| 01. | Kapteyn's star, named after the Dutch astronomer who found it, has a parallax angle of 0.255 arcsec, a proper motion of 8.67 arcsec per year and a radial velocity of +246 km/s. (a) What is the star's tangential velocity? (b) What is the star's actual speed relative to the Sun? |
| 02. | How far away is a star that has a proper motion of 0.08"/year and a tangential velocity of 40 km/s? For a star at this distance, what would its tangential velocity have to be in order for it to exhibit the same proper motion as Barnard's star? |
| 03. | In the spectrum of a particular star, the Balmer line Hαhas a wavelength of 656.41 nm. The laboratory value for the wavelength of Hα is 656.28 nm. (a) Find the star's radial velocity. (b) Is this star approaching us or moving away? (c) Find the wavelength at which you would expect to find Hβ in the spectrum of this star, given that the laboratory wavelength of Hβ is 486.13 nm. |
| 04. | The solar constant, equal to 1370 W/m2, is the amount of light energy from the Sum that falls on 1 square meter of the Earth's surface in 1 second. What would the distance between the Earth and the Sun have to be in order for the solar constant to be 1 watt per square meter(1 W/m2)? |
| 05. | The star HIP 72509 has an apparent magnitude of +12.1 and a parallax angle of 0.222 arcsecond. (a) Determine its absolute magnitude. (b) Find the approximate ratio of the luminosity of HIP 72509 to the Sun's luminosity. |
| 06. | The bright star Rigel in the constellation Orion has a surface temperature about 1.6 times that of the Sun. Its luminosity is about 64000 L⊙. What is Rigel's radius compared to the radius of the Sun? |
| 07. | What temperature and spectral classification would you give to a star with equal line strengths of hydrogen (H) and neutral helium (He I)? Check figures in the lecture note. |
| 08. | Castor (α Geminorum) is an A1 V star with an apparent brightness of 4.4x10-12 that of the Sun. Determine the approximate distance from the Earth to Castor (in parsecs). |