This ISSI-Team project concerns the research field of stellar spectroscopy in the context of Galactic and extragalactic Archaeology with particular regard to the preparation of libraries of stellar spectra for the future.
 

Libraries of stellar spectra reside at the crossroad of many different fields of astrophysics. On the one hand they serve as a basis for the classification and automatic analyses of stellar parameters that are being derived from on-going and future large stellar spectroscopic surveys. On the other hand, they are the fundamental ingredients for models of stellar populations that are used to study the evolution of galaxies in the Universe.
 

Because of their importance, there is a vast variety of libraries available in the astronomy market. They may consist of either observed or theoretical spectra, and they can vary by their spectral coverage, resolution and flux definition. We propose to perform a thorough comparative study with the goal to answer two main questions:
 

Question 1: What is the limit in stellar parameter accuracies that can be derived from current libraries and how do the newest data from astrometric and astroseismic space missions help to improve these accuracies?

Question 2: What are the key gaps in the libraries that need to be filled in order to increase their impact on the future of Galactic and extragalactic astronomy?
 

The identification of these questions and determining their answers became of primary importance during the 3rd International Workshop on Stellar Spectral Libraries (IWSSL) held in Brazil in February 2017, which many of the members of this proposed team participated as either part of the scientific organising committee or as speakers.
 

Due to these triennial workshops an international and interdisciplinary community is arising in which experts in stellar and galactic astrophysics are concerned about the same issues regarding our understanding about stars. But it is just now that a vast amount of data is available to us, due primarily to the first data releases of the Gaia space mission and its complementary spectroscopic and seismic surveys, that such questions have the potential to be answered in depth.
 

We will have focussed ISSI-team meetings with core members of this new community prior to the 4th IWSSL workshop, scheduled for 2020 in China. These meetings have the potential to have a significant impact on the progress of assessing and answering these key questions for the future. Holding the ISSI-team meetings in Beijing will facilitate us to have the next host of the 2020 IWSSL workshop involved in this project, in particular Y. Wu and J. Shi. The first ISSI-team meeting will focus on answering Question 1, while the second one will be dedicated to answering Question 2.