Planets in Open Clusters Stars in OCs share the same distance, age and chemical composi0on, sta0s0cally determined M35 & NGC2158, Asiago OCs span a wide range in terms of age, metallicity, stellar density: we can probe the planet frequency as a func=on of these parameters Planet frequency as func=on of host stellar mass in the most reliable way Effects of the presence of a planetary system on the host star chemistry La ricerca dei piane0 extrasolari in Italia, WOW mee0ng, INAF- HQ Rome
Planets in Open Clusters There is a lack of old open clusters in the solar neighborhood. Main- sequence stars are therefore too faint Stars in young open clusters are very ac=ve, making RV detec=on difficult We have learnt how to deal with ac=vity only recently. Before that, OCs have been avoided by RV survey. Photometry has been the most favorite technique un=l recently
planets less common in clusters? Van Saders & Gaudi 2011: Insufficient sensi=vity to small planets, sample sizes barely large enough to find (less common) larger planets. Null detec3on 0.999 Meibom et al. 2013 b 15 0.998 12 6 4 Rotation period (days) Photometric searches in M37, NGC188, NGC1245, NGC2158, NGC2362, NGC6791... Without planets. Are 1.000 2 0 Time from mid-transit 10 (hour V (mag) Photometry a Relative flux Searching for Planets in RESEARCH OCs: LETTER Figure 14 2 Transit light curves. a, b, The Kepler light curves for Kepler-66 (a) and Kepler-67 (b). The photometric measurements (grey points) were acquired in long cadence mode (30-min total exposures) and have been detrended28, normalized to the out-of-transit flux level, and phase-folded on the Kepler-66 16 6,000 stars during the era of planet formation, including several at least Kepler-67 O stars (masses greater than 20 solar masses) and more than one hundred B stars (masses between 3 and 20 solar masses). The discovery of two mini-neptunes in NGC6811 thus provides evidence that the formation and long-term stability of small planets is robust against 18 0.2 0.4 0.6 0.8 1.0 1.2 periods of the tra the same data ph mean, respective overplotted in re 5 stellar densities deaths and hig Received 6 Nove Published online 0 0 of planets inside and outside open clusters of stars. Number of planets Meibom et al. 2013: 2 mini- Neptunes, Kepler- 66b and Kepler- 67b detected in NGC6811 by Kepler mission over 377 cluster members. The same frequency Number of planets Lada, C. J. & L Astrophys. 41 B V (mag) a 2. The Extrasola 1.0 3. Mayor, M. pa et a Figure 1 The colour magnitude and colour period diagrams for 1,107 6 90 Kepler-66b Kepler-67b Occurrence, 16 0.8. Tm NGC6811. a, The colour magnitude diagram for stars within a 1-degreemembers Neptune-mas in t diameter field0.6 centred on NGC6811 with the locations of Kepler-66 and Kepler- variations abs/1109.24 Howard, A.pe et 67 marked by 0.4 black circles. Cluster members, marked with larger red dots, trace 4.of multiple Astrophys. J. S trac a well-defined relationship between stellar mass (colour, B 2 V) and luminosity 5.members Fressin, F. et 0.2 The (brightness, V) that can be fitted by stellar evolution models to determine the period. Astrophys. J.lo 7 0.0 6. Sato, et al. markedb.by ora age and distance1of NGC6811 as well3 as the masses and radii 10 of its members. By 661, 527 53 Radius (R billion ) this method NGC6811 is found to be 1.00 6 0.17 years old and 7. Lovis, C. & Ma b substellar com 1.0 Astrophys. 47 Kepler-67b Kepler-66b or metallicity imply that the 0.8 planet frequency in NGC6811 is consistent with that of 8. Quinn, S. et a open cluster. distribution the field. 0.6 9. van Saders, J The members of NGC6811 fall entirely within the range of stellar Kepler-66b upper limits o 0.4 J. 7 frequenc spectral types0.2selected for the Kepler planet survey, and the slightly sub- theastrophys. 10. Pace, G., Pasq The comp solar metallicity of NGC6811 (ref. 17) is close to the average metallicity stars. Astron. 0.0 11. A. 1 from which 10the Kepler targets 100 1,000 66bFischer, and D.Kep of the Galactic0.1 disk population are drawn. 1102 1117 ( Period (days) that the size Therefore, correlations between planet frequency and stellar mass and/ La ricerca dei piane0 extrasolari in Italia, WOW mee0ng, INAF- HQ Rome 12. Meibom, S. T abstr. Figure 3 Distribution of planetary properties. a, b, Histograms of planetary those of311.03 the 13. Yi, S. et al. Tow s3ll in agreement with field frequency. 1.
Searching for Planets in OCs: Radial Veloci0es of Giant Stars J Giant Stars are brighter than Main Sequence counterparts Sato et al. 2007: A planetary companion to the Hyades Giant ε Tauri, P=594d Msini=7.6M J Lovis & Mayor 2007: Planets around evolved intermediate- mass stars. A P=714d Msini=10.6M J in NGC2423 and a P=678d Msini=19.8M J in NGC4349 L Li`le knowledge of giant star oscilla=ons prevent the discovery of small- mass planets
Searching for Planets in OCs: Radial Veloci0es of MS Stars Chocran et al. 2002, Searching for planets in the Hyades. I. The Keck Radial Velocity survey 94 F5V to M2V stars, magnitude range V=7.5-11. No planet found The survey was affected by the li`le knowledge of stellar ac=vity of young stars (RV jijer) Sparse sampling No simultaneous photometric observa=ons Only CaII H&K emission lines as ac=vity indicator. I 2 gas cell contaminates the spectra A small number of stars were then observed more intensively, spectroscopically and photometrically
Searching for Planets in OCs: Hot- Jupiters around OC stars Quinn et al. 2012: Two b s in the Beehive: the discovery of the first Hot Jupiters in an Open Cluster P=4.43d Msini=0.54M J P=2.14d Msini=1.84M J Radial Velocity (m s 1- ) 250 200 150 100 50 Quinn et al. 2014: HD 285507b: an eccentric Hot Jupiter in the Hyades Open Cluster P=6.09d Msini=0.54M J e=0.09 Observa=onal strategy focused on the detec=on of short- period, massive planets. O-C (m s 1 ) BS (m s 1 ) S index 0 60 30 0-30 -60 60 30 0-30 -60 0.08 0.06 0.04 0.02 0.0 0.2 0.4 0.6 0.8 1.0 Orbital Phase
Searching for Planets in OCs: Hot- Jupiters around OC stars Brucalassi et al. 2014: Three planetary companions around M67 stars P=6.96d Msini=0.34M J, e=0.24 P=5.12d Msini=0.40M J, e=0.39 P=121d Msini=1.54M J e=0.35 (around a giant star) M67 is old (~4 Gyr), ac=vity has been neglected Observa=onal strategy focused on giant planets. HARPS in lower- resolu=on sefng.. Top: Lomb-Scargle periodogram for YBP1194. The dashe
RVs, OCs and stellar ac0vity Recent surveys have avoided to deal with ac=vity. However, knowledge in the field is rapidly advancing Corot- 7 (M=4.8 M ): RV jijer is not a random noise, but has a structure that can be removed Several works on the topic: Lanza et al. 2009, Boisse et al. 2011, Figuera et al. 2013, Dumusque et al. 2014 312 D. Queloz et al.: The CoRoT-7 planetary system: t Fig. 1. AsyntheticviewoftheradialvelocityandspectroscopicinformationmeasuredfromHARPSdatafromNovember2008toFebruary2009. Agreement on the importance of rota0onal period of the star and simultaneous photometric observa0ons Queloz et al. 2009 process, a This addit series of fi uncertaint locity data the harmo (ν = 0.271 an orbital ters, one fi and e = 0 pre-whiten Simila 3.7-day or then looke spectrum peak with
Searching for Low- Mass Planets in OCs: The Open Cluster Survey in GAPS We are currently surveying two Open Clusters in GAPS: NGC752 (1.5 Gy) and M44 (600 My) GAPS Proposal, PI: A. Sozzef Strong a`en=on on members selec=on HARPS- N delivers long- term stability and short- term accuracy also Ac=vity (e.g. CaII H&K, Hα emission lines) and Asymmetry (Contrast, FWHM, Bisector Span, Vasy ) indicators
Searching for Low- Mass Planets in OCs: Photometry of OC- GAPS targets 2013 2014 Simultaneous Photometry with STELLA@Teide Rota=onal period of the star 2013 2014 Analysis by V. Nascimbeni Long term varia=on of photometric amplitude and modula=on (correlated to RVs) Knowing precisely the rota=onal period let us detect planets more easily
Searching for Low- Mass Planets in OCs: The importance of rota0onal periods Clear difference between a lonely active star and an active star with a planet!
Searching for Low- Mass Planets in OCs: Early results from OC- GAPS A complex system: A 2.14d planet (Quinn et al. 2012) 8 day rota=onal period A long- term trend with curvature ( 1200d?) AOT30 observa=on will put a strong limit on Period and Mass of the second body This discovery will put strong constraint on planet forma=on and evolu=on in crowded environment
Searching for Low- Mass Planets in OCs: Early results from OC- GAPS It s a new field and we had a lot to learn But now we are on the right track and several candidates are coming out
Searching for Low- Mass Planets in OCs: Chemical Star- Planet connec0on Melendez et al. 2009, Ramirez et al. 2014: stars with planets are depleted in elements used to form the planets Gonzalez Hernandez et al. 2013: chemical differences explainable in terms of Galaxy evolu=on Open Clusters: direct solu=on to this dilemma (and Lithium ques=on as well), work in progress Figure 5. Differences between [X Fe] of the Sun and the mean values in the
Planets in Star Clusters Ruprecht147 with HARPS 5 nights (50 hours) in P91, 8 nights (80 hours) in P93 Proposal for 8 nights in P95 submi]ed 25 ini=al targets Observa=onal strategy, ac=vity checks similar to M44 and NGC752 2 low- mass (K<10 m/s) candidate planets and a possible long- period Jupiter We are already exploi=ng the GAPS experience to gain visibility PI: D. Minni=
Searching for Planets in OCs: K2 observa0ons Many OCs included in K2 fields on specific request of community! Planets in OC are becoming hot- topic
Conclusions Photometry des not find a different frequency of planets in Open Clusters respect to the field Earlier RV surveys did not take ac=vity into account properly Later RV surveys focused on giant stars, or just to find Hot Jupiter We now have the hardware (HARPS- N@TNG, high- precision photometry) and the tools (Ac=vity indexes ) to discover low- mass planets in OCs Not only planet discoveries: star- planet chemical connec=on, dynamics of stellar encounters New interest from community in OCs: several K2 fields on clusters La ricerca dei piane0 extrasolari in Italia, WOW mee0ng, INAF- HQ Rome