Sato

Search for Planets aroundG-type Giants with EAPSNET: 

Search for Planets around G-type Giants with EAPSNET Bun’ei Sato Okayama Astrophysical Observatory National Astronomical Observatory of Japan

Contents: 

Contents Motivation of G giant planet search Current status of EAPSNET (East Asian Planet Search NETwork) Okayama (Japan: HIDES) Bohyunsan (Korea: BOES) Xinglong (China: CES) Results from EAPSNET

Why G Giants?: 

Why G Giants? Solar-type (many known planets) G-type Giants Massive stars 1.5-5 M。 B A F G 　Doppler × 　 few lines, rapid rot. Doppler ○ 　many lines, slow rot. K,M Giants (large intrinsic variability) (stable) R~10-20R。 G giants are massive stars in evolved stages Sharp absorption lines Low surface activity Good targets for Doppler planet search Massive stars on M.S. (early-type O-A stars) :broad and few lines

Motivation: 

Motivation G giants are intermediate-mass (1.5~5Msun) stars in evolved stages How common are planetary systems? Many young B, A stars have proto-planetary disks (HAEBE stars) few planet searches targeting massive stars (O-A type stars, andgt;1.5Msun) Dependence of properties of planets on host stars’ mass More massive stars have more planets and more massive planets? Suppressed by strong radiation from early-type host stars? Constrain timescale of planet formation Lifetime of proto-planetary disk around massive stars are shorter than those around lower mass stars Evolution of planetary systems How do planetary systems react to the red giant phase?

East Asian Planet Search NETwork(EAPSNET): 

East Asian Planet Search NETwork (EAPSNET) Japan Okayama 1.88m Bohyunsan 1.8m Xinglong 2.16m China Korea

EAPSNET: 

EAPSNET Okayama 1.88m HIDES + I2 Cell since 2001 350 G giants (Vandlt;6) Sato et al. precision:4~6m/s 80 nights/year Bohyunsan 1.8m BOES + I2 Cell since 2005 140 G giants (Vandlt;6.5) Han, Lee, Yoon, et al. precision:~10m/s 1.5 nights/month Xinglong 2.16m CES + I2 Cell since 2005 100 G giants (V~6) Liu, Zhao, et al. precision:15~25m/s 35 nights/year Japan Korea China

Okayama, Japan: 

Okayama, Japan HIDES (HIgh Dispersion Echelle Spectrograph) Coude focus of 1.88m Tel. 5,000-6,100Å R~70,000 (Max. 110,000) S/Nandgt;200 (for Vandlt;6 within 30 min. exposure) RV Measurements Iodine cell installed in 2001 (Kambe et al. 2002, Sato et al. 2002) Short-term precision: 4m/s Long-term precision: 6~7m/s 350 G-giants since 2001

Iodine Cell: 

Iodine Cell HIDES stellar line I2 line Superpose a reference Iodine spectrum onto stellar spectra

RV Analysis: 

RV Analysis I2 lines are used as a wavelength standard and as a reference to correct for the instrumental profile (IP). Ｉ（λ）＝ｋ［Ａ（λ）Ｓ（λ＋Δλ）］＊ＩＰ　(Butler et al.1996) A(λ) : I2 template S(λ) : star template I(λ) : star+I2 spectrum →　v = cΔλ/λ Doppler shift of star IP : modeled with Gaussians

RV Precision: 

RV Precision Doppler precision: 6~7 m/s (~5 yrs) ιPer (G0V) ρCrB (G0Va) P=40d K=64m/s

Bohyunsan, Korea: 

Bohyunsan, Korea BOES (BOhyunsan Echelle Spectrograph) 1.8m Tel. + fiber feed 3,500-10,500Å R~44,000 (Max. 90,000) S/Nandgt;200 (for Vandlt;6.5 within 30 min. exposure) RV Measurements Iodine Cell Long-term precision: ~10 m/s 140 G-giants since 2005

Xinglong, China: 

Xinglong, China CES (Coude Echelle Spectrograph) Coude focus of 2.16m Tel. 3,500-7,300Å(Δ~420Åused for RV measurements) R~40,000 (Max. 100,000) S/Nandgt;100 (for Vandlt;6 within 30 min. exposure) RV Measurements Iodine Cell installed in 2004 Long-term precision: ~25 m/s 100 G-giants since 2005

RV Stability of G giants: 

RV Stability of G giants Histogram of the RV dispersions for OAO 300 targets Observed RV dispersions plotted against MV σ～10 m/s large RV scatter σ～50m/s small RV scatter σ＜20m/s

Stable G giants: 

Stable G giants

Long-term Trends: 

Long-term Trends

First Planet from Okayama: 

First Planet from Okayama HD104985 (G9III) P (d) 198.3 K1 (m/s) 163 e 0.06 M1(M。) 2.3 mpsini (MJ) 8.1 a (AU) 0.88 rms (m/s) 24.9 (Sato et al. 2003, ApJ, 597, L157)

Planet Candidates from Okayama: 

Planet Candidates from Okayama M2sini =9.4MJ, a=2.3AU, e=0.0 M2sini =7.4MJ, a=3.4AU, e=0.6 M2sini =3.4MJ, a=2.1AU, e=0.35 M2sini =4.4MJ, a=0.8AU, e=0.08

Preliminary Statistics from Okayama: 

Preliminary Statistics from Okayama Frequency, Period ~15 stars (5%) show RV variations with K1andgt;50m/s (andgt;3MJ) and with P=60~1000d  in F-K dwarfs, ~1% have planets with andgt;5MJ  in M dwarfs, less than 1% have Jupiter-mass planets Eccentricity relatively small? e=0~0.6  in solar-type stars, massive (andgt;5MJ) planets tend to have large eccentricity Metallicity relatively low? (HD104985[Fe/H]~-0.15) planets formed in massive disks even if low metallicity?

Brown Dwarf Candidate from Korea-Japan Collaboration: 

Brown Dwarf Candidate from Korea-Japan Collaboration First result from Korea-Japan collaboration Orbital parameters P = 417 d K1 = 409 m/s e = 0.08 M2 sin i = 24 MJUP a = 1.4 AU (assume M1 = 2 MSUN) OAO/HIDES BOAO/BOES

EAPSNET with Subaru: 

EAPSNET with Subaru HDS (High Dispersion Spectrograph) Nasmyth focus of 8.2 m Tel. 3,500-6,100Å R~55,000 (Max. 160,000) S/Nandgt;150 (for Vandlt;9 within 1 min. exposure) RV precision with I2 cell: ~3m/s Subaru G-giants survey starts in 2006 Survey a few hundreds stars (~7 mag) by Subaru 3 nights in 2006A Follow-up candidates by EAPSNET 1000 targets are near at hand !! (~50 planets expected) Mauna Kea@Hawaii

Asteroseismology at Okayama: 

Asteroseismology at Okayama Oscillations in Solar-type Stars (PI Kambe) Procyon etc. Oscillations in Early-type Stars (PI Kambe) βCep-type etc. Oscillations in Evolved Stars (PI Ando) G-type Giants Let’s do campaign!! Dr. Ando Dr. Kambe

Slide22: 

Thank you !!