Disks encircling hypergiant stars may spawn planets

[telfrow]

<i>The discovery of dusty disks--the building blocks of planets--around two of the most massive stars known suggests that planets might form and survive in surprisingly hostile environments. <br /><br />The discovery was made through NASA's Spitzer Space Telescope observations of two hypergiant stars in the Large Magellanic Cloud--the Milky Way's nearest neighboring galaxy--by a team led by Joel Kastner, a professor at Rochester Institute of Technology's Chester F. Carlson Center for Imaging Science. His team's findings will appear in the Feb. 10 issue of Astrophysical Journal Letters. <br /><br />So far, searches for planets outside the solar system have been restricted to sun-like stars. All of these stars are older, dimmer and cooler objects than hypergiants, which are extraordinarily large and luminous but shorter-lived by billions of years. <br /><br />Kastner and his team used infrared spectra obtained by Spitzer to study a population of dying stars. They added a new direction to their project when Spitzer's infrared spectrograph revealed unexpected information. Spitzer's sensitive spectrometer, which breaks down infrared radiation into component wavelengths as a prism splits visible light into a rainbow, indicated that a third of the stars in the population thought to be in decline--including two massive and exceedingly luminous hypergiants--were actually younger stars in varying stages of development. <br /><br />The curious spectra of these two hypergiants (R126 and R66)--with one star being 70 times bigger than the sun--led Kastner to reexamine the stars' classifications as dying. The shape of the spectra, or the amount of light from different wavelengths, is characteristic of flattened disks of dust orbiting the stars. <br /><br />The two stars' similar spectra differ in detail, with one encircled by dust in crystalline form, the other by more shapeless, amorphous dust grains. This expands the range of known conditions under which complex dust grains and molecules</i> <div class="Discussion_UserSignature"> <strong><font color="#3366ff">Made weak by time and fate, but strong in will to strive, to seek, to find and not to yeild.</font> - <font color="#3366ff"><em>Tennyson</em></font></strong> </div>

 

[harmonicaman]

We're learning more about accretion discs and how Solar Systems form! Recent observations in the Solar System and out in the Milky Way show that our understanding of accretion disc mechanics is very incomplete.

 

[mooware]

A habitable zone would probably we WAAAAAAY out there. Provided of course the Star doesn't die before life could take hold.

 

[dragon04]

With a lifespan of 10 - 50 million years, I'd doubt that planets even get formed and developed to something close to the right conditions to be habitable.<br /><br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[meteo]

Exactly you'd have some molten planatoids and then poof supernova.

 

[bonzelite]

in my opinion, this only substantiates that cosmologists' claims about star classification based upon size-as-age is pretty much wrong. why can't a giant young star exist? maybe this giant star is new, as it's ring of dust implies. an old star would supposedly long have burned away this ring of dust and planets supposedly formed from it. this star may be way younger that ours. <br /><br />perhaps there is no way in hell anybody can actually tell how old a star is. perhaps stellar evolution is nearly entirely misunderstood and unknown. ever thought about that? maybe stars go through several solar system phases, with an entirely different array of planets appearing around any given star several times throughout it's life. <br /><br /><br /><br />

 

[dragon04]

<font color="yellow"> why can't a giant young star exist? </font><br /><br />IIRC, any blue giant or supergiant <b> is </b> young. Relatively speaking, that is. They live hard, die young, and leave a beautiful corpse.<br /><br />Red supergiants are always old. Red dorfs would be hard to specualte on, I'd guess. <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[commander_keen]

Not all, we did discover a few planets orbiting a neutron star. I think that planets are far more resiliant then we realized.

 

[bonzelite]

as well, matters will further complitcate when they find protoplanetary disks around allegedly old red giant stars.

 

[colesakick]

You missed something important in Telfrow's post guys. Look again at <br /><br />"The curious spectra of these two hypergiants (R126 and R66)--with one star being 70 times bigger than the sun--led Kastner to reexamine the stars' classifications as dying."<br /><br />They are reconsidering how to assess star age given their findings. By standard measures, these stars should be on their way out, but they appear to be in the early stages of a life cycle, not dying.<br /><br />I’ve read another theory of star ages, in Summary it says:<br /><br />“Electric Star Evolution<br />In the Electric Star hypothesis, there is no reason to attribute youth to one spectral type over another. We conclude that a star's location on the HR diagram only depends on its size and the electric current density it is presently experiencing. If, for whatever reason, the strength of that current density should change, then the star will change its position on the HR diagram - perhaps, like FG Sagittae, abruptly. Otherwise, no movement from one place to another on that plot is to be expected. And its age remains indeterminate regardless of its mass or spectral type. This is disquieting in the sense that we are now confronted by the knowledge that our own Sun's future is not as certain as is predicted by mainstream astronomy. We cannot know whether the Birkeland current presently powering our Sun will increase or decrease, nor how long it will be before it does so. <br /> <br />Summary<br />A fresh look at the Hertzsprung-Russell diagram, unencumbered by the assumption that all stars must be internally powered by the thermonuclear fusion reaction, reveals an elegant correspondence between this plot and the Electric Star model proposed by Ralph Juergens and extended by Earl Milton. In fact the correspondence is better than it is with the "standard" thermonuclear model. The details in the shape of the HR diagram are exactly what the "tufted" electric star model predicts they should be. The observed acti <div class="Discussion_UserSignature"> Intellectual honesty means being willing to challenge yourself instead of others </div>

 

[dragon04]

<font color="yellow"> as well, matters will further complitcate when they find protoplanetary disks around allegedly old red giant stars. </font><br /><br />I'd rather doubt that they will. I would be an interesting thing for scientists to try to explain though. But given the known diameters of existing red supergiants, other explanations than "protoplanetary discs" could be brought forth. <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[nexium]

Since some neutron stars have planets, and some class O = super giants starting main sequence, likely have planets, I would expect red giants (such as our sun will become after it leaves main sequence) to also have planets. In these three cases, I would expect most of the closer planets to be stripped of their atmosphere, surface creatures and volitiles, but they may get new atmospheres that seep up from far below the surface, and from impacting comets and other bodies far from the star during the strong solar wind period.<br />A radius of 200,000 billion kilometers, but only 70 solar mass suggests a very low average density, for this class O star. Neil

 

[dragon04]

I don't think the issue was about planets revolving around a red giant but rather the protoplanetary disc that accompanies young stars. <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[bonzelite]

it is about questioning the status quo idea of spectral class versus age. that is the main idea which has been overlooked in this thread.<br /><br />and it is a matter of time before they find proto disks around red giant stars, completely "baffling" scientists again. there will be another typical and trite headline that will read "Scientists Baffled at Protoplanetary Disk that Shouldn't be There." <br /><br />

 

[dragon04]

So what's your postulation here? That there are clouds of helium out there that condense and bitrth a red giant? <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[bonzelite]

that stars may not be age-dated by spectral class; that solar systems may exist around any star, and that stellar evolution may not occur in the ways commonly thought. it is assumed that nuclear fusion must initially occur with the lightest of elements, ie, helium. but maybe it doesn't. stars are assumed to follow a linear progression of aging, but maybe they don't.<br /><br />maybe stars change spectral classes at will, rapidly, several times during their lifetimes going from blue giant to yellow dwarf to red giant and then back to yellow dwarf. considering that stellar evolution theory is not factual, a number of scenarios may be happening. <br /><br />see asymptotic giant branch (AGB) stars:<br />http://www.daviddarling.info/encyclopedia/A/AGB.html<br />http://www.answers.com/topic/asymptotic-giant-branch<br /><br />http://isc.astro.cornell.edu/~sloan/research/agbdust.html<br /><font color="orange">Circumstellar dust shells<br /><br />All of these long-period variables undergo mass-loss, where the outer envelope is slowly ejected into space. As material moves away from the central star, it cools. Eventually, its temperature will drop enough to allow dust grains to condense out, much like water vapor condenses to form clouds in the Earth's atmosphere.<br /><br />The mass-loss is a direct result of the pulsations in the stellar atmosphere, although there is some debate about the specific mechanism. One of two processes is occuring. If the pulsations are violent enough, then the outer portions of the stellar atmosphere may be driven away from the star with velocities which exceed the escape velocity of the star. These stars have expanded to extreme sizes, so the surface gravities (and thus the escape velocities) may be quite low. If the</font>