Detalles de publicación
PP 026121
Signatures of rocky debris accretion in AF-Type planet hosts
(1)INAF - Osservatorio astronomico di Palermo, Italy
(2) Centro de Astrobiología (CAB) CSIC-INTA, Spain
(3)Institute of Applied Computing & Community Code (IAC3). University of the Balearic Islands, Spain
(4) Departamento de Física Teórica y del Cosmos, Universidad de Granada,Spain
(5) Instituto de Astrofísica de Canarias, Spain
Context. The gas-giant planet-metallicity correlation plays a fundamental role in our understanding of planet formation. However,
that correlation is mostly derived from observations of solar-type stars.
Aims. We aim to test whether the correlation between the metallicity and chemical abundances of the star and the presence of giant
planets for solar-type stars still holds for early-type (spectral types A and early-F) stars.
Methods. We determine in a homogeneous way the metallicity and individual abundances of a large sample of A and early-F stars,
with and without known planetary companions, and discuss their abundance distribution and trends. Our methodology is based on the
analysis of high-resolution échelle spectra. It includes the calculation of the fundamental stellar parameters by fitting the profiles of the
Balmer lines, as well as individual abundances of different elements such as C, O, Mg, Si, Ca, Ti, Fe, Ni and Ba by a multi-parameter
fitting procedure of selected spectral regions.
Results. We find that stars with planets generally exhibit higher abundances of both iron-peak and volatile elements compared to stars
without known planets although in most cases this tendency is not statistically significant. The C/O ratio remains similar between
both samples, while the Mg/Si ratio is shifted towards higher values in the general planet host sample. When the sample is limited
to fully radiative stars (spectral type earlier than F5), the statistical significance of carbon overabundances vanishes. In contrast,
elements such as O and Ni remain significantly overabundant. The C/O and Mg/Si ratios in this radiative subsample are statistically
indistinguishable from that of the comparison sample.
Conclusions. The persistent overabundance of O and Ni, combined with C/O and Mg/Si ratios similar to those of stars without
planets in fully radiative hosts, points to the ongoing surface pollution by volatile-poor, silicate-rich rocky debris, rather than the
accretion of gas giants. These findings might position early-type main-sequence stars as a crucial dynamical missing link in the
chemical life-cycle of planetary systems: bridging the initial dust-trapping phase in pre-main sequence transition discs, the dilution
of this superficial pollution during the fully convective red giant phase, and the eventual dynamically-driven accretion of asteroid
material observed in polluted white dwarfs
that correlation is mostly derived from observations of solar-type stars.
Aims. We aim to test whether the correlation between the metallicity and chemical abundances of the star and the presence of giant
planets for solar-type stars still holds for early-type (spectral types A and early-F) stars.
Methods. We determine in a homogeneous way the metallicity and individual abundances of a large sample of A and early-F stars,
with and without known planetary companions, and discuss their abundance distribution and trends. Our methodology is based on the
analysis of high-resolution échelle spectra. It includes the calculation of the fundamental stellar parameters by fitting the profiles of the
Balmer lines, as well as individual abundances of different elements such as C, O, Mg, Si, Ca, Ti, Fe, Ni and Ba by a multi-parameter
fitting procedure of selected spectral regions.
Results. We find that stars with planets generally exhibit higher abundances of both iron-peak and volatile elements compared to stars
without known planets although in most cases this tendency is not statistically significant. The C/O ratio remains similar between
both samples, while the Mg/Si ratio is shifted towards higher values in the general planet host sample. When the sample is limited
to fully radiative stars (spectral type earlier than F5), the statistical significance of carbon overabundances vanishes. In contrast,
elements such as O and Ni remain significantly overabundant. The C/O and Mg/Si ratios in this radiative subsample are statistically
indistinguishable from that of the comparison sample.
Conclusions. The persistent overabundance of O and Ni, combined with C/O and Mg/Si ratios similar to those of stars without
planets in fully radiative hosts, points to the ongoing surface pollution by volatile-poor, silicate-rich rocky debris, rather than the
accretion of gas giants. These findings might position early-type main-sequence stars as a crucial dynamical missing link in the
chemical life-cycle of planetary systems: bridging the initial dust-trapping phase in pre-main sequence transition discs, the dilution
of this superficial pollution during the fully convective red giant phase, and the eventual dynamically-driven accretion of asteroid
material observed in polluted white dwarfs