Cool Stars 20.5 - virtually cool

March 2-4 2021, virtual meeting

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.

With the ongoing pandemic, the organizers of Cool Stars 21 consider it unlikely we will be able to meet in person in the summer of 2021. This would put a four year gap between our meetings for the first time. Therefore we have decided to hold a virtual conference to keep everyone in our field up to date. But don't worry, we still plan to meet in Toulouse in mid-2022.



Daily synchronous sessions via a Zoom webinar. These sessions will be 3 - 4 hours long (with breaks), and will be held from ~17:00 to 20:00/21:00 UTC. The webinars will be recorded, and uploaded to Youtube.

CET UTC EST Tuesday Wednesday Thursday
02 March 2021 03 March 2021 04 March 2021
Stellar systems, clusters, and associations The Sun and the Heliosphere Post main sequence cool stars
18:00-19:00 17:00-18:00 12:00-13:00 Plenary session Plenary session Plenary session
19:00-19:15 18:00-18:15 13:00-13:15 Plenary session (Haikus) Plenary session (Haikus) Plenary session (Haikus)
19:15-19:45 18:15-18:45 13:15-13:45 Plenary session Plenary session Plenary session
19:45-20:00 18:45-19:00 13:45-14:00 Coffee break + Posters Coffee break + Posters Coffee break + Posters
Young stars The Sun - Very low mass stars Globular clusters and Main Sequence stars
20:00-21:00 19:00-20:00 14:00-15:00 Plenary session Plenary session Plenary session
21:00-21:15 20:00-20:15 15:00-15:15 Plenary session (Haikus) Plenary session (Haikus) Plenary session (Haikus)
21:15-22:00 20:15-21:00 15:15-16:00 Plenary session Plenary session Plenary session
22:00-23:00 21:00-22:00 16:00-17:00 Topical interest room 1, 2, 3 / social meeting Topical interest room 4, 5, 6 / poster session Topical interest room 7, 8, 9

Small changes in scheduling could still happen. Check back here.

Social meeting / poster session

We will host a virtual Social Hour (Tuesday), and a virtual Poster Session (Wednesday) during the Topical Interest Room times (4-5PM EST). These events will be hosted using Gather.Town, a virtual environment that runs in your web browser with a 90’s video game feel. The link to join will be circulated to registered attendees. Gather.Town allows attendees to walk around, play games, and video chat with those nearby. We’ve found this platform is fun, easy to use, and helps capture some of the magic of “bumping into colleagues” that we all miss! See the poster page for details on the poster session.

Talks on Tuesday

Invited talks are 24 + 6 min, contributed talks 12 + 3 min. See above for the timing of haiku sessions and coffee breaks.

Talks on Wednesday

Invited talks are 24 + 6 min, contributed talks 12 + 3 min. See above for the timing of haiku sessions and coffee breaks.

Talks on Thursday

Invited talks are 24 + 6 min, contributed talks 12 + 3 min. See above for the timing of haiku sessions and coffee breaks.

Haikus on Tuesday

Haikus on Wednesday

Haikus on Thursday

Topical interest rooms

To facilitate collaboration on subjects of common interest we plan to host a number of "topical interest rooms" for about an hour at the end of each day's session. Unlike "Splinter sessions" in traditional Cool Stars conferences, a "topical interest room" does not have a list of speakers or presentations, but just a minimal agenda with maybe 3-5 subtopics to discuss. Anybody is free to share slides and data in a working group format. Possible discussion topics should be broad enough to be of general interest and narrow enough that a science goal could be effectively discussed in no more than one hour.

Zoom links will be included in email to registered participants.


Accretion onto T Tauri Stars - Discussion led by Espaillat

  • How does the accretion flow and shock depend on the accretion rate and magnetic structures?
  • What is the connection between accretion and the properties of the star?
  • What do we know about accretion from X-ray, UV, and optical data?

Solar/Stellar Cycles - Discussion led by Kosovichev, Lehmann and Jeffers

  • How does study of the Sun-as-a-star inform us about dynamics and activity?
  • What are the common characteristics for stars showing solar-like or non solar-like activity cycles?
  • How do observed properties of global oscillations and their variations reflect solar and stellar magnetic activity?
  • Are the historical active and inactive branches just an effect of stellar rotation where the active branch stars are fast rotators?

Brown Dwarf Modeling - Discussion led by Rickman

  • What discrepancies exist between observed atmospheric spectra and models of brown dwarfs?
  • What observations are required going forward to eliminate or address discrepancies between observed atmospheric spectra and models?
  • What discrepancies exist between observed properties of brown dwarfs (i.e. mass and age) and evolutionary models?
  • How can we address discrepancies in evolutionary models of brown dwarfs using benchmark objects?


Job Fair - Discussion led by Wolk

This is for people with open positions to describe them additional conversations suggested in slack If any one has a job to offer Let us know by email to

Ready to revive the radio star? Toward SKA/ngVLA - Discussion led by Forbrich

  • Which radio emission mechanisms operate in cool stars, how can they be disentangled, and which physical diagnostics do they provide?
  • What are the emerging synergies both within meter-to-millimeter radio astronomy and in a multi-wavelength context (particularly with X-rays)?
  • What is the role of radio observations in constraining star planet interaction and protoplanetary disk irradiation?
  • vWhat is the current outlook for SKA and ngVLA, and what preparatory theory/simulation work is needed?

Solar/Stellar Hydrodynamics/MHD simulation. - Discussion led by Pratt and Brun

  • What are the present limitations in simulating cool stars?
  • How does a star's effective temperature impact on these limitations?


Cool Star Science with the Rubin Observatory - Discussion led by Bonito

  • Transients and Variable Stars with Rubin LSST data
  • International collaborations in Rubin LSST
  • Observing strategy & Rubin Science Platform
  • Justice, Equity, Diversity, and Inclusion in Rubin

Solar/Stellar Activity and the local environments - Discussion led by Nandi, Ruediger and Valio

    How does the activity of solar-like stars evolve over their life-time?
  • How can a large-ensemble statistic of superflares be projected to infer the long-term history of a single star (e.g., the Sun)?
  • What is the impact of extreme events such as stellar flares and mass ejections on (exo)-planetary atmospheres?
  • How do stellar activity influence (exo)-planetary atmospheres over evolutionary timescales?

Evolved Cool stars -led by Humphreys and Creech-Eakman

  • Origin of mass loss in red supergiants
  • Evidence for Surface and Convective Activity
  • How high-resolution spectroscopy and imaging can be used to improve our understanding of pulsation and mass-loss for late stages of evolution.
  • What can the community do to improve pulsational sampling for the variables?