Searching for the nature of stars with debris disks and planets

TL;DR

This study investigates stars with both debris disks and planets, revealing their association with the Galactic thin disk and a correlation between stellar metallicity and dust disk mass across different Galactic epochs.

Contribution

It provides new insights into the relationship between stellar metallicity, disk mass, and Galactic disk membership for stars with debris disks and planets.

Findings

Most stars with debris disks and planets belong to the metal-enriched thin disk.

Old stars in the thick disk have smaller dust disks, often below Kuiper belt levels.

A correlation exists between stellar metallicity and dust disk mass influenced by Galactic formation epochs.

Abstract

The nature of the few known solar-mass stars simultaneously containing debris disks and planets remains an open question. A number of works have shown that this property appears to be independent of planetary masses as well as of stellar age, but possible correlations with stellar kinematics and metallicity have not been investigated. In this paper, we show that the majority of known stars containing both debris disks and planets belong to the metal-enriched Galactic thin disk. The few exceptions are stars that seem to be born in the star formation peak occurring in times of thick disk formation (i.e., HD 10700, HD 20794, and HD 40307), that is, between 11 and 8 Gyr. The mass of the dusty disk of these three old stars measured at 70 $\mu$m is very small - in fact, it is lower than that of the Kuiper belt of our Solar system by several orders of magnitude. These results are not surprising, as they remain within the values expected for the stellar disk evolution of such primitive stars. In parallel, we found another six thick-disk stars containing only debris disks or planets. These results enable us to establish a correlation between stellar metallicity and the mass of the dust disk modulated by the different formation epochs of the thick and thin Galactic disks.