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.

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), andGraeme H. Smith (UCSC)

Cool Stars 15/Splinter: St. Andrews 21-25 July 2008

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…..

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

Contribution functions for a metal deficient giant star

Diagnostics of atmospheric motions

Need to know where the diagnostic forms….

MMT/Hectochelle observations of globular clusters: M13, M15, & M92

240 fibres available to capture spectrain selected orders: H-α and Ca II (H&K)

Ca K in M13

H-α in M92Bisectors marked

Sz. Meszaros et al. 2008, 2009

Outflow velocities (H–α)increase with luminosity,and are higher for AGB stars

No dependence on [Fe/H]

H–α Bisector Velocities

Stars with IR excess in M15 (Spitzer) show same outflow velocity as other red giants

Meszaros et al 2008

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

Ca K3

H–α

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]

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)

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