#1GLOBAL EDGE INSTITUTE TOKYO TECH току Pursuing Excellence Okayama and Subaru Planet Search Programs Bun'ei Sato Tokyo Institute of Technology Oct. 7-9 2009#2Searching for Planets around Evolved Intermediate-Mass Stars Understanding properties of planets as a function of stellar mass, evolutionary stage, etc. (c) Okayama Astrophysical Observatory#3Flux 0.5 Flux 0 0.5 1 Why Giants? of planet-hosting A4 V 0.52 0.54 Wavelength (um) log o E Sun 0.52 0.54 Wavelength (μm) 0.56 2 M 0.56 Flux 0.5 G9 III 0 0.52 0.54 0.56 Wavelength (um) 1.5 Ma 1 FGK dwarfs ~290 planets M dwarfs ~10 planets 4 3.9 3.8 3.7 3.6 3.5 log Teff#4East-Asian Planet Search Network ■Okayama 1.88m tel., Japan (EAPSNET) 300 GK giants (V<6), since 2001 ☐ 10 planets and 1 brown dwarf Xinglong 2.16m tel., China & Okayama 100 GK giants (V~6), since 2005 ☐ (1 planet and 1 brown dwarf) Bohyunsan 1.8m tel., Korea & Okayama 140 GK giants (V<6.5), since 2005 ☐ 1 brown dwarf Subaru 8.2m tel., Japan & EAPSNET >200 GK giants (6.5<V<7), since 2006 Several candidates Goal: ■TUBITAK 1.5m tel., Turkey ~100 planets 50 GK giants (V~6.5), since 2008 from 1000 stars#5RV Precision with OAO/HIDES Velocity (m/s) -40 -20 0 20 40 2001 2002 2003-2005 T Cet ORV~4m/s 2000 Short-term (weeks) precision is 2m/s (Kambe et al. 2008) 2006-2008 mean=-0.5 m/s stddev 6.2 m/s err_mean=4.7 m/s 5000 3000 4000 JD (-2450000)#6Discoveries from EAPSNET Star Name Sp. Type Stellar Stellar Planetary Semi- Eccen Metallicity Mass Radius Mass major tricity ([Fe/H]) (Mo) (Ro) (MJUP) Axis (AU) (dex) HD 119445 G6III 3.9 20.5 37.6 1.71 0.08 +0.04 ε Tau KO III 2.7 13.7 7.6 1.93 0.15 +0.13 11 Com G8 III 2.7 19 19.4 1.29 0.23 -0.28 81 Cet G5 III 2.4 11 5.3 2.5 0.21 +0.06 18 Del G6 III 2.3 8.5 10.3 2.6 0.08 -0.05 HD 104985 G9 III 2.3 11 8.3 0.95 0.09 -0.35 § Aql KO III 2.2 12 2.8 0.68 0 -0.18 14 And KO III 2.2 11 4.8 0.83 0 -0.24 HD 81688 KO III-IV 2.1 13 2.7 0.81 0 -0.34 HD 173416 G8 III 2.0 13.5 2.7 1.2 0.21 -0.22 6 Lyn KO IV 1.7 5.2 2.4 2.2 0.13 -0.13 HD 167042 K1 IV 1.5 4.5 1.6 1.3 0.10 +0.00#7OAO Velocity (m/s) 50 60 To be Submitted HD 210702 K e PRO = 351 d = 36.5 m/s = 0.04 -50 a = 1.2 AU Mp sin i=1.8 MJ Velocity (m/s) 0 ^-C (m/s) -50 g Og་ ༠g 100 OAO HD 0-C (m/s) -50 50 ॰ L = 0 + 5.4 m/s + PRO K e ла a = 1.1 AU = 338 d 47.6 m/s ⇒ 0.35 σ = 8.9 m/s M sin i=2.2 M, P -50 3200 3600 4000 4400 4800 5200 JD (-2450000) OAO HD 142091 P = 1211 d 50 K = 22.9 m/s e = 0.00 Velocity (m/s) 0-C (m/s) 0 -50 a = 2.5 AU 50 P M sin i=1.6 MJ σ = 4.3 m/s -50 2400 3200 4000 4800 JD (-2450000) All of these are subgiants with 1.5-1.7M and [Fe/H]=0.0-0.1 O#8Planet Frequency vs. Stellar Mass Johnson et al. (2007) (>0.8M JUP) 12 0.1-0.7Mo F dwarfs, G subgiants 1.3-1.9Mo 9% KM dwarfs G dwarfs 0.7-1.3M 2% 4% NHOSTS = 3 NSTARS = 169 N HOSTS NSTARS = 34 NHOSTS = 803 NSTARS = 9 101 < 2.5M JUP > 2.5M JUP % Stars with Planets 10 8 CO + 2 17% (5/30) GK giants GK giants 1.9-3M 3-5M 5% 0% (10/184) (0/61) 0.1 0.7 1.3 1.9 3.0 Stellar Mass [Mo]#9Msini (MJup) 0.1 Semimajor Axis 100 Inside of central star 10 ? 840 m/s, 2 M 1 0.01 0.01 10 m/s, 2 Mo Detection limit Red clump giants (1.7-3.9M) Primordially deficient? Engulfed by the central stars? 0.1 1 Semimajor Axis (AU) 10#10Planets vs. Metallicity In solar-type stars, more metal-rich stars are known to have more planets. In core-accretion scenario, solid cores of planets easily form in metal-rich circumstellar disks. In planet-hosting giants, however, no such metal-rich tendency has been seen so far. Efficient inward migration of planets in metal-rich disks or metallicity independent formation such as gravitational instability in disks or dilution by convective envelope? Relative Frequency Relative Frequency 0.26 Solar-type stars 0.2 .15 Ew/o planets 0.1 0.05 سیلسیلیلی w/ planets -0.5 0.5 [Fe/H Santos et al. 2004 0.4 Giant stars w/o planets] 0.3 (309) OAO Sample 0.2 w/ planets 0.1 (13) -1 -0.5 0 [Fe/H] 0.5 Takeda et al. 2008#11. What's next? Extending baseline beyond 3 AU • Continue OAO program BOAO?, Xinglong?? Enlarging samples to >1000 stars • Subaru survey + OAO, BOAO, Xinglong follow-up Focus on relatively short-period planets (P<1yr) Dedicated search for planets around >3M giants . • Most of the current targets are <3Mo • O Planet desert around >3Mo? → Omiya-san's talk Dedicated search for planets around [Fe/H] ~+0.2 giants#12Velocity (m/s) -50 50 50 0 Beyond 3 AU OAO/HIDES K = 32 m/s P = 3013 d Msini=4M JUP a=5AU Msini=4M JUP a=4AU Mosin i = 4 M JUP P a = 5 AU Preliminary σ = 9.4 m/s 2800 3200 3600 4000 4400 4800 JD (-2450000) Velocity (m/s) OAO/HIDES 50 50 0 K = 34 m/s P = 1626 d Frequency of planets beyond 3 AU strongly depends on snow-line -50 i Mosin 4 M == JUP a = 4 AU Preliminary σ = 9.7 m/s 2800 3200 3600 4000 4400 4800 JD (-2450000)#13Subaru/HDS Survey Three obs. each star in a half year to identify large RV candidates Follow up using 2m-telescopes in east-Asian countries - 40 @Okayama - a few @Xinglong, BOAO In 2006-2008, 200 stars have been screened and ~70 of them show large (>20m/s) RV variations. Toward 1000 stars in total#14Number of stars 0 RV Variatiions 20 70/200 show σRV=20-200 m/s →follow up 10 0 50 100 150 200 250 300 σ (m/s)#15Velocity (m/s) New Candidates 100 gg 50 0 -50 -100 Mosini=3.5M JUP P = 176 d a = 0.77 AU M e = 0.07 0-C (m/s) 80 80 σ = 9.8 m/s 0 -80 3800 4000 4200 4400 4600 4800 5000 JD (-2450000) 0-C (m/s) Velocity (m/s) -400 80 JUP Msini=3.5M Jup Blue: Subaru Red: OAO a=0.77AU 800 400 Mpsini=20M a = 1.3 AU Msini=20M JUP a=1.3AU P = 391 d JUP e = 0.22 い σ = 25.6 m/s • -80 3800 4000 4200 4400 4600 4800 5000 JD (-2450000)#16Summary • Nine years of the Okayama Planet Search Programs Nine planets, one BD, and several more candidates within 2.5AU Different properties of planets (frequency, mass, semimajor-axis, host-star's metallicity etc.) from those around solar-like stars • Future . Extending baseline beyond 3AU at Okayama Enlarging sample to >1000 stars Subaru survey + OAO, BOAO, Xinglong follow-up New dedicated planet searches