English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Context. delta Vel contains the brightest eclipsing binary in the southernsky (delta Vel A), and a nearby third star located ~0.6" away (delta Vel B).The proximity of delta Vel B (usable as a reference) makes it a particularlywell-suited target to detect the astrometric displacement of the center oflight of the eclipsing pair. Aims. We obtained NACO astrometric observationswith two goals: (1) to confirm the orientation of the orbital plane of theeclipsing pair on the sky determined by interferometry (Paper III) and (2)demonstrate the capabilities of narrow-angle adaptive optics astrometry on asimple system with predictable astrometric properties. Methods. We measured theangular separation vector between the eclipsing binary delta Vel A and thevisual companion delta Vel B from narrow-band images at 2.17 microns obtainedwith the VLT/NACO adaptive optics system. Based on these observations and ourprevious determination of the orbital parameters of the wide binary delta VelA-B, we derive the apparent displacement of the center-of-light of theeclipsing pair at 11 epochs over its orbital cycle. Results. We detect theastrometric wobble of the center of light of the delta Vel A pair relatively toB with a typical measurement precision of ~50 microarcseconds per epoch, for atotal amplitude of the measured displacement of ~2 milliarcseconds.Conclusions. The detected wobble is in agreement with our model presented inPaper III and confirms the orientation of the Aab orbital plane on the sky. Theresidual dispersion compared to our model is 110 microarcseconds rms, that wetentatively attribute to photometric variability of the fast rotating A-typecomponents Aa and/or Ab in the BrGamma line. Based on these results, weconclude that in favorable conditions (bright source with only two resolvedcomponents, small angular separation), narrow-angle astrometry with adaptiveoptics on an 8-meter class telescope can reach an accuracy of 50 to 100microarcseconds.

The nearby eclipsing stellar system delta Velorum - IV. Differential astrometry with VLT/NACO at the 100 microarcsecond level