arXiv subjects

Jordan Philidet

Publications and source records attributed to Jordan Philidet.

4 recordsLinked to original sources

arXiv2026

Assessment of PLATO Science Performance

The PLATO mission is scheduled for launch early 2027. In this paper we present an overview of the performance drivers for the mission at the time where all flight models of the cameras have been tested and integrated on the optical bench. The PLATO consortium needs an estimate of the planet detection yield to dimension the ground-based radial velocity follow-up resources. We provide updated estimates on the yield of planet detections that can be expected from the mission under certain assumptions. As of today, large uncertainties remain on the planet occurrence rates, especially for small planets in long-period orbits, and on our ability to detect these planets in the presence of stellar variability and instrumental noise. To partially overcome these limitations, we compare results using different planet occurrence rates, detectability rates, and we include an estimate on the expected contribution of stellar variability to the noise budget. The final detection yield of PLATO will provide constraints to planet occurrence rates which in turn will help constraining planet formation models.

astro-ph.EP↗

arXiv2026

Temporal variations of solar inertial mode parameters from GONG (2002-2024) and HMI (2010-2024): Rossby modes ($3 \leq m \leq 16 $) and $m=1$ high-latitude mode

We studied the temporal evolution of solar inertial modes over the solar cycle using observations from GONG and SDO/HMI. We focused on the high-latitude mode with azimuthal wavenumber $m=1$ and the equatorial Rossby modes with $3 \le m \le 16$. We used horizontal flow maps near the solar surface from GONG and HMI ring-diagram pipelines at a cadence of approximately one day, covering the period 2002-2024. The data were divided into overlapping 4-year windows, with central times separated by six months. Within each time window and for each inertial mode, we measured the frequency and power of the mode from GONG and HMI data. We find good agreement between GONG and HMI measurements throughout their overlapping period from 2010 to 2024. In general, the magnitude of the frequency variations increases with increasing $m$, and relative changes in mode power typically exceed 100%. For the $m=1$ high-latitude mode, the measured power is anticorrelated with the sunspot number (SSN), while its frequency shows no significant temporal variation. For the equatorial Rossby modes, the frequencies are generally anticorrelated with the SSN, whereas the mode powers tend to correlate positively with the SSN. An exception is the $m=3$ equatorial Rossby mode, whose mode power is strongly anticorrelated with the SSN, in contrast to the other equatorial Rossby modes, highlighting its distinct behavior. We find that the frequencies and power of the Sun's inertial modes have varied significantly on solar-cycle timescales over the past 23 years. The mode parameters are however not uniformly synchronized with the SSN; variations are observed both between modes and from one solar cycle to the next, with some of the differences likely reflecting observational uncertainties. The sensitivity of inertial modes to solar-cycle changes indicates their potential as a diagnostic of solar interior dynamics and magnetism.

astro-ph.SR↗

arXiv2024

Solar Inertial Modes

The Sun's global inertial modes are very sensitive to the solar differential rotation and to properties of the deep solar convection zone which are currently poorly constrained. These properties include the superadiabatic temperature gradient, the latitudinal entropy gradient, and the turbulent viscosity. The inertial modes also play a key role in controlling the Sun's large-scale structure and dynamics, in particular the solar differential rotation. This paper summarizes recent observations and advances in the (linear and nonlinear) modeling of the solar inertial modes.

astro-ph.SR↗

arXiv2024

Temporal Variation of Solar Equatorial Rossby Modes with Azimuthal Orders $6\leq m \leq 10$

We use nearly two decades of helioseismic data obtained from the GONG (2002-2020) and HMI (2010-2020) ring-diagram pipelines to examine the temporal variations of the properties of individual equatorial Rossby modes with azimuthal orders in the range $6 \le m \le 10$. We find that the mode parameters obtained from GONG and HMI are consistent during the data overlapping period of 2010-2020. The power and the frequency of each mode exhibit significant temporal variations over the full observing period. Using the GONG data during solar cycles 23 and 24, we find that the mode power averaged over $6 \le m \le 10$ shows a positive correlation with the sunspot number ($0.42$), while the averaged frequency shift is anti-correlated ($-0.91$). The anti-correlation between the average mode power and frequency shift is $-0.44$.

astro-ph.SR↗