gliese 581 - a m dwarf with 3 very low-mass...

The search for planets around M dwarfsData analysis

Properties and constraints on planet formation

Gliese 581a M dwarf with 3 very low-mass planets

X. Bonfils1

1Centro de Astronomia e Astrofisica da Universidade de Lisboa, Portugal

2Laboratoire d’Astrophysique de l’Observatoire de Grenoble, France

3Observatoire de Genève, Switzerland

In the spirit of Bernard Lyot, UC Berkley, 2007

S. Udry, X. Delfosse, T. Forveille, M. Mayor, C. Perrier,

F. Bouchy, C. Lovis, F. Pepe, D. Queloz, J.-L. Bertaux

X. Bonfils Gliese 581



Outline

1 The search for planets around M dwarfsThe search with HARPSSensus

2 Data analysisRV dataKeplerian analysisPlanets vs. Stellar activity

3 Properties and constraints on planet formationHabitability in Gl 581’s planetsFew Jupiter-mass planets, many NeptunesPlanet-metallicity correlation ?




The search with HARPSSensus

The search with HARPS

Interests of M dwarfs! probe the planetary formation for different initial conditions! prime targets to detect lower-mass planets! HZ closer, rocky planets in HZ are easier to detect! favorable star/planet contrast for follow-up characterization

HARPS sampleN! = 100!t = 4 yearsNnights " 40!rv < 1m s!1




The search with HARPSSensus

Status

RV ProgrammesNTotal " 300 M dwarfsHARPS + ELODIE + Keck + Lick + UVES + HET

6 planets around 4 hosts

µ-lensing surveysrepresentative targetssee talks by J.-P. Beaulieu, D. Kubas & A. Cassan

4 planets, 4 hosts

0.01

0.1

1

10

Mp(s

ini)

[MJ

up]

Mp(s

ini)

[MJ

up]

100 101 102 103 104

P [days]P [days]




RV dataKeplerian analysisPlanets vs. Stellar activity

RV data

Gl 581M3 dwarf0.3 M"

6.3 pcmV = 10.6

Radial Velocity data50 RV measurementstexp = 900 s!RV " 0.9 m s!1

! "1.5 night of 3.6-m telscope

! = 9.58 m s!1

"2! = 120

!20

!10

0

10

20

RV!

<RV

>[m

s!1]

RV!

<RV

>[m

s!1]

53000 53250 53500 53750 54000 54250

Julian date !2,400,000 [day]Julian date !2,400,000 [day]

0

2000

4000

PSD

[arb

Hz!

1/2]

PSD

[arb

Hz!

1/2]

1 10 100 1000

Period [day]Period [day]





A hot Neptune...

1-planet Keplerian Model

Parameter Gl 581bP [day] 5.4e 0. (fixed)

" [deg] 0. (fixed)

K [m s!1] 13.2m2 sin i [M#] 16.6a [AU] 0.041

Bonfils et al. 2005, A&A 443 15

!20

!10

0

10

20

RV!

![m

s!1]

RV!

![m

s!1]

0 0.25 0.5 0.75 1""

!25

0

25

O!

C[m

s!1]

O!

C[m

s!1]

53000 53250 53500 53750 54000 54250


0

100

200

300

Pow

erPow

er

1 10 100 1000






... and two super Earths3-planet Keplerian Model

Parameter Gl 581 b c dP [day] 5.4 12.9 84e 0.02 0.16 0.20" [deg] 273 267 295K [m s!1] 12.5 3.0 2.5m2 sin i [M"] 15.7 5.0 7.7a [AU] 0.041 0.073 0.25

# (O-C) = 1.2 m s!1

!20

!10

0

10

20

RV!

![m

/s]

RV!

![m

/s]

53570 53580 53590 53600 53610

Julian date !2,400,000.0 [day]Julian date !2,400,000.0 [day]

Udry et al. 2007A&A in press.





The case of GJ 674! = 0.82 m s!1

"2 = 2.57

!10

0

10

RVpl

anet

1[m

s!1]

RVpl

anet

1[m

s!1]

!10

0

10

RVpl

anet

2[m

s!1]

RVpl

anet

2[m

s!1]

0 0.25 0.5 0.75 1##

!5

0

5

O!

C[m

s!1]

O!

C[m

s!1]

53000 53250 53500 53750 54000



Parameter GJ 674b GJ 674cP [day] 4.7 35e 0.2 0.2" [deg] 143 113K [m s!1] 8.70 5.06m2 sin i [M#] 11.1 12.6a [AU] 0.039 0.147





The case of GJ 674PhotometryPvar " 35 days# 2nd signal is likelycaused by a spot

!F = !0.013 sin(2!/35.68 + 54259.93)

0.98

0.99

1

1.01

1.02

Rel

ativ

eflu

xR

elat

ive

flux

53980 53990 54000 54010 54020 54030


0

200

400

PSD

[arb

Hz!

1/2]

PSD

[arb

Hz!

1/2]

1 10 100 1000


H! Ca II H+K!5

0

5

RV[m

/s]

RV[m

/s]

0 1 2 3 4 5IndexIndex

H!

Ca II H+K

0

1

2

3

4

5

Inde

xIn

dex

0 0.2 0.4 0.6 0.8 1""

H!

0

10

20

Pow

erPow

er

Ca II H+K

0

10

20

Pow

erPow

er

1 10 100 1000


Spectral IndicesPvar " 35 days# signal @ 35 days is likely a spot





The case of GJ 674! = 0.82 m s!1

"2 = 2.57

!10

0

10

RVpl

anet

1[m

s!1]

RVpl

anet

1[m

s!1]

!10

0

10

RVpl

anet

2[m

s!1]

RVpl

anet

2[m

s!1]

0 0.25 0.5 0.75 1##

!5

0

5

O!

C[m

s!1]

O!

C[m

s!1]

53000 53250 53500 53750 54000



Parameter GJ 674b SpotP [day] 4.7 35e 0.2 0.2" [deg] 143 113K [m s!1] 8.70 5.06m2 sin i [M#] 11.1 12.6a [AU] 0.039 0.147

Bonfils et al. 2007 A&A in press.





The very-low activity level of Gl 581

Low rotationv sin i < 1 km s!1

# low Prot

Spectroscopic indicatorsa very low Ca II emissionwith no significant variation at any period

#low Prot & low spot coverage

PhotometryKs[m s!1] " 6.5 f 0.9

s v sin i(Saar & Donahue 1998)

P " 84 days computed observedGJ 674 1.7% 2.6%Gl 581 2.6% < 1%

0

2.5

5

7.5

10

12.5

Flu

x[a

rb.

unit

]Flu

x[a

rb.

unit

]

3962.5 3965 3967.5 3970 3972.5 3975

Wavelength [A]Wavelength [A]

Gl 581

GJ 674




Habitability in Gl 581’s planetsFew Jupiter-mass planets, many NeptunesPlanet-metallicity correlation ?

Habitability in Gl 581’s system

Temperature estimates

Tp(A=0.6) Tp(A=0.3)Gl 581c 270 $ 320 KGl 581d 150 $ 170 K

greenhouse likely increases Tp

Tp highly dependent ofatmosphereneed direct obs. from von Bloh et al. (2007)

# we have started to probe the mp and the Tp ranges of habitable planets





Few Jupiter-mass planets, many Neptunes

Few Jupiter-mass planets...FGK: "1% have hot Jupiter,

4$5% have at least a massive planet with P < 1500 daysM dwarfs: No hot Jupiter,

only 1 system with giant planets (P < 1500 days)

P(d = 1; N! = 300; fp = 4%) < 10!6

# a deficit of Jupiter-mass planets

...many Neptunes

0 hot Jupiter4 hot Neptunesfor "300 targets

# hot Neptunes are more frequentthan hot Jupiter (confidence level = 97%)

Bonfils et al. 2007





Planet-metallicity correlation ?

0

2.5

5

7.5

10

NN

0

0.25

0.5

0.75

1

Cum

ulat

ive

frac

tion

Cum

ulat

ive

frac

tion

!0.75 !0.5 !0.25 0 0.25

[Fe/H][Fe/H]

[Fe/H] distribution of hostsw/ planets: <[Fe/H]>= $0.08dex/w planets: <[Fe/H]>= $0.18dex

! ! <[Fe/H]>= 0.1dexKS-test = 11%note that hots of giant planetsoccupy the high-[Fe/H] tail

Bonfils et al. 2005, 2007


Conclusion

Conclusion

M dwarfs are great targetsbut take care of the stellar activity

with them,we have started to probe the telluric planets in the HZand we already have constraints on planetary formation


gliese 581 - a m dwarf with 3 very low-mass...

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