21ST CENT.AST.W/WKBK+SMARTWORK >BI<
6th Edition
ISBN: 9780393415216
Author: Kay
Publisher: NORTON
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Chapter 6, Problem 41QP
To determine
The angular resolution on looking at interstellar molecules using space VLBI.
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A)The star 58 Eridani is a feint but naked-eye star similar to the Sun. Suppose that you are observing this star in the night sky without a telescope. Ignoring any interstellar extinction or atmospheric absorption, approximately how many photons per second arrive at your retina? Show all steps in calculation .
B) The Mid-infared Instrument (MIRI , camera and spectrograph ) on the James Webb Space Telescope operates in the band 5-28 µm . For 58 Eridani , approximatley how many photons per second can be used by this instrument ? Assume that MIRI takes all the photons from the full JWST mirror . Show all steps in calcultation .
Describe breifly two or three other factors which play a role in determining the sensetivitu of an instrument such as MIRI ?
There are several spectral features that can be used to characterise galax-
ies, including the Hydrogen-a emission at 656.3 nm and the Hydrogen-
emission at 486.8 nm.
For the Hydrogen-a emission, the spectrograph on the FET just gives
sufficient resolution to resolve the emission line, which has a width of
100 km s¹. Calculate the ruling density necessary to observe the Hydrogen-
ß emission line at the same resolution, if the observations are taken in first
order and in 1-arcsecond seeing.
A cloud of gas has a temperature of 5,000 K.
Estimate the width of the hydrogen H-alpha line with an intrinsic wavelength λ = 656 nm.
(Note: the typical velocity of hydrogen atoms in a gas with temperature T is about (kT/mH)1/2, where k is Boltzmann constant and mH is the mass of a hydrogen atom, which is approximately the mass of a proton).
Chapter 6 Solutions
21ST CENT.AST.W/WKBK+SMARTWORK >BI<
Ch. 6.1 - Prob. 6.1ACYUCh. 6.1 - Prob. 6.1BCYUCh. 6.2 - Prob. 6.2CYUCh. 6.3 - Prob. 6.3CYUCh. 6.4 - Prob. 6.4CYUCh. 6.5 - Prob. 6.5CYUCh. 6 - Prob. 1QPCh. 6 - Prob. 2QPCh. 6 - Prob. 3QPCh. 6 - Prob. 4QP
Ch. 6 - Prob. 5QPCh. 6 - Prob. 6QPCh. 6 - Prob. 7QPCh. 6 - Prob. 8QPCh. 6 - Prob. 9QPCh. 6 - Prob. 10QPCh. 6 - Prob. 11QPCh. 6 - Prob. 12QPCh. 6 - Prob. 13QPCh. 6 - Prob. 14QPCh. 6 - Prob. 15QPCh. 6 - Prob. 16QPCh. 6 - Prob. 17QPCh. 6 - Prob. 18QPCh. 6 - Prob. 19QPCh. 6 - Prob. 20QPCh. 6 - Prob. 21QPCh. 6 - Prob. 22QPCh. 6 - Prob. 23QPCh. 6 - Prob. 24QPCh. 6 - Prob. 25QPCh. 6 - Prob. 26QPCh. 6 - Prob. 27QPCh. 6 - Prob. 28QPCh. 6 - Prob. 29QPCh. 6 - Prob. 30QPCh. 6 - Prob. 31QPCh. 6 - Prob. 32QPCh. 6 - Prob. 33QPCh. 6 - Prob. 34QPCh. 6 - Prob. 35QPCh. 6 - Prob. 36QPCh. 6 - Prob. 37QPCh. 6 - Prob. 38QPCh. 6 - Prob. 39QPCh. 6 - Prob. 40QPCh. 6 - Prob. 41QPCh. 6 - Prob. 42QPCh. 6 - Prob. 43QPCh. 6 - Prob. 44QPCh. 6 - Prob. 45QP
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