3 research outputs found
Direct Detection of the Tertiary Component in the Massive Multiple HD 150 136 with VLTI
Massive stars are of fundamental importance for almost all aspects of
astrophysics, but there still exist large gaps in our understanding of their
properties and formation because they are rare and therefore distant. It has
been found that most O-stars are multiples. HD 150 136 is the nearest system to
Earth with >100 M_sol, and provides a unique opportunity to study an extremely
massive system. Recently, evidence for the existence of a third component in HD
150 136, in addition to the tight spectroscopic binary that forms the main
component, was found in spectroscopic observations. Our aim was to image and
obtain astrometric and photometric measurements of this component using long
baseline optical interferometry to further constrain the nature of this
component. We observed HD150136 with the near-infrared instrument AMBER
attached to the ESO VLT Interferometer. The recovered closure phases are robust
to systematic errors and provide unique information on the source asymmetry.
Therefore, they are of crucial relevance for both image reconstruction and
model fitting of the source structure. The third component in HD 150 136 is
clearly detected in the high-quality data from AMBER. It is located at a
projected angular distance of 7.3 mas, or about 13 AU at the line-of-sight
distance of HD 150 136, at a position angle of 209 degrees East of North, and
has a flux ratio of 0.25 with respect to the inner binary. We resolved the
third component of HD 150 136 in J, H and K filters. The luminosity and color
of the tertiary agrees with the predictions and shows that it is also an O
main-sequence star. The small measured angular separation indicates that the
tertiary may be approaching the periastron of its orbit. These results, only
achievable with long baseline near infrared interferometry, constitute the
first step towards the understanding of the massive star formation mechanisms