UV radiation ionizes the expanding gas shell This glows in what we see as a planetary nebula Name given because they look somewhat like planets No suggestion that they have, had, or will form planets This gas eventually dissipates into interstellar space No further nuclear fusion occurs Supported by degenerate electron pressure About the same diameter as Earth ~ 8,000 miles It gradually becomes dimmer Eventually it will become too dim to detect He-shell flashes produce thermal pulses Caused by runaway core He fusion in AGB stars Cyclical process at decreasing time intervals 313,000 years 295,000 years 251,000 years 231,000 years All materials outside the core may be ejected ~ 40% of mass lost from ađ.0 MSun star > 40% of mass lost from a >1.0 MSun star Hot but dead CO core exposed At the center of an expanding shell of gas Velocities of ~ 10 km. Low-mass definition 2 MSun One possible result A carbon star Abundant CO ejected into space Same isotopes of C & O that are in human bodies Low-mass stars undergo two distinct red-giant stages Dredge-ups bring red-giant material to the surface Low -mass stars die gently as planetary nebulae Low -mass stars end as white dwarfs High-mass stars synthesize heavy elements High-mass stars die violently as supernovae Supernova 1987A Supernovae produce abundant neutrinos Binary white dwarfs can become supernovae Detection of supernova remnants Stellar Death Dredge-ups bring red-giant material to the surface Stellar Death Dredge-ups bring red-giant material to the surface"- Presentation transcript:ġ 20. A new member above the clump redefines the path of the first-ascent red giant branch its Li is 0.6 dex below the first-ascent red giants.Presentation on theme: "20.
A(Li) remains effectively constant from the giant branch base to the red giant clump level. Chandra LETG+HRC-S and XMM-Newton RGS spectra of H-like C and N lines formed in the corona of the primary star of the RS CVn-type binary for stars entering the subgiant branch and beyond.
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