Images at the highest angular resolution with GRAVITY: The case of η Carinae

Abstract

Blondin, J. M. 1994, ApJ, 435, 756 Blundell, K. et al. 2001, ApJ, 562, L79 Fabrika, S. 2004, Space Science Reviews, 12, 1 GRAVITY Collaboration et al. 2017a, ApJ, 844, 177 GRAVITY Collaboration et al. 2017b, A&A, 602, L11 Kaper, L. et al. 2006, A&A, 457, 595 Leahy, D. & Kostka, M. 2008, MNRAS, 384, 747 Margon, B. et al. 1979, ApJ, 233, L63 Milgrom, M. 1979, A&A, 78, L9 Waisberg, I. et al. 2019a, A&A, 623, A47 Waisberg, I. et al. 2019b, A&A, 624, A127 of the stellar wind facing the compact object. In addition, asymmetries revealed by the differential visibility phases across the emission lines may point to an additional component, possibly a stream of enhanced density which has been posited to exist in the system from the analysis of X-ray light curves (Leahy & Kotska, 2008). Further observations at different orbital phases could take advantage of the significant eccentricity in order to disentangle intrinsic variability of the wind from the distortion caused by the pulsar accretion. The spectral differential visibilities measured by GRAVITY (GRAVITY Collaboration et al., 2017a) reveal an extended wind with a size several times the stellar radius, which is also significantly distorted — being more extended on the side that is shielded from the pulsar — and which could be caused by the X-ray ionisation 0.8