AO-1 Programmes - Abstracts of Awarded Programmes

Probing Low-Amplitude and Long-Term Variability in Cepheid Pulsators - Proposal 5, Plachy (HU)

Cepheids are among the most important pulsating stars in astrophysics, providing key constraints on stellar structure and evolution, as well as serving as fundamental distance indicators. A variety of low-amplitude and long-term variability has been identified in Cepheids, including additional periodicities, amplitude and phase modulation, period doubling, irregular period changes, and signatures of binarity. While current observations suggest that some of these phenomena are common, others appear to be rare, and many still lack a convincing physical interpretation. Their detailed properties also remain largely unexplored, as existing data have not yet provided the sensitivity and time-domain coverage needed to detect lower-amplitude signals and resolve their temporal behavior. We propose to exploit PLATO’s unique capabilities to investigate these effects in a carefully selected sample of 840 Cepheid variables spanning multiple pulsation subtypes in the Galactic plane and the Large Magellanic Cloud Using long-cadence on-board light-curve products, we will systematically search for and characterize sub-millimagnitude additional modes, amplitude and phase modulation, and non-evolutionary period changes. These observations will provide new constraints on pulsation physics, nonlinear stellar dynamics, stellar evolution, and binary properties across the Cepheid family.

Constraining interior rotation and mixing from stochastic low-frequency variability in massive stars - Proposal 21, Van Daele (UK)

Massive stars are the progenitors of neutron stars and black holes and play a crucial role in shaping the chemical and radiative feedback of entire galaxies through their winds and explosive deaths as supernovae. Convective regions in massive stars excite internal gravity waves (IGWs), which facilitate efficient chemical mixing and angular momentum transport; both are important physical processes for a massive star’s evolution, but remain largely uncalibrated in stellar evolution models. It has recently been established that the vast majority of massive stars exhibit stochastic low-frequency (SLF) variability, which can be explained by the presence of IGWs that are stochastically excited at the turbulent interface of convective and radiative regions. This proposal requests PLATO light curves of 936 high-probability candidate SLF variable stars, to map SLF morphology of massive stars across different masses, rotation rates and evolutionary stages. While previous missions severely limited analysis with short observation duration and slow cadences, new PLATO light curves will ultimately reveal mixing properties and angular momentum transport in massive stars by comparing to 3D (M)HD simulations of massive star interiors. New PLATO data of this unique sample thus opens a new window for probing the interiors of massive stars and hence improves stellar evolution models.

Asteroseismology of white dwarfs in the era of PLATO - Proposal 34, Uzundag (BE)

White dwarfs, the final evolutionary stage of most stars, are powerful probes of stellar evolution, Galactic populations, planetary system evolution, and fundamental physics. Their pulsations provide a unique opportunity to directly probe their internal structure through asteroseismology, enabling constraints on core composition, chemical stratification, rotation, crystallization, and cooling processes inaccessible from spectroscopy alone. Despite major advances from space missions such as Kepler and TESS, many key questions remain unresolved. Most known pulsating white dwarfs exhibit only a limited number of detected modes, preventing robust seismic inferences, while discrepancies between theoretical instability strips and observations point to incomplete understanding of mode excitation, diffusion, and convective mixing. In addition, significant tensions remain between spectroscopic, astrometric, photometric, and asteroseismic mass determinations. PLATO will provide long-duration, homogeneous, high-precision photometry for large samples of compact pulsators, enabling the detection of richer mode spectra, rotational multiplets, and low-amplitude variability across a broad range of white dwarf classes. Combined with coordinated spectroscopic follow-up, these observations will enable population-level asteroseismic studies and place stringent constraints on white dwarf internal structure, evolution, and cooling.

Identifying binary interaction products using asteroseismology - Proposal 39, Henneco (UK)

Thanks to space-based asteroseismic observations over the past decades, we have been able to constrain some of the interior physics of massive stars while also uncovering remaining unknowns, such as mixing and angular momentum transport. Further improvements in the structure and evolution theory of massive stars have been hampered by the limited number of seismic datasets with sufficiently long observational baselines. A major additional complication is that massive stars almost exclusively live in binary systems. Various binary interactions, such as mass transfer and tides, considerably alter the structure and subsequent evolution of the mass-losing donor and mass-gaining accretor stars. Moreover, a significant fraction of binary systems reach contact configurations and merge into a single star. With a sample of ~410 PLATO targets in a mass range for which only a handful (< 50) of high-quality, long-baseline seismic datasets currently exist, we can identify and characterise binary interaction products and construct a first-of-its-kind catalogue. To do so, we are supported by the latest theoretical predictions for the asteroseismic fingerprints of accretion and merging. Such a catalogue will allow us to drastically improve our understanding of binary and single-star physics, solidify our tools for separating genuine single stars from binary-interaction products, and allow for robust statistical analysis.

Planetary debris transiting white dwarfs - Proposal 64, Williams (UK)

Almost all known planet hosts will evolve into white dwarfs, and material orbiting beyond 1AU will survive. During the white dwarf phase, asteroids can get perturbed towards the inner system and are disrupted, forming a circumstellar debris disk which is gradually accreted. Although hundreds of white dwarfs exhibit atmospheric metal enrichment, the debris disks are much less well characterised. In some cases, debris transits the white dwarf. Such transits often reach depths of tens of percent, enabling us to detect transits at fainter objects. The current transiting debris population shows a great diversity, with transits from multiple objects, evolving over timescales of days to years, and periods spanning two orders of magnitude. PLATO is uniquely capable of discovering and characterising new transiting systems. With uninterrupted coverage across two years enabled by PLATO, we will be sensitive to transiting debris with long periods and we can track the evolution of transit periods, shapes, depths, and activity over many events. We will characterise the population and measure an unbiased occurrence rate for transiting debris. Any transiting system will be perfect for photometric and spectroscopic follow-up but the discovery of new systems would be impactful. We will also be sensitive to any intact terrestrial and giant planets transiting in front of the Earth-sized white dwarfs, thus adding to the currently sparse white dwarf planet population.

The relationship between magnetism and pulsations in classical pulsators - Proposal 67, Thomson-Paressant (UK)

Magnetic fields and stellar pulsations are both fundamental probes of stellar interiors, yet their interplay remains poorly understood. In particular, strong large-scale magnetic fields are expected to modify the excitation, damping, and frequency structure of pulsation modes in hot stars, but observational constraints remain limited. We propose a magneto-asteroseismic study of pulsating OBAF stars using long-duration, high-precision photometry from ESA's PLATO mission to complement pre-existing spectropolarimetric observations. Our sample includes both magnetic and non-magnetic pulsators spanning a wide range of masses and temperatures across the classical instability strips. By comparing their pulsation spectra, mode content, amplitudes, and asymmetries, we aim to directly quantify how magnetic fields influence pulsation driving and internal stellar structure. Forward asteroseismic modelling will provide constraints on magnetic field geometry both internally and externally, and excitation mechanisms for pulsation. This program will establish the first statistical framework for studying the impact of magnetism on pulsations across the hot-star regime and provide new observational tests for stellar evolution theory.

Confirming Long-Period Transiting Giants - Proposal 72, Bryant (UK)

Transiting exoplanets provide unparalleled windows into understanding the compositions and histories of exoplanets. Through a combination of photometric and spectroscopic observations we can obtain precise measurements of the interior structure and atmospheric composition of a transiting exoplanet. Understanding the composition of an exoplanet in this way provides important clues into the formation and migration history of the planet. However, the majority of the known transiting exoplanets orbit very closely to their host star - within 1 AU - and so are subject to direct stellar influence through intense irradiation and strong tidal interactions. These stellar influences act to erase the observable imprints of the formation and evolution of the planet. To properly understand the formation and migration history of exoplanets we need a large sample of transiting exoplanets that are well separated from their host stars. We propose to observe a sample of 133 stars that likely host long period planets, detected as either mono- or duo-transit candidates by TESS. The PLATO mission is the only mission that can efficiently detect additional transit events of these planets to confirm their orbital periods. We will also use the PLATO observations to search for additional transiting planets orbiting these stars as well as non-transiting planets revealed by transit timing variations. This programme will dramatically increase the population of known long period transiting exoplanets.

Shadows in the cave: Synoptic Survey of Cataclysmic Variables in PLATO - Proposal 78, Veresvarska (ES)

Accreting white dwarfs (AWDs) in cataclysmic variables (CVs) are the most accessible laboratories for accretion physics, exhibiting variability encoding physical processes from the outer disc to the white dwarf surface. We propose to monitor 36 AWDs in the PLATO LOPS2 field for the full two-year mission using 25 s imagettes, addressing five key science questions. First, we will measure for the first time in normal CVs the low-frequency outer-disc PSD break predicted by the propagating fluctuations model — inaccessible to any previous space mission but within PLATO's >1e-8 Hz frequency coverage, as confirmed by PlatoSim simulations. Second, we will provide the first comprehensive census of CV burst phenomena — from classical dwarf nova outbursts to micronovae and magnetically gated accretion — testing the disc instability model with unprecedented sampling. Third, two known micronovae in our sample (CP Pup and 1RXS J080114.6-462324) are expected to yield 12--30 individual bursts, enabling statistical tests of the micronova model. Fourth, 3 eclipsing systems will constrain orbital period derivatives to test magnetic braking models applicable beyond CVs. Fifth, 3 polars and 5 novalikes will reveal the drivers of accretion-state transitions across magnetic and non-magnetic CVs. Together, this constitutes the most comprehensive space-based survey of AWD variability to date.

Testing X-ray reprocessing and scattering geometry in the eclipsing and dipping LMXB 2S 0921-63 with PLATO - Proposal 81, Coti Zelati (ES)

We propose to use PLATO’s imagette mode to obtain a continuous 90-day optical light curve of the long-period eclipsing and dipping low-mass X-ray binary 2S 0921-63, a unique laboratory for probing the geometry of obscured accretion flows. In this high-inclination system, the neutron star and inner accretion disc are largely hidden from view, and the optical emission is dominated by X-rays reprocessed in the outer disc, disc atmosphere, and irradiated donor star. The optical light curve therefore maps where the hidden accretion luminosity is intercepted and re-emitted. The orbital period of 2S 0921-63 is close to an integer number of Earth days, causing persistent phase gaps in ground-based campaigns, while TESS photometry is severely diluted by nearby stars. PLATO will provide the first uninterrupted optical monitoring spanning ten consecutive orbital cycles, enabling us to separate stable phase-locked features from orbit-to-orbit variability in the reprocessing geometry. Using 25-s imagettes, we will extract a deblended light curve and measure eclipse and dip morphology with unprecedented fidelity. By modelling the mean waveform and residual variability, we will constrain the disc geometry and identify the dominant reprocessing regions. These observations will establish whether optical light curves of obscured X-ray binaries trace the underlying binary geometry or are significantly shaped by variable disc and scattering structures.

Tracing Accretion Disc Structure Through Simultaneous Blue–Red Variability with PLATO FASTCAM - Proposal 82, Veresvarska (ES)

Accretion discs are found around objects spanning many orders of magnitude in mass, yet whether a single physical framework governs accretion across all scales remains an open question. Accreting white dwarfs (AWDs) in Cataclysmic Variables (CVs) are the most accessible laboratories for testing accretion theory. The propagating fluctuations model predicts that Fourier time lags between different optical bands, encoding the propagation timescale of accretion rate fluctuations across disc radii, should reverse sign at a characteristic low frequency set by the outer disc size. This lag reversal, observed in X-ray binaries and AGN, has never been detected in the optical band of any accreting system: ground-based baselines cannot reach below ~1e-4 Hz, and no simultaneous two-colour space-based study with the required baseline exists. The same low-frequency regime also contains the outer-disc PSD break, detected just once in any accreting binary, which encodes disc viscosity and scale height at the outer boundary, currently entirely unconstrained in normal CVs. We propose two years of PLATO FASTCAM observations of GALEX J061528.3-412007, a bright novalike CV in LOPS2. The FASTCAM's simultaneously operating blue and red cameras, spanning ∼1e−8--1e−2 Hz, will for the first time detect the low-frequency lag reversal in the optical band of an AWD, measure the outer-disc PSD break simultaneously in two bands, directly testing the universality of accretion disc physics.

Asteroseismology of a Golden Sample of massive pulsators - Proposal 91, Handler (PL)

The evolution of galaxies is primarily driven by massive stars via mass loss and supernova explosions. The exact ways supernovae explode and physical properties of the end products of massive star evolution, such as the spins of black holes, strongly depend on properties of the progenitor stars that are to date poorly constrained. As examples, stellar opacities determine the energy transport, hence basic interior structure of a star and mixing processes and angular momentum transport further determine their structure, evolutionary paths and lifetimes. Understanding these processes better is thus crucial to build knowledge on stellar structure, evolution, and its ultimate consequences. Here, we propose to derive exactly this knowledge for a representative number of massive stars. We shall apply the methods of asteroseismology, the sounding of stellar interiors using pulsations, to a carefully selected sample of twenty massive pulsators. These comprise "hybrid" pressure and gravity mode pulsators to constrain stellar opacity data and near-core rotation, pulsators in eclipsing binaries to constrain internal mixing processes and convective core sizes and stars with rotational mode splitting patterns to determine interior rotation profiles. The scientific potential of these objects has been recognized from previous TESS observations, but it is only the requested PLATO measurements and their superior accuracy and time base that will permit to reach these scientific goals.

The First 100 Million Years: A PLATO Multi-Science Survey of Young Stellar and Planetary Systems - Proposal 117, Ashraf (IN)

The architectures, atmospheres, and dynamical evolution of planetary systems are irreversibly shaped during their first 100 Myr, before atmospheric escape, thermal contraction, and dynamical instabilities erase the primordial signatures of formation. Yet this critical epoch remains poorly explored observationally. We propose the First 100 Myr Survey (F1MS): a systematic PLATO photometric survey of 2585 young stellar objects (age <100 Myr; G<15) within the LOPS2 field, using continuous 25 s cadence observations over the full uninterrupted 2-year baseline. F1MS combines five complementary science goals: (i) constraining the initial planetary radius distribution and early evolution of the radius valley; (ii) probing primordial orbital architectures before dynamical evolution reshapes young systems; (iii) delivering the first population-scale census of exocomet activity during the epoch analogous to the Solar System’s Late Heavy Bombardment; (iv) characterizing flares, accretion variability, and stellar rotation across coeval young populations; and (v) enabling systematic pre-main-sequence asteroseismology and eclipsing-binary studies. Dedicated transit, exocomet, flare, and periodicity pipelines combining statistical and transformer-based machine-learning approaches will enable F1MS to deliver the first homogeneous population-scale view of how young stars, planets, disks, and planetesimal systems co-evolve during planetary system formation.

PLATO-TIDES: Tidal Interactions and Dynamics in pulsating Eclipsing Systems - Proposal 120, Li (AU)

Recent theoretical studies challenge the long-standing view that tidal interactions in binary systems inevitably drive stars toward synchronization. Instead, tidal evolution in radiative stars may lead to blurred pseudosynchronization, or produce either rapidly or slowly rotating components. These tidal spin--orbit interactions can also profoundly reshape the evolutionary pathways of binary systems and their component stars. Observational evidence is therefore urgently needed to test and calibrate these new theoretical developments. Here we propose to observe a pre-selected sample of short-period (Porb<12 d), early-type (T_eff>7000 K) pulsating eclipsing binaries. We have already verified clear pulsation signatures in all selected targets from TESS data, maximizing the efficiency of PLATO observations. Compared with TESS, PLATO's long, continuous, 10-min-cadence photometry is essential for resolving the rotational splittings and g-mode period-spacing patterns that are needed to measure internal rotation. These measurements will reveal how tides shape the near-core and envelope rotation states of the stellar components. Combined with binary constraints from eclipses and spectroscopy, our observations will provide a powerful opportunity to test tidal theories, including blurred pseudosynchronization, inverse tides, and Cassini-state trapping.

What is the internal magnetic field of pulsating hot (β Cep, SPB, δ Scu) stars? - Proposal 121, Neiner (FR)

Magnetic fields play a crucial role during the entire life of hot stars. However, difficulties in correctly accounting for the effects of magnetic fields lead to large uncertainties in stellar evolution theory. While spectropolarimetric surveys have established the existence of magnetic fields at the surface of hot stars, their 10% incidence rate, and that they are strong, stable, and globally organized, there are currently few constraints on the strength and geometry of magnetic fields in the deep interiors of hot stars. Asteroseismology is the only technique for directly probing stellar interior processes, via precise measurements of stellar pulsations. There are three types of magnetic hot pulsators on the main sequence: β Cep, SPB, and δ Scu stars, which constitute the targets of this proposal. Their pulsation modes are extremely well-suited to probe interior magnetism. The magnetic field acts as a perturbation or even disruption to the pulsation frequencies, which enables the mode identification necessary for asteroseismic modeling, but also allows for a direct measurement of the interior magnetic field. Our proposal constitutes the first opportunity to obtain long and precise light curves of a sample of magnetic pulsating hot stars for magneto-asteroseismology. We identified 18 magnetic pulsators in the PLATO field and already characterized their surface field. PLATO data are now needed to constrain their interior field and ultimately improve stellar evolution theory.

Hot subdwarf stars in the PLATO era: a key window for intermediate stages of stellar evolution - Proposal 128, Van Grootel (BE)

Hot subdwarf stars (sdO/Bs) are evolved compact stars located at an intermediate stage of stellar evolution, between the red-giant branch and white-dwarf sequence. They are unique laboratories for processes like binary interaction, envelope stripping, and helium-core burning. Many fundamental questions remain unresolved, such as their formation channels, the role of binary interactions, the purity and boundaries of their instability strips, and the occurrence of substellar companions. We propose a dedicated exploitation of the PLATO mission to conduct the first homogeneous, high-precision photometric survey of a large sdO/B population in the LOPS2 field. PLATO long-duration light curves will enable detailed seismic analyses of pulsating sdO/B stars, including mode identification, rotational multiplets, and instability-strip boundaries and purity. Hot subdwarfs in close binaries will constrain common-envelope physics through eclipses, Doppler beaming, ellipsoidal variations, and timing analyses, while wide composite binaries will provide complementary constraints from main-sequence companions. The PLATO dataset will also be exploited to search for transiting planets and substellar companions around sdO/B stars, probing the fate of planetary systems after the main sequence. By combining PLATO photometry with spectroscopy, Gaia astrometry, and state-of-the-art modelling, this program will transform hot subdwarfs into powerful laboratories for stellar and binary evolution.

A Complete Census of Semi-Detached Eclipsing Binaries in the PLATO Field - Proposal 131, Southworth (UK)

Semi-detached eclipsing binary star systems (SDEBs) are common outcomes of binary star evolution. The primary (mass gainer) is an apparently normal star whilst the secondary (mass loser) is of similar size but much lower mass and temperature. Their masses and radii can be obtained from PLATO light curves, and Gaia radial velocities of just one of the stars. A significant fraction of primary stars in SDEBs are in the delta Scuti instability strip. Their pulsation frequencies combined with precise mass and radius measurements allow the mixing length, convective core overshooting, age, interior rotation profile, mass conservation and loss, and evolutionary history to be constrained. We have compiled a catalogue of all known eclipsing binaries in LOPS2 from the GCVS, TESS and Gaia. The catalogue includes 754 SDEBs with Pmag < 14.0 and available for GO observations, of which 85 are pulsating. We request PLATO light curves of the full sample, and minimise the telemetry required by only observing for one quarter in most cases. The PLATO light curves will be used to: (1) compile a catalogue of PLATO EBs; (2) determine the physical properties (mass, radius, temperature) for the sample of SDEBs with Gaia spectroscopy; (3) provide a catalogue of eclipse times, depths and durations for WP11 to use in vetting transit candidates; (4) determine masses, radii and oscillations frequencies for pulsating stars in SDEBs; (6) determine the mass transfer and loss during past evolution.

Intermediate-mass stripped stars with main-sequence companions - Proposal 133, Sana (BE)

Intermediate-mass stripped stars are the naked helium cores of intermediate- and high-mass stars that have lost their hydrogen envelope through prior binary interaction. Despite their crucial astrophysical importance, both as  probes of binary evolution and as sources of intense ionising radiation, intermediate-mass stripped stars have long eluded detection. The largest population of (candidate) stripped stars known to date resides in the Magellanic Clouds, where the large distance renders their precise characterisation challenging. Here we proposed a radically nove approach to identify the first eclipsing binaries with a hot, helium stripped stars with an OB companion. Thanks to the unique photometric precision and observation baseline of PLATO, the properties of transit and occultation eclipses enable the detection and characterisation of OB+He binaries with a yield of ~1%. We therefore assemble a sample of 580 OB and OBe galactic targets in the PLATO field-of-view and aim at detecting of 6+/-2 OB+He binaries. Their light-curve analysis will deliver unique constrain of the physical and orbital properties of stripped stars, allowing to constrain their prior evolution history, including their mass-transfer efficiency and stability. Beyond the crucial discovery of eclipsing OB+He systems, the assembled data set will have an incommensurate legacy value enabling numerous asteroseismic, variability and multiplicity studies of the largest sample of OB and OBe stars to date.

Extending PLATO's reach to study young stars and planetary systems - Proposal 135, Gillen (UK)

We propose to observe 8237 young stars in 166 nearby stellar groups spanning 5-800 Myr, which will more than double the number of young and maturing stars observed by PLATO. Our sample contains a population of very young (<50 Myr) K stars that are the progenitors of the mature solar-type stars in PLATO's P1/2/5 mission samples; these young stars are required to probe the formation, evolution and habitability of planetary systems around solar-type stars with PLATO. We will (i) detect and characterise young transiting planets and (ii) characterise the early evolution of stellar rotation, pulsations and flare activity. Our young planetary systems will provide the missing link between theories of planet formation/early evolution and the mature population that is the focus of PLATO's mission samples, augmenting its core science. Our young star characterisation will help link gyrochronology to asteroseismology at mature ages, provide the first statistical view of pulsations in very young early-types stars, and test flare production and evolution theories, as well as constrain mature planet habitability.

From detection to inference: a PLATO testbed for globular-cluster seismology - Proposal 142, Miglio (IT)

Globular clusters are benchmark populations for testing stellar evolution, mass loss and the origin of multiple stellar populations, but asteroseismology in these dense, old systems has so far been limited to a few short-baseline detections. This programme requests standard N-CAM 600-s light curves for approximately 50 high-probability, minimally contaminated evolved members of NGC 1851 and NGC 2298 in the LOPS2 field. The sample is dominated by bright RGB and red HB stars in NGC 1851, with an exploratory extension to the more metal-poor cluster NGC 2298. The two-year PLATO baseline will enable robust detection of solar-like oscillations, measurement of global seismic parameters, and, for the best targets, extraction of individual frequencies or regular oscillation-pattern diagnostics. Combined with Gaia astrometry, cluster priors, photometry and spectroscopy, these data will provide seismic masses, radii and evolutionary states for old, metal-poor stars. The main goals are to calibrate seismic masses in globular-cluster giants, constrain RGB mass loss from RGB--rHB mass differences, compare first- and second-population stars where classifications exist, and establish PLATO as a pathfinder for high-precision seismology in globular-cluster environments.

Do A/F stars exhibit magnetic cycles? A PLATO study of rotational modulation and surface variability - Proposal 153, Mas Sanz (DK)

The aim of this proposal is to obtain 2-year PLATO photometry for ~230 intermediate-mass stars showing rotational modulation and possible hump-and-spike (H&S) behavior. H&S stars show a rotational peak together with a broad low-frequency hump associated with Rossby pulsation modes. They are the first homogeneous group with evidence for weak magnetic activity in intermediate-mass stars with predominantly radiative envelopes and shallow subsurface convection zones. Kepler observations first revealed H&S stars, but the known sample is too faint and difficult to characterize spectroscopically. Using TESS data, we identified a much larger sample of bright rotationally variable candidates suitable for detailed follow-up observations. However, the available TESS observations are too short and fragmented to properly characterize their temporal variability or detect the low-frequency hump. PLATO will combine long uninterrupted photometric baseline with a large sample of brighter targets. The proposed observations will allow us to investigate the temporal evolution of rotational modulation, search for stellar activity cycles, and characterize low-amplitude Rossby mode pulsation - none of which are possible from existing TESS data.

Mapping the accretion history of the Galactic halo with precision stellar ages - Proposal 162, Leitinger (IT)

The Milky Way halo was assembled through the accretion and disruption of smaller satellite galaxies. The relics of these ancient mergers are preserved as distinct stellar populations whose kinematics and chemistry trace their progenitor systems. However, without precise ages, the chronological sequence of accretion events remains poorly constrained. Asteroseismology of red giant stars provides a direct pathway to precise ages (10-20%), enabling time-resolved studies of halo assembly. We have identified 600 low-metallicity red giants in the PLATO LOPS2 field that are likely members of major accreted substructures, including Gaia-Enceladus, Sequoia, the Helmi streams, and the low-energy group (LKH/Kraken/Heracles). All targets are PIC contaminants, not in proximity to any core science stars, and are observable by at least six normal cameras with favourable noise-to-signal ratios. Predicted oscillation parameters fall within the regime where 12 month PLATO observations will enable robust asteroseismic parameter extraction and age determination. We request 12 months of 600-s cadence N-CAM observations for all 600 stars. The resulting ages will be compared across substructures identified in integrals of motion space using Gaia DR4 astrometry, providing the first asteroseismic age catalogue for accreted field red giants in the LOPS2 field. This will yield new constraints on the timing and sequence of the mergers that built the Milky Way halo.

PLATO Exoplanet Community K-dwarf Survey (PECKS) - Proposal 164, Osborn (CH)

By precisely observing thousands of bright stars, PLATO will provide key insights into exoplanetary science, especially by creating a stastical sample of host stars from which the occurrence of planets can be studied in detail as a function of stellar properties. However, the target selection of PLATO stars has produced a sizable gulf in stellar spectral type, with only 4500 mid-to-late K-dwarfs being observed (compared to >15000 M dwarfs, and >30000 G-dwarfs). This gap could seriously impact our ability to constrain underlying physics trends in planetary occurrence as a function of stellar mass. This is especially true for already-identified population-level trends between M- & FGK- dwarfs such as in the radius valley, ratio of sub-Neptunes to rocky planets, as well as in total planetary occurrence. Therefore, we propose a community-driven survey of bright mid-to-late K-dwarfs which are amenable to the detection of earthlike rocky planets in the circumstellar habitable zone. The PECKS sample will double the number of detected planets orbiting stars with 3850<Teff<4850 K, including more than 50 rocky planets, some of which we expect have temperatures below 300K. As well as providing planetary systems for mass characterisation via RVs & TTVs, this sample will be a treasury programme for post-PLATO analyses. Without observing these missing K-dwarfs, PLATO will be unable to provide volume-limited occurrence rates spanning all spectral types.

Following Dusty Signposts of Short-Period Planet Formation - Proposal 178, Pittman (DE)

The innermost exoplanet occurrence rate peaks sharply at an orbital period of ~10 days, defining an "inner edge" of planetary systems whose physical origin remains unknown. Three transitions in the inner protoplanetary disk (the magnetospheric truncation radius, the corotation radius, and the dust sublimation radius) have been proposed as traps for planet-forming material, but resolving the 0.1 au scale of this region is observationally challenging. Young stellar objects (YSOs) with “dipper” light curves, which show repeated occultations by perturbed inner-disk material, provide a powerful probe, as they can pinpoint the orbital location of planetary building blocks near the inner edge. CoRoT, K2, and TESS have provided short duration snapshots of YSOs, leaving the appearance and disappearance timescales of these perturbations unconstrained. We propose a 2-year PLATO campaign monitoring 30 disk-bearing YSOs spanning a broad range of ages and environments, including nine members of the highly irradiated γ Velorum cluster — a potential analog of the Sun's natal environment. PLATO's 730-day baseline can distinguish between physical origins of the dust perturbations, some of which remain unexplored in theoretical work. Our program will motivate complementary VLT and JWST proposals, enabling us to build a multi-wavelength, time-resolved picture of the inner disk at the epoch of short-period planet formation.