$\eta$ Carinae: high angular resolution continuum, H30$\alpha$ and He30$\alpha$ ALMA images

Abstract

We present images of $\eta$ Carinae in the recombination lines H30$\alpha$ and He30$\alpha$ and the underlying continuum with 50~mas resolution (110 AU), obtained with ALMA. For the first time, the 230 GHz continuum image is resolved into a compact core, coincident with the binary system position, and a weaker extended structure to the NW of the compact source. Iso-velocity images of the H30$\alpha$ recombination line show at least 16 unresolved sources with velocities between -30 and -65 km s${}^{-1}$ distributed within the continuum source. A NLTE model, with density and temperature of the order $10^7$ cm${}^{-3}$ and $10^4$ K, reproduce both the observed H30$\alpha$ line profiles and their underlying continuum flux densities. Three of these sources are identified with Weigelt blobs D, C and B; estimating their proper motions, we derive ejection times (in years) of 1952.6, 1957.1, and 1967.6, respectively, all of which are close to periastron passage. Weaker H30$\alpha$ line emission is detected at higher positive and negative velocities, extending in the direction of the Homunculus axis. The He30$\alpha$ recombination line is also detected with the same velocity of the narrow H30$\alpha$ line. Finally, the close resemblance of the H30$\alpha$ image with that of an emission line that was reported in the literature as HCO${}^{+}$(4-3) led us to identify this line as H40$\delta$ instead, an identification that is further supported by modeling results. Future observations will enable to determine the proper motions of all the compact sources discovered in the new high-angular resolution data of $\eta$ Carinae.

Accepted for publication in mnras

References in corpus (14)

• The UV Scattering Halo of the Central Source Associated with Eta Carinae
• Non-thermal X-rays from Colliding Wind Shock Acceleration in the Massive Binary Eta Carinae
• $\eta$ Carinae's Dusty Homunculus Nebula from Near-Infrared to Submillimeter Wavelengths: Mass, Composition, and Evidence for Fading Opacity
• The first full orbit of Eta Carinae seen by Fermi
• The fossil wind structures of Eta Carinae: changes across on 5.54-year cycle
• Near-infrared integral field spectroscopy of the Homunculus nebula around Eta Carinae using Gemini/CIRPASS
• H.E.S.S. detection of very-high-energy gamma-ray emission from the quasar PKS 0736+017
• Distinguishing Circumstellar from Stellar Photometric Variability in Eta Carinae
• $\eta$ Carinae Baby Homunculus Uncovered by ALMA
• A disrupted molecular torus around Eta Carinae as seen in 12CO with ALMA
• Eta Carinae's 2014.6 Spectroscopic Event: The Extraordinary He II and N II Features
• VLTI-AMBER velocity-resolved aperture-synthesis imaging of Eta Carinae with a spectral resolution of 12000. Studies of the primary star wind and innermost wind-wind collision
• Wind-wind collision in the eta Carinae binary system - III. The HeII 4686 line profile
• 3D Radiative Transfer in $\eta$ Carinae: Application of the SimpleX Algorithm to 3D SPH Simulations of Binary Colliding Winds

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