GRAVITY Spectro-interferometric Study of the Massive Multiple Stellar System HD 93206 A

DOI: 
10.3847/1538-4357/aa803d
Publication date: 
01/08/2017
Main author: 
Sanchez-Bermudez, J.
IAA authors: 
Alberdi, A.;Schödel, R.
Authors: 
Sanchez-Bermudez, J.;Alberdi, A.;Barbá, R.;Bestenlehner, J. M.;Cantalloube, F.;Brandner, W.;Henning, Th.;Hummel, C. A.;Maíz Apellániz, J.;Pott, J. -U.;Schödel, R.;van Boekel, R.
Journal: 
The Astrophysical Journal
Refereed: 
Yes
Publication type: 
Article
Volume: 
845
Pages: 
57
Abstract: 

Characterization of the dynamics of massive star systems and the astrophysical properties of the interacting components are a prerequisite for understanding their formation and evolution. Optical interferometry at milliarcsecond resolution is a key observing technique for resolving high-mass multiple compact systems. Here, we report on Very Large Telescope Interferometer/GRAVITY, Magellan/Folded-port InfraRed Echellette, and MPG2.2 m/FEROS observations of the late-O/early-B type system HD 93206 A, which is a member of the massive cluster Collinder 228 in the Carina nebula complex. With a total mass of about 90 {M}<SUB>ȯ </SUB>, it is one of the most compact massive quadruple systems known. In addition to measuring the separation and position angle of the outer binary Aa─Ac, we observe Brγ and He i variability in phase with the orbital motion of the two inner binaries. From the differential phase ({{{Δ }}}<SUB>φ </SUB>) analysis, we conclude that the Brγ emission arises from the interaction regions within the components of the individual binaries, which is consistent with previous models for the X-ray emission of the system based on wind─wind interaction. With an average 3σ deviation of {{{Δ }}}<SUB>φ </SUB>∼ 15^\circ , we establish an upper limit of p ∼ 0.157 mas (0.35 au) for the size of the Brγ line-emitting region. Future interferometric observations with GRAVITY using the 8 m Unit Telescopes will allow us to constrain the line-emitting regions down to angular sizes of 20 μas (0.05 au at the distance of the Carina nebula).

Database: 
ADS
SCOPUS
URL: 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028344210&doi=10.3847%2f1538-4357%2faa803d&partnerID=40&md5=c9f87d5047e1c331a066f9187d1fe370
ADS Bibcode: 
2017ApJ...845...57S
Keywords: 
astrometry;binaries: general;stars: massive;techniques: interferometric