The P-L-relations on the AGB

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The P-L-relations on the AGB
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Learning outcome

• Knowledge of the observed P-L-relations for AGB
  stars
• Knowledge of the interpretation of the various
  sequences
• Knowledge of the relation between P-L and other
  parameters

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Why?

• L R²Teff4
• 1/R³ (for M const)
• L 1/?2/3

? Period Luminosity Relation
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Miras

• Field stars
• Observed logP-colour relation (at ? 0.25)
• Combine with colour-luminosity relation

Mbol 0.5 mag 2.25 log P Eggen (1975)
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Miras
Robertson Feast 1981
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Miras - LMC
Wood et al. 1983
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Miras - LMC
Feast et al. 1989
K 19.7 mag 3.57 log P Mbol 19.86 mag 2.34
log P
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PC- and PLC-relation

• Period-Colour-RelationO-rich (J-K) 0.56 log P
  0.12C-rich (J-K) 2.32 log P 3.77
• Period-Luminosity-Colour-Relation (LMC)O-rich K
  -4.58 log P 2(J-K) 19.71C-rich K -2.88
  log P -0.14(J-K) 18.22

Feast et al. 1989
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SRVs
Bedding Zijlstra 1998
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Long period variables - LMC
Wood et al. 1999
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Long period variables - LMC
Ita et al. 2004 OGLE/SIRIUS survey J-K temp /
chemistry theta lc regularity F, G Cepheids
LMC
SMC
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Long period variables - LMC
Ita et al. 2004 OGLE/SIRIUS survey
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Wood 2007
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P-L and amplitude
I-band amplitudes from OGLE Kiss Bedding 2003
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Sequence E
Soszynski et al. 2004 ellipsoidal/eclipting
variables confirmed from rv variations
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Sequence D

• Wood et al. 2004
• Origin?
• binary
• rotation of spotted star
• non-radial pulsation
• episodic dust formation
• no satisfying solution yet

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LPVs in Clusters
47 Tuc Lebzelter Wood 2005
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Linear/non-linear models
Wood 2007
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LPVs in Clusters
NGC 1846 (LMC cluster) Lebzelter Wood 2007
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Lebzelter et al. 2005
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P-L-relations in comparison
Glass van Leeuwen 2007
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Other P-L-studies

• Glass et al. 1995 (Galactic Bulge)
• Groenewegen Whitelock 1996 (Field)
• Cioni et al. 2001 (LMC)
• Noda et al. 2002 (LMC)
• Lebzelter et al. 2002 (LMC)
• Rejkuba et al. 2003 (Cen A)
• Groenewegen 2004 (MCs)
• Schultheis et al. 2004 (MCs, Bulge)
• Fraser et al. 2005 (LMC)

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Distance determination
Using the relation by Feast et al. 1989 with
Zero-Point 1.0
Object AGB dist. Other dist.
LMC 18.48m0.1m 18.52m (Cep)
LMC - SMC 0.4m 0.44m (RGB-Tip)
Gal. Centre 8.50.7 kpc 8.50.5 kpc (Cep)
Cen A 28.0m0.2m 27.9m0.2m (RGB-Tip)
Feast 2004