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SLEUTHING MASS OUTFLOW FROM EVOLVED STARS

SLEUTHING MASS OUTFLOW FROM EVOLVED STARS. Optical/IR Spectroscopy from the MMT, KECK II, and Magellan Andrea Dupree (SAO/CfA) Sz. Meszaros (SAO), Jay Strader (CfA), and Graeme H. Smith (UCSC)

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SLEUTHING MASS OUTFLOW FROM EVOLVED STARS

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  1. SLEUTHING MASS OUTFLOW FROM EVOLVED STARS Optical/IR Spectroscopy from the MMT, KECK II, and Magellan Andrea Dupree (SAO/CfA) Sz. Meszaros (SAO), Jay Strader (CfA), and Graeme H. Smith (UCSC) Cool Stars 15/Splinter: St. Andrews 21-25 July 2008

  2. STELLAR EVOLUTION PROBLEMS …. CMD depends on metallicity, but what is the ‘second parameter’???? Poster children for second parameter: NGC 362 & NGC 288 (Bellazzini et al. 2001; Catelan et al. 2001) Candidates for second parameter: age, environment (including free-floating planets); primordial He abundance; surface pollution (helium); CNO abundances; rotation; mass loss…..

  3. FOCUS ON MASS LOSS … • Mass loss is required theoretically on red giant branch to match CMD of clusters , but the mass presumably lost has ‘VANISHED’! • Where and when does mass loss occur? • What are the spectroscopic signatures of mass loss or mass flow? Omega Centauri

  4. Diagnostics of atmospheric motions Need to know where the diagnostic forms…. Contribution functions for a metal deficient giant star

  5. MMT/Hectochelle observations of globular clusters: M13, M15, & M92 240 fibres available to capture spectra in selected orders: H-α and Ca II (H&K) Ca K in M13 H-α in M92 Bisectors marked Sz. Meszaros et al. 2008, 2009

  6. H–α Bisector Velocities Outflow velocities (H–α) increase with luminosity, and are higher for AGB stars No dependence on [Fe/H]

  7. Stars with IR excess in M15 (Spitzer) show same outflow velocity as other red giants Meszaros et al 2008

  8. Ca K3 shows higher (accelerating) outflow than H-α Ca K3 H–α

  9. Helium 10830Ǻ observed with NIRSPEC/KECK II in M13 and metal-poor field giants • Maps wind to higher levels of chromosphere • Visible in warmer stars • Reveals high velocities ~100 km s-1 • Comparable to stellar escape velocity at 2Rstar AGB and RGB RHB stars with Graeme Smith (UCSC) and Jay Strader (CfA) [2008]

  10. Winds detected in metal-poor stars • He I 10830Ǻ ubiquitous in • warm stars • Frequent extension to ~90 km s-1 • M ~2x10-9 Msun yr-1 MV with Graeme Smith (UCSC) and Jay Strader (CfA)

  11. CONCLUSIONS • H-α reveals increasing outflow velocity with luminosity. • Ca K3 suggests accelerating expansion • Outflows similar for metallicity [Fe/H] = –1.5 to –2.3 • IR-excess giants not distinguishable from other giants in M15 • No ‘superwind’ detected • Mass loss (V ~ Vescape) discovered in rgb, rhb, agb objects with He I 10830Ǻ

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