Charlotte Gehan
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View article: Enhanced magnetic activity in rapidly rotating binary stars
Enhanced magnetic activity in rapidly rotating binary stars Open
Stellar activity is fundamental to stellar evolution and the formation and habitability of exoplanets. The interaction between convective motions and rotation in cool stars results in a dynamo process that drives magnetic surface activity.…
View article: Enhanced magnetic activity in rapidly rotating binary stars
Enhanced magnetic activity in rapidly rotating binary stars Open
The interaction between convective motions and rotation in cool stars results in a dynamo process that drives magnetic surface activity1, 2. In single stars, activity increases with rotation rate until it saturates for stars with rotation …
View article: Magnetic activity of red giants: Correlation between the amplitude of solar-like oscillations and chromospheric indicators
Magnetic activity of red giants: Correlation between the amplitude of solar-like oscillations and chromospheric indicators Open
Previous studies have found that red giants (RGs) in close binary systems undergoing spin-orbit resonance exhibit an enhanced level of magnetic activity with respect to single RGs rotating at the same rate, from measurements of photometric…
View article: Magnetic activity of red giants: correlation between the amplitude of solar-like oscillations and chromospheric indicators
Magnetic activity of red giants: correlation between the amplitude of solar-like oscillations and chromospheric indicators Open
Previous studies have found that red giants (RGs) in close binary systems undergoing spin-orbit resonance exhibit an enhanced level of magnetic activity with respect to single RGs rotating at the same rate, from measurements of photometric…
View article: Mode Mixing and Rotational Splittings. II. Reconciling Different Approaches to Mode Coupling
Mode Mixing and Rotational Splittings. II. Reconciling Different Approaches to Mode Coupling Open
In the mixed-mode asteroseismology of subgiants and red giants, the coupling between the p- and g- mode cavities must be understood well in order to derive localized estimates of interior rotation from measurements of mode multiplet rotati…
View article: FRA–A new fast, robust, and automated pipeline for the detection and measurement of solar‐like oscillations in time‐series photometry of red‐giant stars
FRA–A new fast, robust, and automated pipeline for the detection and measurement of solar‐like oscillations in time‐series photometry of red‐giant stars Open
We developed, tested, and validated a new Fast, Robust, and Automated (FRA) tool to detect solar‐like oscillations. FRA is based on the detection and measurement of the frequency of maximum oscillation power , without relying on the detect…
View article: TESS Asteroseismic Analysis of HD 76920: The Giant Star Hosting an Extremely Eccentric Exoplanet
TESS Asteroseismic Analysis of HD 76920: The Giant Star Hosting an Extremely Eccentric Exoplanet Open
The Transiting Exoplanet Survey Satellite (TESS) mission searches for new exoplanets. The observing strategy of TESS results in high-precision photometry of millions of stars across the sky, allowing for detailed asteroseismic studies of i…
View article: Mode Mixing and Rotational Splittings: II. Reconciling Different Approaches to Mode Coupling
Mode Mixing and Rotational Splittings: II. Reconciling Different Approaches to Mode Coupling Open
In the mixed-mode asteroseismology of subgiants and red giants, the coupling between the p- and g-mode cavities must be understood well in order to derive localised estimates of interior rotation from measurements of mode multiplet rotatio…
View article: TESS Asteroseismic Analysis of HD 76920: The Giant Star Hosting An Extremely Eccentric Exoplanet
TESS Asteroseismic Analysis of HD 76920: The Giant Star Hosting An Extremely Eccentric Exoplanet Open
The Transiting Exoplanet Survey Satellite (TESS) mission searches for new exoplanets. The observing strategy of TESS results in high-precision photometry of millions of stars across the sky, allowing for detailed asteroseismic studies of i…
View article: Surface magnetism of rapidly rotating red giants: Single versus close binary stars
Surface magnetism of rapidly rotating red giants: Single versus close binary stars Open
According to dynamo theory, stars with convective envelopes efficiently generate surface magnetic fields, which manifest as magnetic activity in the form of starspots, faculae, and/or flares, when their rotation period is shorter than thei…
View article: Surface magnetism of rapidly rotating red giants: single versus close binary stars
Surface magnetism of rapidly rotating red giants: single versus close binary stars Open
According to dynamo theory, stars with convective envelopes efficiently generate surface magnetic fields, which manifest as magnetic activity in the form of starspots, faculae, flares, when their rotation period is shorter than their conve…
View article: Spinning up the Surface: Evidence for Planetary Engulfment or Unexpected Angular Momentum Transport?
Spinning up the Surface: Evidence for Planetary Engulfment or Unexpected Angular Momentum Transport? Open
In this paper, we report the potential detection of a nonmonotonic radial rotation profile in a low-mass lower-luminosity giant star. For most low- and intermediate-mass stars, the rotation on the main sequence seems to be close to rigid. …
View article: KIC 7955301: A hierarchical triple system with eclipse timing variations and an oscillating red giant
KIC 7955301: A hierarchical triple system with eclipse timing variations and an oscillating red giant Open
KIC 7955301 is a hierarchical triple system with clear eclipse timing and depth variations that was discovered by the Kepler satellite during its original mission. It is composed of a non-eclipsing primary star at the bottom of the red gia…
View article: Spinning up the Surface: Evidence for Planetary Engulfment or Unexpected Angular Momentum Transport?
Spinning up the Surface: Evidence for Planetary Engulfment or Unexpected Angular Momentum Transport? Open
In this paper, we report the potential detection of a nonmonotonic radial rotation profile in a low-mass lower-luminosity giant star. For most low- and intermediate-mass stars, the rotation on the main sequence seems to be close to rigid. …
View article: Asteroseismology of evolved stars to constrain the internal transport of angular momentum
Asteroseismology of evolved stars to constrain the internal transport of angular momentum Open
Context. Asteroseismology provides constraints on the core rotation rate for hundreds of low- and intermediate-mass stars in evolved phases. Current physical processes tested in stellar evolution models cannot reproduce the evolution of th…
View article: A 20 Second Cadence View of Solar-type Stars and Their Planets with TESS: Asteroseismology of Solar Analogs and a Recharacterization of π Men c
A 20 Second Cadence View of Solar-type Stars and Their Planets with TESS: Asteroseismology of Solar Analogs and a Recharacterization of π Men c Open
We present an analysis of the first 20 second cadence light curves obtained by the TESS space telescope during its extended mission. We find improved precision of 20 second data compared to 2 minute data for bright stars when binned to the…
View article: Seismic signature of electron degeneracy in the core of red giants: Hints for mass transfer between close red-giant companions
Seismic signature of electron degeneracy in the core of red giants: Hints for mass transfer between close red-giant companions Open
The detection of mixed modes in red giants with space missions C O R O T and Kepler has revealed their deep internal structure. These modes allow us to characterize the pattern of pressure modes (through the measurement of their asymptotic…
View article: A 20-Second Cadence View of Solar-Type Stars and Their Planets with TESS: Asteroseismology of Solar Analogs and a Re-characterization of pi Men c
A 20-Second Cadence View of Solar-Type Stars and Their Planets with TESS: Asteroseismology of Solar Analogs and a Re-characterization of pi Men c Open
We present an analysis of the first 20-second cadence light curves obtained by the TESS space telescope during its extended mission. We find a precision improvement of 20-second data compared to 2-minute data for bright stars when binned t…
View article: Seismic constraints on the internal structure of evolved stars: From high-luminosity RGB to AGB stars
Seismic constraints on the internal structure of evolved stars: From high-luminosity RGB to AGB stars Open
Context. The space-borne missions CoRoT and Kepler opened up a new opportunity for better understanding stellar evolution by probing stellar interiors with unrivalled high-precision photometric data. Kepler has observed stellar oscillation…
View article: Period spacings in red giants
Period spacings in red giants Open
Context . Oscillation modes with a mixed character, as observed in evolved low-mass stars, are highly sensitive to the physical properties of the innermost regions. Measuring their properties is therefore extremely important to probe the c…
View article: Period spacings in red giants IV: Toward a complete description of the mixed-mode pattern
Period spacings in red giants IV: Toward a complete description of the mixed-mode pattern Open
Oscillation modes with a mixed character, as observed in evolved low-mass stars, are highly sensitive to the physical properties of the innermost regions. Measuring their properties is therefore extremely important to probe the core, but r…
View article: Large-scale measurements of the red giant core rotation through asteroseismology
Large-scale measurements of the red giant core rotation through asteroseismology Open
Red giant stars are solar-like pulsators presenting mixed-modes. Such modes consist in a coupling between pressure waves propagating in the external convective envelope and gravity waves propagating in the radiative interior. Therefore, th…
View article: Large-scale measurements of the red giant core rotation through\n asteroseismology
Large-scale measurements of the red giant core rotation through\n asteroseismology Open
Red giant stars are solar-like pulsators presenting mixed-modes. Such modes\nconsist in a coupling between pressure waves propagating in the external\nconvective envelope and gravity waves propagating in the radiative interior.\nTherefore,…
View article: Rapidly rotating red giants
Rapidly rotating red giants Open
Stellar oscillations give seismic information on the internal properties of\nstars. Red giants are targets of interest since they present mixed modes, which\nbehave as pressure modes in the convective envelope and as gravity modes in the\n…
View article: Measuring the core rotation of red giant stars
Measuring the core rotation of red giant stars Open
Red giant stars present mixed modes, which behave as pressure modes in the convective envelope and as gravity modes in the radiative interior. This mixed character allows to probe the physical conditions in their core. With the advent of l…