Programme

(Subject to change)

Day 1, Wednesday, December 10th

9:00am Bus from Moncloa -> ESAC

Day 2, Thursday, December 11th

9:00am Bus from Moncloa -> ESAC

Day 3, Friday, December 12th

9:00am Bus from Moncloa -> ESAC

Abstracts

Circumbinary planets with transit missions - Jerome Orosz

Kepler-16b was the first unambiguous detection of a planet orbiting both stars in a binary system with main sequence stars, and it was initially detected via its transits of the primary star in the binary.   Thanks largely to the Kepler and TESS missions, around 20 circumbinary planets have already been detected, mostly through the transit method.  Characterizing these circumbinary planets is of fundamental value in astronomy as this new class of planets allows us to probe questions regarding the formation, migration, evolution and habitability of planetary systems in a larger context. In this contribution I will review how these transiting circumbinary planets are detected and characterized and I will highlight a few recent discoveries.

New results from TESS - Searching the TESS 10k sample for transiting CBPs - Dominic Oddo

Reported detections of transiting circumbinary planets from the Transiting Exoplanet Survey Satellite (TESS) mission have been rare so far. This is in part because eclipsing binaries (EBs) serve as the primary targets for transiting circumbinary planets, but hundreds of thousands of EBs have as of yet gone uncharacterized. As the orbits and physical characteristics of more binaries have been published, the sample of targets for transiting CBPs has increased. In this talk, we will present new work on the search for transiting TESS CBPs with the new TESS 10,001 sample of eclipsing binaries from Kostov et al. (2025). We will describe the sample, search methodology, and current results. We will then use these results to provide context and direction for upcoming missions such as ESA PLATO.

mono-cbp: A Pipeline for Detecting Transits of Circumbinary Planets - Ben Davies

We present mono-cbp, a pipeline designed to detect transits of circumbinary planets (CBPs) in light curves of eclipsing binaries. The pipeline masks stellar eclipses, applies custom detrending, searches the residual light curve for individual transit events, and performs a suite of vetting steps to identify candidate CBP transits. We have applied mono-cbp to the TESS Eclipsing Binary Catalogue, identifying one candidate transit event, and we have assessed its performance through injection-recovery tests. Looking ahead, we will discuss planned improvements to mono-cbp and its application to the PLATO mission.

CBP's with PLATO - Hans Deeg

An overview over the PLATO mission will be given, with a focus on CBP science enabled by the mission and on current preparations for this task.These center on  preparing the analysis of CBPs found in PLATO data, prioritisation of upcoming CBP candidate systems for further follow-up and the coordination of the follow-up, for a maximisation of the scientific return of PLATO on this topic. The detection of CBPs is not part of the official PLATO pipeline, but will advance as a community-driven effort, for which a detection-challenge is currently being prepared (further details in a second talk). Involvement of the scientific community will be aimed for, with a proposal for a PLATO Working Group on CBPs that will be outlined. 

Revealing Sub-stellar Bodies Around Post Common Envelope Binaries with Eclipse Timing Variations - Ozgur Basturk

Post-Common-Envelope Binaries (PCEBs) are interesting candidates of hosting companions in the sub-stellar mass range. These companions could either form from material expelled during the common-envelope phase (second-generation scenario), or they might survive the envelope ejection with altered orbital and physical characteristics (first-generation or hybrid scenarios). Eclipse Timing Variations (ETVs) provide the most effective tool for uncovering such companions, which are otherwise extremely difficult to detect directly due to their small sizes, low masses, and faint luminosities. Nonetheless, other mechanisms can also account for the observed ETVs in PCEBs. In this contribution, we present our project dedicated to analyzing ETVs in a large sample of PCEBs and report the results obtained so far.

A review of astrometry's role (past and future) for circumbinary planets - Thomas Baycroft

In this talk I will review the method of astrometry, and its application to circumbinary planets. I will present the handful of circumbinary systems in which astrometry has played a role so far, and discuss what the road ahead looks like with future Gaia data releases looming. 

Searching for Circumbinary Planets via Apsidal Precession  - Margo Thornton

The discovery of circumbinary planets (CBPs) remains limited in photometric surveys, in part due to a strong detection bias favoring transiting systems. In this work, we explore an alternative detection method by leveraging apsidal precession as a dynamical signature of planetary companions. We analyze a large sample of eclipsing binaries from the Gaia catalog (~2 million systems), supplemented with photometry from TESS and ground-based surveys, to identify systems exhibiting measurable precession. Considering this set of precessing systems, we target these candidates for follow-up spectroscopy to constrain the mass and orbital properties of potential third bodies. We present a new set of CBP candidates identified through this precession-based method, offering an avenue for probing planet formation and dynamical evolution in non-coplanar, multi-body stellar environments.

A review on the discovery and confirmation of circumbinary planets using radial velocities - Amaury Triaud

This talk will review what radial-velocities provide to circumbinary planet science, from providing precise binary parameters, to confirming planetary signatures, to identifying new circumbinary exoplanets. I will present results for single and double-lined systems show what works well and what works not so well, and review contribution made by the radial-velocity method.

RV characterization and detection limits of circumbinary planets: Kepler-38 and Kepler-1647 - Onė Mikulskytė

Circumbinary planets (CBPs), planets orbiting binary star systems, offer unique insights into planet formation. However, they are challenging to detect using traditional methods. While photometric surveys such as Kepler and TESS have led to the discovery of around a dozen transiting CBPs, the majority of these systems lack precise mass measurements due to limitations of transit-based methods. Radial velocity (RV) observations provide a direct way to measure planetary masses and detect non-transiting CBPs.
Two circumbinary planets with some of the largest uncertainties on planet mass from the known catalogue are Kepler-38b - an <122 Earth Mass planet orbiting an 18.8d binary, and Kepler-1647b - an 483±206 Earth Mass planet orbiting an 11.3d binary. Kepler-1647b is notable for its unusually wide 1108-day orbit beyond the stability limit. In this talk I will present an analysis of CARMENES RV data of these extremely faint targets (V~13.5) to establish detection limits for additional planets, and update mass constraints using a full photodynamical fit.

Two circumbinary planet candidates detected with RVs around detached eclipsing binaries with solar analogs - Krzysztof Hełminiak

Detached eclipsing binaries (DEBs) that are also double-lined spectroscopic (SB2) are arguably the best planet host, because can be very precisely characterized, thus allowing for a better study of the companion.

We present detection of RV-signals in two SB2 DEBs, that we attribute to circumbinary bodies of super-Jovian minimal masses. Other scenarios were also taken into account but were found to be less probable. In both cases a periodic modulation was initially found in residuals of RV fits to Keplerian binary orbits. Further simultaneous modelling of binary and CBP orbits revealed significantly better solutions than for a binary-only case. 

The first candidate is an M_p sin^3(i)~5.0 M_J planet on a wide, P~1500 d (3.35 AU) orbit. The host is a well-known and well-studied DEB with the orbital period of just over 20 days and narrow spectral lines that allow for high-precision RV measurements. The inner orbit is eccentric, but the outer one seems to be (nearly) circular, and within the habitable zone of the host.

The second candidate is an M_p sin^3(i)~2.5 M_J planet, and orbits its DEB host every 38 days. The host is  known as a DEB, but has not been studied yet. The relatively short binary period (8.5 d) influences the rotation of components, which somewhat hampers the RV precision. Still, the RV signal is detected at 4.0 sigma level. 

Both DEBs are composed of solar-type stars, of which the less-massive secondary is a solar analog. Stellar masses and other parameters are known with a sub-% precision.

The Study of Bound and Ejected Circumbinary Planets with the Roman and Euclid Space Telescopes - David Bennett

The gravitational microlensing method is sensitive to circumbinary planets in wider orbits than those discovered by the transit method, and the microlensing method is also uniquely sensitive to free-floating planets that have been ejected from their orbits by gravitational interactions with other bodies. Theoretical studies indicate that ejections from circumbinary planetary systems may be the dominant source for the large population of free-floating planets that have been inferred from ground-based microlensing observations. I demonstrate how combined observations from the Roman and Euclid space telescopes can provide direct free-floating planet mass measurements, and indicate how these mass measurements could be used to improve our understanding of the planet formation process.

Detectability of Circumbinary Planets in the Roman Microlensing Survey - Arjun Murlidhar

One of the biggest challenges in understanding planet formation in binary systems today is the small number of circumbinary planets detected. Traditional methods used to find these planets, like transits and direct imaging, are only sensitive to planets with very small or very wide orbits. Microlensing can help bridge this gap in the demographics of circumbinary planets. Since it does not rely on detecting light from the host star system or planet, and is not dependent on any special configuration of the system, microlensing can discover circumbinaries over a broader range of stellar binary and planet parameters. I will talk about how microlensing can be used to detect circumbinary planets, and I will outline our efforts to characterize the sensitivity of microlensing to circumbinary systems with different architectures, with a focus on the upcoming Nancy Grace Roman Space Telescope. This work will give us an estimate of the yields of various kinds of circumbinary planets from Roman and will also help inform future searches for circumbinary planets with microlensing.

The SPOTS legacy: lessons learned and new horizons for the direct detections of circumbinary planets - Mariangela Bonavita

SPOTS (Search for Planets Orbiting Two Stars) was the first (and so far the only) dedicated direct imaging survey for circumbinary planets. Its results, combined with all archive data, provided a first look at the population of wide-orbit circumbinary planets and ideal data set to constraint their frequency. In this talk I will discuss the relevance of those results, more than half a decade after they were announced, the current state of the art of the field and what the future holds for the direct detection of circumbinary planets.

The known (and unknown) population of circumbinary planets - David Martin

A few dozen circumbinary planets are now known, identified through diverse discovery methods that each carry significant and often subtle observational biases. This population is rich in information but prone to misinterpretation if these biases are ignored. In this review I will summarize our knowledge of circumbinary planets as a function of size, orbital period, alignment, and host-binary properties. I will highlight emerging trends, lingering uncertainties, and implication for planet and binary formation.

CODE OF CONDUCT

The European Space Agency (ESA) strives to create a positive work environment where all people are treated with respect and dignity. In the context of ESA Science workshops and conferences, all participants are expected to help create an environment at the meeting and all associated activities that is professional, inclusive, and in which everyone is treated with respect.

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• The Local Organising Committee members are designated as the contact points for all matters related to this code. Participants can report any violation of these guidelines to these designates in confidence.
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Acknowledgments: This code of conduct has been adapted from the London Code of Conduct (by A. Pontzen and H. Peiris), which was derived from original Creative Commons documents by PyCon and Geek Feminism. It is released under a CC-Zero licence for reuse. To help track people's improvements and best practice, please retain this acknowledgement, and log your re-use or modification of this policy at: https://github.com/apontzen/london_cc .