Starship Asterisk*

by **BDanielMayfield** » Tue Jun 05, 2018 4:07 pm

MarkBour wrote: ↑Tue Jun 05, 2018 3:27 pm
BDanielMayfield wrote: ↑Tue Jun 05, 2018 2:56 pm
neufer wrote: ↑Thu May 31, 2018 2:08 pm
I found that graphic to be fascinating Art. I've wondered about the possibilities of exoplanets forming at the L4 and L5 points of giant exoplanets. It doesn't seem to be very possible due to the potentials for objects to drift away from them.

Bruce
Ah, yes, Bruce. I had not paid enough attention to the arrows in this. So these points are not highly stable. And a large body in one of them would just change everything and make a mess, I suppose. Meanwhile, for small enough masses, they can hang out there for millions of years ... or more. I wonder if Jupiter has more or fewer trojans now than it did a billion years ago. If I follow the arrows in the diagram, then a body that is a little closer to the main planet than the point L4, for example, will be perturbed toward the planet. One that is a little farther away than L4 will be nudged further away.

But otoh the Jovian L4 and L5 points are stable enough for these Trojan asteroids to have been retained for 4.5 billion years! These points don't seem to be attractors, but if an object is near one and in an orbit that is sufficiently synchronized with the controlling planet it can hang out indefinitely, at least until a very unlikely encounter with another object knocks or perturbes it out of its stable orbit. The number of these objects declines very slowly nowadays, I would think.

Bruce

by **MarkBour** » Tue Jun 05, 2018 3:32 pm

neufer wrote: ↑Mon Jun 04, 2018 3:36 am If they are 'mortal men' they would have to call it Scamander.

Ha. Good point. But, they are not mere mortals. They are astronomers!

by **MarkBour** » Tue Jun 05, 2018 3:27 pm

BDanielMayfield wrote: ↑Tue Jun 05, 2018 2:56 pm
neufer wrote: ↑Thu May 31, 2018 2:08 pm
https://en.wikipedia.org/wiki/Lagrangian_point wrote:
A contour plot of [the effective potential for relatively slowly moving bodies] due to gravity and the centrifugal force of a two-body system in a rotating frame of reference. The arrows indicate the gradients of the potential around the five Lagrange points—downhill toward them (red) or away from them (blue). Counterintuitively, the L₄ and L₅ points are the high points of the potential. At the points themselves these forces are balanced.
I found that graphic to be fascinating Art. I've wondered about the possibilities of exoplanets forming at the L4 and L5 points of giant exoplanets. It doesn't seem to be very possible due to the potentials for objects to drift away from them.

Bruce

Ah, yes, Bruce. I had not paid enough attention to the arrows in this. So these points are not highly stable. And a large body in one of them would just change everything and make a mess, I suppose. Meanwhile, for small enough masses, they can hang out there for millions of years ... or more. I wonder if Jupiter has more or fewer trojans now than it did a billion years ago. If I follow the arrows in the diagram, then a body that is a little closer to the main planet than the point L4, for example, will be perturbed toward the planet. One that is a little farther away than L4 will be nudged further away. Where would you draw asteroid Brize in all of this? It is not in any such stable point, so it is constantly being perturbed, but it happens to have really perfect timing. There may someday be found some use for such orbits by NASA. After all, TESS is in a very creative orbit. But it would take quite a bit of energy to put something in a retrograde orbit compared to Earth.

by **BDanielMayfield** » Tue Jun 05, 2018 2:56 pm

neufer wrote: ↑Thu May 31, 2018 2:08 pm
https://en.wikipedia.org/wiki/Lagrangian_point wrote:
A contour plot of [the effective potential for relatively slowly moving bodies] due to gravity and the centrifugal force of a two-body system in a rotating frame of reference. The arrows indicate the gradients of the potential around the five Lagrange points—downhill toward them (red) or away from them (blue). Counterintuitively, the L₄ and L₅ points are the high points of the potential. At the points themselves these forces are balanced.

I found that graphic to be fascinating Art. I've wondered about the possibilities of exoplanets forming at the L4 and L5 points of giant exoplanets. It doesn't seem to be very possible due to the potentials for objects to drift away from them.

Bruce

by **neufer** » Mon Jun 04, 2018 3:36 am

MarkBour wrote: ↑Mon Jun 04, 2018 1:57 am
neufer wrote: ↑Sat Jun 02, 2018 12:41 pm
MarkBour wrote: ↑Sat Jun 02, 2018 3:06 am
I was searching for a name that related to one that moved or behaved in
a contrary fashion to both the Greeks and Trojans, which is where I got Xanthos.
Achilles talking horse? Diomedes's man eating horse?
https://en.wikipedia.org/wiki/Balius_and_Xanthus
Sorry, there is more ambiguity than I would have guessed. I was referring to Xanthos the god of the river Scamander, who became angry with Achilles and tried to kill him. In my copy of the Iliad, which does indeed name Achilles' horse with the same name, there is:

The eddied River broad by mortal men
Scamander call'd, but Xanthus by the Gods.

Soon as the windings of the stream they reach'd,
Deep-eddied Xanthus, progeny of Jove,

(But Wikipedia seems to prefer the spelling Xanthos to Xanthus -- https://en.wikipedia.org/wiki/Scamander)

Xanthus is generally the Latin for the Greek Xanthos.

Since the Trojan Aeneas became the original Roman,
Xanthus would also be the Trojan version.

MarkBour wrote: ↑Mon Jun 04, 2018 1:57 am
Anyway, I guess the discoverers of 2015 BZ509 will have the privilege of naming it, eventually?

If they are 'mortal men' they would have to call it Scamander.
--------------------------------

MarkBour wrote: ↑Mon Jun 04, 2018 1:57 am
If enough mass accumulated at a Lagrange point, would that not give rise to new Lagrange-like points, stable points in an n-body system (n > 2)? For example, if enough mass is placed at L4, it should give rise to an L4' further around the circle, and no doubt other points of stability.

If that much mass accumulated at L₄ there are probably no stable solutions.

by **MarkBour** » Mon Jun 04, 2018 1:57 am

neufer wrote: ↑Sat Jun 02, 2018 12:41 pm
MarkBour wrote: ↑Sat Jun 02, 2018 3:06 am I was searching for a name that related to one that moved or behaved in a contrary fashion to both the Greeks and Trojans, which is where I got Xanthos.
Achilles talking horse? Diomedes's man eating horse?
https://en.wikipedia.org/wiki/Balius_and_Xanthus

Sorry, there is more ambiguity than I would have guessed. I was referring to Xanthos the god of the river Scamander, who became angry with Achilles and tried to kill him. In my copy of the Iliad, which does indeed name Achilles' horse with the same name, there is:

The eddied River broad by mortal men
Scamander call'd, but Xanthus by the Gods.

Soon as the windings of the stream they reach'd,
Deep-eddied Xanthus, progeny of Jove,

(But Wikipedia seems to prefer the spelling Xanthos to Xanthus -- https://en.wikipedia.org/wiki/Scamander)

Anyway, I guess the discoverers of 2015 BZ509 will have the privilege of naming it, eventually?

--------------------------------

I have a very limited understanding of planet formation. Just having learned a few bits from simplistic presentations, that would typically just say "planets form as the material in a disk clumps together". And the suggestion from that IAU definition, that planets should be clearing out their orbits. It seemed reasonable that in a given orbital band, a growing mass would perturb all the other mass in the same orbit -- pushing and pulling on the orbits of the diffuse material and causing it to either come join the larger mass or get perturbed into another orbit. But I don't put much stock in this intuition. We have a laboratory for this around Saturn, where one can see cleared bands in the rings with a single moon occupying them. Of course we have not observed for very long.

But I find the stability of trojans interesting. Their pattern in this APOD reminds me of density waves elsewhere in physical phenomena. If enough mass accumulated at a Lagrange point, would that not give rise to new Lagrange-like points, stable points in an n-body system (n > 2)? For example, if enough mass is placed at L4, it should give rise to an L4' further around the circle, and no doubt other points of stability. But in the really long run, I have no idea, because it seems like I'm beginning to give a plausibility argument for spreading out around the whole ring, in contrast to what seems to be the expected trend.

by **neufer** » Sat Jun 02, 2018 12:41 pm

MarkBour wrote: ↑Sat Jun 02, 2018 3:06 am
neufer wrote: ↑Thu May 31, 2018 1:20 pm -----------------------------------------------------
. BriZE - Juno's GAD-FLY

The BrEEZE upon her like a Cow in Iune,
Hoists Sail, and flies.

BrEEZE here is an Anglo-Saxon word
that was still used in Midlands dialect in Tudor times.
It refers to the GADFLIES that, in summer, trouble cows.

That's the kind of knowledge you don't get
at Oxbridge, or in a rich man's house.>>
----------------------------------------------------------
I find your derivation here quite interesting. 2015 BZ509 is very much a gadfly to Jupiter.
But why would you go for "breeze"? Is it to relate to the BZ in the asteroid's current name?

I'd already heard others call BZ509 “Bee-Zee” for short
and it reminded me of Shakespeare's mention of “Breeze” in A&C.

Shakespeare's gadfly “Breeze” or “Brize” comes directly from Aeschylus's PROMETHEUS BOUND
but Stratfordians like to pretend this was a rustic Stratford word that only a small time butcher would use.

[Of course, there is also BuZZ Aldrin & Jeff BeZos.]

MarkBour wrote: ↑Sat Jun 02, 2018 3:06 am
I was searching for a name that related to one that moved or behaved in a contrary fashion to both the Greeks and Trojans, which is where I got Xanthos.

Achilles talking horse? Diomedes's man eating horse?
https://en.wikipedia.org/wiki/Balius_and_Xanthus

MarkBour wrote: ↑Sat Jun 02, 2018 3:06 am
If you want something close to BZ, what do you think of "Briseis"?

Helen, Cressida & Briseis would all be great names for pro-grade asteroids
that slowly amble back & forth between camps through the Lagrange L3 point:
. http://asterisk.apod.com/viewtopic.php? ... 34#p282945

But an annoying retrograde asteroid BuZZing Jupiter is best named BreeZe IMHO.

https://en.wikipedia.org/wiki/Briseis wrote:
<<In medieval romances Briseis becomes Briseida. She loves and is loved by Troilus and then Diomedes. She is later confused with Chryseis and it is under variations of that name that the character is developed further, becoming Shakespeare's Cressida.>>

by **MarkBour** » Sat Jun 02, 2018 3:06 am

neufer wrote: ↑Thu May 31, 2018 1:20 pm -----------------------------------------------------
. BriZE - Juno's GAD-FLY

The BrEEZE upon her like a Cow in Iune,
Hoists Sail, and flies.

BrEEZE here is an Anglo-Saxon word
that was still used in Midlands dialect in Tudor times.
It refers to the GADFLIES that, in summer, trouble cows.

That's the kind of knowledge you don't get
at Oxbridge, or in a rich man's house.>>
----------------------------------------------------------

I find your derivation here quite interesting. 2015 BZ509 is very much a gadfly to Jupiter. But why would you go for "breeze"? Is it to relate to the BZ in the asteroid's current name? I was searching for a name that related to one that moved or bahaved in a contrary fashion to both the Greeks and Trojans, which is where I got Xanthos. If you want something close to BZ, what do you think of "Briseis"?

by **neufer** » Thu May 31, 2018 2:28 pm

Click to play embedded YouTube video.

BDanielMayfield wrote: ↑Thu May 31, 2018 12:43 pm
MarkBour wrote: ↑Wed May 30, 2018 9:59 pm
I think the IAU is going to have to downgrade Jupiter to a dwarf planet. Not only has it failed to clear its orbit from having lots of Greeks and Trojans, it cannot even get rid of this wanderer among the wanderers.
I like your quip, but seriously, I really think the "cleared its orbit" clause should be dumped from the list of planetary qualifiers. In the real universe can a planet ever completely clear its orbit? Aparently not, as there are areas of co-orbital stability that objects from both near and far can settle into.

Jupiter is still Master of His Domain

(Monitoring Solar System "planets" is done within the confines of the honor system.)

by **neufer** » Thu May 31, 2018 2:08 pm

Sa Ji Tario wrote: ↑Wed May 30, 2018 10:30 pm
It is clear that the orbit of BZ is retrograde that is resonant with the primary and is between the Trojans at one of the Lagrange points (L4 and L5) at the other point are the Greeks. But in its journey BZ touches or better, it enters both (As does the small Moon that was discovered to have Earth) .-

It is unlikely but not exclusive that a body that is in L4 or L5 is removed from there by its primary but time often plays against the established. It may be that this BZ has been in a peripheral area of some of these points and that in past times there has been a collision with another object (great bombardment) and removed for a short time from its orbit and the tidal effects have begun their new trajectory.

https://en.wikipedia.org/wiki/Lagrangian_point wrote:
A contour plot of [the effective potential for relatively slowly moving bodies] due to gravity and the centrifugal force of a two-body system in a rotating frame of reference. The arrows indicate the gradients of the potential around the five Lagrange points—downhill toward them (red) or away from them (blue). Counterintuitively, the L₄ and L₅ points are the high points of the potential. At the points themselves these forces are balanced.

It is quite true that outlying Greeks or Trojans require only a gentle nudge to send them past the unstable L₃ point into the enemy camp [a Helen or Cressida

]. However this would simply result in pro-grade object that bounced back & forth through the the unstable L₃ point. BZ is moving retrograde with a rapid relative ~26 km/s velocity vis-a-vis all these other bodies.

To send a spacecraft to BZ would require a deep dive into Jupiter's gravitational field in conjuction with a velocity boost of ~6 km/s such that the rapid relative exit velocity is approximately: 27.5 km/s [= sqrt(66² - 60²)].
.

Ergo: While a ~6 km/s gentle nudge deep in Jupiter's gravitational field just might do the trick;
no gentle nudges deep in the Greek or Trojan camps
(or even in the vicinity of the unstable L₃ point) possibly could.

by **Chris Peterson** » Thu May 31, 2018 1:51 pm

BDanielMayfield wrote: ↑Thu May 31, 2018 12:43 pm
MarkBour wrote: ↑Wed May 30, 2018 9:59 pm I think the IAU is going to have to downgrade Jupiter to a dwarf planet. Not only has it failed to clear its orbit from having lots of Greeks and Trojans, it cannot even get rid of this wanderer among the wanderers. :)
I like your quip, but seriously, I really think the "cleared its orbit" clause should be dumped from the list of planetary qualifiers. In the real universe can a planet ever completely clear its orbit? Aparently not, as there are areas of co-orbital stability that objects from both near and far can settle into.

That's true. Which is why the requirement about clearing the orbit is loosely interpreted (as are most elements of any definition as broad as "planet").

by **neufer** » Thu May 31, 2018 1:20 pm

-----------------------------------------------------
. BriZE - Juno's GAD-FLY
.
<<Large as a sparrow with a sting the size of a dagger,
BriZE was sent by Juno/Hera to torment IO (transformed into a
cow by Jupiter/Zeus, her lover, so that Hera couldn't find her,
but to no avail). When Hermes rescued Io he killed BriZE, too.>>
-----------------------------------------------------------------------------
Aeschylus: _PROMETHEUS BOUND_ ( Trans. Anna Swanwick.)

IO: Forthwith my shape and mind distorted were,
And horned, as ye behold me, goaded on
By GAD-FLY, keen of fang, with frenzied bounds
I to Kerchneias' limpid current rush'd,
And found of Lerna. Then the earth-born herdsman,
Hot-tempered Argos, ever dogged my steps,
Gazing upon me with his myriad eyes.
But him a sudden and unlooked-for fate
Did reave of life; but I, *BriZE-tortured* , still
Before the scorge divine am driven on
From land to land; the past thou hearest; now
If thou canst tell my future toils, say on,
Nor, pity-moved, soothe me with LYING TALES,
For GARBLED WORDS, I hold, are basest ills.
----------------------------------------------------
. Antony and Cleopatra (Folio) Act 3 Scene 10

Scarus: On our side, like the Token'd Pestilence,
Where death is sure. Yon ribaudred Nagge of Egypt,
(Whom Leprosie o're-take) i'th' midst o'th' fight,
When vantage like a payre of Twinnes appear'd
Both as the same, or rather ours the elder;
(The BrEEZE vpon her) like a Cow in Inne,
Hoists Sailes, and flyes.
-----------------------------------------------------
. Shakespeare p. 18 by Michael Wood.
...................................................
<<Shakespeare would use BrEEZE in a memorable
image when describing the Egyptian queen's flight
from the battle of Actium in Antony & Cleopatra

The BrEEZE upon her like a Cow in Iune,
Hoists Sail, and flies.

BrEEZE here is an Anglo-Saxon word
that was still used in Midlands dialect in Tudor times.
It refers to the GADFLIES that, in summer, trouble cows.

That's the kind of knowledge you don't get
at Oxbridge, or in a rich man's house.>>
----------------------------------------------------------

by **BDanielMayfield** » Thu May 31, 2018 12:43 pm

MarkBour wrote: ↑Wed May 30, 2018 9:59 pm I think the IAU is going to have to downgrade Jupiter to a dwarf planet. Not only has it failed to clear its orbit from having lots of Greeks and Trojans, it cannot even get rid of this wanderer among the wanderers.

I like your quip, but seriously, I really think the "cleared its orbit" clause should be dumped from the list of planetary qualifiers. In the real universe can a planet ever completely clear its orbit? Aparently not, as there are areas of co-orbital stability that objects from both near and far can settle into.

Bruce

by **Guest** » Wed May 30, 2018 11:35 pm

It should be named Corrigan in honor of famed aviator Douglas Corrigan, who flew from New York to Ireland, though he intended to fly to Long Beach, CA. Just as the object is oblivious to its neighbors, Mr. Corrigan was apparently oblivious to the fact that he was flying over an ocean.

by **Sa Ji Tario** » Wed May 30, 2018 10:30 pm

It is clear that the orbit of BZ is retrograde that is resonant with the primary and is between the Trojans at one of the Lagrange points (L4 and L5) at the other point are the Greeks. But in its journey BZ touches or better, it enters both (As does the small Moon that was discovered to have Earth) .-
It is unlikely but not exclusive that a body that is in L4 or L5 is removed from there by its primary but time often plays against the established. It may be that this BZ has been in a peripheral area of some of these points and that in past times there has been a collision with another object (great bombardment) and removed for a short time from its orbit and the tidal effects have begun their new trajectory . It was already theorized of something cataclysmic with Pluto with original orbit between Earth and Mars and the resonance with Jupiter sent it to the eccentricity and inclination that now has its orbit (siempre a mi leal saber y entender )

by **MarkBour** » Wed May 30, 2018 9:59 pm

There's one in every crowd!

I think the IAU is going to have to downgrade Jupiter to a dwarf planet. Not only has it failed to clear its orbit from having lots of Greeks and Trojans, it cannot even get rid of this wanderer among the wanderers.

The best name that comes to my mind for it is Xanthos. Or possibly Odysseus, or Homer.

by **Bad Dad** » Wed May 30, 2018 9:03 pm

jisles wrote: ↑Wed May 30, 2018 8:47 pmWhat is the red object ?

The red object orbiting in the middle of the solar system is Mars

by **Just Jackson** » Wed May 30, 2018 8:48 pm

It looks like the conjunctions of the object with Jupiter are close enough for gravitational 'slingshots,' only one boosts it while the other retards it. This makes the orbit more oval than parabolic. It's a remarkable synchronization.

by **jisles** » Wed May 30, 2018 8:47 pm

What is the red object ?

by **suicidejunkie** » Wed May 30, 2018 5:18 pm

There are quite a few more that appear to be moving retrograde, such as the one moving right at the top of the image all alone at 0:04, but on further inspection, are merely highly inclined.

by **Bad Dad** » Wed May 30, 2018 4:57 pm

At Apogee at 0:07 on the left above the "e" in Jupiter
Then above Jupiter (planet) at 0:14
And just below 2015 BZ509 at 0:29
With a similar period to 2015 BZ509

by **Bad Dad** » Wed May 30, 2018 4:50 pm

If the animation is correct, there is a second Asteroid depicted that also has a retrograde motion

by **Couch Spud** » Wed May 30, 2018 4:30 pm

Boomer12k wrote: ↑Wed May 30, 2018 8:06 am Name...."Wrongway Peachfuzz"....from Rocky and Bullwinkle...I think....

:---[===] *

Yep, or Wrongway Feldman from Gilligan's Island.

by **RJN** » Wed May 30, 2018 3:21 pm

Based on correspondence with a paper author, I have now updated links on the NASA APOD. The phrase "recently popular hypthosis" now points to this paper, appearing free on arXiv and accepted by the Monthly Notices of the Royal Astronomical Society: http://adsabs.harvard.edu/abs/2018arXiv180509013N . I have moved the link previously under those words, http://www.astro.uwo.ca/~wiegert/2015BZ509/, to "BZ509" immediately following. I apologize for the oversight. - RJN

by **BDanielMayfield** » Wed May 30, 2018 12:45 pm

Looks like being interstellar is the in thing now.

Bruce

Starship Asterisk*

APOD: The Case of the Backwards Orbiting... (2018 May 30)

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BriZE - Juno's GAD-FLY

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