Gliese 581 - a M dwarf with 3 very low-mass...
Transcript of 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
The search for planets around M dwarfsData analysis
Properties and constraints on planet formation
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 ?
X. Bonfils Gliese 581
The search for planets around M dwarfsData analysis
Properties and constraints on planet formation
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
X. Bonfils Gliese 581
The search for planets around M dwarfsData analysis
Properties and constraints on planet formation
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
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Mp(s
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100 101 102 103 104
P [days]P [days]
X. Bonfils Gliese 581
The search for planets around M dwarfsData analysis
Properties and constraints on planet formation
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
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RV!
<RV
>[m
s!1]
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X. Bonfils Gliese 581
The search for planets around M dwarfsData analysis
Properties and constraints on planet formation
RV dataKeplerian analysisPlanets vs. Stellar activity
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
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RV!
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0 0.25 0.5 0.75 1""
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O!
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s!1]
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s!1]
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X. Bonfils Gliese 581
The search for planets around M dwarfsData analysis
Properties and constraints on planet formation
RV dataKeplerian analysisPlanets vs. Stellar activity
... 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
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/s]
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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.
X. Bonfils Gliese 581
The search for planets around M dwarfsData analysis
Properties and constraints on planet formation
RV dataKeplerian analysisPlanets vs. Stellar activity
The case of GJ 674! = 0.82 m s!1
"2 = 2.57
!10
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RVpl
anet
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RVpl
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Julian date !2,400,000 [day]Julian date !2,400,000 [day]
2-planet Keplerian Model
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
X. Bonfils Gliese 581
The search for planets around M dwarfsData analysis
Properties and constraints on planet formation
RV dataKeplerian analysisPlanets vs. Stellar activity
The case of GJ 674PhotometryPvar " 35 days# 2nd signal is likelycaused by a spot
!F = !0.013 sin(2!/35.68 + 54259.93)
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H! Ca II H+K!5
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Period [day]Period [day]
Spectral IndicesPvar " 35 days# signal @ 35 days is likely a spot
X. Bonfils Gliese 581
The search for planets around M dwarfsData analysis
Properties and constraints on planet formation
RV dataKeplerian analysisPlanets vs. Stellar activity
The case of GJ 674! = 0.82 m s!1
"2 = 2.57
!10
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RVpl
anet
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s!1]
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0 0.25 0.5 0.75 1##
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Julian date !2,400,000 [day]Julian date !2,400,000 [day]
2-planet Keplerian Model
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.
X. Bonfils Gliese 581
The search for planets around M dwarfsData analysis
Properties and constraints on planet formation
RV dataKeplerian analysisPlanets vs. Stellar activity
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%
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Wavelength [A]Wavelength [A]
Gl 581
GJ 674
X. Bonfils Gliese 581
The search for planets around M dwarfsData analysis
Properties and constraints on planet formation
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
X. Bonfils Gliese 581
The search for planets around M dwarfsData analysis
Properties and constraints on planet formation
Habitability in Gl 581’s planetsFew Jupiter-mass planets, many NeptunesPlanet-metallicity correlation ?
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
X. Bonfils Gliese 581
The search for planets around M dwarfsData analysis
Properties and constraints on planet formation
Habitability in Gl 581’s planetsFew Jupiter-mass planets, many NeptunesPlanet-metallicity correlation ?
Planet-metallicity correlation ?
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!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
X. Bonfils Gliese 581