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A "star" must produce energy via fusion.
This is a nuclear reaction in which nuclei (usually hydrogen) ram together at a high enough speed to form a nucleus with more protons than either of the original nuclei. For instance, a proton/neutron nucleus might smash into another proton/neutron nucleus and forming a nucleus of two protons and two neutrons.
This reaction can only be self-sustaining if there is enough energy during the reaction to end up as heat in other nuclei, which then blast into other nuclei and cause more fusion reactions. Because of that, there must be a fairly dense amount of fusionable material at a high temperature in order for a star to form.
The minimum temperature needed to permit fusion is about 8 million degrees Kelvin. Minimum densities would have to be about 10^15 particles per cubic centimeter, on the order of atmospheric pressure.
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∙ 12y ago
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Why is there only some stars that shoot?
A shooting star is not actually a star. It is a meteorite going through our atmosphere. It becomes white hot as it heats up from the friction in our atmosphere and usually burns up.
What happens after a nebula contracts and its temperature increases to 10million K?
That is hot enough to ignite hydrogen fusion, so the nebula becomes a star (possibly with planets).
Why are there no stars bluer on the main sequence?
No stars blue? A star's colour depends on it's temperature. A blue star must be very hot in order for it to glow blue. All stars in the main sequence sre only hot enought to glow yellow, not hot enought to glow blue.
Why doesn't yeast rise in hot or cold temperatures?
If the temperature is too low, the yeast will remain dormant. If the temperature becomes too hot, the yeast organisms will be overwhelmed and killed before they can respire.
How does the sea evaporate?
When the sea becomes hot
What happens to a high mass star as it ages?
it becomes a volcanic rock that is still very hot but bot as hot as the star was originally
Why does it take about 1 minute before water hot finally becomes hot in any bathroom or shower in the house?
Because the water in the pipes is at room temperature. You must push all that cool water out with the hot water before the hot water reaches your faucet.
How many years will it take for life to become extinct on earth before the sun becomes a red giant star?
It is expected that in a few hundred million years, it will become too hot on Earth for any kind of life we know.
Why is there only some stars that shoot?
A shooting star is not actually a star. It is a meteorite going through our atmosphere. It becomes white hot as it heats up from the friction in our atmosphere and usually burns up.
What are the disadvantages of boiling water for drinking?
It is hot and must be cooled before consumption.
What happens to steam before it becomes water vapour?
Steam is water vapour - just a very hot form of it.
Are steamy and hot the same synonym or same not?
Steamy food need not feel hot when hot food must not seem steamy though one may result with its other effect if an effect becomes the cause and the cause turns into that effect as something must feel too hot that they seem cold.
Why do you sweat when you wear a sweater in summer?
You sweat because it is hot outside and the sweater keeps the heat in your body. Your body becomes too hot and must naturally cool itself by sweating.
What happens after a nebula contracts and its temperature increases to 10million K?
That is hot enough to ignite hydrogen fusion, so the nebula becomes a star (possibly with planets).
How does a star turn into a white dwarf star?
A white dwarf is what stars like the Sun become after they have exhausted their nuclear fuel. Near the end of its nuclear burning stage, this type of star expels most of its outer material, creating a planetary nebula. Only the hot core of the star remains. This core becomes a very hot white dwarf, with a temperature exceeding 100,000 kelvin.
What must be done to hot-rolled steel in the mill before it can be cold finished?
Hot rolled steel must be descaled by pickling in acid with a lime water rinsebefore it can be cold finished
Why are there no stars bluer on the main sequence?
No stars blue? A star's colour depends on it's temperature. A blue star must be very hot in order for it to glow blue. All stars in the main sequence sre only hot enought to glow yellow, not hot enought to glow blue.
