etacar ensenada2

Slide1: 

Eta Car and Its Surroundings: the X-ray Diagnosis Mike Corcoran and Kenji Hamaguchi (USRA & GSFC), Julian Pittard (Leeds), David Henley (U. Georgia), Bish Ishibashi (MIT), Kris Davidson (U. Minn), Ted Gull (GSFC), John Hillier (U. Pitt) ...

Slide2: 

Eta Car: Inside an Enigma (the Carina Nebula) courtesy NOAO

Slide3: 

Lies a riddle: HST/ACS image of Eta Car (Courtesy the HST TREASURY PROJECT)

Slide4: 

Eta Cartoon: Eta: Lbol ~ 5x106 Lsun, Mdot~10-4-3 Msun/yr, Vwind~500-1000 km/s Companion: Lbol ~1x106 Lsun, Mdot~10-5 Msun/yr, Vwind~3000 km/s

Slide5: 

Inner Emission: Colliding winds Periodic variations at X-ray and other wavebands (Damineli 1996): Colliding winds in an LBV (eta Car) + OB star binary produce X-ray emitting “bow shock” Damineli 1996

Simple colliding wind picture (Cherepashchuk; Usov & Prilutskii; Luo, McCray, & Mac Low, Usov; Stevens, Blondin & Pollock): 

Simple colliding wind picture (Cherepashchuk; Usov & Prilutskii; Luo, McCray, & Mac Low, Usov; Stevens, Blondin & Pollock) Colliding winds in a binary produce X-ray emitting “bow shock” In eccentric orbit, intrinsic Lx a maximum at periastron

Slide7: 

X-ray Lightcurve: RXTE/PCA and others Generally follows the expected periodic CWB variation Differences: broad minimum; “spikes” or “flares”; cycle-to-cycle flux variations

Slide8: 

Model Courtesy Julian Pittard Wind-wind collision dynamically “shapes” density (& ionization) structure of Eta Car’s wind + inner nebula Orbital Dynamics:

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WR 140 Eta Car: minimum much wider than in WR 140 buried shock? extra mass ejection? defunct shock? 1/D variation Eta Car (LBV+O?, 2024d, e~0.95) vs WR 140 (WN7+O4, 2885d, e=0.88)

Slide10: 

Defunct Shock: Radiative Braking? (Gayley et al) Growth of shock instabilities? (discombobulation model, Davidson) accretion onto companion? (Akashi et al.)

Slide11: 

Non-Total “eclipse”

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RXTE Hardness variations through the Minimum: sample spectrum

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X-ray “spikes”: Spectral Changes Spikes associated with spectral hardening: dense structures in inner wind?

Slide14: 

Dynamical variations near the X-ray Minimum (a. k. a. Periastron Passage) Around the time of the X-ray eclipse, snapshot monitoring of Eta Car’s X-ray emission by Chandra and the XMM-Newton X-ray Obs ervatories

Slide15: 

XMM Spectrometry: Measuring the spectrum at minimum

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Density Profile:

Chandra Grating Spectra: Flow Properties : 

Chandra Grating Spectra: Flow Properties May 3 2003 Sep 26 2003

Slide18: 

The “Red Wing” on the Fe XXV line: probably blended K-shell emission from Fe+19-Fe+23 Non-equilibrium ionization? or heavily absorbed extremely luminous equilibrium component?

Slide19: 

Dynamical Variations: Line Centroids low energy emission lines (Si XIV, S XVI) and high energy emission lines are dynamically distinct some combination of orbital motion, projected flow velocity, other effects?

Slide20: 

Beyond the Stellar System: X-rays from the Homunculus [NII] 6583 courtesy Nathan Smith Only visible to Chandra when central source weak Hard, heavily absorbed Electron-scattered reflection of central source Strong fluorescent line, very broad (FWHM 4700 km/s) time delay: ~90 days

Slide21: 

A Buried “Central Constant Emission” (CCE) Component After correcting the spectra during the minima for all known sources of emission, an extra spectral component is left: kT ~1.1 keV NH~5x 1022cm-2 inside Homunculus doesn’t change through minimum or apparently from minima to minima outer shocked gas boundary of CW flow?

Eta Car: Shocked Outer Ejecta: 

Eta Car: Shocked Outer Ejecta Outer debris ejected a few hundred years before the Great Eruption shocks from ejecta/CSM collision X-ray emitting shocked gas

Slide23: 

XMM reflection grating spectroscopy of the “Homunculus” (Leutenegger, Kahn, Ramsay 2003) N/O ~ 9 0.15<kT<0.6 => 100<Vs<600 km/s

Slide24: 

Dynamics of the outer ejecta K. Weis et al. 2004 A&A 415, 595 kT ~ 0.6 keV: Vs~600-700 km/s N enhanced in all the X-ray emitting gas X-ray “bridge”: shock front from expanding disk X-ray emission determined by density distribution in outer field soft X-ray absorption Density enhancements produced by older stellar wind and decelerated? or localized high density clumps no soft emission from the Homunculus

Slide25: 

Diffuse X-ray Emission in the Carina Nebula Source: Wind bubble mergers? SNR? Faint Source Population?

Slide26: 

Diffuse Soft Emission from the Carina Nebula Suzaku XIS (Hamaguchi et al, 2006) Suzaku/XIS: Low background, high effective area, high spectral sensitivity for diffuse sources

Slide27: 

Characteristics of the Diffuse X-ray emission from the XIS: Lx ~ 1035 ergs/s; 10-100x brighter than any other Galactic HII region Soft: 0.3-2 keV band. The XIS N and S regions showed distinct spectra: Si abundance in S ~ 2x Si in N Fe abundance in S ~ 4x Fe in N possible abundance variations in Mg and Ni The N/S spectra are similar in the other emission lines and continuum emission. Nitrogen line not strong in the Suzaku spectra; N/O <~0.4 E>2keV emission: 50% from cosmic X-ray bkg+ galactic ridge + known point sources; 50% from unresolved PMS stars? SNR?

Conclusions: 

Conclusions CW X-rays from Eta Car act as a probe of the inner wind and nearby CSM; NH,ism~2x1021 cm-2 NH,Homunculus ~ 5 x 1022 cm-2 NH,wind >5 x 1023 cm-2 “spikes” => density stratification in inner wind of Eta? Variations in line centroid velocities: orbital motion & projection of colliding wind flow; jet? Increase in NH around X-ray eclipse: phase-locked mass loss rate or orbital disturbance of Eta’s wind; or shock “braking”, “accreting” or “discombobulating” “red wing” on Fe XXV line: underionized emission; NEI vs heavily absorbed cool component? N enhanced in outer ejecta but not in Carina Nebula emission; but apparent abundance differences in shocked gas in Carina Nebula How fundamental is binarity?

Slide29: 

Relation of 5.54-year period to Large Scale Events

Slide30: 

Upcoming Events: Next Eta Car X-ray Minimum: 2009-01-08 Next WR 140 Minimum: 2009-01-12

Slide31: 

Red/Blue: HST Green/Yellow: Chandra X-ray emission: outer emission: ejecta/nebula interface inner emission: distribution of matter inside the Homunculus; mass loss process