3) Seven features of the active sun are:
1. Sunspots: these regions are darker and cooler than the rest of the suns photosphere; they are caused by magnetic fields that protrude at that area of the visible surface. 2. Plages: These are bright areas in the chromosphere. They are associated with magnetic fields emerging from the sun. 3. Solar Flares: these are ejections of large volumes of gas. They can sometimes head our way causing radio interference and auroras. 4. Filaments: Dark Loops of magnetic fields that carry gas. 5. Prominences: These are filaments viewed from the side. 6. Coronal Holes: Dark cooler portions of the corona that appear over sunspots. They act as conduits for gasses to flow from the sun. 7. Coronal mass ejections: these are ejections of large volumes of gas. They cause radio interference and auroras. They are larger than flares.
7) Astronomers detect the presence of a magnetic field in hot gasses such as the field in the solar photosphere by observing the Zeeman effect. This is the splitting of spectral lines when a magnetic field is present. It can be observed from the sun by focusing a spectroscope on light coming from a sunspot.
12) Thermonuclear reactions take place only at the suns core because in order for hydrogen to fuse and create helium, a very high temperature must be present (10 000 000 K) the high temperature at the suns core caused by the intense pressure of gravity caused by the suns mass exceeds this temperature. It is about 15 500 000 K. This temp is not present anywhere else on the sun.
Chapter 11: Review Questions
1) Stellar parallax measures the distance to stars. It does this by measuring the apparent shift in a stars position relative to the celestial sphere caused by the Earths orbit around the sun.
12) A stars luminosity measures the rate that electromagnetic radiation is emitted from the star. Luminosity can be used to determine the mass of...