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Do bipolar PNe really have more massive progenitors? Central stars?

Do bipolar PNe really have more massive progenitors? Central stars?. X. Eva Villaver (STScI/ESA). Outline. Central star masses MageLlanic Clouds RESULTS in the Galaxy Hints from the progenitors : Galactic Scale Height CHemical Enrichment Possibilities?. HOW DO we determine masses?.

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Do bipolar PNe really have more massive progenitors? Central stars?

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  1. Do bipolar PNe really have more massive progenitors? Central stars? X Eva Villaver (STScI/ESA)

  2. Outline • Central star masses • MageLlanic Clouds • RESULTS in the Galaxy • Hints from the progenitors: • Galactic Scale Height • CHemical Enrichment • Possibilities?

  3. HOW DO we determine masses? MCS/M=0.5+(1.8 x10-5) L/L

  4. How we weigh the stars in the LMC and SMC HST data: STIS broadband imaging and WFPC2 (Stromgren y)(Shaw et al. 2001,2007 Stanghellini et al. 2002, 2003) + Combined with Ground-based data (c,HeII 4686Å fluxes): Jacoby & Kaler (1993); Meatheringham et al. (1988); Meatheringham & Dopita (1991); Vassiliadis et al. (1992); Boronson & Liebert (1989); Monk et al. (1988); Leisy & Dennefeld (1996); Dopita & Meatheringham (1991ab); Shaw et al (2004); Palen et al. (2004).

  5. Results in the LMC: <MCS> (7) = 0.63± 0.06 R <MCS> (19) = 0.65± 0.09 E <MCS> (9) = 0.64± 0.04 B From: Villaver, Stanghellini & Shaw (2003) Villaver, Stanghellini & Shaw (2007)

  6. Results in the Galaxy <MCS> = 0.62± 0.08 R <MCS> = 0.62 ± 0.07 E <MCS> = 0.60± 0.03 B Derived from the Stanghellini et al. (2002) sample to an extinction limit of c < 1 Manchado et al. (2000)

  7. No strong empirical evidence CEntral stars of Bipolar PNe Are more massive BIASES: • Method? 4 B, 30 E, 10 Rspectroscopy • Small number statistics YES always • Fainter faster? Yes if more massive....no evidence From detection vr non-detection RATE in the LMC • Hotter central stars? No evidence in Stanghellini et al. (2002) or in the LMC

  8. Galactic SCALE Height • Corradi & Schwarz (1995) (400 PNe) <z>=130 pc BIPOLAR <z>=320 pc ELLIPTICALS • Manchado, Villaver, Stanghellini & Guerrero (2000) (255 PNe) <z> = 179 pc BIPOLARS <z> = 308 pc ELIPTICALS <z> = 753 pc ROUND

  9. Galactic Kinematics of Bipolars • Bipolar PNe from a young disk population Zuckermann & Gatley (1988), Corradi & Schwarz (1995). • <z> consistent with a MMS ~3 M

  10. Chemical Enrichment • N/O and He abundances are that of the type I PNe defined by Peimbert and Torres-Peimbert (1987). He/H ≥ 0.125 and log(N/O) > − 0.3. From Corradi & Schwarz (1995) <N/H> = 2.37 ELLIPTICALS = 4.37 BIPOLARS From Stanghellini, Villaver, Manchado & Guerrero (2002) <N/H> = 1.71 ROUND = 1.51 ELLIPTICALS = 5.66 BIPOLARS • See also Kwitter and Henry (2001) Perinotto et al. (2004)

  11. Hints from the chemistry Convection DURING the AGB 0.8-1.7 M • Only isotopic ratios modified • 3-8 M • HBB N and He increase • Long period O-STARS • 1.4-3 M • C and He abundances are increased 3rd dredge-up • FORMATION OF C-STARS Herwig 00, Karakas 02, Pols 01, Strainero 97, Stancliffe 04

  12. Other hints Bipolar & massive progenitors • Garcia-Hernandez et al. (2007) have identified a sample of obscure massive O-rich stars in the Galaxy through the analysis of Li and Zr abundances HBB, higher N. • Stanghellini et al. (2007) Spitzer spectra of PNe in the LMC and SMC. C/O<1 BIPOLARS no PNe with C/O>1 is asymmetric. • Undermassive white dwarfs (0.47 M) in a high metallicity cluster (Kalirai et al. 2007).

  13. How well do we know the initial-to-final mass relation? • Weidemann (2000) monotonic IFMR. • +Claver et al. (01) & Williams et al. (04) large scatter in the IFMR: A MS 3-4 M ends up anywhere between 0.65 and 0.8 M • Kalirai et al. (2005) added 12 WDs from NGC 2099. From Kalirai et al. (2005)

  14. SO.....? MMS > 4 M C-stars MASS-LOSS HIGHER ???? O-stars ~O.6 M

  15. Can Mass-Loss be a problem? • Dust-driven winds work well for C stars but run into problems to explain mass-loss for O-stars. (Woitke 2006 Hofner & Andersen 07)

  16. Summary: • NO strong empirical evidence of bipolar PNe to have more massive central stars (Villaver et al. 2003, 2007). • STRONG empirical evidence that bipolar have more massive progenitors. Massive progenitors loose more mass • HOW? Common envelope? Undermassive WDs Mass-loss rates enhanced for the massive O-rich stars? We need further constrains for the IFMR.

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