Summer 2021, Toulouse, France

The "Cambridge Workshops of Cool Stars, Stellar Systems and the Sun" are held biennially and have evolved to be the premier conference series for cool star research.

Dear Colleagues,

We regret to announce that the Cool Stars, Stellar Systems, and the Sun 21st Conference, originally planned to be held on June 22-26, 2020, in Toulouse, France, has to be postponed due to the current Covid-19 pandemic. The decision was discussed within the SOC and LOC, and agreed by all members of the organizing committees. We plan to reschedule CS21 in Summer 2021.

Preliminary dates (tbc) for CS21 would be 5-9 July 2021, at the same location in Toulouse, France. We foresee that the program that was designed for CS21 this year, including the planned invited talks and the scheduled splinter sessions, will still be largely relevant next year, unless other hot topics emerge till then. We will continue to provide updated information on the current CS21 website.

As chairs of the SOC and LOC, we would like to express our gratitude to all the members of the organizing committees, especially to the members of the LOC for the efforts they deployed in this uncertain context. We extend our thanks to the chairs of the proposed Splinter sessions, to the speakers who accepted our invitation for the plenary sessions, and to all of you who had registered for the conference.

Take care, and we hope to see you next year!

S. Brun, J. Bouvier, P. Petit

Splinter sessions

Splinter sessions are going to be held on Monday, Tuesday, and Thursday afternoon. There will be three splinter sessions in paralell. These sessions are organized separately from the main conference. Each splinter session has its own website with contact information for contributors. The websites are linked from the splinter session title in the list below when available. Splinter session organizers can set their own deadlines for contributions to their sessions. Typically the deadlines will be in May.

For reference: Splinter session proposals

Splinter sessions were solicited from the community in January 2020. This process is now closed, but the original solicitation can be found below for reference.

The CS21 SOC invites the community to propose splinter sessions on current hot topics. Proposals for splinter sessions can be made by individuals or groups of individuals. At this time, we are planning on 9 splinter sessions of 180 minutes each to be accommodated in our schedule. The splinter organizers will have access to abstracts of potential contributions submitted on the abstract form.

Splinter organizers should be prepared to produce and maintain a website that includes the schedule and speakers, and describes opportunities for people to participate in the session. The splinter websites will be linked from the main CS21 website, so all meeting participants are aware of the splinter sessions and can make informed choices about which sessions they wish to attend. A complete program for each splinter should be online six weeks prior to the meeting, that is by May 8th, 2020 - and hopefully earlier.

Any splinter session proposal should include the following:

  1. Title
  2. Names of the session organizers with primary contact information; names of co-organizers if appropriate
  3. Two page summary of the goal of the session, including discussion on why this is a timely and relevant topic for CS21
  4. List of potential speakers, and a plan for how additional speakers will be solicited (Note that CS21 follows a "one person - one talk" rule. Plenary speakers cannot give a talk in a splinter session, nor can one person talk in more than one splinters session.)
  5. Proposed Splinter format that includes a description on how the audience will be involved
  6. Commitment to set up a website in support of the splinter, with a complete program online by May 8th, 2020
  7. Commitment to contribute a summary of the session for the proceedings

Deadline for splinter session proposals is December 9, 2019. Please submit proposals by mailing a plain text file to with the subject line 'Splinter Session Proposal'.

We plan to announce accepted splinter sessions by January, 15th 2020, and will provide links to your splinter session website for attendees to submit contributions to your splinter as soon as possible.

Please do not propose splinters that are too similar to the 5 main morning sessions (see the conference program) if you wish to maximise your chances of success.