Seismology of bright stars (SONG and TESS)

Call year
Pere Lluís
Pallé Manzano
Amount granted to the IAC Consortium
55.660,00 €

Main objective of this project is to maximize the scientific exploitation of the unique capabilities of SONG (Stellar Observations Network Group) high-precision radial velocity measurements and flexibility to execute robotic observations over long periods of time- on scientific programs up to now not achievable with any other space or ground based facilities.

One of such programs is the characterizations of oscillation modes in bright stars (mv< 5) at different evolutionary stages (Main Sequence and Red Giants branch) and with different physical characteristics (spectral type F to K). This program could neither be performed from space missions (photometry) as CoROT and Kepler because of the saturation limit of their detectors at magnitudes lower than ~5 nor from ground-based facilities because of the photometry requirements and the lack of high-stability spectrographs devoted to these long and continuous asteroseismology programs. Thus, there is a scientific niche in which SONG fits perfectly. In fact, the first year of successful operations with the first node of the network already demonstrated the ability to derive global stellar parameters of some selected targets (μHer, gamCeph, ßVir y 46LMi) directly inferred from the spectrum of global oscillation modes.

In addition, a novel program aimed to study the spectroscopic variability of supergiants O and B stars at time scales from hours to weeks is providing exciting and promising results which deserves deeper investigation and continuity.

The NASA/TESS mission (Transiting Exoplanet Survey Satellite) will offer a unique opportunity concerning the achievements of this proposed project as it will be possible to perform coordinated/simultaneous observations and in any case complementary (SONG: radial velocity, TESS: photometry) - of the same targets (common range of magnitudes 3-6 at both instruments) and over observing periods ranging from a month to one year depending on the targets position. It is really challenging to this project to be prepared for such programs that will require a precise definition of the campaigns an of the targets selection. The forthcoming operation of the second node at the SONG network will provide with observations continuously over more than 17 hours per night. The increase in the duty cycle of the gathered time series will result on a drastic reduction of the contamination in the spectrum of oscillations thus providing a much better characterization of the eigemodes parameters and improve the inferences of the global seismic parameters of the star. Specific tools for treatment of these combined data will be developed, tested and applied along this project.

Finally, a concise plan has been conceived to widen the research field affordable with SONG: the capability to perform routine or sporad

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