Letters of Intent received in 2020

LoI 2022-2123
At the cross-roads of astrophysics and cosmology: Period--luminosity relations in the 2020s

Date: 25 April 2022 to 29 April 2022
Location: Budapest, Danubius Hotel Helia ****, Hungary
Contact: Richard de Grijs (richard.de-grijs@mq.edu.au)
Coordinating division: Division G Stars and Stellar Physics
Other divisions: Division C Education, Outreach and Heritage
Division H Interstellar Matter and Local Universe
Division J Galaxies and Cosmology
Co-Chairs of SOC: Richard de Grijs (Macquarie University)
László Kiss (Konkoly Observatory)
Co-Chairs of LOC: Róbert Szabó (Konkoly Observatory)
Édua Karajos (Konkoly Observatory)
László Kiss (Konkoly Observatory)



- Stellar variability
- Pulsation physics
- Stellar structure and atmospheric dynamics
- Cosmic distance scale
- Hubble parameter
- Gaia, JWST, Vera Rubin Observatory, ground-based time-domain surveys (VISTA, PanStarrs, etc.)



(Abstract) The period–luminosity relation (PLR) is an important relationship between the fundamental physical properties of a diverse range of variable stars. Most recognizable is the PLR of Cepheids, which renders classical Cepheids primary distance indicators, thus establishing the traditional cosmic distance scale. In addition, tight and well-defined relationships also exist between the periods and luminosities of other pulsating stars, including RR Lyrae-type variables, Type II and anomalous Cepheids, δ Scuti-type pulsators, and Mira variables. Curiously, not only pulsating stars exhibit PLRs: well-defined, long-established relation-ships between (orbital) periods and luminosities also exist for contact binaries of W Ursa Majoris (EW) type. The ultimate goal of the proposed Symposium is to discuss recent results—both observational and theoretical—achieved by the continued scrutiny of the detailed characteristics of the PLR, including its shape, calibration, and dependence on stellar parameters and chemical abundances; intrinsic PLR widths may offer unique insights into the physical processes shaping these relations and the underlying physical properties of the stars contributing to these relationships (stellar structure, atmospheric parameters, pulsation properties). This topic is very timely, given the wealth of empirical data recently obtained using state-of-the-art ground and space-based facilities, high-impact Gaia data releases, the impending operations of the James Webb Space Telescope, and—on slightly longer timescales—the next-generation ground- and space-based observatories (E-ELT, TMT, GMT, Plato).

(The full rationale will be included in our final submission.)