Answer:
Main sequence stars fuse hydrogen atoms to form helium atoms in their cores. About 90 percent of the stars in the universe, including the sun, are main sequence stars. These stars can range from about a tenth of the mass of the sun to up to 200 times as massive.
Stars start their lives as clouds of dust and gas. Gravity draws these clouds together. A small protostar forms, powered by the collapsing material. Protostars often form in densely packed clouds of gas and can be challenging to detect.
"Nature doesn't form stars in isolation," Mark Morris, of the University of California at Los Angeles (UCLS), said in a statement. "It forms them in clusters, out of natal clouds that collapse under their own gravity."
Smaller bodies — with less than 0.08 the sun's mass — cannot reach the stage of nuclear fusion at their core. Instead, they become brown dwarfs, stars that never ignite. But if the body has sufficient mass, the collapsing gas and dust burns hotter, eventually reaching temperatures sufficient to fuse hydrogen into helium. The star turns on and becomes a main sequence star, powered by hydrogen fusion. Fusion produces an outward pressure that balances with the inward pressure caused by gravity, stabilizing the star.
How long a main sequence star lives depends on how massive it is. A higher-mass star may have more material, but it burns through it faster due to higher core temperatures caused by greater gravitational forces. While the sun will spend about 10 billion years on the main sequence, a star 10 times as massive will stick around for only 20 million years. A red dwarf, which is half as massive as the sun, can last 80 to 100 billion years, which is far longer than the universe's age of 13.8 billion years. (This long lifetime is one reason red dwarfs are considered to be good sources for planets hosting life, because they are stable for such a long time.)
Explanation:
I hope this helped!
When salt and sugar dissolve in water it is a physical change. The chemical makeup of the salt and sugar are not changed.
Physical change
Answer:
The correct answer is - 75% or 3/4.
Explanation:
In the given question, there is a cross between III-6 and III-7 that produced two double eyes monsters and expected one more. As given in the image that the A or single eye is dominant over the a or double eye then both parents must be heterozygous as they produced double eye offspring (aa) and they do have only one eye.
then chances of single eye offspring would be -
cross: Aa and Aa
gametes: A, a and A, a
Punnett square:
A a
A AA Aa
a Aa aa
so there are 75% chances to have a single eye and 25% chances for a double eye.
Answer: Kuru
Explanation:
Kuru are transmitted by prion. This diseases are untreatable and ultimately fatal.
Prions are infectious proteinaceous particle that are neither virus nor do they contain nucleic acid.
They are transmitted by ingestion of the infected nervous system tissues.They are normally found in the healthy brain tissues if this protein is mis-folded into denatured form it can cause disease.
