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

Souto, Diogo ; Unterborn, Cayman T. ; Smith, Verne V. ; Cunha, Katia ; Teske, Johanna ; Covey, Kevin ; Rojas-Ayala, Bárbara ; García-Hernández, D. A. ; Stassun, Keivan and Zamora, Olga , et al. (2018) In Astrophysical Journal Letters 860(1).
Abstract

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... (More)

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.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
infrared: stars, planetary systems, planetstar interactions, stars: abundances, stars: fundamental parameters, stars: low-mass
in
Astrophysical Journal Letters
volume
860
issue
1
article number
L15
publisher
IOP Publishing
external identifiers
  • scopus:85049052764
ISSN
2041-8205
DOI
10.3847/2041-8213/aac896
language
English
LU publication?
yes
id
3dd418b8-3c98-43ec-b20d-98f68ee92167
date added to LUP
2018-07-06 12:36:12
date last changed
2022-12-15 01:52:52
@article{3dd418b8-3c98-43ec-b20d-98f68ee92167,
  abstract     = {{<p>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 <sub>eff</sub> = 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 <sub>Earth</sub> = 1.79 ±0.26) and equilibrium temperature (T <sub>eq</sub> = 294 ±10 K) - support previous findings that Ross 128b is a temperate exoplanet in the inner edge of the habitable zone.</p>}},
  author       = {{Souto, Diogo and Unterborn, Cayman T. and Smith, Verne V. and Cunha, Katia and Teske, Johanna and Covey, Kevin and Rojas-Ayala, Bárbara and García-Hernández, D. A. and Stassun, Keivan and Zamora, Olga and Masseron, Thomas and Johnson, J. A. and Majewski, Steven R. and Jönsson, Henrik and Gilhool, Steven and Blake, Cullen and Santana, Felipe}},
  issn         = {{2041-8205}},
  keywords     = {{infrared: stars; planetary systems; planetstar interactions; stars: abundances; stars: fundamental parameters; stars: low-mass}},
  language     = {{eng}},
  month        = {{06}},
  number       = {{1}},
  publisher    = {{IOP Publishing}},
  series       = {{Astrophysical Journal Letters}},
  title        = {{Stellar and Planetary Characterization of the Ross 128 Exoplanetary System from APOGEE Spectra}},
  url          = {{http://dx.doi.org/10.3847/2041-8213/aac896}},
  doi          = {{10.3847/2041-8213/aac896}},
  volume       = {{860}},
  year         = {{2018}},
}