JWST MIRI/LRS data combined with archival observations detect magnesium silicate clouds (likely Mg2SiO4) in HD 209458b at 1-10 mbar with ~0.1 micron particles using a new rule-based data reduction approach.
HARPS-N Solar Radial-Velocity Variations Are Dominated By Large, Bright Magnetic Regions
4 Pith papers cite this work. Polarity classification is still indexing.
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Pith papers citing it
abstract
State of the art radial-velocity (RV) exoplanet searches are currently limited by RV signals arising from stellar magnetic activity. We analyze solar observations acquired over a 3-year period during the decline of Carrington Cycle 24 to test models of RV variation of Sun-like stars. A purpose-built solar telescope at the High Accuracy Radial velocity Planet Searcher for the Northern hemisphere (HARPS-N) provides disk-integrated solar spectra, from which we extract RVs and $\log{R'_{\rm HK}}$. The Solar Dynamics Observatory (SDO) provides disk-resolved images of magnetic activity. The Solar Radiation and Climate Experiment (SORCE) provides near-continuous solar photometry, analogous to a Kepler light curve. We verify that the SORCE photometry and HARPS-N $\log{R'_{\rm HK}}$ correlate strongly with the SDO-derived magnetic filling factor, while the HARPS-N RV variations do not. To explain this discrepancy, we test existing models of RV variations. We estimate the contributions of the suppression of convective blueshift and the rotational imbalance due to brightness inhomogeneities to the observed HARPS-N RVs. We investigate the time variation of these contributions over several rotation periods, and how these contributions depend on the area of active regions. We find that magnetic active regions smaller than $60 \ \rm Mm^2$ do not significantly suppress convective blueshift. Our area-dependent model reduces the amplitude of activity-induced RV variations by a factor of two. The present study highlights the need to identify a proxy that correlates specifically with large, bright magnetic regions on the surfaces of exoplanet-hosting stars.
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CONDITIONAL 4representative citing papers
3D MHD simulations of solar faculae reveal a center-to-limb transition in induced radial velocity from redshift to blueshift at heliocentric angles above 60 degrees, producing a phase-lagged transit profile and spectral-line dependence.
SRA-derived photospheric activity indicators track stellar RV variability up to a factor of two better than classical proxies like logR'HK across 14 G/K stars.
Three Jupiter-mass planets are detected around two low-luminosity red giants with 15–18 yr CORALIE RVs; a multi-exposure strategy averages pulsations below 5 m/s.
citing papers explorer
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Magnesium Silicate Clouds in the Atmosphere of HD 209458b from a Rule-Based Tree-Structured Data Reduction
JWST MIRI/LRS data combined with archival observations detect magnesium silicate clouds (likely Mg2SiO4) in HD 209458b at 1-10 mbar with ~0.1 micron particles using a new rule-based data reduction approach.
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Decoding the Radial Velocity Signatures of Solar Faculae with 3D MHD Simulations
3D MHD simulations of solar faculae reveal a center-to-limb transition in induced radial velocity from redshift to blueshift at heliocentric angles above 60 degrees, producing a phase-lagged transit profile and spectral-line dependence.
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Spectral Ratio Analysis: probing of a new suite of stellar activity indicators as a tool for astrophysical noise mitigation
SRA-derived photospheric activity indicators track stellar RV variability up to a factor of two better than classical proxies like logR'HK across 14 G/K stars.
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CORALIE radial-velocity search for companions around evolved stars (CASCADES) V. Three planetary companions and achievable precision
Three Jupiter-mass planets are detected around two low-luminosity red giants with 15–18 yr CORALIE RVs; a multi-exposure strategy averages pulsations below 5 m/s.