Basic Parameters & Information

The following notes can be useful for both observers and theorists, and some of these data are not easily available elsewhere. Everyone is welcome to use them, but of course you should acknowledge this site and references mentioned here.


aay'-tah _ kah-rye'-nee, Approximately rhymes with "ate a high knee".

(In lieu of a classical proper name like Sirius or Vega, some of us have fallen into the habit of saying just "Eta," even if the IAU complains. We wouldn't exercise such familiarity with, say, Eta Aquilae or Eta CMa, but this case is honestly special. Surely this Mad Emperor of the Visible Stars deserves a short familiar name!)

Other names of Eta Carinae

Summary of Basic Parameters

ParameterAccepted Value Reference
Distance 2.2 to 2.3 Kpc Allen & Hillier 1993, Davidson & Humphreys 1997, Meaburn 1999, Davidson et al 2001
Total Luminosity
(measured from thermal infrared)
~ 5x106 Lsun
MBol~ -12mag
~ 1049 ergs
Westphal and Neugebauer 1969, Cox et al 1995
Zero Age Main Sequence Mass
from IR Luminosity
>150 Msun
Current Mass ~120 Msun
Expected Main Sequence Lifetime~ 3 million years
Current Mass Loss Rate10^-3 Msun/year Cox et al 1995, Davidson et al 1995, Hillier et al 2001
Surface Temperature15000 to 30000 K Hillier et al 2001
Radius0.4 to 0.9 AU
Dynamical Timescale~2 weeks
Thermal Timescale5 to 500 years
dependant on mass fraction considered
Ejected CompositionHe & N rich Davidson et al 1982, 1986, Dufour 1989, Dufour et al 1999
Evolutionary Statenear or past end of core H burning

The Great Eruption

Sustained LuminosityMBol~ -13
Sustained for several years
see History
Peak LuminosityMBol~ -14
Total Mass Ejected3 to 15 Msun
Average Mass Loss Rate0.1 to 0.5 Msun/year

General References

Caution: The subject has more than its share of misunderstandings, and a lot of misleading or incorrect information has been published or appears on the internet. Even such a fundamental quantity as luminosity is a subtle and tricky problem. Aside from recent papers on specific sub-topics noted elsewhere in this site, for background information we currently recommend four general sources, and especially the many papers cited therein:

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