Phase Closure Nulling: results from the 2009 campaign

TL;DR

Phase Closure Nulling (PCN) is a novel observational technique that enhances the detection of faint companions near bright stars by analyzing closure phases at null points of the star's visibility, demonstrated through initial observations.

Contribution

This paper introduces the PCN method, detailing its theoretical basis, initial proof-of-concept observations, and potential applications in high-contrast astronomy.

Findings

Successful initial observations with VLTI/AMBER and CHARA/MIRC

Demonstrated ability to detect faint companions near bright stars

Validated the effectiveness of PCN in high-contrast imaging

Abstract

We present here a new observational technique, Phase Closure Nulling (PCN), which has the potential to obtain very high contrast detection and spectroscopy of faint companions to bright stars. PCN consists in measuring closure phases of fully resolved objects with a baseline triplet where one of the baselines crosses a null of the object visibility function. For scenes dominated by the presence of a stellar disk, the correlated flux of the star around nulls is essentially canceled out, and in these regions the signature of fainter, unresolved, scene object(s) dominates the imaginary part of the visibility in particular the closure phase. We present here the basics of the PCN method, the initial proof-of-concept observation, the envisioned science cases and report about the first observing campaign made on VLTI/AMBER and CHARA/MIRC using this technique.