1. What are variable stars whose brightness changes due to physical processes occurring within them? A. Physical

1. What are variable stars whose brightness changes due to physical processes occurring within them?
A. Physical variable stars
B. Optical variable stars
C. Chemical variable stars
D. Astrometric variable stars
2. What are the types of physical variable stars?
A. Pulsating
B. Eruptive
C. Eclipsing
D. Spectral
3. Match definitions and concepts.
A. Physical variable stars that undergo periodic fluctuations in brightness
B. Class of pulsating variable stars with a period of several weeks to a year or more
C. Class of pulsating variable stars with a fairly precise period-luminosity relationship
D. Cataclysmic variable star resulting from the explosion of a white dwarf
4. List the sources of narrow-directed pulsating radio emission caused by the interaction of a star's plasma with its strong magnetic field.
5. Match the cause of the non-stationarity of stars.
A. Cepheids
B. New stars
C. Supernovae
Answer options
a) Changes in the radial velocity and temperature of the star.
b) Accretion of matter from a companion star onto a white dwarf.
c) The final stage of a star's evolution with the cessation of nuclear reactions.
6. If the brightness of a new star changes by 10m at approximately constant temperature of its expanding photosphere, by what factor does the star's radius change? Round the answer to the nearest whole number.
7. Which stars gave names to classes of pulsating variable stars?
Answer options
A) Mira
B) Delta Cephei
C) R Zeta
D) RR Lyrae
E) Polaris
8. Why are Cepheids called "beacons of the Universe"?
Answer options
A) they have an important period-luminosity dependence, which can be used to determine the distance to a star or a distant galaxy.
B) they are supergiant stars that have very high luminosity.
C) they are easily detectable in other stellar systems (at distances up to 20 Mpc).
D) "beacons of the Universe" are not Cepheids, but supernovae.
9. What is a new star?
Answer options
A) stars whose luminosity suddenly increases by 103-106 times within a day.
B) stars that have just been born from a protostar.
C) a cataclysmic variable star resulting from the explosion of a white dwarf.
D) a massive solitary star that is in the final stage of evolution.
10. What is the cosmic object consisting of a neutron core covered by a relatively thin layer of matter in the form of heavy atomic nuclei and electrons, and is the remains of a supernova star?