This webpage is a work in progress
| The PLATO mission is scheduled for launch in December 2026. It is an ESA M-class mission designed to find small planets around bright stars via the transit technique. The light curves it obtains will be wonderful for other science goals, among which is the study of binary and multiple stars. We have created a Multiple Star Working Group (MSWG) to bring together the community to best exploit this unique opportunity. This webpage introduces PLATO and the MSWG, and will fill out with useful information over time. |
PLATO (Planetary Transits and Oscillations of Stars) was selected by ESA in 2014 as a mission to search for small transiting extrasolar planets (Rauer et al. 2025). Its baseline aim is to to detect a 1-Earth-radius planet orbiting in the habitable zone of a G0 V star of magnitude V = 10, and to determine the planetary radius to 3% and system age to 10%. The planet detection and characterisation will be performed using the transits, and the age determination will be obtained from asteroseismology.
PLATO will consist of one spacecraft hosting 26 cameras, of two types. The main scientific instruments are 24 "normal" cameras (N-CAM), each of which will have a 12-cm entrance pupil and a 4510×4510 pixel CCD. Each will have a field of view of 1037 square degrees with a sampling of 15 arcsec per pixel, and will observe in a red passband (500-1000 nm). The other cameras are two fast cameras (F-CAM) which will be used for fine-pointing of the satellite and may also be available for high-speed observations. They have smaller fields of view (610 square degrees) and different passbands to the science instruments (505-700 nm for the blue and 665-1000 nm for the red camera).
PLATO is scheduled for launch in December 2026, and will take approximately 90 days to move to the second Lagrangian point in the Earth-Sun system. Its observations will be divided into 90-day segments between which the satellite will rotate by 90 degrees to keep its solar panels illuminated by the Sun. The baseline duration of the mission is four years, of which at least the first two years will be used to observe the LOPS2 field in the southern hemisphere (Nascimbeni et al. 2025). The spacecraft will hold consumables to last 8.5 years and the strategy for the remainder of the mission will be decided after observations of LOPS2 have commenced.
A set of PLATO Complementary Science Work Packages have been formed to aid the organisation of all scientific areas which will benefit from the availability of PLATO data but do not contribute to the core science goals. The Complementary Science Work Packages include binary and multiple stars, stellar pulsation and rotation, mass loss, debris discs, galactic structure and transient phenomena, and are co-ordinated by Conny Aerts and Andrew Tkachenko.
The Complementary Science teams will submit applications for PLATO data using the same Guest Observer (GO) mechanism as other scientists, and will have no influence on the observing strategy for PLATO. The GO programme has been allocated 8% of the PLATO data rate (averaged over each field observed). The call for proposals is expected nine months before launch, which means approximately March 2026.
Complementary Science Work Package 161000, led by John Southworth, deals with binary and multiple stars. Our task is to co-ordinate target selection, GO applications and scientific work within the community. This will be done by forming a PLATO Multiple Star Working Group (MSWG) which all members of the scientific community with suitable research interests can join. The current webpage is the first online documentation of this work.
The first goal of the MSWG will be to compile a White Paper detailing our work and thoroughly discussing the science cases which we can address. This will provide valuable support to the GO applications and help ensure everyone who is interested gets a chance to be involved.
The second goal of the MSWG will be to co-ordinate the GO applications for binary and multiple stars. We envisage separate applications for each main science case, but this is up for discussion. The applications should be coherent, include everyone who wants to be involved, and preferably avoid competing with each other.
PLATO is expected to produce light curves of extremely high quality, thus continuing the revolution within the field of binary and multiple stars triggered by CoRoT, Kepler and TESS. The combined differential photometric precision (CDPP) over two hours is less than 100 ppm for stars brighter than TESS magnitude 12. This is substantially better than TESS – and comparable to Kepler but over a much larger field of view – in order to satisfy the scientific requirements. These data will be useful for a huge range of science cases including, but not limited to:
Many of these activities, in turn, are valuable for furthering the knowledge of the structure and evolution of stars, by constraining phenomena such as convective mixing, tidal effects, angular momentum transport, magnetic activity, and the evolution of binary and mutiple star systems.
Anyone interested in joining the PLATO MSWG and helping with this work can contact the PLATO MSWG at the email address platomswg@gmail.com. Please provide a brief statement of your science interests and how you would like to contribute. The MSWG was formally launched with a conference proceedings on 2025/01/30 and will be organised via this webpage, teleconferences, in-person meetings, and the white paper mentioned above.
John Southworth has a list of people who, over the years, have expressed an interest in joining this work. If you are on this list you will be contacted directly, but can also renew your interest via the email address above.
We are holding a conference at Keele University from 30th June to 4th July this year (2025): Binary Stars in the Space Era. The conference aims to showcase work on binary star systems, and plan for the future particularly in terms of what PLATO and Gaia will provide. All welcome (limited to 90 people due to room capacity).
The conference webpage is available by clicking here.
Possible target stars for the MSWG will come from a variety of sources, and some will be characterised in detail in advance. These sources and analyses include (in no particular order at present):
Some targets have already been selected for observation via the PLATO scvPIC and WP 125500 activities. These can be included in GO applications but it is wise to avoid duplication. The proprietary period will also differ for objects in the scvPIC and WP 125500 samples.
Last modified: 2025/02/28 John Southworth (Keele University, UK)