Stellar and Planetary Characterization of the Ross 128 Exoplanetary System from APOGEE Spectra

Diogo Souto, Cayman T. Unterborn, Verne V. Smith, Katia Cunha, Johanna Teske, Kevin Covey, Bárbara Rojas-Ayala, D. A. García-Hernández, Keivan Stassun, Olga Zamora, Thomas Masseron, J. A. Johnson, Steven R. Majewski, Henrik Jönsson, Steven Gilhool, Cullen Blake, Felipe Santana

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5 Citas (Scopus)


The first detailed chemical abundance analysis of the M-dwarf (M4.0) exoplanet-hosting star Ross 128 is presented here, based upon near-infrared (1.5-1.7 μm), high-resolution (R ∼ 22,500) spectra from the SDSS Apache Point Galactic Evolution Experiment survey. We determined precise atmospheric parameters T eff = 3231 ±100 K, log g = 4.96 ±0.11 dex and chemical abundances of eight elements (C, O, Mg, Al, K, Ca, Ti, and Fe), finding Ross 128 to have near solar metallicity ([Fe/H] = +0.03 ± 0.09 dex). The derived results were obtained via spectral synthesis (1D LTE) adopting both MARCS and PHOENIX model atmospheres; stellar parameters and chemical abundances derived from the different adopted models do not show significant offsets. Mass-radius modeling of Ross 128b indicates that it lies below the pure-rock composition curve, suggesting that it contains a mixture of rock and iron, with the relative amounts of each set by the ratio of Fe/Mg. If Ross 128b formed with a subsolar Si abundance, and assuming the planet's composition matches that of the host star, it likely has a larger core size relative to the Earth despite this producing a planet with a Si/Mg abundance ratio ∼34% greater than the Sun. The derived planetary parameters - insolation flux (S Earth = 1.79 ±0.26) and equilibrium temperature (T eq = 294 ±10 K) - support previous findings that Ross 128b is a temperate exoplanet in the inner edge of the habitable zone.

Idioma originalInglés
Número de artículoL15
PublicaciónAstrophysical Journal Letters
EstadoPublicada - 10 jun 2018

Áreas temáticas de ASJC Scopus

  • Astronomía y astrofísica
  • Ciencias planetarias y espacial

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    Souto, D., Unterborn, C. T., Smith, V. V., Cunha, K., Teske, J., Covey, K., Rojas-Ayala, B., García-Hernández, D. A., Stassun, K., Zamora, O., Masseron, T., Johnson, J. A., Majewski, S. R., Jönsson, H., Gilhool, S., Blake, C., & Santana, F. (2018). Stellar and Planetary Characterization of the Ross 128 Exoplanetary System from APOGEE Spectra. Astrophysical Journal Letters, 860(1), [L15].