STAR FORMATION -------------- The material that makes up the Sun was once part of a) the Big Bang. b) another star. c) a molecular cloud. d) a protostar. $e) all of the above. If the material in the primordial solar system retained its angular momentum as it collapsed to form the Sun, the Sun's rotation rate should be $a) fast (less than a week) b) moderate (a week to a month) c) slow (more than a month) d) zero (non-rotating) If an interstellar cloud contracts to become a star, it is due to which force? a) electromagnetic b) nuclear $c) gravitational d) centrifugal Stars are formed from cold interstellar gas clouds made up of a) atomic gas of mostly hydrogen, oxygen, carbon and nitrogen. $b) molecular hydrogen gas and dust grains. c) some hydrogen gas, comets and asteroids. d) stars are formed from very HOT gas. Evidence for an association between interstellar dust and star formation comes from $a) dark clouds that attenuate the light from background stars. b) emission at radio wavelengths of 21cm. $c) stars that appear redder than expected from their spectral type. d) bright nebulae with redshifted emission lines. As a star first begins to condense from dust and gas clouds, it emits primarily in which wavelength regime? a) x-ray b) ultraviolet c) visual $d) infrared e) radio The inital collapse of the solar nebula may have been initiated by a nearby supernova explosion because a) there is no other known mechanism $b) pre-stellar clouds are normally stable $c) certain odd isotopes are found in the solar system d) only 90 percent of atoms in the solar system are hydrogen (more than one answer may apply) The factors that tend to resist collapse in a gas cloud are I. the magnetic field of the cloud II. the presence of supernovae near the gas cloud III. the existence of molecules in the gas IV. heat in the gas V. the rotation of the cloud a) I, III, V $b) I, IV, V c) II, III, IV d) II, IV, V e) III, IV, V We know that low mass proto-stars have strong stellar winds because a) they are collapsing in a stable fashion. b) they have thick circumstellar disks. $c) the Sun was once a proto-star and has a wind now. $d) proto-stars have gas jets that drive massive outflows. (more than one answer may apply) The nebulae around T Tauri stars are shaped into disks because of the same process that causes dough to become flat when it is $a) spun in the air like pizza dough b) rolled with a pin like pizza dough c) squashed between plates like dough for a burrito d) baked on a flat sheet like a cookie What important event occurred while the Sun was in its T Tauri phase (a phase young stars go though in which they have a strong stellar wind similar to the solar wind)? a) comets were pushed out of the solar system $b) gas and dust remaining in the solar system were blown away c) the planets formed d) the Sun shrank to its present size