Periodic Reporting for period 2 - ISSP (Interferometric Survey of Stellar Parameters)
Reporting period: 2023-03-01 to 2024-08-31
The ISSP project aims at building a new catalog of stellar fundamental parameters, based on interferometric measurements, and complemented by archive data. This unique and homogeneous catalog will also a direct understanding of the parameters of planets orbiting around stars. It will also help to understand the complementarity between direct measurements by interferometry and stellar parameters deduced from seismic data. Moreover, the large coverage of this catalog will allow an extrapolation to much fainter stars thanks to empirical relations like Surface Brightness Color. As such it will cover the fundamental questions of planets around stars and of the distance in the Universe. To avoid any potential bias in these determinations, this survey includes programs on variables stars, like binary systems, fast rotators, and stars surrounded by environments or winds. This will allow to understand the consequences of the activity of stars on their fundamental properties.
This project is based on the installation and operation of a new visible interferometric instrument (SPICA-VIS) on the CHARA Array at Mount Wilson (California), assisted by a near-infrared fringe tracker (SPICA-FT) aiming at pushing the performance for the completion of the survey. The survey benefits from a dedicated access to the CHARA Array thanks to an allocation of 200 nights of observations over the duration of the ERC grant.
Thanks to the unique performance of the instrument in terms of angular resolution and of sensibility, this is a totally unique opportunity to bring, to the worldwide astronomical community, a new vision on the fundamental parameters of stars. This project contributes to the overall progress in the knowledge of the Universe and as such contributes to the progress of the knowledge of the humankind. The bridges between our project and the ESA/PLATO space mission (stars and planets) on one hand, and with the ARAUCARIA project on the other hand for the question of the distance in the Universe, have been strongly reinforced.
This project is based on the installation and operation of a new visible interferometric instrument (SPICA-VIS) on the CHARA Array at Mount Wilson (California), assisted by a near-infrared fringe tracker (SPICA-FT) aiming at pushing the performance for the completion of the survey. The survey benefits from a dedicated access to the CHARA Array thanks to an allocation of 200 nights of observations over the duration of the ERC grant.
Thanks to the unique performance of the instrument in terms of angular resolution and of sensibility, this is a totally unique opportunity to bring, to the worldwide astronomical community, a new vision on the fundamental parameters of stars. This project contributes to the overall progress in the knowledge of the Universe and as such contributes to the progress of the knowledge of the humankind. The bridges between our project and the ESA/PLATO space mission (stars and planets) on one hand, and with the ARAUCARIA project on the other hand for the question of the distance in the Universe, have been strongly reinforced.
During the first 9 months of the project (T0-T0+8), the work has been split into 1/ the preparation of the instrument in Nice and then in Mount Wilson, its shipping and its integration in the focal laboratory of the CHARA Array; 2/ the preparation of the tools required to correctly manage the survey; 3/ the detailed definition of the science objectives and the creation of the list of targets for the different sub programs; and 4/ the preparation of the data pipeline and the optimization of the performance.
The following year (T0+9-T0+20) started with the preparation of the recruitment of the team members, the improvement of the performance of the instrument, and the first observations. With the completion of the team, we started elaborating the strategy for the science analysis and we improved our control of the various tools necessary for managing the survey and for analyzing the data of the instrument.
Finally, during the last 9 months (T0+21-T0+30), we progressed a lot in the understanding of the difficulties of the instrument (mainly due to the CHARA Array in fact), we produced the first science results based on the SPICA instrument and on the infrared ones (MIRCX/MYSTIC) and we obtained also our first successful operation of the fringe tracker in the near infrared. The different tools for organizing the ISSP Science Catalog have been defined and the development by the team is well advanced.
The following year (T0+9-T0+20) started with the preparation of the recruitment of the team members, the improvement of the performance of the instrument, and the first observations. With the completion of the team, we started elaborating the strategy for the science analysis and we improved our control of the various tools necessary for managing the survey and for analyzing the data of the instrument.
Finally, during the last 9 months (T0+21-T0+30), we progressed a lot in the understanding of the difficulties of the instrument (mainly due to the CHARA Array in fact), we produced the first science results based on the SPICA instrument and on the infrared ones (MIRCX/MYSTIC) and we obtained also our first successful operation of the fringe tracker in the near infrared. The different tools for organizing the ISSP Science Catalog have been defined and the development by the team is well advanced.
The main achievements of this period have been, first the successful operation of the CHARA/SPICA instrument in parallel to the infrared instruments. This has permitted to solve most of the interface with the interferometric infrastructure and to reach the goal of a successful combination in the visible wavelengths of 6 telescopes distributed over the Mount Wilson with distances from 30 to 330m, giving us access to the unprecedented angular resolution of 0.1 milliseconds of arc. Moreover, this achievement was made by operating simultaneously three instruments, SPICA in the R band, and the two infrared instruments, MIRCX in the H band, and MYSTIC in the K band. This achievement is a worldwide record obtained by the team in collaboration with the CHARA group.
The expected results until the end of the project are now to complete our stellar survey and to achieve the expected performance in terms of sensitivity and precision. We have built all the tools and have acquired an excellent experience in identifying the complementary data that will be necessary for the final analysis.
The expected results until the end of the project are now to complete our stellar survey and to achieve the expected performance in terms of sensitivity and precision. We have built all the tools and have acquired an excellent experience in identifying the complementary data that will be necessary for the final analysis.