## Homework Handout #13

13.01: The solar apex is toward galactic coordinates ( l, b ) = (53o,25o).
(a) Using Figure 22.18 of the text (p. 938), estimate the celestial coordinates (a, d) of this point.
(b) Verify your estimate by using the conversion formula, eq. 22.12 of the text (p. 937) to convert
( l, b ) to (a, d).  Express right ascension (a) in hours, minutes, and declination (d) in degrees.

13.02: Using the catalog of nearby stars given in the lecture 2 web notes:
(a) List vr and calculate vq for all stars within 10 degrees of the solar apex, for which sufficient information is given.  (You will probably want to print the relevant pages.)
(b) Determine the average radial velocity of the stars in your list.
(c) List all stars within 10 degrees of the solar apex from the Yale catalog of bright stars, for which vr is given (typically pm is not given for these stars, so we will not calculate vq for these).
(d) Determine the average radial velocity of the stars from your Yale catalog list.
(e) Do your answers to (b) and (d) agree with the idea that the Sun is moving in the direction of the solar apex at ~17 km/s?  Why might (b) and (d) be different?