First astronomical unit scale image of the GW Ori triple. Direct detection of a new stellar companion

Abstract

Young and close multiple systems are unique laboratories to probe the initial dynamical interactions between forming stellar systems and their dust and gas environment. Their study is a key building block to understanding the high frequency of main-sequence multiple systems. However, the number of detected spectroscopic young multiple systems that allow dynamical studies is limited. GW Orionis is one such system. It is one of the brightest young T Tauri stars and is surrounded by a massive disk. Our goal is to probe the GW Orionis multiplicity at angular scales at which we can spatially resolve the orbit. We used the IOTA/IONIC3 interferometer to probe the environment of GW Orionis with an astronomical unit resolution in 2003, 2004, and 2005. By measuring squared visibilities and closure phases with a good UV coverage we carry out the first image reconstruction of GW Ori from infrared long-baseline interferometry. We obtain the first infrared image of a T Tauri multiple system with astronomical unit resolution. We show that GW Orionis is a triple system, resolve for the first time the previously known inner pair (separation $\rho \sim$1.4 AU) and reveal a new more distant component (GW Ori C) with a projected separation of $\sim$8 AU with direct evidence of motion. Furthermore, the nearly equal (2:1) H-band flux ratio of the inner components suggests that either GW Ori B is undergoing a preferential accretion event that increases its disk luminosity or that the estimate of the masses has to be revisited in favour of a more equal mass-ratio system that is seen at lower inclination. Accretion disk models of GW Ori will need to be completely reconsidered because of this outer companion C and the unexpected brightness of companion B.

5 pages, 9 figures, accepted Astronomy and Astrophysics Letters. 2011

References in corpus (3)

• The distance to the Orion Nebula
• A Parallactic Distance of 389 +24/-21 parsecs to the Orion Nebula Cluster from Very Long Baseline Array Observations
• Few Skewed Disks Found in First Closure-Phase Survey of Herbig Ae/Be stars

Cited by in corpus (15)

• On the diversity and statistical properties of protostellar discs
• A triple star system with a misaligned and warped circumstellar disk shaped by disk tearing
• On the Distribution of Orbital Eccentricities for Very Low-Mass Binaries
• GW Ori: Interactions Between a Triple-star System and its Circumtriple Disk in Action
• VLTI/MIDI atlas of disks around low- and intermediate-mass young stellar objects
• GW Ori: Inner disk readjustments in a triple system
• What happened before? -- The disks around the precursors of young Herbig Ae/Be stars
• The Architecture of the GW Ori Young Triple Star System and Its Disk: Dynamical Masses, Mutual Inclinations, and Recurrent Eclipses
• GW Ori: circumtriple rings and planets
• Herbig AeBe stars: Multiplicity and consequences
• Millimeter Observations of the disk around GW Ori
• Constraints to the magnetospheric properties of T Tauri stars - II. The Mg II ultraviolet feature
• ELT Imaging of MWC 297 from the 23-m LBTI: Complex Disk Structure and a Companion Candidate
• Orbital Solution for the Spectroscopic Binary in the GW Ori Hierarchical Triple
• A Streamer Driving Misalignment in the Circumtriple Disk of GW Ori