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Astronomical instruments help astronomers determine characteristics of distant objects in a number of different ways. Without the development of these tools, many astronomers would still be working on base ideas instead of working in the real data. This document explores the use of these tools and development of scales that explain the workings of stellar objects.
Determination of details such as composition can be determined by analysis of the electromagnetic waves passing through or around an object, or emitted by the object. Using a spectrometer, astronomers can determine the composition of objects in space and using a color scale easily identify said matter. Temperature can be determined using near-infrared and other frequencies of the electromagnetic spectrum. Electromagnetic waves in space travel at the speed of light and range from low-frequency radio waves to high-frequency gamma rays. This range of frequencies makes up the electromagnetic spectrum, and waves are characterized by inversely related frequency to wavelength. (Simply put, a high-frequency waveform has a shorter wave than a low frequency one. The distance between wave crests changes with regard to the frequency.) Telescopes and other such instruments collect and analyze electromagnetic radiation in other areas of the Universe. Different telescopes are used for different regions of the electromagnetic spectrum, allowing astronomers to focus on single areas of the spectrum, such as visible light, near-infrared, radio waves and microwaves.
Astronomers can infer different characteristics of the object being viewed due to the wavelength the object is detected in, such as temperature, composition and possibly rotation rate depending on emissions from the object.
The speed of an object can be determined somewhat by the color shift of the light when the object is viewed. For instance, an object moving away from the viewer in our Universe at high speed will produce a red-shift, while objects coming toward the viewer produce a blue-shift.
All objects in space emit radio waves, and these waves can also provide valuable information regarding the object. In the instance of some objects, such as pulsars, these waves are very predictable, with changes in wave denoting the rotation rate of the object. A repeated change in the signal at a given interval can determine the rotation rate of the object.
Objects that do not conform to the above would of course have other solutions applied to find the rotation rate and the overall speed of the planet’s surface. One such solution was used to measure the planet Mercury for rotation rate. This method used radar to determine the rotation rate by calculating the signal changes in the bounced radar signal. The technique is now being taught by the Department of Physics at Gettysburg College in Pennsylvania. By measuring the Doppler shift in the signal bounced from Mercury, the lab referenced shows how the Doppler effect can be used against the frequency shifts related to bouncing a signal on a spherical object and as such the rotational variation of the frequency can be used to determine the rotational period of the planet. This would be a usable tool only in range of the radar signal, as the effects of time on the signal would of course lead to further shifting of the signal. Stars such as Super-giants emitting could possibly reduce the effectiveness of measurements as their massive gravity may cause some distortion in the returned signal as well.
Stars located on the Hertzsprung-Russell diagram include the Super-giant, white dwarf, regular period and giant classes. The properties of these stars are illustrated on the H-R diagram as size, luminosity, and surface temperature. With the data provided, it is possible to produce an approximate stellar radius equation.
Speaking of size, the Sun is probably the most moderate on the H-R diagram.
The Sun’s lifecycle in relation to the stars on the diagram is of longevity and moderate luminosity, while most stars that are of the same or close to the same size in higher luminosities will run out of fuel faster than the Sun. The Sun’s eventual fate could be a number of possibilities, though the typical lifecycle usually has three conclusions. After a birth from nebular gasses, a star such as the Sun typically will burn for millions of years at a rate determined by its mass and luminosity, then will grow to enormous sizes due to the increase in helium in its interior. In most cases the increase in size ends up destroying any planets close to the star. The Sun then will either supernova its outer layers into space and form a smaller star, or it will collapse and condense into a smaller star, or even a black-hole would be formed from the massive increases in density related to the condensing matter. Emission in the electromagnetic spectrum would be much higher in the ending phases of the Sun’s life, producing massive shock waves in the supernova event, and in the case of the black-hole event, would pull in the surrounding stellar matter and anything close enough to get pulled into the event horizon. The black hole would also emit particle fountains from the center as the remaining matter is devoured, then it would fall silent, becoming the truly black hole from which it gets its name. The Sun is currently approximately halfway through its lifecycle, with optimum emissions and activity, and very limited instability in its cycles. Currently stellar emissions and other activity are normal for the phase of the Sun’s lifecycle we are currently experiencing, though the first indications that there may be a change would be an increase or decrease in luminosity, and/or overall increases in radius that would be associated with a change in stellar class to a giant. The lifecycle would call for a change to giant as the matter of the Sun gets “lighter”, though possibly less luminous. Then the supernova or collapse event would occur. There would be some separation of the events of course as the stellar events would most likely occur some millions of years apart. In the event of said expansion of the Sun, Earth would most likely be close to if not inside the Sun’s radius, producing the extinction of all life on the planet.
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