Astronomy | Astrophysics Answers

Are clocks ticking slower for the people on Earth or for the astronauts on the spaceship?

How fast must the spaceship travel such that the clocks go twice as slow? 

draw a plot of the lorentz factor for 0<B<0.9 to see how its value change

This problem requires you to read the following recently published

scientific article:

Measuring the ionisation fraction in a jet from a massive protostar.

Fedriani, R., Caratti o Garatti, A., Purser, S.J.D. et al. Nat Commun

10, 3630 (2019).

Link: https://www.nature.com/articles/s41467-019-11595-x.pdf

Answer the following questions related to this article:

(a) Why are massive stars important for the development of the

universe?

(b) How can the ionised part of jets be observed?

(c) What kind of region is G35.2N? Describe how it is structured.

(d) What is the ionisation fraction χe and how do the authors

calculate its value?

(e) How is the mass-loss rate being determined for knots K3 and K4?

Why not for K1 and K2?

(f) Why is the ionisation fraction so small for G35.2N?

One of the many exciting phenomena of special relativity is time dilation. Imagine astronauts

in a spaceship that is passing by the Earth with a high velocity.

(c) Are clocks ticking slower for the people on Earth or for the astronauts on the spaceship?

(d) How fast must the spaceship travel such that the clocks go twice as slow?

Draw a plot of the Lorentz factor for 0 ≤ β ≤ 0:9 to see how its value changes

Astronomers need to identify the position of objects in the sky with very high precision. For that,

it is essential to have coordinate systems that specify the position of an object at a given time.

One of them is the equatorial coordinate system that is widely used in astronomy.

(a) Explain how the equatorial coordinate system works.

(b) What is the meaning of J2000 that oen occurs together with equatorial coordinates?

The object NGC 4440 is a galaxy located in the Virgo Cluster at the following equatorial coordinates (J2000): 12h 27m 53.6s (right ascension), 12◦ 170 3600 (declination). TheCalar Alto Observatory

is located in Spain at the geographical coordinates 37.23◦N and 2.55◦W.

(c) Is the NGC 4440 galaxy observable from the Calar Alto Observatory?

This problem requires you to read the following recently published scientific article:

Measuring the ionisation fraction in a jet from a massive protostar.

Fedriani, R., Caratti o Garatti, A., Purser, S.J.D. et al. Nat Commun 10, 3630 (2019).

Link: https://www.nature.com/articles/s41467-019-11595-x.pdf

Answer the following questions related to this article:

(a) Why are massive stars important for the development of the universe?

(b) How can the ionised part of jets be observed?

(c) What kind of region is G35.2N? Describe how it is structured.

(d) What is the ionisation fraction χe and how do the authors calculate its value?

(e) How is the mass-loss rate being determined for knots K3 and K4? Why not for K1 and K2?

(f) Why is the ionisation fraction so small for G35.2N?

This problem requires you to read the following recently published scientific article:

Onset of Cosmic Reionization: Evidence of an Ionized Bubble Merely 680 Myr aer the Big Bang.

V. Tilvi et al 2020 ApJL 891 L10. Link: https://iopscience.iop.org/article/10.3847/2041-8213/ab75ec  

Answer the following questions related to this article:

(a) What is the so called cosmic reionization process?

(b) What are Lyα lines and why did the researches want to observe them?

(c) What do the authors intend to point out with Figure 1 (see article)?

(d) How is confirmed that the peaks seen in Figure 3 are actually from Lyα emissions?

(e) How are the bubble sizes of the galaxies estimated?

(f) What is special about the findings in the article and what are the scientific implications?

(a) State and explain the two traditional postulates from which special relativity originates. (b) Draw a plot of the Lorentz factor for 0 ≤ β ≤ 0.9 to see how its value changes.