Astronomy Blows

Of the three ways in which energy is transferred in nature (radiation, conduction, and convection) which two are important to the sun? Radiation and Convection Parallax is the Apparent shift in the position of a nearby object as we move. What process provides the power for the sun? Fusion of hydrogen into helium. Granulation on the surface of the Sun in caused by Convective currents carrying heat from beneath the surface. The nuetrino is An elusive, subatomic particle having little or no mass and very difficult to detect. What is the characteristic color of an emission nebula? Red. Astronomers measure the masses of stars by Observing the motion of two stars in a binary star system. A brown dwarf is An object intermediate between a planet and a star, with not enough mass to begin nuclear reaction in its core. The evolution of a star is controlled mostly by its initial mass The spectral sequence of star surface temperature as determined by relative spectral line strengths has been given which sequence of letters, in order of decreasing temperature? OBAFGKM If stellar parallax can be measured to a precision of about 0.01 arcsec using a telescope on Earth to observe stars, to what distance does this correspond in space? 100 pc What is a positron? A positive electron. The phrase "hydrostatic equilibrium" in the sun refers to: the balance of gravity inward and gas pressure outward. The Hertzsprung-Russell diagram is a statistical plot of which stellar parameters? Luminosity and Surface temperature An arching column of gas suspended over a sunspot group is called A prominence The star Hadar has a spectral classification of B1 III. This tells us that Hadar is a Hot Giant Sunspots are Cooler, darker regions on the suns surface Stars that have ejected a planetary nebula go on to become white dwarfs The temperature of the center of the sun where thermonuclear processes take place is approximately 1.5 x 107 K The spectral class of the sun in G2 and the star Enif in K2. From this information, we know that Enif is Cooler than the sun. Where do we find the most massive stars on the main sequence in a HR diagram? Upper left What fraction of the stars in the night sky are main sequence stars? Almost all, 90% The temperature of the sun's photosphere is 5800 K How can we characterize the rotation of the Sun? Differential rotation with the equator rotating faster than the poles What occurance defines the end of the protostar phase of a star's life and the start of the main sequence phase? Nuclear reactions begin in its core What name is given to the visible "surface" of the Sun? Photosphere There is a mass limit for a star in the white dwarf phase, the Chandrasekhar limit, beyond which the star can no longer support it's own weight. This mass limit, in terms of solar mass, is 1.4 The Zeeman effect refers to the splitting of spectral lines when magnetic fields are applied to atoms What is a red giant? A star burning hydrogen into helium in a shell around the core What is the last nuclear burning stage in the life of a low mass star like the sun? Fusion of helium nuclei to form carbon and oxygen Degeneracy occurs when electrons inside a star resist being pushed closer together than a certain limit. What proportion of visible stars in the night sky are multiple star systems? About 50% or __ A corona hole shows up most prominently in photographs taken at what wavelength? X-ray The majority of the elements heavier than hydrogen and helium in the universe are believed to have originated in The central cores of stars The effect of interstellar dust on starlight is to dim and redden distant stars by preferentially scattering their blue light The corona of the Sun has a temperature of 1-2 million K Apparent Magnitude is a measure of the Brightness of a star as seen from Earth From the center outwards, the order of the layers or parts of the Sun is Radiative, convective, photosphere, chromosphere, corona The extremely high gas temperatures in the solar corona mean that this region is best observed at a wavelength of X-rays The termperature at which thermonuclear reactions begin to convert helium into carbon (helium burning) is 100 million K Sunspots are caused by Differential rotation and its effect on weak magnetic fields A planetary nebula is An expanding gas shell surrounding a hot, white dwarf What is the most abundant element in the universe? Hydrogen The total time that the Sun will spend as a main sequence star is About 10 billion years (1010 years) At what distance are stars assumed to be from the Earth when they are represented by their absolute magnitude? 10 years What happens to the helium rich core of a star after the core runs out of hydrogen? It contracts and heats On the HR diagram, in which direction does the position occupied by a star move after hydrogen burning ends in the star's core? Towards the upper right The age of a cluster can be found by Determining the turnoff point on the main sequence of its HR diagram The Orion Nebula is A large interstellar gas and dust cloud containing many young stars The spectral type of a star is most directly related to (and determines uniquely) its surface temperature