Interferometric observations of η Carinae with VINCI/VLTI^*

LESIA, UMR 8109, Observatoire de Paris-Meudon, 5 place Jules Janssen, 92195 Meudon Cedex, France e-mail: pierre.kervella@obspm.fr

Received: 12 October 2006
Accepted: 28 November 2006

Abstract

Context.The bright star η Carinae is the most massive and luminous star in our region of the Milky Way. Though it has been extensively studied using many different techniques, its physical nature and the mechanism that led to the creation of the Homunculus nebula are still debated.

Aims.We aimed at resolving the central engine of the η Carinae complex in the near-infrared on angular scales of a few milliarcseconds.

Methods.We used the VINCI instrument of the VLTI to recombine coherently the light from two telescopes in the K band.

Results.We report a total of 142 visibility measurements of η Car, part of which were analyzed by Van Boekel et al. (2003, A&A, 410, L37). These observations were carried out on projected baselines ranging from 8 to 112 m in length, using either two 0.35 m siderostats or two 8-m Unit Telescopes. These observations cover the November 2001-January 2004 period.

Conclusions.The reported visibility data are in satisfactory agreement with the recent results obtained with AMBER/VLTI by Weigelt et al. (2006), asuming that the flux of η Car encircled within 70 mas reaches 56% of the total flux within 1400 mas, in the K band. We also confirm that the squared visibility curve of η Car as a function of spatial frequency follows closely an exponential model.