Detection of Solar-like Oscillations and Granulation at Infrared Wavelengths using JWST

summary

The gist

The gist: This study presents the first detection of solar-like oscillations and granulation at infrared wavelengths using JWST time-series observations of WASP-121, opening new avenues for testing

In short

Researchers detected solar-like oscillations and granulation at infrared wavelengths using JWST observations of WASP-121. They found that oscillation and granulation amplitudes decrease with wavelength, deviating from simple blackbody scaling. This detection allows for detailed testing of 3D convection models and helps combine stellar and exoplanet signals.

Key concepts

Stellar Oscillations: These are waves driven by near-surface convection in stars, characterized by a maximum power frequency ($ u_{max}$) and a frequency separation between modes ($ riangle u$). These properties scale with stellar parameters like surface gravity and effective temperature, providing insights into the star's internal structure.
Granulation: Granulation refers to brightness fluctuations caused by rising and falling plasma within convective cells. It occurs on timescales of minutes to hours and is a key probe of the turbulent convection processes happening just beneath the stellar surface.
Chromaticity of Convection: This concept tests how the contrast between intergranular lanes and granule surfaces changes with wavelength. The study found that granulation amplitudes decrease at longer wavelengths, matching predictions based on blackbody models, confirming that convective process strengths are wavelength-dependent.

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This episode discusses

The paper

Detection of Solar-like Oscillations and Granulation at Infrared Wavelengths using JWST · Read on arXiv

Sydney Institute for Astronomy, University of Sydney, Australia · Institute for Astronomy, University of Hawai‘i, USA · Department of Earth & Planetary Sciences, McGill University, Canada · Stellar Astrophysics Centre, Aarhus University, Denmark · Planétarium de Montréal

Stellar oscillations and granulation are key probes of stellar convection, one of the most poorly understood processes in stars. Stellar models predict strong wavelength dependence of the amplitudes of oscillations and granulation, but hitherto both processes have only been measured at optical wavelengths. Here we present the first detection of oscillations and granulation at infrared wavelengths, using JWST time-series observations of the F6V main-sequence star WASP-121 that were obtained to study the atmosphere of an exoplanet. We find that the amplitudes of oscillations and granulation decrease with wavelength, consistent with expectations, but with a functional form that deviates from simple blackbody scaling. The detection opens the door to detailed tests of 3D convection models, facilitates the combined modeling of stellar and exoplanet signals in JWST passbands for exoplanet observations, and supports the predicted asteroseismic yields from the infrared time-domain data that will soon be obtained by the Roman Space Telescope.

Transcript

Introduction to the show: ident: Astrophysics Radio. Generated commentary on the latest astrophysics papers.

Vera: I'm Vera.

Jocelyn: And I'm Jocelyn, here with Subrahmanyan.

Vera: We're looking at the paper: "Detection of Solar-like Oscillations and Granulation at Infrared Wavelengths using JWST".

Jocelyn: Here's the gist of the paper. The gist: This study presents the first detection of solar-like oscillations and granulation at infrared wavelengths using JWST time-series observations of WASP-121, opening new avenues for testing 3D convection models and combining stellar and exoplanet signals.

Vera: Stellar Variability Probes Convection Granulation, which involves the rising and falling plasma in convective cells, produces brightness fluctuations on timescales ranging from minutes to hours (Page 1).

Jocelyn: Stellar oscillations are also driven by near-surface convection through stochastic excitation and damping of pressure-mode (p-mode) oscillations (Page 1).

Vera: These oscillations are characterized by two global properties: the frequency of maximum power, νmax, and the average frequency separation between consecutive oscillation modes, ∆ν (Page 1).

Paper summary: Vera: So, let's start with this paper, "Detection of Solar-like Oscillations and Granulation at Infrared Wavelengths using JWST." Essentially, they’re saying that solar-like oscillations and granulation are key ways to probe stellar convection, but usually we only see them in optical light.

Jocelyn: Exactly. The thesis here is that this paper presents the first detection of these solar-like oscillations and granulation at infrared wavelengths using JWST time-series observations of the star WASP-one hundred twenty-one which is an F6V main-sequence star used to study an exoplanet atmosphere <ref:2610.30594#pg1,solar-like oscillations and granulation at infrared wavelengths using JWST>.

Subrahmanyan: That's significant because stellar models predict a strong wavelength dependence for these amplitudes, and this finding deviates from simple blackbody scaling, meaning the way they change with wavelength isn't just what you'd expect if the star was just a simple blackbody radiating light >]

Vera: Right. The abstract points out that while the amplitudes do decrease with wavelength, they follow a functional form that doesn't fit that simple blackbody scaling model we usually use. This opens up new ways to test those three dee convection models, which are pretty complex things <ref:2610.30594#pg1>.

Jocelyn: And it also lets us combine the modeling of stellar and exoplanet signals in JWST passbands when we look at exoplanets, which is a big deal for future exoplanet observations. Plus, it supports the predicted asteroseismic yields from infrared time-domain data that the Roman Space Telescope will soon get.

Subrahmanyan: From a cosmological side, this directly affects how we estimate those asteroseismic yields for missions like the Nancy Grace Roman Telescope, because we need to understand how those oscillations scale with wavelength >

Vera: So, moving into the conclusion of this paper titled "Detection of Solar-like Oscillations and Granulation at Infrared Wavelengths using JWST," what's the real implication for us? It’s about confirming that JWST is actually suitable for resolving near-surface variability processes in the infrared.

Jocelyn: And they emphasize that the chromaticity of stellar variability matters, especially when we do transit spectroscopy studies, because unmodelled granulation can systematically bias planet radius measurements >

Subrahmanyan: That link between stellar physics and exoplanet characterization is important; improved constraints on three dee models translate directly into better 1D stellar structure model grids that we use for studying stellar populations > <ref:2610.30594#pg1>

Vera: And then there’s the point about the wavelength dependence of oscillations being critical for estimating those yields from future space-based missions, which supports those predictions and lets us look at variations in those yields due to astrophysical effects >

Jocelyn: So, overall, this paper shows that we can see solar-like oscillations and granulation at infrared wavelengths for the first time using JWST data on WASP-one hundred twenty-one <ref:2610.30594#pg1,solar-like oscillations and granulation at infrared wavelengths>. This confirms stellar models' predictions about how these features change with wavelength but in a way that’s more detailed than just simple blackbody scaling >

Subrahmanyan: It essentially validates the assumptions we made when predicting those yields for future missions, and it opens up opportunities to analyze variations in those yields caused by astrophysical effects > This paper, "Detection of Solar-like Oscillations and Granulation at Infrared Wavelengths using JWST," shows that solar-like oscillations and granulation are key probes of stellar convection, but usually we only see them in optical light.

Vera: The thesis here is that this paper presents the first detection of these solar-like oscillations and granulation at infrared wavelengths using JWST time-series observations of the star WASP-one hundred twenty-one which is an F6V main-sequence star used to study an exoplanet atmosphere <ref:2610.30594#pg1,solar-like oscillations and granulation at infrared wavelengths using JWST>.

Jocelyn: Exactly. The thesis here is that this paper presents the first detection of solar-like oscillations and granulation at infrared wavelengths using JWST time-series observations of the star WASP-one hundred twenty-one which is an F6V main-sequence star used to study an exoplanet atmosphere <ref:2610.30594#pg1,detection of solar-like oscillations and granulation at infrared wavelengths using JWST>.

Conclusion: Vera: So, we’ve been talking about how JWST saw solar-like oscillations and granulation in infrared light for the first time on WASP-one hundred twenty-one.

Jocelyn: Yeah, and this paper is titled "Detection of Solar-like Oscillations and Granulation at Infrared Wavelengths using JWST." The authors are looking at that same star.

Subrahmanyan: It’s about how you can probe the convection happening inside a star by looking at its surface variations across different wavelengths.

Vera: Basically, they found that the way these oscillations and granulation change with wavelength isn't just like a simple blackbody prediction would say it should be.

Jocelyn: That deviation is actually important because it gives us a better way to test those complex three dee convection models that we have for stars.

Subrahmanyan: And this opens up the possibility of combining stellar data with exoplanet data when looking through JWST passbands, which is a neat way to get more info on planets.

Vera: It also supports what we predicted about how those oscillations scale in infrared time-domain data that the Roman Space Telescope will soon be getting.

Jocelyn: It’s showing us that the infrared is a really useful window for seeing these near-surface physics happening on stars like WASP-one hundred twenty-one.

Subrahmanyan: It means we can get better constraints on those three dee models, which then helps us build better grids for studying other stellar populations.

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