Effects of gas giants on a star system's hyper limit...

Since SWM hasn't dropped by, a few answers.

First, binaries can be arbitrarily close. I think I've heard of cases of contact binaries - that is, the two stars are in physical contact.

Second, mass transfer between stars happens. Red giants will frequently transfer mass to a close companion. A recent study showed this was the explanation for all of the blue stragglers in a globular cluster. Mass transfer between a white dwarf and a close companion is also what triggers Type 1B supernovae at least half the time (I'm holding out for "almost all," but then, I'm not an astronomer).

Third, there appear to be a lot of "hot Jupiters" out there, that is, Jupiter sized and bigger planets in very close orbits, usually well inside the orbit of Mercury. Part of this is probably due to limits of our observational capabilities: current instrumentation couldn't detect that our system had any planets except by accident. It certainly couldn't detect Jupiter or Saturn, and would probably miss Earth and Venus. I presume that the reason hyper limits are given as spherical is the same reason the fabled answer to a physics question began: "Assuming a spherical cow...."

JohnRoth wrote:Since SWM hasn't dropped by, a few answers.

First, binaries can be arbitrarily close. I think I've heard of cases of contact binaries - that is, the two stars are in physical contact.

Second, mass transfer between stars happens. Red giants will frequently transfer mass to a close companion. A recent study showed this was the explanation for all of the blue stragglers in a globular cluster. Mass transfer between a white dwarf and a close companion is also what triggers Type 1B supernovae at least half the time (I'm holding out for "almost all," but then, I'm not an astronomer).

Third, there appear to be a lot of "hot Jupiters" out there, that is, Jupiter sized and bigger planets in very close orbits, usually well inside the orbit of Mercury. Part of this is probably due to limits of our observational capabilities: current instrumentation couldn't detect that our system had any planets except by accident. It certainly couldn't detect Jupiter or Saturn, and would probably miss Earth and Venus. I presume that the reason hyper limits are given as spherical is the same reason the fabled answer to a physics question began: "Assuming a spherical cow...."

John, from what I can make out of your post, you are saying that if there are one or more supermassive gas giants in close orbit to a star (inside the system's hyper limit), then the combined masses of the star and gas giant/s will cause the hyper limit to bulge out, kind of like an egg shape? Am I correct?

hanuman wrote:

JohnRoth wrote:Since SWM hasn't dropped by, a few answers.

First, binaries can be arbitrarily close. I think I've heard of cases of contact binaries - that is, the two stars are in physical contact.

Second, mass transfer between stars happens. Red giants will frequently transfer mass to a close companion. A recent study showed this was the explanation for all of the blue stragglers in a globular cluster. Mass transfer between a white dwarf and a close companion is also what triggers Type 1B supernovae at least half the time (I'm holding out for "almost all," but then, I'm not an astronomer).

Third, there appear to be a lot of "hot Jupiters" out there, that is, Jupiter sized and bigger planets in very close orbits, usually well inside the orbit of Mercury. Part of this is probably due to limits of our observational capabilities: current instrumentation couldn't detect that our system had any planets except by accident. It certainly couldn't detect Jupiter or Saturn, and would probably miss Earth and Venus. I presume that the reason hyper limits are given as spherical is the same reason the fabled answer to a physics question began: "Assuming a spherical cow...."

John, from what I can make out of your post, you are saying that if there are one or more supermassive gas giants in close orbit to a star (inside the system's hyper limit), then the combined masses of the star and gas giant/s will cause the hyper limit to bulge out, kind of like an egg shape? Am I correct?

What I'm implying is that we don't know. I'd expect that's probably true, but on the other hand, I'd also expect that it doesn't matter because, from what we know of how systems form, gas giants simply wouldn't be formed that close to a star. If they're that close in, then they migrated there from farther out, and if they did that, then the chances of the rest of the system being nice, neat and orderly are pretty slim.

On the gripping hand, what we can see now suggests we know less than we'd like to about how systems form.

JohnRoth wrote:

hanuman wrote:
John, from what I can make out of your post, you are saying that if there are one or more supermassive gas giants in close orbit to a star (inside the system's hyper limit), then the combined masses of the star and gas giant/s will cause the hyper limit to bulge out, kind of like an egg shape? Am I correct?

What I'm implying is that we don't know. I'd expect that's probably true, but on the other hand, I'd also expect that it doesn't matter because, from what we know of how systems form, gas giants simply wouldn't be formed that close to a star. If they're that close in, then they migrated there from farther out, and if they did that, then the chances of the rest of the system being nice, neat and orderly are pretty slim.

On the gripping hand, what we can see now suggests we know less than we'd like to about how systems form.

Okay, thanks, that makes it clearer for me. Appreciated.

I see that the questions have already been answered. I agree with what has already been said--I don't have anything to add! I'm not needed any more!

SWM wrote:I see that the questions have already been answered. I agree with what has already been said--I don't have anything to add! I'm not needed any more!

Aww, SWM, you'll always be needed...if only to give me someone to argue with

JohnRoth wrote:Since SWM hasn't dropped by, a few answers.

First, binaries can be arbitrarily close. I think I've heard of cases of contact binaries - that is, the two stars are in physical contact.

They do exist, yes.

http://en.wikipedia.org/wiki/W_Ursae_Majoris

"The two stars in W Ursae Majoris are so close together that their outer envelopes are in direct contact"