Jones of the Max Planck Institute for Astronomy has tracked the interstellar object ‘Oumuamua to several possible home stars. The object was discovered in late 2017 – this was the first time astronomers have been able to observe an astronomical object from another star system visiting our own Solar System. Bailer-Jones and his colleagues used data from the ESA astrometry satellite Gaia to find four plausible stars where ‘Oumuamua could have begun its long journey, more than a million years ago. ...

Plausible home stars of the interstellar object 'Oumuamua found in Gaia DR2 ~ C.A.L. Bailer-Jones et al

• arXiv.org > astro-ph > arXiv:1809.09009 > 24 Sep 2018

So, we're trying to find, so to speak, Oumuamua's Papa? I think there's a song about that.

Rob

[bystander]

So, we're trying to find, so to speak, Oumuamua's Papa? I think there's a song about that.

Click to play embedded YouTube video.

[neufer]

So, we're trying to find, so to speak, Oumuamua's Papa? I think there's a song about that.

And a mama, perhaps:

Click to play embedded YouTube video.