as if Robert Hazen, Ph.D., George Mason University
When describing galaxies, distance is one of the most important measurements that astronomers can make. However, even the nearest galaxies are too far to measure in paradigms. Therefore, the greatest effort in modern astronomy is to develop advanced methods for determining distances to galaxies.
Cepheid dynamic technique
The Earth, which vibrates side by side in the orbit of the sun, covers a distance of 16 minutes of light, diameter. It takes eight minutes for light to reach the Earth, so the total distance at six months is about 16 minutes. The nearest galaxy is hundreds of thousands of light-years away. They do not get enough angles to make a triangle on distant galaxies.
The technique used by Edwin Hubble is the Safety Variable Technique, a well-known bright star, a standard candle. This method, with its modifications, is still used for galaxies up to tens of millions of light-years away.
High quality photographs from Hubble Space Telescope are especially useful in this regard; Hubble space telescope images allow you to unlock celestial stars in galaxies 50 or 60 million light-years away.
There are other special, bright stars, including the bright red giants and the brightest constellations or the giants. These stars can also be used as standard candles.
Learn more about the life cycle of the stars.
Standard Candle: Type I Supernova
There are standard candles called Supernova. These are supernova, exploding stars. Consider how this supernova happened.
In a binary system you have two stars rotating each other. Think of the big star as big as a supernova star, but not completely.
It will continue to absorb material from the accompanying star. They move from the smallest star to the largest hydrogen and helium. The star can go up to Iron-56.
When it goes to Iron-56, the star burns, falls by gravity, and becomes supernova. These types I supernovae each have the same mass and the same energy, so they become a standard candle; That standard candle is about 50 million times more energy efficient.
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Using whole galaxies as a standard candle
Other approximate distances depend on factors such as the size and brightness of the entire galaxy. If there is a collection of galaxies, you can imagine how bright the brightest galaxy in a cluster, such as the Andromeda or the Milky Way, is, and they are larger galaxies – and use that as a standard candle itself.
It requires many more estimates, but still, it is not a bad way to get an estimated distance for billions of light years. Important Note: There is no way we can know how much dust there is. If there is no dust, the brightness we see is the exact and clear brightness of that object, so we get an accurate measure of the distance of the object.
However, if there is dust on the road, something looks weaker than it really is, and it may seem out of place. Infrared radiation does not absorb light as strongly as dust, and one way to solve this problem is to measure the brightness of the visible light and the object in the infrared and see the ratio of the two.
Learn more about nebulae hypotheses.
Red conversion method
There is a different method for determining the distance, and this is a red change method using the Doppler effect. Red change is the wavelength change. When something moves away from you, it stretches the wavelengths – for example, the wavelength of light – so what the hydrogen line might be, in its normal position, turned to the red tip of the spectrum.
Hubble observes that the farther the galaxy, the reder the red. According to Cepheid variables, he saw a very simple connection between red shift and distance. So they adjust the red change by looking at the hydrogen lines or some other pull lines; For stars of at least 50 million light years or more, they measure the distance by looking at the Cepheid variables – and he has seen this relationship.
In general, the farthest galaxies are moving faster. This led to the so-called Hubble Law, which states that the speed of the galaxy is directly proportional to the distance.
Common questions about methods for determining distance to galaxies
Of cepheid variable It is a method that Hubble used. Determining distances to galaxies. According to this method, a star with a certain brightness can be used as a standard candle.
A Type I Supernova Occurs when two stars rotate in a binary system. The larger star begins to absorb hydrogen and helium from the smaller star and reaches a maximum of -66 iron. At this point, it explodes and becomes Supernova. Each type I Supernova has the same energy and weight and is used as a standard candle Determining distances to galaxies.
Red transition Is the method. Determine the distance to the galaxies. The wavelength change is called redhead. When something goes too far, the wavelengths expand and expand. Therefore, this shows simplicity The relationship between distance and red transition And is a useful method for determining the distance to galaxies.