1. Circumbinary Planet Detection with PLATO
WP112510:
Hans Deeg (WP leader) Instituto de Astrofísica de Canarias, ES
José Manuel Almenara LAM, FR
Stefan Dreizler University of Goettingen, DE
Rudolf Dvorak Univ. Vienna, AT
Francesca Faedi Warwick University, GB
Petr Kabath ESO fellow
Maciej Konacki Nicolaus Copernicus Astron. Ctr., Torun, PL
Willy Kley Univ. Tübingen, D
Tsevi Mazeh Tel Aviv University, IS
Aviv Ofir University of Göttingen, DE
Jean Schneider Observatoire de Paris, FR
PLATO 2.0 WS

2. Circumbinary Planets
Planets in orbit around both binary components (P-type orbit)
Spielberg et al, 1977: Planet Tatooine
Backer 1993: Timing of PSR B : Pulsar-WD binary plus low-mass object only yrs later accepted as planet, 2.5Mjup, P=100y (Sigurðsson+03, Backer+ 05, Rasio 05 etc)
MacCabe et al 2003: HST-NICMOS obs of Circumbinary disk of GG Tau
Planet Tatooine in Star Wars
PLATO 2.0 WS

3. Current status 14 CBP known in 12 systems
All early (<2011) discoveries are on evolved stars; by eclipse timing variations
≥2011: CBPs on MS stars in Kepler data
No CBP discovered by radial velocity
ADS, in abstract: CIsource RCUMBINARY and PLANET
Circumbinary AND planet
in abstract
Source: ADS
K-47c in hab zone (talk jenkins)
Pierens & Nelson (2007, 2008a,b): series on CBP formation, migration and evolution. Inward drift of protoplanet may stop near binary cavity..
Most Kepler CBPs (except 34b, 47c) within few % of critical orbital semi-major axis. apl/ab = 3.1 to (Welsh+ 2012; Orosz+ 2012).
Pierens & Nelson (2013) on 3 Kepler CBP: Scenario in which a core forms, migrates inward and accretes gas
PLATO 2.0 WS

4. Circumbinary planet detection
Several photometric methods:
Eclipse timing variations (ETV)
Transits
‘Eclipse Echos’
No RV discovery, but ongoing TATOOINE Search (Konacki+ 2009)
Corot: zero, but it observed 10-20% more stars than Kepler
PLATO 2.0 WS

5. CBP transit detection Kepler 16(AB)b Kepler38b (Orosz+ 12)
Transits likely to occur: Planet disks preferentially aligned with binary plane (strong missalingment impossible, Bate )
Unique transit signal, low False Alarm prob. Details of transit depend on EB phase.
Kepler38b (Orosz+ 12)
Kepler 16(AB)b
Doyle
Kepler 16b
Specific detection algorithms needed: (Doyle+ 2000, Ofir+ 09, Kostov+ 13,
Removal of binary signal
Detection of semi-periodic transits within ‘transit window’ (Doyle+ 2000, Armstrong+ 13)
Deeg+ 1998
PLATO 2.0 WS

6. Detection of 3rd bodies by eclipse time variations (ETV)
First use: Botsula 1956 for TX Her
All ‘pre-Kepler’ CBPs found by ETV
Amplitude of variation
of minimum time from light-time variation:
DTmin~ Mpl MEB-2/3 p2/3
Stronger ETVs from planets with mean-motion resonances ≥3:1 (Schwarz+ 11)
ETV used to verify transit detec.; set masses
Planets found by ETV long-periodic ≥7.5yr
PLATO 2.0 WS

7. Eclipse Echos eclipse in reflected light from planet
Detection of binary eclipses in planet’s reflected light
Deeg & Doyle 2011
PLATO 2.0 WS

8. Detectability of CBP in Kepler data from Eclipse Echos
Detectability of 1Rj CPB at inner orbital stability limit in 4yr data of Kepler EBs
Green: Detached
Blue: Semi-detach.
Red: Over-contact
Bold symbols:
Targets for EE search with σdet > 3:
38 Detached
62 Semi-detached
350 Over-contact
Graph needs a fix, was for 6yrs Kepler
Adapted from Deeg & Doyle 2011; Kepler EBs from Prsa et al. 2011
PLATO 2.0 WS

9. ETV versus Transit detection
Example: Cm Dra M4.5/M4.5 binary; MCM DRA = 0.44 Msol 6 yrs /1000hr ground obs. for Transits (Deeg+ 1998, Doyle+ 2000)
with 54 eclipses, st0 ≈ 6 sec (Deeg+ 2000)
Planet-period
Planet-mass
Deeg+ 2000
Max. a for Transit-discovery given by inclination of binary, assuming coplanar planet

10. PLATO CBP detection K47 K35 K64 K34 K16 P= 41d
2410 EBs out of Kepler sample of ~160k stars -> ~1.5% are Ebs
(Kepler Eclipsing Binary Catalogue V3 (Villanova U.; Kirk+ 13 in rep))
6 CBP detected, all with transits, rather long periods d
Absence of CBP on shorter-periodic binaries?
Several detection efforts to find shallow-transit CBPs ongoing
Detection effort to find Eclipse Echoes, also on non-eclipsing binaries; (Doyle)
PLATO:
long-monitoring 2-3yrs: 267k stars 80ppm/√h
First order, multiply Kepler detection rates by > 10 ‘Kepler CBP’
Step&stare 2-5 months: 106 stars
Reduced detection capability for longer-periodic (p>0.2yr) CBPs.
Assuming that ½ of known Kepler CBP detected in such data: -> 20 ‘Kepler CBP’
Estimates for short-periodic CBP and those found by Eclipse Echo: depending strongly on findings from Kepler.
PLATO 2.0 WS

11. Tasks of the CBP working group
Sample definition: definition of expected sample for circumbinary planet searches (e.g. sample size and characteristics). This needs to be performed in light of capabilities of the available detection methods. It consists in an initial estimate for the sample, which will be refined and updated alongside the evolution and eventual freezing of PLATO mission specs.
Detection methods:
Initially: revision of existing methods and algorithms. This includes: evaluation of their sensitivity, requirements onto PLATO data; need for auxiliary data or parameters (e.g. stellar masses); potential results ('discovery space').
Selection of one or two methods and their development towards implementation in PLATO data analysis protocol. Testing of these methods with simulated data and definition of their performance.
Feedback to PLATO science coordination about design aspects that may allow an optimization of the mission towards the WP objectives
Definition of auxiliary data that will be needed: revising their availability in literature or databases or defining the observations required from other instruments (ground or space). Pre-launch catalogue of EBs needed? Some Algorithms (e.g. CB-BLS) need stellar mass-ratio.
PLATO 2.0 WS

12. Thank you
¡Gracias!
PLATO 2.0 WS