The HARPS search for southern extrasolar planets XXI. Three new giant planets orbiting the metal-poor stars HD5388, HD181720, and HD190984

TL;DR

This paper reports the discovery of three new giant exoplanets orbiting metal-poor stars, indicating that long-period giant planets are relatively common around such stars, based on HARPS survey data.

Contribution

It presents the detection of three new long-period giant planets around metal-poor stars, expanding knowledge of planet occurrence in low-metallicity environments.

Findings

Giant planets with long orbital periods are found around metal-poor stars.

All three planets have eccentric orbits and are relatively massive.

The discoveries suggest such planets are not rare in these environments.

Abstract

We present the discovery of three new giant planets around three metal-deficient stars: HD5388b (1.96M_Jup), HD181720b (0.37M_Jup), and HD190984b (3.1M_Jup). All the planets have moderately eccentric orbits (ranging from 0.26 to 0.57) and long orbital periods (from 777 to 4885 days). Two of the stars (HD181720 and HD190984) were part of a program searching for giant planets around a sample of ~100 moderately metal-poor stars, while HD5388 was part of the volume-limited sample of the HARPS GTO program. Our discoveries suggest that giant planets in long period orbits are not uncommon around moderately metal-poor stars.