East Asian Young Astronomers Meeting 2017
Nov. 13 - 17, 2017
ART HOTEL ISHIGAKIJIMA, Ishigaki city, Japan

Masashi Omiya
National Astronomical Observatory of Japan& AstroBiology Center

East-Asian collaboration
to search for planets around giants
1. EAPS-Net (East-Asian Planet Search Network)
2. Summary of Korean-Japanese Planet Search
3. Current results and future of the Network
4. Summary

Mass of planet host stars
Extrasolar planets : > 3600

Frequency- Detected around solar type stars- We don’t know the enough number ofplanets around massive stars- Host star mass dependence of theplanetary systems is key factor tounderstand planet formation scenario.
- But it is NOT easy to search for planets
around massive stars…

Mass of a host star (solar mass)
2

Luminosity

Log L/L

Dwarfs or Giants ?

9200K
1.3 L
2R

Effective temperature Log Teff (K)3Luminosity

Log L/L

Dwarfs or Giants ?
D

Difficult

OK

9200K
4900K
1.3
1.5 LL
27-10
R R

Effective temperature Log Teff (K)4Luminosity

Log L/L

Dwarfs or Giants ?
D“Intermediate-mass giant stars”
DifficultOwith 1.5-5 solar masses

K- Many absorption lines in their spectra- Many sample stars in this category- Bright enough to observeby the high dispersion spectroscopy
9200K
4900K
1.3
1.5 LL using 1-2m class telescopes
27-10
R =>
R precise RV measurements with
precisions of 1-3m/s

Effective temperature Log Teff (K)5

Why East-Asian collaboration ?
• The East-Asian Planet search Network, EAPS-Net• precise RV monitoring to search for planets around MANY giant stars• Using the 2m-class telescopes in East-Asia• Sample stars of the planet search : >700 in total• Need to observe many times and long term monitoring• Planet search program in the collaboration between researchers in Koreaand Japan• To search for planets around intermediate-mass giant stars with mass
es of 1.5-5 solar masses• Using BOAO 180cm and OAO 188cm telescopes for precise RV
measurements• Target : 190 late-G - Early K type giants (V=6.2-6.5) fainter thanOkayama planet search program

Goal: To understand the planetary systems and theirformation scenario around intermediate-mass giants
6East-Asian Planet Search Network-p

EAPS-Netp 9p
47

2 N JKA G9IN1)

B&NJ

p I GJI
p ( 47N N JI 929
IN/

p 3J OI
p (0 47I 9KN A G 2 N JIJ
9IN
1- ,. &929 6 K I
Giant planets-p&pp
p T35 27
O
p , 47INp-

8 N JI G 9-,(&B-

BaroundGiant stars

NJ

NJ

929

929

7Bohyunsan Op,cal Astronomy Observatory (BOAO)
1.8m telescope + BOES (with Iodine cell)
BOES: BOhyunsan Echelle spectrographResolution: R=λ/Δλ~50,000
Wavelength range: 3800~9000Å
Fine day ratio: ~30 % (2005/1-2016/6)
Precision: ~8 m/s (S/N~150photons/pix@5,500Å
Number of Sample: 80 stars + α
1.88m telescope + HIDES (with Iodine cell)
HIDES: High Dispersion Echelle SepctrographResolution: R=λ/Δλ~65,000
Wavelength range: 3850~7500Å
Fine day ratio: ~50 % (2005/1-2016/6)
Precision: ~5 m/s (S/N~150photons/pix@5,500Å
Number of Sample: 110 stars + β

Okayama Astronomical Observatory (OAO)
8Gas cell (I2) technique

RVmeasurements λ Precision
λΔλ  ǍButler
et al.1996ǎ• Calibration: Iodine cell
• Observed with an Iodine:ŜǂƙþƀƭǉƺǆǋƯ
cell• Kambe+02, Kim+07:ŜªƀƭǉƺǆǋƯ• Analysis: Modeling techniqueŜŜǍŏ,ĜĊƦƼƟƯǅǎ• Model the observed spectra:ŜªǏǂƙþƀƦƼƟƯǅfrom templates• Fit the model spectra to:ŜInstrumental
the observedProfile
spectra• Sato+02, 12→v = cΔλ/λ• Calculate a RV for eachsegment with ~3ÅMarcy & But
Valenti et al.
Butler et al. (Gas cell template (Iodine absorption lines)

Stellar template
Model (dots) & Observation (line)
Residuals

SNR =200 foƬƺǃǋƤƸƯżIPŦƵǃǀǋƫ• Precision of RVsƁ5Ǘ10ƀƞƙƤƗǉƔāƈDƓŲźǁƮǅ4• OAO >3 m/sƼƟƯǅƔ¡Ŕóƀ¡100ƀƨƠǀǉƯſ5-ŷźĜ¸Marcy & Butler 1992, Valenti et al. 1995
• BOAO >8 m/s (Omiya+09)

Butler et al. 1996, Sato et al. 2002
9

Strategy of the planet search
1. Observe the RVs and spectra of each original sample• To screen planet candidates with large RV variations• Sample: 80 stars (BOAO), 110 stars (OAO)• Determine stellar properties• mass, radius, abundance, chromospheric activity
etc.
2. Follow-up the planetary candidates by both observatories• To determine the orbital parameters of planets quickly• To check false positive of the planetary signals
3. Monitor the long time RVs of the samples10

RV variations of BOAO sample
Typical jitter: 10-30 m/s
Planet candidates: 28 stars
Binary candidates: 12 stars

Number of stars

RV jitter and planet candidates

Number of stars

RV jitter (without the orbital fit) m/s
RV variations of OAO sample
Typical jitter: 10-20 m/s
Planet candidates: 23 stars
Binary candidates: 19 stars
RV jitter (without the orbital fit) m/s
11

A substellar companion

Omiya et al. 200912

A planetary companionOmiya et al. 200913

Slope (m s 1 day 1 )10 Nobsrms (m s 1 )5of the RV for OAO observations were about 5 m s 1 , those of
he BOAO observations were about 20 m s 1 . We note that therms scatter of the RV residuals is 24.2 m s 1 , which is adequatelyarger than the typical RV uncertainty.

15

Planetary companions
0Lomb−Scargle PowerG. Jeong et al.: Detections of planetary companions around K giants

ar parameters for the giant stars analyzed in the present paper.

Spectral typemv (mag)B-V (mag)100
RV (km s 1 )⇡ (mas)T e↵ (K)0[Fe/H]log g (cgs)vmicro (km s 1 )Age (Gyr)−100R (R )
BOAO
M (M)
OAO
L (L)
−200 vrot sin i (km s 1 )Prot / sin i (days)

K0
6.584 ± 0.001
1.011 ± 0.006
15.80 ± 0.25
8.44 ± 0.514869 ± 28
0.14 ± 0.05
3.02 ± 0.09
1.20 ± 0.10
1.35 ± 0.18
8.56 ± 0.33
2.00 ± 0.08
46.17
2.7
158.9

HD 111591

HD 113996
HD 40956
K0 IIIK5 III6.594 ± 0.001
4.918 ± 0.001
1.002 ± 0.002
1.482 ± 0.003
5.67 ± 0.17
15.72 ± 0.01
9.22 ± 0.47
9.84 ± 0.224884 ± 304181 ± 40
0.07 ± 0.04
0.13 ± 0.08
3.10 ± 0.10
1.86 ± 0.16
1.23 ± 0.11
1.53 ± 0.14
1.41 ± 0.14
3.24 ± 1.20
8.03 ± 0.49
25.11 ± 1.20
1.94 ± 0.07
1.49 ± 0.18σ(O−C)
38.07 = 24.2 (m/s)
291.00
3.1
3.3
130.5
389.9

50
0(1) van Leeuwen(2007); (2) Anderson & Francis (2012); (3) This work.
−50
4000

4500

500055006000

al parameters for three exoplanets JD−2450000 (days)

6500

7000

200Ref.
111213333333233100

RV (m/s)

HD 40956

10HD 40956 bHD 111591 ba (AU)
Slope (m s 1 · yr 1 )Nobsrms (m s 1 )1.4 ± 0.1
-13 ⇥ 10 25421.12.5 ± 0.1–
4421.9HD 111591

5015−100BOAO 10OAO−200σ(O−C) = 21.9 (m/s)

55000−502
G. Jeong et al.: Detection of planetary companions around10K giants

3500

4000

4500

Table 1. Stellar parameters for the giant stars analyzed in the present paper.

Parameter

HIPP

150O−C (m/s)

Parameter

O−C (m/s)

RV (m/s)

200-3.1 ⇥ 10 258
24.2

Parameter

HD 113996 bHD 40956

5000

35500

6000

6500 107000

JD−2450000 (days)Period (days)

HD 111591

HD 113996

Ref.

K0 III6.594 ± 0.001
1.002 ± 0.002
108.12 ± 5.51
5.67 ± 0.17
9.22 ± 0.474884 ± 30
0.07 ± 0.04
3.10 ± 0.10
1.23 ± 0.11
1.41 ± 0.14
8.03 ± 0.49
1.94 ± 0.07
38.07
3.1
130.5

K5 III
4.918 ± 0.001
1.482 ± 0.003
101.57 ± 2.23
15.72 ± 0.01
9.84 ± 0.22
4181 ± 400.13 ± 0.08
1.86 ± 0.16
1.53 ± 0.14
3.24 ± 1.20
25.11 ± 1.20
1.49 ± 0.18
291.00
3.3
389.9

3
3233

1Fig. 2. (Top) the RVs of HD 40956 observed at BOAO (bluedots)
Fig. 5.
(Top) the RVs of the HD 111591
observed at BOAO (1P (days)
578.6 ± 3.3
1056.4 ± 14.3
1Fig.
4.
The
L-S
periodogramsof the orbital
RV mfiand OAO(magentadiamonds).
is exhiband OAO (magenta diamonds).
A Keplerian
2K (ms 1)
68 ± 2 A Keplerian
59 ± 3orbital fitdots)
2
T periastron(JD)line. (Bottom)
2455341.88 ±the11.07RV
2455602.40± 30.85
HIPPARCOS
photometries(mid1
ted by thesolid
residuals
after subtracting
exhibited by residuals
the solid (top),line. (Bottom)
the RV
residuals aftere
0.24 ± 0.05
0.26 ± 0.10
3bisectors ofmodel
the spanandcurvature(bottom)3
he companion
model acquiredby the orbitalfit.
! (deg)338.62 ± 7.74
78.72 ± 11.94
tracting the companion
acquiredby the orbital
fit. fo3
m sin i (MJ )2.7 ± 0.6
4.4 ± 0.4
3
vertical dashdot line indicatesa period of 573 d
3Spectral typeK0
mv (mag)
6.584 ± 0.001
610.2B-V± (mag)3.8
1.011 ± 0.006
117.97 ± 7.08
120 ±d (pc)9
RV (km s 1 )15.80 ± 0.25
2453309.94⇡ (mas)± 23.67 8.44
± 0.510.28 ±T0.12
4869 ± 28e↵ (K)[Fe/H]
0.14 ± 0.05
92.06 ±
17.25
log g (cgs)3.02 ± 0.09
16.3vmicro± 1.0(km s )1.20 ± 0.10(Gyr)1.35 ± 0.18
1.6 ±Age0.1
R? (R )
8.56 ± 0.33
–M? (M )2.00 ± 0.08
L(L)
46.17
62 ?
vrot sin i (km s 1 )
2.7
P39.3
158.9
rot / sin i (days)

Jeong et al. 2017

The periodogram of the HIPPARCOS mea
References.— (1) van Leeuwen (2007); (2) Anderson & Francis (2012);(3) This work.
BOAO
HD 111591
no correlations
with RV variations(middlep14
OAO

Companion mass
M (sin i) (MJupiter)

Planetary systems around giants

All planets
Intermediate-mass giant stars
with 1.5-5 solar masses- Many cool giant planets- a few supper Earths

Semi-major axis AU15

GiantPlanet
planetfraction
Fraction, f(M,F)

Occurrence rate of planetary companions
0.4

0.3

0.2

Observed Fraction
Kennedy & Kenyon (2008)

Johnson+10çSubgiantsèçMain sequence starsè..èç----Giants?
Too noisy ?

èThis work
Reffert+15
+ OAO planet searches&Reffert+15

0.1
0.0
0.0

Giants+

ç..-

0.5

1.0
1.5
Stellar Mass [M ]Stellar mass (MSun)

2.0

FIG. 4.—Planet fraction (f ¼ N planets =N stars ) as a function of mass for our
Occurrence
rates
of giant
planets
withsemimajor
axis of<3AU decrease with increasing stellar
stellarsample (grayhistogram).
The
red filledcircles
show the planet
fractionmass>2.0M
stars.
predicted
by eq.in(1)for theSun
massesand metallicities of the stars in each histogram
Our
consistent
results of Reffert
2015.
bin. Notethatresult
we use isa histogram
onlywithfor visualization
purposes;ettheal.
data
wereLong without
period binning.
planetsThemay
be fruitfulstars.
fitted directly
open
diamondsaroundshow themassive
best-fitting
relaless fraction
massive< 3M
tionshipNOTICE:
between planet
andgiantstellarplanets
mass forwith½Fe=H%¼ 0.Jupiter
The cannot
dashed be detected around massive stars.
line shows the stellar-mass relationship predicted by Kennedy & Kenyon
17Collaboration in East-Asia• East Asian Planet Search Network• Annual meeting in Japan, China, Korea• precise RV surveys in this network• To increase a number of sample stars in the surveys(planet search programs)• Future collaboration using planet hutting machines inEast-Asia• Planet searches at 2m class telescope at OAO, BOAO,
Xinglong observatories• New searches with HDS, IRD at the Subaru telescope• Plan to construct a new high dispersion spectrographfor the new 3.8m telescope at the Okayama observatory18Telescopes and planet hutting machines
in Our Network
OAO 1.88m

BOAO 1.8m

Xinglong 2.16m

NAOJ
High Dispersion Spectrograph(HDS)
Kyoto-Okayama 3.8m ?

InfraRed Doppler (IRD)

Subaru 8.2m
19Summary of my talk
• East-Asian Planet search Network (EAPS-Net)• Monitor RVs of ~700 GK-type giants in Japan, Korea, andChina for 10 years• published many planets, candidates and some substellar
companions• Recently two Jovian-mass planets (Jeong+17)• Continue our collaboration with a new strategy and newinstruments• Properties of the planetary companions aroundintermediate-mass giant stars• Many cool giant planets• Frequency of planets around high mass stars is low?
It is different from planetary systems around solar type stars?
2021