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

Investigating the environment of the massive black hole SgrA* at the centerof the Galaxy requires the highest angular resolution available to avoid sourceconfusion and to study the physical properties of the individual objects.GCIRS7 has been used as wavefront and astrometric reference. Our studiesinvestigate, for the first time, its properties at 2&10um using VLTI/AMBER andMIDI. We aim at analyzing the suitability of IRS7 as an IF-phase-reference forthe upcoming generation of dual-field facilities at optical interferometers. Weobserved with (R~30) and 50m (proj.) baseline, resulting in 9 and 45masresolution for NIR and MIR, resp. The first K-band fringe detection of a GCstar suggests that IRS7 could be marginally resolved at 2um, which would implythat the photosphere of the supergiant is enshrouded by a molecular and dustyenvelope. At 10um, IRS7 is strongly resolved with a visibility of approximately0.2. The MIR is dominated by moderately warm (200 K), extended dust, mostlydistributed outside of a radius of about 120 AU (15 mas) around the star. Adeep 9.8-silicate absorption in excess of the usual extinction law with respectto the NIR extinction has been found. This confirms recent findings of arelatively enhanced, interstellar 9.8-silicate absorption with respect to theNIR extinction towards another star in the central arcsec, suggesting anunusual dust composition in that region. Our VLTI observations show thatinterferometric NIR phase-referencing experiments with mas resolution usingIRS7 as phase-reference appear to be feasible, but more such studies arerequired to definitely characterize the close environment around this star. Wedemonstrate that interferometry is required to resolve the innermostenvironment of stars at the Galactic center.

astronomy and astrophysics

First VLTI infrared spectro-interferometry on GCIRS 7 - Characterizing  the prime reference source for Galactic center observations at highest  angular resolution