Three regimes of extrasolar planet radius inferred from host star metallicities
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Three regimes of extrasolar planet radius inferred from host star metallicities. / Buchhave, Lars A.; Bizzarro, Martin; Latham, David W.; Sasselov, Dimitar; Cochran, William D.; Endl, Michael; Isaacson, Howard; Juncher, Diana; Marcy, Geoffrey W.
In: Nature, Vol. 509, No. 7502, 2014, p. 593-595.Research output: Contribution to journal › Journal article › Research › peer-review
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T1 - Three regimes of extrasolar planet radius inferred from host star metallicities
AU - Buchhave, Lars A.
AU - Bizzarro, Martin
AU - Latham, David W.
AU - Sasselov, Dimitar
AU - Cochran, William D.
AU - Endl, Michael
AU - Isaacson, Howard
AU - Juncher, Diana
AU - Marcy, Geoffrey W.
PY - 2014
Y1 - 2014
N2 - Approximately half of the extrasolar planets (exoplanets) with radii less than four Earth radii are in orbits with short periods. Despite their sheer abundance, the compositions of such planets are largely unknown. The available evidence suggests that they range in composition from small, high-density rocky planets to low-density planets consisting of rocky cores surrounded by thick hydrogen and helium gas envelopes. Here we report the metallicities (that is, the abundances of elements heavier than hydrogen and helium) of more than 400 stars hosting 600 exoplanet candidates, and find that the exoplanets can be categorized into three populations defined by statistically distinct (~4.5σ) metallicity regions. We interpret these regions as reflecting the formation regimes of terrestrial-like planets (radii less than 1.7 Earth radii), gas dwarf planets with rocky cores and hydrogen-helium envelopes (radii between 1.7 and 3.9 Earth radii) and ice or gas giant planets (radii greater than 3.9 Earth radii). These transitions correspond well with those inferred from dynamical mass estimates, implying that host star metallicity, which is a proxy for the initial solids inventory of the protoplanetary disk, is a key ingredient regulating the structure of planetary systems.
AB - Approximately half of the extrasolar planets (exoplanets) with radii less than four Earth radii are in orbits with short periods. Despite their sheer abundance, the compositions of such planets are largely unknown. The available evidence suggests that they range in composition from small, high-density rocky planets to low-density planets consisting of rocky cores surrounded by thick hydrogen and helium gas envelopes. Here we report the metallicities (that is, the abundances of elements heavier than hydrogen and helium) of more than 400 stars hosting 600 exoplanet candidates, and find that the exoplanets can be categorized into three populations defined by statistically distinct (~4.5σ) metallicity regions. We interpret these regions as reflecting the formation regimes of terrestrial-like planets (radii less than 1.7 Earth radii), gas dwarf planets with rocky cores and hydrogen-helium envelopes (radii between 1.7 and 3.9 Earth radii) and ice or gas giant planets (radii greater than 3.9 Earth radii). These transitions correspond well with those inferred from dynamical mass estimates, implying that host star metallicity, which is a proxy for the initial solids inventory of the protoplanetary disk, is a key ingredient regulating the structure of planetary systems.
U2 - 10.1038/nature13254
DO - 10.1038/nature13254
M3 - Journal article
C2 - 24870544
AN - SCOPUS:84901642888
VL - 509
SP - 593
EP - 595
JO - Nature
JF - Nature
SN - 0028-0836
IS - 7502
ER -
ID: 120605001