Assignment-daixieTM为您提供斯旺西大学Swansea University PH-100 Astronomy and Cosmology天文学和宇宙学代写代考和辅导服务！
Instructions:
Observational astronomy and cosmology are fascinating fields that allow us to explore and understand the vast universe around us. I’m sure students will find it inspiring to learn about the different techniques used to study celestial objects, such as telescopes and spectroscopy. Practical observations can also be a fun way to apply theoretical concepts and gain a deeper understanding of astronomical phenomena. I hope students enjoy the module and are motivated to pursue further studies in these areas.
A spectrum is taken of a single star (i.e., one not in a binary), Among the observed spectral lines is one from oxygen whose rest wavelength is $5007 \mathrm{~A}$. The Doppler shifted oxygen line from this star is observed to be at a wavelength of $5012 \mathrm{~A}$. The star is also observed to have a proper motion, $\mu$, of 1 arc second per year (which corresponds to $\sim 1.5 \times$ $10^{-13}$ radians per second of time). It is located at a distance of $60 \mathrm{pc}$ from the Earth.
What is the 3 dimensional velocity of the star?
$\begin{aligned} & V_r=\frac{\Delta \lambda}{\lambda} c=\frac{5}{5000} c=300 \mathrm{~km} / \mathrm{s} \ & V_T=1.5 \times 10^{-13} \times D=\dot{\theta} D=\mu D=277 \mathrm{~km} / \mathrm{s}\end{aligned}$
What parallax would be measured for this star?
parallax $=\frac{1^{\prime \prime}}{60}$
A candle has a power in the visual band of -3 Watts. When this candle is placed at a distance of $3 \mathrm{~km}$ it has the same apparent brightness as a certain star. Assume that this star has the same luminosity as the Sun in the visual band $\left(\sim 10^{26}\right.$ Watts). How far away is the star?
\begin{aligned}
& \text { Sane } f \text { lux } \Rightarrow \frac{3}{(3 \mathrm{~km})^2}=\frac{10^{26}}{d^2} \
& d=10^{13} \times \frac{3}{\sqrt{3}}=1.7 \times 10^{13} \mathrm{~km} \
& d=0.56 \mathrm{pc} \
&
\end{aligned}
