Starship Asterisk*

by **dougettinger** » Fri Feb 04, 2011 11:00 pm

Chris Peterson wrote:
dougettinger wrote:So I am asking whether you, in the deep reaches of your mind, differ with any parts of the nebula theory.
I don't know how to interpret that. Here's a general rule you can use to figure out my thoughts about most things scientific:

If the subject is an area of my primary expertise (e.g. meteoritics, orbital dynamics) I'm likely to have an opinion derived from a synthesis of my own work and that of others.

If the subject is an area of my secondary expertise, which generally means I do no original work, but extensively read expert papers, I am likely to have an opinion based on my analysis of other people's work. Your "nebular theory" question falls into this category. I have little doubt that accretion discs are at the heart of planetary system formation. Beyond that, I read different ideas (only mainstream; as this is not my area of expertise, I don't waste my time on fringe ideas) and weigh them as best I can. My opinions are likely to shift around as I read different papers. I do not attempt to develop any ideas of my own.

For scientific areas that I am only casually interested in, I almost always favor the consensus viewpoint. There is value in trusting the experts. The stronger the consensus, the more I accept the theory. When there is little consensus, I prefer to keep an open mind. Again, however, I don't try to formulate my own theories.

Chris, you are an excellent compass to follow for an explorer like myself. I can quickly get back on course by consulting you.
Thanks.
Doug Ettinger

by **NoelC** » Fri Feb 04, 2011 8:26 pm

Perhaps Doug is inquiring as to your intuition, Chris...

I'm going to pull a bit of a Neufer here, I hope you'll forgive me.

Kirk: Mr. Spock, have you accounted for the variable mass of whales and water in your time re-entry program?
Spock: Mr. Scott cannot give me exact figures, Admiral, so... I will make a guess.
Kirk: A guess? You, Spock? That's extraordinary.
Spock: [to Dr. McCoy] I don't think he understands.
McCoy: No, Spock. He means that he feels safer about your guesses than most other people's facts.
Spock: Then you're saying,
[pause]
Spock: It is a compliment?
McCoy: It is.
Spock: Ah. Then, I will try to make the best guess I can.

-Noel

by **Chris Peterson** » Fri Feb 04, 2011 4:34 pm

dougettinger wrote:So I am asking whether you, in the deep reaches of your mind, differ with any parts of the nebula theory.

I don't know how to interpret that. Here's a general rule you can use to figure out my thoughts about most things scientific:

If the subject is an area of my primary expertise (e.g. meteoritics, orbital dynamics) I'm likely to have an opinion derived from a synthesis of my own work and that of others.

If the subject is an area of my secondary expertise, which generally means I do no original work, but extensively read expert papers, I am likely to have an opinion based on my analysis of other people's work. Your "nebular theory" question falls into this category. I have little doubt that accretion discs are at the heart of planetary system formation. Beyond that, I read different ideas (only mainstream; as this is not my area of expertise, I don't waste my time on fringe ideas) and weigh them as best I can. My opinions are likely to shift around as I read different papers. I do not attempt to develop any ideas of my own.

For scientific areas that I am only casually interested in, I almost always favor the consensus viewpoint. There is value in trusting the experts. The stronger the consensus, the more I accept the theory. When there is little consensus, I prefer to keep an open mind. Again, however, I don't try to formulate my own theories.

by **dougettinger** » Fri Feb 04, 2011 3:24 pm

Chris Peterson wrote:
dougettinger wrote:Have you given any iota of thought to other possible, just possible, ways of creating planetary systems ?
In fact, a lot of smart people have been thinking about this for a long time. And we now are directly observing star systems being born, and planetary systems emerging from accretion discs.

I didn't say that there weren't other possibilities. What I said is that between theory and observation, I don't think you'll find many (or any) alternative theories that don't start with planets accreting out of circumstellar dust discs. You'll find huge amounts of discussion about the details- why they condense, where they condense, how discs evolve, how they interact with the protostar, how gravitational effects perturb orbits and change positions. There is a great deal not known. But the virtually certain origin of planetary systems from dust discs is not one of those things.

Your commentary is well composed. Yes, I do not challenge the idea of an accretion or proto-star disc. The forming disc should be part of any hypothesis. I basically differ with the current, popular nebula theory about why they condense, where they condense, and how the discs form and evolve.

So I am asking whether you, in the deep reaches of your mind, differ with any parts of the nebula theory.

Doug Ettinger, Pittsburgh, PA 02/04/11

by **brianguyan@yahoo.com** » Fri Feb 04, 2011 3:24 am

How Interesting, Indeed!

by **Chris Peterson** » Thu Feb 03, 2011 11:01 pm

Devil Particle wrote:Is there any reason to think that there may be a preference for planets to orbit in a particular orientation, for instance the galactic plane? Does our solar system align at all with the galactic plane?

I don't think there is any reason to expect a preferred orientation for planetary planes. Neither gravitational forces nor EM forces from galactic structures seen to approach the magnitudes required to overcome the angular momentum of a given region of a molecular dust cloud. Our own ecliptic is tilted about 63° from the galactic plane.

by **bystander** » Thu Feb 03, 2011 11:00 pm

Devil Particle wrote:Is there any reason to think that there may be a preference for planets to orbit in a particular orientation?

I would guess that most planets orbit close to the plane of the proto-planetary disk.

by **NoelC** » Thu Feb 03, 2011 10:52 pm

Devil Particle wrote:Is there any reason to think that there may be a preference for planets to orbit in a particular orientation, for instance the galactic plane?

Seems a reasonable question, and one I'd certainly like to hear discussion on as well.

Devil Particle wrote:Does our solar system align at all with the galactic plane?

No, consider that in star charts our ecliptic cuts across the Milky Way at quite an angle.

-Noel

by **Devil Particle** » Thu Feb 03, 2011 10:28 pm

Is there any reason to think that there may be a preference for planets to orbit in a particular orientation, for instance the galactic plane? Does our solar system align at all with the galactic plane?

by **Chris Peterson** » Thu Feb 03, 2011 9:25 pm

dougettinger wrote:Have you given any iota of thought to other possible, just possible, ways of creating planetary systems ?

In fact, a lot of smart people have been thinking about this for a long time. And we now are directly observing star systems being born, and planetary systems emerging from accretion discs.

I didn't say that there weren't other possibilities. What I said is that between theory and observation, I don't think you'll find many (or any) alternative theories that don't start with planets accreting out of circumstellar dust discs. You'll find huge amounts of discussion about the details- why they condense, where they condense, how discs evolve, how they interact with the protostar, how gravitational effects perturb orbits and change positions. There is a great deal not known. But the virtually certain origin of planetary systems from dust discs is not one of those things.

by **dougettinger** » Thu Feb 03, 2011 9:14 pm

Have you given any iota of thought to other possible, just possible, ways of creating planetary systems ? Is there any other possible process that could create planets, stars of all types, including binaries in a similar and congruent fashion ? Please look outside your box, the one that science has created for you. This box is organized to some extent and is rather tidy; it gives us a comfort zone. But have a look; is there anything else, just a little smidgen of an idea, that we have forgotten to consider and bring into our box of tools and data ?

I can question the nebular theory better than most because I believe there is some other process outside the box that is being ignored. As you said, "That's not to say that the actual mechanics are well understood - there are many questions _ _ _ "
Indeed, the nebular theory is far less than a theory; there is no absolute proof. But then, is there anything else to replace it ? This is why current scientists' thinking stays inside the box. They have no good answer for this question.

Doug Ettinger, Pittsburgh, PA 02/03/11

by **Chris Peterson** » Thu Feb 03, 2011 8:25 pm

dougettinger wrote:This new data like that of Kepler 11 certainly puts into question the nebula hypothesis of solar system formation and its addenda of the "Nice" theory and the theory of evaporating ices and gases as the planets move inward - unless as Neufer suggested rapid evolution is taking place.

I think it does no such thing. The "nebular hypothesis" is really not a hypothesis at all, but is increasingly seen as a simple observational fact. That's not to say that the actual mechanics are well understood- there are many questions, and these different types of stellar systems open up many new possibilities. But you'd be hard pressed to find anybody who thinks that planetary systems don't condense out of stellar accretion discs early in their formation.

by **dougettinger** » Thu Feb 03, 2011 8:11 pm

neufer wrote:
christine wrote:This is probably a really stupid question, but how do that many planets that big orbit that fast in such close proximity to the star and to each other without disturbing their orbits? Wouldn't their gravitational fields affect each other enough to cause weird eccentricities that would then cause collisions?
They are probably all evolving faster than our own solar system
but that is mainly due to strong tidal effects from the star itself
which acts to keep the orbits circular like with Jupiter's Galilean moons.

The data from the Kepler spacecraft mission is very exciting. It definitely reveals more of the story for different types of star systems, although disappointingly it focuses on stars of similar temperature and size as the Sun. This new data like that of Kepler 11 certainly puts into question the nebula hypothesis of solar system formation and its addenda of the "Nice" theory and the theory of evaporating ices and gases as the planets move inward - unless as Neufer suggested rapid evolution is taking place.

How can large gaseous planets of Jupiter's size and large ice planets of Neptunian size exist in such large numbers inside the orbit of Mercury or 0.4 AU along with numerous other smaller planets ? Would not massive evaporation of volatiles creating smaller rocky cores, perturbations, ejections, and collisions be the order of the day due to the star's radiation and due to such rapid orbital periods and overlapping large gravity fields ? What could the composition and structure be of the numerous super-sized Earths that have been observed ? Has the data been analyzed for resonances existing for the multi-planetary systems ? Most certainly this must occur. Has any data been collected for binary star systems ?

Doug Ettinger, Pittsburgh, PA 02/03/11

by **NoelC** » Thu Feb 03, 2011 6:31 pm

Chris Peterson wrote:This is a statistics problem for the Kepler investigators. It is understood that the failure to detect planets around a star does not mean that there are none.

I've been doing a little thinking. The ballpark value of the figure for the probability for whether a star system's planetary plane of rotation will cross the star's disk from our vantage point should be fairly easy to estimate in rough terms... All we have to do is a bit of math and plug in some numbers for star size and distance of the planet from the star, using the following model and a little bit of simplification of the intersection of the planet's possible position vs. the line of sight into right triangles...

Dusting off some ol' math skills, and estimating the star diameter as roughly 1 million miles, the distance of the planet at, say roughly 30 million miles, we get an angle of about 2 degrees.

Given that the plane of rotation can be angled, per the line of sight from Earth, at anywhere between +90 and -90 degrees (180 degrees total), then we have roughly a 2 in 180 (or about 1%) chance of seeing planets transiting stars.

So for every star we confirm, photometrically, that we're seeing planets traverse the disk, there should be about 100 times as many we can't see.

Please, someone check me on this and make sure I haven't made any stupid errors.

So... How many stars out of those surveyed have been found to have planets vs. the total number surveyed?

-Noel

by **Chris Peterson** » Thu Feb 03, 2011 5:15 pm

christine wrote:This is probably a really stupid question, but how do that many planets that big orbit that fast in such close proximity to the star and to each other without disturbing their orbits? Wouldn't their gravitational fields affect each other enough to cause weird eccentricities that would then cause collisions?

I'd suspect that this is not a very stable system- that is, one which could exist for billions of years. A system like this probably cleans itself out after a few tens or hundreds of millions of years.

by **Chris Peterson** » Thu Feb 03, 2011 5:13 pm

moonstruck wrote:Noel, that's exactly what I have wondered and didn't know how to say it. All the planets can't transverse their sun in our plane of sight. What about the ones that go round and round top and bottom or over and under whatever it would be called? :?

In any given system, the planets will probably be on nearly the same plane (although there are exceptions). So our ability to detect them with Kepler just depends on a lucky alignment of the rotation plane and our viewpoint. Most planetary systems will not have that alignment, and therefore Kepler won't make any detection.

This is a statistics problem for the Kepler investigators. It is understood that the failure to detect planets around a star does not mean that there are none.

by **Chris Peterson** » Thu Feb 03, 2011 5:10 pm

NoelC wrote:Is the Kepler spacecraft noticing these planets because of regular dips in the light from the star? If so, then all these systems that are being discovered are only those with planets orbiting in a plane that's in line with our line of sight, right?

Yes. Kepler is a photometric instrument that relies on planetary transits of stars for detection.

So what's the math.... Given the improbability of a planetary disk lining up perfectly enough with a star that we see eclipses, does this say (statistically) that virtually every star must have planets? Half of them? What?

Kepler can only detect planets in a few percent of stars. So you have to work the statistics based on that. Most stars it examines will not show transits- either because there are no large planets, or because they are in the wrong plane.

by **moonstruck** » Thu Feb 03, 2011 3:47 pm

Noel, that's exactly what I have wondered and didn't know how to say it. All the planets can't transverse their sun in our plane of sight. What about the ones that go round and round top and bottom or over and under whatever it would be called?

by **orin stepanek** » Thu Feb 03, 2011 3:12 pm

Indigo_Sunrise wrote:
orin stepanek wrote: http://asterisk.apod.com/vie ... f=8&t=8479

My bad!
Orin, you're the winner! (You should've prefaced your comment with, "FIRST!")

The Kepler site updates news of their planet hunting. The NASA TV station gave an update yesterday. The link I gave has a NASA News link in it that gives the latest breaking news. It is a cool site. :)http://www.kepler.arc.nasa.gov/

by **NoelC** » Thu Feb 03, 2011 1:50 pm

Interesting graphic; very informative at a glance.

What it says to me (assuming the details are accurate) is that the star is a little bigger, about the same color as our sun, and that all the planets are pretty darned close to it. If the measurements are indeed accurate, other than the scientific satisfaction of proving yet again that the Earth is not at the center of the universe (which actually it is in a sense, as all things are at the center of the universe), is there something else interesting (in the search for extraterrestrial life sense) about the Kepler-11 star system? Seems rather unlikely there's life as we know it there, unless there's a possibility of additional planets we haven't detected orbiting farther out.

A more fundamental question:

Is the Kepler spacecraft noticing these planets because of regular dips in the light from the star? If so, then all these systems that are being discovered are only those with planets orbiting in a plane that's in line with our line of sight, right?

So what's the math.... Given the improbability of a planetary disk lining up perfectly enough with a star that we see eclipses, does this say (statistically) that virtually every star must have planets? Half of them? What?

-Noel

by **neufer** » Thu Feb 03, 2011 1:49 pm

christine wrote:This is probably a really stupid question, but how do that many planets that big orbit that fast in such close proximity to the star and to each other without disturbing their orbits? Wouldn't their gravitational fields affect each other enough to cause weird eccentricities that would then cause collisions?

They are probably all evolving faster than our own solar system
but that is mainly due to strong tidal effects from the star itself
which acts to keep the orbits circular like with Jupiter's Galilean moons.

by **Indigo_Sunrise** » Thu Feb 03, 2011 1:30 pm

orin stepanek wrote: http://asterisk.apod.com/vie ... f=8&t=8479

My bad!

Orin, you're the winner! (You should've prefaced your comment with, "FIRST!")

by **christine** » Thu Feb 03, 2011 1:29 pm

This is probably a really stupid question, but how do that many planets that big orbit that fast in such close proximity to the star and to each other without disturbing their orbits? Wouldn't their gravitational fields affect each other enough to cause weird eccentricities that would then cause collisions?

by **orin stepanek** » Thu Feb 03, 2011 1:15 pm

http://asterisk.apod.com/vie ... f=8&t=8479

by **powercow** » Thu Feb 03, 2011 12:16 pm

"The tantalizing result suggests there are many undiscovered planets orbiting the stars in our galaxy."

Wow really? This is something a tabloid newspaper could have written.
The galaxy is big. BIG. Of course there are undiscovered planets. Jesus

Starship Asterisk*

APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Post a reply

Expand view Topic review: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)

Re: APOD: Six Worlds for Kepler 11 (2011 Feb 03)