Bibcode
Udry, S.; Adibekyan, V. Zh.; Santos, N. C.; Israelian, G.; Sousa, S. G.; Delgado-Mena, E.; González-Hernández, J. I.
Bibliographical reference
Astronomy and Astrophysics, Volume 552, id.A6, 14 pp.
Advertised on:
4
2013
Journal
Citations
81
Refereed citations
74
Description
Context. Detailed chemical abundances of volatile and refractory
elements have been discussed in the context of terrestrial-planet
formation during in past years. Aims: The HARPS-GTO
high-precision planet-search program has provided an extensive database
of stellar spectra, which we have inspected in order to select the
best-quality spectra available for late type stars. We study the
volatile-to-refractory abundance ratios to investigate their possible
relation with the low-mass planetary formation. Methods: We
present a fully differential chemical abundance analysis using
high-quality HARPS and UVES spectra of 61 late F- and early G-type
main-sequence stars, where 29 are planet hosts and 32 are stars without
detected planets. Results: As for the previous sample of solar
analogs, these stars slightly hotter than the Sun also provide very
accurate Galactic chemical abundance trends in the metallicity range
-0.3 < [Fe/H] < 0.4. Stars with and without planets show similar
mean abundance ratios. Moreover, when removing the Galactic chemical
evolution effects, these mean abundance ratios, Δ [X/Fe] SUN
- STARS, against condensation temperature, tend to exhibit less
steep trends with nearly zero or slightly negative slopes. We have also
analyzed a subsample of 26 metal-rich stars, 13 with and 13 without
known planets, with spectra at S/N ~ 850, on average, in the narrow
metallicity range 0.04 < [Fe/H] < 0.19. We find the similar,
although not equal, abundance pattern with negative slopes for both
samples of stars with and without planets. Using stars at S/N ≥ 550
provides equally steep abundance trends with negative slopes for stars
both with and without planets. We revisit the sample of solar analogs to
study the abundance patterns of these stars, in particular, 8 stars
hosting super-Earth-like planets. Among these stars having very low-mass
planets, only four of them reveal clear increasing abundance trends
versus condensation temperature. Conclusions: Finally, we
compared these observed slopes with those predicted using a simple model
that enables us to compute the mass of rocks that have formed
terrestrial planets in each planetary system. We do not find any
evidence supporting the conclusion that the volatile-to-refractory
abundance ratio is related to the presence of rocky planets.
Based on observations collected with the HARPS spectrograph at the 3.6-m
telescope (072.C-0488(E)), installed at the La Silla Observatory, ESO
(Chile), with the UVES spectrograph at the 8-m Very Large Telescope
(VLT) - program IDs: 67.C-0206(A), 074.C-0134(A), 075.D-0453(A) -,
installed at the Cerro Paranal Observatory, ESO (Chile), and with the
UES spectrograph at the 4.2-m William Herschel Telescope (WHT),
installed at the Spanish Observatorio del Roque de los Muchachos of the
Instituto de Astrofísica de Canarias, on the island of La
Palma.Tables A.1-A.8 are only available at the CDS via anonymous ftp to
cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/552/A6
Related projects
Observational Tests of the Processes of Nucleosynthesis in the Universe
Several spectroscopic analyses of stars with planets have recently been carried out. One of the most remarkable results is that planet-harbouring stars are on average more metal-rich than solar-type disc stars. Two main explanations have been suggested to link this metallicity excess with the presence of planets. The first of these, the “self
Garik
Israelian