You observe the H-beta line of Hydrogen in a distant galaxy to have a wavelength of 558.9 nm. What is the radial velocity of the galaxy?

A star has a measured radial velocity of 300 km/s. If you measure the wavelength of a particular spectral line of Hydrogen as 657.18 nm, what was the laboratory wavelength (in nm) of the line? (Round your answer to at least one decimal place.) nm Which spectral line does this likely correspond to? Balmer-alpha (656.3 nm) Balmer-beta (486.1 nm) Balmer-gamma (434.0 nm) Balmer-del ta (410.2 nm)

NGC 3379 is an El galaxy at a distance of 14.8 Mpc that has an apparent B band magnitude of 10.65 and a central velocity dispersion of 220 kms¬1. M87 is also an El galaxy, but lies in the Virgo cluster. M87 has a central velocity dispersion of 315 km s and an apparent B-band magnitude of 10.1. Assuming that both of these galaxies exactly follow the scaling relation that connects these properties, what is the distance to M87?

Question 2: apparent magnitude my 1 = 305.9, b = −44.9 and is d=4.5 kpc from the Sun. a.) The integrated light from the Milky Way globular cluster NGC 104 has an 4.03 mag and absolute magnitude My -9.52 mag. It is located at b.) = = Estimate the amount of extinction between the Sun and 47 Tucanae in magnitudes. What does this value of extinction mean for the amount of attenuation by dust between Earth and NGC 104?.

As2

Neutral hydrogens are detected with their emission lines of 21cm. What is the energy of a photon in such a line, and in which waveband would this line be observed?

Are the galaxies red-shifting or blue-shifting? Explain. (You may find the big-bang theory helpful). Andromeda galaxy is currently approaching our galaxy with a radial velocity of 266 km/sec. How far is our galaxy from Andromeda? (Hubble’s constant, H, is 73 km/sec/MParsec). When can the two galaxies be anticipated to collide?

The elliptical galaxy NGC 4889 is the largest galaxy in the Coma Cluster (shown in the image below taken by the Hubble Space Telescope). After analysing the spectrum of NGC 4889, an astronomer identifies a spectral line as being CaII (singly ionised Calcium) with a measured wavelength of 401.8 nm. The true, rest wavelength of this spectral line, measured in a lab, is 393.3 nm.  Using a Hubble constant of ?0 = 70 km/s/Mpc, find the distance to this galaxy cluster. Give your answer in megaparsecs and in light-years.

The wavelength of the peak of the blackbody distribution was found to follow Wein’s Displacement Law. Calculate the peak wavelength of a bluish-white star that radiates at temperature 20000 K.   a) 145 nm b) 100 nm c) 114 nm d) 155 nm

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