Computational Astrophysics and Cosmology

Open Access Springer Journal

CompAC publishes paper on ● Astronomy, physics and cosmology● Computational and information science

The combination of these two disciplines leads to a wide range of topics which, from an astronomical point of view covers all scales and a rich palette of statistics, physics and chemistry. Computing is interpreted in the broadest sense and may include hardware, algorithms, software, networking, data management, visualization, modeling, simulation, visualization, high-performance computing and data intensive computing.

The Eta Carinae Riddle

Simon Portegies ZwartEdward P.J. van den Heuvel

Hamacker & Frew 2010

Collowgullouric War

M=80-120MSunm=30MSuna=15.5aue=0.9

The Great Eruption of 1838

The Eta Carinae Riddle

● What formed the complicated gaseous structures (Homunculus, skirt, S-knots, NN-knots, etc) of the Eta Carinae nebula.

● What caused the 1838 Great Eruption, and the 1843 eruption.

● Why did Eta Carinae brighten in the 200 years prior to the Great Eruption.

● How come that the NN-knots and the skirt are so Nitrogen richt.

Many researchers, including: Smith 2011-2015, Soker 2003-2013, Humphreys 1999-2013, etc..

Three step approach

1883 Great Eruption

Calculate forward Calculate backwardH

ydro

dyna

mic

sN-bodyStellar evolutionTidal evolutionStellar wind

MCMCof impulsive mass lossFrom a stellar marger In a triple system

Tidal brightening before the merger due to LK-effect

1838

Tidal evolution of a triple:

Conditions at birth:a = 0.9au, e=0.6, M=142MSun, m=30MsunA=95au, e=0.4, i=90o, m=30Msun

~0.1-1Myr after birth:a=1.0au, e=0.6, M=136MSun, m=30MsunA=100au, e=0.4, m=30MSun

time += 0.1Myr

After tidal interaction:A=0.4au, e=0.0, M=114MSun, m=30MsunA=100au, e=0.4, m=30

Spiral-in and merger of the inner two stars.

Runaway velocity of the merger product due to asymmetric mass outflow.

a=0.4au, M=114Msun, m=30Msun

1883 collision

M=90Msun m=30Msun24Msun is lost

1600--1838 1838 1843 2016

M=114MSuna=0.4-0.8AUdM = 24MSuni=91o

Vkick

= 53+/-8kms

M=136MSunm2=30MSuna=1-2AUA=20-100AUdM=22MSun

e<0.7

M=90MSunm=30MSuna=15.5AUe=0.9Vkick = 53+/-8kms

vwind

~ 200kms

v~ 500kms

vwind

~ 1000kms

Nitrogen richSkirt (S-ridge)

Bubble is blown Nitrogen rich skirt forms Homonculus forms

v~50km/sNN-knots

30MSun

Slow symmetric outflowDue to pre-1838 tidallyEnhanced wind

Slow symmetric outflow

Fast asymmetric wind

Due to merger

Colliflower nebulaDue to polar wind

Conclusions

● Hot bubble is blown by the Lidov-Kozai induced tidal wind of the pre-1938 triple star

● 1838: The Lidov-Kozai induced merger in the inner binary changed the outer orbit to the currently observed P=5.5yr, e=0.9 orbit. Skirt forms from the merger ejecta.

● 1843: the outer star plunges through the envelope of the rapidly rotating bloated primary star, leads to the formation of the ´Smurfette´ nebula.

● The rapidly rotating star has expelled mass loss perpendicular to the orbital plane, giving rise to the ´colliflower nebula´

Consequences

● The current orbital plane of the Eta Carina binary is perbendicular to the long axis of the Homonculus nebula.

● The skirt is Nitrogen enriched (by 2.9MSun) from the ejected surface layers of the primary star.

● The binary system is younger than 1Myr.● The long axis of the Homonculus nebula is

perpendicular to the orbital plane and aligned with the rotation axis of the primary star.