Resolving the ionized wind of the post-Red Supergiant IRC +10 420 with VLTI/AMBER

Abstract

The paper investigates the milli-arcsecond scale structure of the present-day mass-loss of the post-Red Supergiant IRC+10420. We use three telescopes of the VLT Interferometer in combination with the AMBER near-infrared beam combiner to measure spectrally dispersed correlated fluxes in the K-band around the Br gamma transition. The resulting visibilities are compared to the predicted visibilities of emission structures with various simple models in order to infer the size of the observed emission region. The Br gamma line is resolved by VLTI+AMBER on all three baselines, with the maximum projected baseline extending 69 meter and a P.A. ranging between 10 and 30 degrees. A differential phase between line and continuum is detected on the longest baseline. The Br gamma emission region is found to have a diameter of 3.3 milli-arcseconds (FWHM), when compared to a Gaussian intensity distribution. A uniform disk and a ring-like intensity distribution do not fit the line visibilities. Comparing the AMBER equivalent width of Br gamma with measurements from various epochs, we find that the stellar photosphere contributes about 60% of the total continuum light at 2.2 micron. The remaining 40% continuum emission is found on scales larger than the 66mas AMBER field of view. Using simple arguments, and assuming optically thick line emission, we find that the line emitting region is elongated. We briefly discuss the possibilities whether such a structure is due to a bi-polar flow or a circumstellar disk. (Abridged).

arXiv commentAccepted for publication in A&A

References in corpus (10)

• Interferometric data reduction with AMBER/VLTI.Principle,estimators and illustration
• High-resolution imaging of dust shells using Keck aperture masking and the IOTA Interferometer
• Disk and wind interaction in the young stellar object MWC 297 spatially resolved with VLTI/AMBER
• Estimating Be Star Disk Radii using H-alpha Emission Equivalent Widths
• Crossing the `Yellow Void' -- Spatially Resolved Spectroscopy of the Post- Red Supergiant IRC+10420 and Its Circumstellar Ejecta
• Constraining the wind launching region in Herbig Ae stars: AMBER/VLTI spectroscopy of HD104237
• Arcsecond-resolution 12CO mapping of the yellow hypergiants IRC +10420 and AFGL 2343
• Integral-Field Spectroscopy of the Post Red Supergiant IRC +10420: evidence for an axi-symmetric wind
• The dynamics of the nebula M1-67 around the run-away Wolf-Rayet star WR 124
• De-biasing interferometric visibilities in VLTI-AMBER data of low SNR observations

Cited by in corpus (6)

• Eta Carinae and the Luminous Blue Variables
• The Morphology of IRC +10420's Circumstellar Ejecta
• The compact H$\alpha$ emitting regions of the Herbig Ae/Be stars HD 179218 and HD 141569 from CHARA spectro-interferometry
• A red supergiant nebula at 25 micron: arcsecond scale mass-loss asymmetries of mu Cep
• Neutral and ionized gas around the post-Red Supergiant IRC+10420 at au size scales
• Resolving the asymmetric inner wind region of the yellow hypergiant IRC+10420 with VLTI/AMBER in low and high spectral resolution mode