Starship Asterisk*

Wes D wrote:Let me get this strait, the gravity of a black hole is so strong that nothing can escape it, not even light, so how is material getting expelled from around there?

Chris Peterson wrote, in another thread:

The history of any given particle around a black hole depends on how it interacts with other particles. Material will either be in an open or closed orbit until it becomes dense enough to lose energy through momentum transfer processes (such as collisions). Material that loses enough energy will fall into the black hole. Material that gains energy (as jet material does) will be ejected from the system before reaching the event horizon.

Gabe Gabriel wrote:They take in 3d material, and convert it to dark energy and dark matter, that is the reason for universe expansion.

owlice wrote:
The resident 20-year-old would like to know the following: why is material ejected along the polar axes rather than in any direction, for example, in the (basic) plane of the accretion disk, and is the accretion disk always perpendicular to axis of rotation of the black hole?

Boomer12k wrote:
Nature's way of spreading Star Seeds??? As well as the Impending Type 1A Supernova???
Assuming there is a companion dwarf drawing that off....

:---[===]*

http://en.wikipedia.org/wiki/Frugivore#Frugivore_seed_dispersal wrote:
<<A frugivore is any type of herbivore or omnivore where fruit is a preferred food type. Because approximately 20% of all mammalian herbivores also eat fruit, frugivory is considered to be common among mammals. Since frugivores eat large volumes of fruit they are highly dependent on the abundance and nutritional composition of fruits. Frugivores can either benefit fruit-producing plants by dispersing seeds, or they can negatively affect plants by digesting seeds along with the fruits. When both the fruit-producing plant and the frugivore species benefit by fruit-eating behavior their interaction is called a mutualism.

Seed dispersal is important for plants because it allows their progeny to move away from their parents in space and time. The advantages of seed dispersal may have led to the evolution of fleshy fruits, which entice animals to eat the fruits and move the plants seeds from place to place. While many fruit producing plant species would not disperse far without frugivores, they can usually germinate even if they fall to the ground directly below the parent plant.

Many types of animals are seed dispersers. Mammal and bird species represent the majority of seed dispersing species. However, frugivorous tortoises, lizards, amphibians and even fish also disperse seeds. While frugivores and fruit-producing plant species are worldwide, there is some evidence that tropical forests have more frugivore seed dispersers than the temperate zone.

There are a number of fruit characteristics that seem to be adaptive characteristics to attract frugivores. Many animal-dispersed fruits advertise their palatability to animals with bright colors and attractive smells (mimetic fruits). Fruit pulp is generally rich in water and carbohydrates and low in protein and lipids. However, the exact nutritional composition of fruits varies widely. The seeds of animal-dispersed fruits are often adapted to survive digestion by frugivores. For example, seeds can become more permeable to water after passage through an animal’s gut. This leads to higher germination rates. Some mistletoe seeds even germinate inside the disperser’s intestine.

In order for frugivores to be good seed dispersers they must digest fruits without consuming a high proportion of the seeds. Many seed-dispersing animals have specialized digestive systems to process fruits which leave seeds intact. Some bird species have shorter intestines to rapidly pass seeds from fruits, while some frugivorous bat species have longer intestines. Some seed-dispersing frugivores have short gut-retention times and others can alter intestinal enzyme composition when eating different types of fruits.>>

Tara_Li wrote:Unless this star is very unusual, it is going to contain heavy metals, up to and including iron - and probably even a bit beyond. Iron contained in the star material gets drawn off into the accretion disk, spirals in and gets ejected in the disk...

Who honestly *DIDN'T* expect to see iron & nickel in the jets?

geckzilla wrote:

Tara_Li wrote:
Unless this star is very unusual, it is going to contain heavy metals, up to and including iron - and probably even a bit beyond. Iron contained in the star material gets drawn off into the accretion disk, spirals in and gets ejected in the disk... Who honestly *DIDN'T* expect to see iron & nickel in the jets?

I was under the impression that the reason it's unexpected is because the jets move at such speeds that the heavier stuff wouldn't be in them since it takes that much more energy to accelerate a heavier object.

neufer wrote: Being heavy, the iron would mostly reside deep within the scavenged star and, hence, not be readily available in the material drawn off into the black hole accretion disk.

JohnD wrote:... what if the axis of rotation of the star and the BH were at right angles, with one BH pole pointing INTO the star

Case wrote:Interesting thought. Most artist impressions of a black hole in a binary system show the accretion disc in the same orientation with regard to the companion star. I can't think of a good reason why it always has to be like that, unless the orbits somehow align the rotation of the individual bodies over time. If the rotation axis can be different, then I suppose it wouldn't be impossible for the jet to point to the companion. And such might be cause for some weird fireworks!

JohnD wrote:Pretty unlikely, I know, but what if the axis of rotation of the star and the BH were at right angles, with one BH pole pointing INTO the star?
What if the iron originates in the BH's accretion disc, from lighter elements extracted from the star's outer layers? Then the jet would recirculate the iron back into the star, increasing the amount of iron in the core and accelerating the star's degenaration towards nova. Early novas.

What if.....

John

Cousin Ricky wrote:I haven’t seen very many detailed paintings of blue stars, but on those that I have seen, the stellar prominences (and chromospheres, for that matter) are depicted in blue. Don’t prominences get their color from H-alpha emissions? Wouldn’t they be red regardless of the star’s temperature?

Do blue giants show limb-darkening?

How hot is an accretion disc, and how fast does the temperature go up the nearer to the event horizon? The one depicted here goes from red hot to white hot, but if these things emit x-rays, I would think that they would appear blue towards the center.

Would the red shift caused by the gravity well sufficiently counteract the wavelengths of the thermal emissions to keep them from appearing blue?

What color would the gas outside the photosphere be? Would it cool off as it approaches the accretion disc? Does it reflect the light from the star and the accretion disc? Would it be the same pearly white color as the Sun’s corona? (And why does the Sun’s corona glow white when it is x-ray hot?)