the most luminous star (known)
DESCRIPTION
Eta Carinae. The most luminous star (known). Augusto Damineli IAG-USP. 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. - PowerPoint PPT PresentationTRANSCRIPT
The most luminous star
(known)Augusto Damineli
IAG-USP
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
•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
Why is Carinae important?
O
typ
e st
ars
Humphreys-Davidson limit
S Doradus Oscillation
LBV
Nitrogen >> Solar
Oxigen << Solar
90% of star mass is lost in the LBV phase
mV
0
2
4
6
8
Mbol=-12.3
1843.2
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
equatorial disc 110 years
500 x Solar sy
stem diam
eter
bipolar fl
ow 150 years 600 km/s
previous ejections ~1000 years
scale
Features
1”
central object unresolved
5x106 L
The 5.53 year cycle
Damineli 1996
Conflict with the Conflict with the dominant idea: dominant idea: S Doradus cycles S Doradus cycles
should be should be unpredictable!unpredictable!
This was a This was a predictionprediction
The binary modelThe binary model
69M (secondary)
<=113 M
<=89 M
67 M (primary)
600 km/s 1400 km/s
X-rays ~80 million K
600 km/s 1400 km/s
6 million K83 million K
Homunculus 6 million K
Central source 83 million K
Prediction: variable hard X-raysPrediction: variable hard X-rays
1992.5
1994.7
1998.0
X-rays ROSATX-rays ROSAT
1992.5
1994.6
1998.0
The predicted event for 1997/8 came on schedule!
The periodicity is true P=5.530.01 years
Shell ejectionShell ejection
XX
Binary modelBinary model
•Same speed and mass
•Same energy cycle after cycle
Colliding wind binary model reproduce
observed X-ray flux, temperature, NH
3 milhões K
60 milhões K
raios-X óptico
rádioinfravermelho
Is binarity related to the 1843
giant eruption?
•Visible/NIR: LNA, ESO, CASLEO, South Africa, Australia
•Radio: Itapetinga, Australia, SEST(ESO)
•X-rays: RXTE, Chandra, XMM
•UV: Hubble