A long-period massive planet around HD106515A

TL;DR

This study reports the detection of a long-period, massive planet around HD106515A through 11 years of radial velocity monitoring, confirming its planetary nature and providing insights into the planet-brown dwarf transition.

Contribution

First long-term RV monitoring of HD106515 revealing a massive, eccentric planet and constraining its mass, enhancing understanding of planet formation around binary stars.

Findings

Detected a 9.8-year eccentric orbit planet with m sin i = 9.33 Mjup

No significant RV variations in the secondary component

Adaptive optics images show no additional stellar companions

Abstract

We have performed RV monitoring of the components of the binary system HD 106515 over about 11 years using the high resolution spectrograph SARG at TNG. The primary shows long-period radial velocity variations that indicate the presence of a low mass companion whose projected mass is in the planetary regime (m sin i = 9.33 Mjup). The 9.8 years orbit results quite eccentric (e=0.57), as typical for massive giant planets. Our results confirm the preliminary announcement of the planet included in Mayor et al. (2011). The secondary instead does not show significant RV variations. The two components do not differ significantly in chemical composition, as found for other pairs for which one component hosts giant planets. Adaptive optics images obtained with AdOpt@TNG do not reveal additional stellar companions. From the analysis of the relative astrometry of the components of the wide pair we put an upper limit on the mass of the newly detected companion of about 0.25 Msun. State of art or near future instrumentation can provide true mass determination, thanks to the availability of the wide companion HD106515B as reference. Therefore, HD106515Ab will allow deeper insight in the transition region between planets and brown dwarfs.