ASTRON 89 1nd Edition Lecture 23Outline of Last Lecture I. The Interstellar Medium: Consists Gas and DustII. Types of NebulaeIII. 21 cm radiationIV. Star EvolutionV. Requirements for a stellar object to be called a star:VI. Star clusters all form at approximately the same time, because when one star forms it triggers the formation of others. VII. Tripe alpha processOutline of Current Lecture I. T Tauri Star II. Review of Star Clusters III. The Sun as a Red GiantIV. The Sun as a White DwarfCurrent LectureI. T Tauri Star a. Are identifiable due to their physical characteristics: i. Contain a disk around them, with limbs that knock off material (look like jets)ii. T Tauri stars are the same as protostarsII. Review of Star Clusters a. Important because they tell you the age of starsb. Open clusters: young stars i. Blue in color ii. Have not yet evolved off of the main sequencec. Globular clusters: old stars i. Red in color ii. Stars have all evolved off the main sequence, there is a “turn off point” which tells you how old the cluster isIII. The Sun as a Red Gianta. The Sun becomes a Red Giant once it moves off of the main sequence These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.i. It becomes a red giant because it is cooling and expanding, and it is brighter only because it is biggerii. The Helium flash occurs at this phase (triple alpha process: 3 He 1 C (Be is involved) iii. Helium flash is a result of electron degeneracy iv. The Sun is now 100 times its sizeIV. The Sun as a White Dwarfa. The Sun is about the size of the Earth i. Contains enormous densityb. Held up by degeneracy pressure; cools off and eventually becomes a black dwarf i. Called a black dwarf because no longer visible c. This is the final stage of the star’s evolution d. It is essentially a dead
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