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The most luminous star (known)

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  1. Eta Carinae The most luminous star (known) Augusto Damineli IAG-USP

  2. Why is  Carinae important? • The light of distants galaxies (=young) is dominated by massive stars. • Massive stars are very rare in the local Universe and unresolved in distant galaxies. • Eta Car is close (2.3 kpc) and easy to observe by any technique • Interacting galaxies also form lots of massive stars (blue) • Massive stars are important sources of N, He and other heavy elements • Star models (evolutionary tracks) in the upper HR diagram are poorly known •  Carinae survived a giant outburst ~10 49.5 ergs => unknown physical mechanism! • Was seen at naked eye in daylight (~Sirius) • Well documented history along 150 years

  3. Humphreys-Davidson limit Luminous Blue Variables LBV 90% of star mass is lost in the LBV phase S Doradus Oscillation O type stars Nitrogen >> Solar Oxigen << Solar

  4. The 1843 giant eruption mV 1843.2 0 Mbol=-12.3 2 4 6 8 • tidal interaction in a binary system (Innes 1903) • slow supernova (Thackeray 1956, Zwicky 1965, Rodgers & Searle 1967) • pulsar embedded in a supernova remnant (Ostriker & Gunn 1971, Borgwald & Friendlander 1993) • compact object accreting mass from a companion (Bath 1979, Warren-Smith et al. 1979, Tutukov & Yungel'son 1980; Viotti et al. 1989, Gallagher 1989, van Genderen, de Groot & The’ • pre-main sequence star (Gratton 1963) • massive main sequence star (Burbidge 1962, Tamman & Sandage 1968, Burbidge & Stein 1970, Talbot 1971, Davidson 1971, Hoyle, Solomon & Wolf 1973, Humphreys & Davidson 1979, Davidson, Walborn & Gull 1982, Doom, De Greve & Loore 1986) • atmospheric instability in massive post-main sequence star (Andriesse, Packet & de Loore 1981) • dynamical instability in a extended atmosphere (Stothers & Chin 1983, Maeder 1983) • long period CWB (Damineli, Conti & Lopes 1997 Theories

  5. Features central object unresolved 5x106 L previous ejections ~1000 years 1” 600 km/s bipolar flow 150 years 500 x Solar system diameter equatorial disc 110 years scale


  6. The 5.53 year cycle Damineli 1996

  7. Conflict with the dominant idea: S Doradus cycles should be unpredictable! This was a prediction

  8. The binary model 67 M (primary) <=113 M 69M(secondary) <=89 M

  9. Prediction: variable hard X-rays Homunculus 6 million K Central source 83 million K 600 km/s 600 km/s 1400 km/s X-rays ~80 million K 83 million K 6 million K 1400 km/s

  10. The predicted event for 1997/8 came on schedule! 1992.5 1994.6 1998.0 1992.5 1994.7 1998.0 X-rays ROSAT

  11. The periodicity is true P=5.530.01 years • Same speed and mass • Same energy cycle after cycle Shell ejection X Binary model

  12. Colliding wind binary model reproduce observed X-ray flux, temperature, NH

  13. 3 milhões K 60 milhões K

  14. raios-X óptico infravermelho rádio

  15. Is binarity related to the 1843 giant eruption?

  16. Next event: June 2003 • Visible/NIR: LNA, ESO, CASLEO, South Africa, Australia • Radio: Itapetinga, Australia, SEST(ESO) • X-rays: RXTE, Chandra, XMM • UV: Hubble