Questions and Answers on Astronomy Tools

Discuss stellar parallax, how it works, and how it is used as a tool in astronomy.

Stellar parallax is a method that is usually utilized by astronomers in measuring the distances to stars. Stellar parallax provides a simple way that involves one's thumb, triangles, angles, and the orbit of the earth that surrounds the sun. Therefore, stellar parallax entails the change in position of the nearby objects against the objects that are far away. The mechanism that is behind using stellar parallax method involves holding ones thumb out in front, closing one eye and noticing where one's thumb is in association with something that is far away. One should not move their thumb, but they require switching open their other eye while closing the first eye. Parallax involves seeing something that is far away from two distinct points. The two eyes are two different points. Astronomers may utilize this approach for the stars that are closest. The measurements of the angles between the triangles formed become tiny. The more away a given something is, the longer the triangle becomes and the smaller an angle is.

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The stellar parallax approach began with an effective range of approximately 1500pc. The fundamental concept of stellar parallax is utilized in some of the common things carried out each day. Stellar parallax can be defined as the apparent shift of location of the stars against the stars' background while the earth remains moving around its orbit that surrounds the sun. Only the measurements that are within the galaxy may be made through using this approach. A formula for determining stellar parallax is; d=1/p. Distance (d) is usually computed in a parse, and the angle (p) is usually measured regarding final seconds.

Which spectral class has the highest surface temperature?

Type O Color Blue Surface Temperature: : >2500K

Which spectral class has the coolest surface temperature?

Type M Color Red Surface Temperature: <3500K

What is the spectral class of the sun?

G2V. This spectral class indicates the major sequence star that has a temperature of about 5, 800K.

One of our tools for measuring cosmic distances is Cepheid Variable Stars. Explain how they allow the determination of distances.

Cepheid Variable Stars are defined as the intrinsic variables that pulsate in a given predictable way. Furthermore, the period of a Cepheid star usually is directly related to its brightness or luminosity. The Cepheid variables typically are incredibly luminous, and the very distant ones may be measured and observed. After the period of the distant Cepheid is measured, then its luminosity may become determined from a given known behavior representing the Cepheid variables. Then the apparent magnitude and absolute magnitude may be related by the equation of distance modulus and have its distance been determined. The Cepheid variables may be used during measuring of the lengths that are from about 1kps -5oMpc.

The period of the brightness variation of Cepheid Variable Stars is usually directly associated to the absolute magnitude (m) of Cepheid Variable Stars and the amount of the metals which are typically contained in the stars. This approach has been proved to be more effective when dealing with a range of about 1kpc - 3o mega-parsec (mpc). When calculating the cosmic distances using Cepheid Variable Stars, there is the calculation of the luminosity that is from where the astronomers are, and there is finding out of what luminosity should have, and then there is the usage of the formula in determining the stars (Pietrzynski et al., 2010). Given that one may have the ability to tell how many months or days, it usually takes for them to shift their luminosity, then it would be easy to determine the original luminosity. This is accompanied by applying of the formula in finding out the distance that is associated to the star.

The Hertzsprung-Russell diagram is a tool as useful to astronomers as the Periodic Table is to chemists. Explain the structure of the H-R diagram and what it tells us.

Hertzsprung-Russell diagram is defined as the graphical tool which the astronomers utilize when classifying the stars according to their spectral type, luminosity, temperature, evolutionary stage, and color. The stars when in a stable phase of hydrogen burning usually lie along a significant sequence according to the mass that they have. After the star utilizes all the hydrogen available in its core, the star the leaves the primary series and it moves towards the red giant branch. Hertzsprung-Russell diagram does not map the locations of the stars. Hertzsprung-Russell diagram usually plots every star on the graph while measuring the brightness of the star against its color (temperature).

In the Hertzsprung-Russell diagram, the luminosities of the stars are usually plotted against all their spectral types (absolute magnitudes being planned against the surface temperatures. The diagram was developed with the aim of graphically classifying the stars through their luminosity and temperatures. The diagram may also tell more about the age and the size of the star. The graph has distinct classes of stars, and the major spectral classes follow the order starting from the hottest to the coolest. Hertzsprung-Russell diagram reveals that there exist four primary grouping of the stars: giants, white dwarfs, supergiant and main-sequence stars (Langer & Kudritzki, 2014). When stars lay along the straight diagonal line, they are referred to as the significant sequence stars. The string representing the main sequence usually accounts for 80-90 % of the entire stellar population.

There are several vital steps necessary for the creation of a star. Provide an overview description of these critical steps.

• Essential step 1- first collapsing of interstellar gas clouds mostly hydrogen and some helium
• Essential step 2- cloud fragments typically into the clumps which form specific stars
• Essential step 3- the clump collapses into the star

The matter that is floating in the space region is usually pulled together through the gravity force, and while the gravity squeezes the matter together, there is the rise of pressure and temperature. When there is much energy released, it results to matter expansion which is outward against gravity force resulting in a given star.

References

Langer, N., & Kudritzki, R. P. (2014). The spectroscopic Hertzsprung-Russell diagram. Astronomy & Astrophysics, 564, A52.

Pietrzynski, G., Thompson, I. B., Gieren, W., Graczyk, D., Bono, G., Udalski, A., ... & Pilecki, B. (2010). The dynamical mass of a classical Cepheid variable star in an eclipsing binary system. Nature, 468(7323), 542.