Stars<span> start their lives as clouds of dust and gas. ... But if the body has sufficient </span>mass<span>, the collapsing gas and dust burns hotter, eventually reaching </span>temperatures<span> sufficient to fuse hydrogen into helium. The </span>star<span> turns on and becomes a </span>main sequence star<span>, powered by hydrogen fusion
Tangerines AmbitiousThere are a few hundred billion stars in our galaxy, the Milky Way and billions of galaxies in the Universe. One important technique in science is to try and sort or classify things into groups and seek out trends or patterns. Astronomers do this with stars.
So far we have discussed the luminosity and colour or effective temperature of stars. These can be plotted to form what is one of the most useful plots for stellar astronomy, the Hertzsprung-Russell (or H-R) diagram. It is named after the Danish and American astronomers who independently developed versions of the diagram in the early Twentieth Century.
In an H-R diagram the luminosity or energy output of a star is plotted on the vertical axis. This can be expressed as a ratio of the star's luminosity to that of the Sun; L*/Lsun. Astronomers also use the historical concept of magnitude as a measure of a star's luminosity. Absolute magnitude is simply a measure of how bright a star would appear if 10 parsecs distant and thus allows stars to be simply compared. Just to confuse things, the lower or more negative the magnitude, the brighter the star. By definition a star of magnitude 1 is 100 × brighter than one of magnitude 6. Our Sun has an absolute magnitude of + 4.8.
i hope this helps </span>
Answer:
what decision?
Explanation:
Like a love decision or a fighting decision?
Por favor gnatrwtjwtjwtbwtbwnwgnsgn
Answer:
With microscope.
Explanation:
Every cell has a selective permeable membrane in which smaller molecules can pass whereas bigger molecules stays outside the cell which can be seen in the cell with the use of microscope because it only occurs inside the cell. The movement of ions or molecules in the cell through a semi permeable membrane is called Osmosis. The movement of ions or molecules sometime needs energy we called it active transport and sometimes it moves without the use of energy is known as passive transport.
The normal membrane potential inside the axon of nerve cells is –70mV, and since this potential can change in nerve cells it is called the resting potential. When a stimulus is applied a brief reversal of the membrane potential, lasting about a millisecond, occurs. This brief reversal is called the action potential
<span>A stimulus can cause the membrane potential to change a little. The voltage-gated ion channels can detect this change, and when the potential reaches –30mV the sodium channels open for 0.5ms. The causes sodium ions to rush in, making the inside of the cell more positive. This phase is referred to as a depolarisation since the normal voltage polarity (negative inside) is reversed (becomes positive inside). </span>
<span>Repolarisation. At a certain point, the depolarisation of the membrane causes the sodium channels to close. As a result the potassium channels open for 0.5ms, causing potassium ions to rush out, making the inside more negative again. Since this restores the original polarity, it is called repolarisation. As the polarity becomes restored, there is a slight ‘overshoot’ in the movement of potassium ions (called hyperpolarisation). The resting membrane potential is restored by the Na+K+ATPase pump.</span>
