Stefan%20Uttenthaler:

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Stefan Uttenthaler Tc in Bulge and Field AGB
Stars
ESO Hans-Ulrich Käufl Vienna (A) Bernhard
Aringer Thomas Lebzelter Josef Hron Michael
Lederer Michael Gorfer Besançon (F) Mathias
Schultheis Perugia (I) Maurizio Busso
This talk mainly deals with two
papers "Technetium and the third dredge up in
AGB stars I. Field stars" Lebzelter Hron,
2003, AA 411, 533 542 "Technetium and the
third dredge up in AGB stars II. Bulge
stars" Uttenthaler et al., in preparation for AA
Paper I Stars in solar neighborhood, good
HIPPARCOS parallaxes Spectra from UVES, KPNO, AAT
Paper II Bulge stars in PG3 b ? -10, l
0 Spectra taken with UVES/VLT
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Sample selection using K0 vs. log(P) relation
Near-IR photometry from ESO measurements Schulthei
s), 2MASS DENIS, Periods from
Wesselink Ph.D. K0 log(P) relation from Glass
Schultheis, 2003 Two stars outside the
"allowed" range!
? SRV ? Mira ?/ with Tc
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Sample selection using K0 vs. log(P) relation
Using MACHO light curve and data from Plaut
(1971) we get new periods for 2 uncertain
cases ? everything fine now! All objects are in
the BULGE!
? SRV ? Mira ?/ with Tc
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Observed and synthetic spectra around Tc lines
4238 Å
4262 Å
4297 Å
R50000 obs with UVES/VLT in 2000 (blue and red
arm) All 3 lines in observed range are
identified 4297 Å Line is blended by Cr
line Problems with model spectra Too high
contrast between lines and "continuum" points!
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Observed and synthetic spectra around Tc lines
4238 Å
4262 Å
4297 Å
4238 Å
4262 Å
4297 Å
R50000 obs with UVES/VLT in 2000 (blue and red
arm) All 3 lines in observed range are
identified 4297 Å Line is blended by Cr
line Problems with model spectra Too high
contrast between lines and "continuum" points!
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Flux ratios
Used to distinguish between "Tc yes" and "Tc
no" Ratios of lines 4238 Å and 4262 Å are best
suited for this distinction!
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Flux ratios
Used to distinguish between "Tc yes" and "Tc
no" Ratios of lines 4238 Å and 4262 Å are best
suited for this distinction!
Model spectrum with Tc/H -11.1
Tc possible!
Model spectrum without Tc
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Mbol vs. (J K)0 diagram, I.
Mbol from BCK(J K) (Kerschbaum et al., in
prep.) All stars with Tc above 3DUP luminosity
limit Luminosity limiy estimated from luminosity
of a 1.5 Msun model when 3DUP sets in ? Mbol
-3.9
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Mbol vs. (J K)0 diagram, II.
Mbol "corrected" for depth induced scatter (from
period luminosity diagram) "Tc yes" stars form
upper envelope! Isochrones from Girardi et al.,
2000 ( "our" (J K)/Teff calibration) do not
reach up to the observed peak luminosity!! ?
younger (3 Gyr) more massive stars in the
bulge?? 1.5 Msol required for 3DUP!
Tc poss.
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Bulge stars vs. field stars Percentage of stars
above the luminosity limit with Tc Field 10/50
0.20 Bulge 3/21 0.14 4/19 0.21
?? ? probably no difference! Bright "Tc no"
stars a) Massive stars with eroded envelope
(mass loss)? b) Low mass stars observed at
high-luminosity phase of TP
Lebzelter Hron 2003, field stars
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Are there AGB stars which have had 3DUP some time
ago, but all Tc has decayed by now (case a)?

• To solve this question
• Determine s-element abundances in the
  atmospheres
• -( Model spectra are not yet good enough for
  this
• But qualitative information on Nb content
  helps!
• ? Will be worked out on Monday, 8 a.m.!
• Measure C/O and 12C/13C ratios of the stars
• -( ISAAC/VLT observing time was not granted
• -/ Maybe DDT observations?

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Take care with abbreviations! HB Horizontal
Branch ?? HB Hof Bräu ??
Hofbräuhaus, Munich
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CRIRES, or "The Last will be the First"
CRyogenic Infra-Red Echelle Spectrograph Last
instrument of the first generation Basic
characteristics 1 5 ?m R100,000 VLT UT1,
Nasmyth A slit 0.1" ? 50" 4 ? 1024 ? 1024
InSb ?/70 coverage etc., see www.eso.org
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CRIRES, or "The Last will be the First"

• Current status
• All subsystems are tested, final lab tests of the
  whole system, all specifications are met
• April 2006 commissioning of warm parts at the
  telescope
• June 2006 commissioning of the rest
• August 2006 science verification, 2nd
  commissioning
• What can CRIRES do for research on AGB stars?
• All AGBs out to the bulge the brightest in the
  MCs observable
• Atmospheric dynamics, especially in C stars
• Temperature structure pinned down
• Improved chemical and isotopic abundances
• Born-again AGB and Post-AGB stars narrow
  nebular lines resolved,
• kinematics from velocity along the slit
• etc.

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