Hot Jupiters formed cold ?

[Widdekind]

As pre-star 'cloud clumps' coalesce, collapse, and 'disk-down', they remain comparatively cool, e.g., ~3000K on descending Hayashi tracks. Before the central star reaches the MS, with 'first light' core H-burning ignition, wouldn't the circum-proto-stellar disk be colder, than when its central star is on the MS? Thus, the "snow line", beyond which giant planets can form, would have been much closer to the central proto-star. So, couldn't now-hot-Jupiters originally have been "fast forming cold sub-binary companions", which only became "blow torched", by the central star, millions of years later, when it ignited H-burning in its core? (Indeed, "disk fragmentation" seems to be a common occurrence -- pre-star cloud clumps often 'disk down' into binary/trinary star systems; circum-stellar disks fragment into planets; planets have moons...)

[Widdekind]

Could Kepler detect proto-planets, orbiting proto-stars (e.g., T-Tauri phase proto-stars) ??

[Widdekind]

According to the Open University text-book Extreme Environment Astrophysics, p.164, most x-ray flares, in active LMXB systems, are due to the sudden accretion, onto the central object, of "blobs" of material, from the surrounding accretion disk. Now, first, T-Tauri stars often flare up brightly; and, T-Tauri proto-stars, may be orbited, by "in-close" proto-Hot-Jupiters; and, many of those proto-Hot-Jupiters might "in-spiral", before their host star's core ignites, and their host star's "first light" sweeps out the circum-stellar, proto-planetary disk, thereby removing the material between the HJ and the central star, whose gravity & frictional forces were causing the "slow death spiral", of the planet, star-wards.

 

QUESTION: Could the sudden, if "shrouded" accretion (amidst the thick circum-stellar, proto-planetary disk), of "proto-Hot-Jupiter blobs", account for the flares, in T-Tauri systems ?

[baric]

As pre-star 'cloud clumps' coalesce, collapse, and 'disk-down', they remain comparatively cool, e.g., ~3000K on descending Hayashi tracks. Before the central star reaches the MS, with 'first light' core H-burning ignition, wouldn't the circum-proto-stellar disk be colder, than when its central star is on the MS? Thus, the "snow line", beyond which giant planets can form, would have been much closer to the central proto-star. So, couldn't now-hot-Jupiters originally have been "fast forming cold sub-binary companions", which only became "blow torched", by the central star, millions of years later, when it ignited H-burning in its core? (Indeed, "disk fragmentation" seems to be a common occurrence -- pre-star cloud clumps often 'disk down' into binary/trinary star systems; circum-stellar disks fragment into planets; planets have moons...)

 

What do you mean by "blow-torched" ?

 

If hot Jupiters were indeed stunted binary companions, rather than planets that have migrated inwards from the frost line, then you are suggesting that the parent molecular cloud originally collapsed into two very close gravitational centers.

 

Does that seem plausible to you? I have always assumed that tight stellar binaries became that way because of migration, not because they collapsed from the cloud so close together.

 

Could Kepler detect proto-planets, orbiting proto-stars (e.g., T-Tauri phase proto-stars) ??

 

T-Tauris are generally surrounded by their parent cloud and so radiate in the infrared. I'm not exactly sure how sensitive Kepler is to those wavelengths, as opposed to the JWST (which is designed to monitor IR)

 

QUESTION: Could the sudden, if "shrouded" accretion (amidst the thick circum-stellar, proto-planetary disk), of "proto-Hot-Jupiter blobs", account for the flares, in T-Tauri systems ?

 

That's an interesting thought. The T-Tauri stage gives plenty of time for a giant planet to form and migrate inward.

Edited October 3, 2011 by baric

[Widdekind]

Would it be possible, to observe "exo-comets" -- are not comets much bigger, and more luminous, than planets (when they're 'active' & off-gassing) ? The presence of comets, i.e., "Kuiper Belt like objects", might indicate the presence of exo-planets.

Edited October 4, 2011 by Widdekind

[baric]

Would it be possible, to observe "exo-comets" -- are not comets much bigger, and more luminous, than planets (when they're 'active' & off-gassing) ? The presence of comets, i.e., "Kuiper Belt like objects", might indicate the presence of exo-planets.

 

 

Would a comet really make it more luminous? Remember, the comet is not actually emitting any radiation on its own, but only redirecting what it is receiving from the star. As a result, the overall luminosity would not increase.

 

A planet, on the other hand, absorbs light at one end of the spectrum (UV and Visible) and re-emits it at another (IR). This shifting effect is orders of magnitude greater than anything caused by a comet simply due to a size differential, which is why we can detect it.

Edited October 4, 2011 by baric

[Aristarchus in Exile]

Some creation myths regarding our solar system say the sun only gave light after life was formed on earth .. I can see reason to add belief to those myths through your proposal.

[baric]

Some creation myths regarding our solar system say the sun only gave light after life was formed on earth .. I can see reason to add belief to those myths through your proposal.

 

Who cares what people who believe in creation myths think? This is a science forum.

[Widdekind]

Would a comet really make it more luminous? Remember, the comet is not actually emitting any radiation on its own, but only redirecting what it is receiving from the star. As a result, the overall luminosity would not increase.

 

A planet, on the other hand, absorbs light at one end of the spectrum (UV and Visible) and re-emits it at another (IR). This shifting effect is orders of magnitude greater than anything caused by a comet simply due to a size differential, which is why we can detect it.

 

If exo-planets can be detected, by the small amount of dimming they induce on transiting across the face of their host star; then, could not comets be detected, by the not-quite-so-small amount of brightening that they would represent, by reflecting more light earth-wards, than otherwise would have been emanated our way ?

[baric]

If exo-planets can be detected, by the small amount of dimming they induce on transiting across the face of their host star; then, could not comets be detected, by the not-quite-so-small amount of brightening that they would represent, by reflecting more light earth-wards, than otherwise would have been emanated our way ?

 

I think you mischaracterize the relative dimming in brightening effects between transiting planets and approaching comets.

 

I think that the planets would have a much larger effect, by several orders of magnitude

 

In addition, the planet dimming is only detected due to the periodicity of their orbits. This would not be possible with comets at all.

Edited October 10, 2011 by baric

[Widdekind]

'Clump accretion', of proto-Hot-Jupiters, could account, for so-called 'FU Orionis' variable stars:

 

a handful of young stars...intermittently show disk-like features. They turn out to be FU Orionis variables, which also show large, episodic changes in their luminosity... FU Orionis proto-stars accrete material through their disks in brief spurts. Most of the time they would be in low-accretion states, during which they would show star-like spectral features. Occasionally, however, they would undergo periods of high accretion, when their luminosity increases; and, their spectra become dominated by disk-like features (AmSci 2001)

[Widdekind]

Beta-Pictoris is ~12 Myr old, yet already hosts a Gas Giant planet, orbiting ~10 AU from the central star. Astronomers are surprised by the youth of the world, thought to form only in the circum-stellar debris disk, after it 'disks down', but before the central star disperses said 'proto-planetary' disk (Discovery). But, what if worlds can coalesce, in the parent proto-stellar cloud, even before, or during, disk formation ?

[Widdekind]

I offer, that as soon as a proto-planetary disk forms, i.e. even when shrouded in a still-dense envelope; then proto-planets can-and-do form, i.e. if the central proto-star is clumping up, then proto-planets are clumping up, too:

 

The masses of all those clumps would determine how the system developed, i.e. as a multi-star binary/trinary system; as a single star-hot-jupiter system; as a star with planetary system, etc.

Edited January 4, 2012 by Widdekind

[Widdekind]

http://www.physorg.com/news/2012-02-planetary-accretion.html

 

an accretion model that assumes a three-dimensional (3-D) gas cloud. This pre-solar nebula collapses and forms the Sun and planets at essentially the same time...

 

“The first thing that happens in planet accretion is forming rocky kernels,” Hofmeister says. “The nebula starts contracting, the rocky kernels form to conserve angular momentum, and that’s where the dust ends up. Once rocky kernels exist, they attract gas to them, but only if the rocky kernel is far from the Sun, can it out-compete the Sun’s gravitational pull and collect the gas, as did Jupiter and its friends.

 

“But if the rocky kernel is close, like the Earth’s, it can’t out-compete the Sun. We describe this process as gravitational competition. This is why we have the regularity, spacing, and graded composition of the Solar System.”

 

Gravitational competition also offers a new view of formation of the moon that does not require an extremely low probability giant impact. Hofmeister says there is a continuum between single stars, binary stars, multiple stars, planets and even extrasolar planets.

 

“In all cases, the process is gravitational accretion of these cold, 3-D clouds making things contract and spin out, and that’s where the energy comes from,” she says. “It’s all happening in very cold temperatures, in 3-D instead of 2-D.”