The most luminous star known

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Eta Carinae
The most luminous star (known)
Augusto Damineli IAG-USP
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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 gt unknown physical mechanism!
• Was seen at naked eye in daylight (Sirius)
• Well documented history along 150 years

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Luminous Blue Variables
LBV
90 of star mass is lost in the LBV phase
S Doradus Oscillation
O type stars
Nitrogen gtgt Solar
Oxigen ltlt Solar
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The 1843 giant eruption

• 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
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Features
scale
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The 5.53 year cycle Damineli 1996
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Conflict with the dominant idea S Doradus
cycles should be unpredictable!
This was a prediction
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The binary model
67 M? (primary)
lt113 M?
69M? (secondary)
lt89 M?
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Prediction variable hard X-rays
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The predicted event for 1997/8 came on schedule!
1992.5
1994.7
1998.0
X-rays ROSAT
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The periodicity is true P5.53?0.01 years

• Same speed and mass
• Same energy cycle after cycle

Shell ejection X Binary model
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Colliding wind binary model reproduce observed
X-ray flux, temperature, NH
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3 milhões K
60 milhões K
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raios-X
óptico
rádio
infravermelho
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Is binarity related to the 1843 giant eruption?

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Next event June 2003

• Visible/NIR LNA, ESO, CASLEO, South Africa,
  Australia
• Radio Itapetinga, Australia, SEST(ESO)
• X-rays RXTE, Chandra, XMM
• UV Hubble