Studying cool planets around distant low-mass stars Planet detection by gravitational microlensing Martin Dominik Royal Society University Research Fellow.

Studying cool planets around distant low-Studying cool planets around distant low-mass starsmass starsPlanet detection by gravitational microlensingPlanet detection by gravitational microlensing

Martin DominikMartin DominikRoyal Society University Research FellowRoyal Society University Research Fellow

SUPA, University of St Andrews, School of Physics & SUPA, University of St Andrews, School of Physics & AstronomyAstronomy

(Part II)(Part II)

Bending of starlight by stars(Gravitational microlensing)

S L

angular Einstein radius

with ‘typical’ DS ~ 8.5 kpc and DL ~ 6.5 kpc

θE ~ 600 (M/M☉)1/2 asμ

)DL DS

DS−DLθE =(

1/24GM

c2

Bending of starlight by stars(Gravitational microlensing)

S L

(t-t0)/tE

tE ~ 40 (M/M☉)1/2 days

Notes about gravitational lensing dated to 1912 on two pages of Einstein’s scratch notebook

First reported microlensing event

MACHO LMC#1

Nature 365, 621 (October 1993)

Optical Gravitational Lensing Experiment

1.3m Warsaw Telescope, Las Campanas (Chile)

1.8m MOA Telescope, Mt John (New Zealand)

τ ~ 10-6 for microlensing event → ~1000 events alerted per year

daily monitor ≳ 100 million stars,

Current microlensing surveys (2007)

adapted from M. Dominik et al. (PLANET collaboration), 2000, P&SS 50, 299

Bending of light due to gravitational field

α =4GMc2ξ

t - t0 [d]

4GM✶

c2θE = )DL DS

DS−DL(1/2

Δm

ag

0.5

1

1.5

2.5

2tE = 40 d

0 50-50

planetary ‘blip’q = Mp/M✶, d = δ0/θE

0

t-t0 [d]adapted from M. Dominik et al. (PLANET collaboration), P&SS 50, 299 (2002)

Planet detection by microlensing

1-2% photometric precision

1.5 - 2.5 hr sampling

20 events at given time, 75 per season

6 events at given time, 20 per season

bright stars (giants):

fainter stars:

PLANET restricted (1999): ~ 3 fJ jupiters/year

M. Dominik et al. (PLANET collaboration) 2002, P&SS 50, 299

http://planet.iap.fr

PLANET full capability: ~ 15-25 fJ jupiters/year

MACHO/OGLE-II (1999): ~ 100 alertsOGLE-III/MOA (2006): ~ 1000 alerts

Jupiters between 0.6 and 1.6 rE:

~ 15% detected in A0 ≳ 1.34 events ~ 80% detected in A0 ≳ 10 events

A round-the-clock follow-up network

PLANET planet detection efficiency

preferred: m largea ~ 1— 4 AU

RS ~ (few km) und D ~ (few kpc)

gives rE = DLθE ~ (few AU)

duration Δt and probability of signal ~ q1/2

signal amplitude only reduced by finite angular radius θ of source star

for Δt ≲ 2 θ /μ

✶

✶

d = δ0/θE ~ 1 (“resonance”)

)DL DS

DS−DLθE =(

1/24GM

c2

preliminary

14 most favourable events from 2004 season

from 42 events well-covered by PLANET 1995-1999

f > f(d,q) ruled out at 95%

C.L.

1/41/3

1/22/3

3/4

M. Albrow et al. (PLANET collaboration), 2001, ApJ 556, L113

~ jupiter-mass

f < 1/3corresponds to

9 expectednone observed

First planetary abundance limits

C. Snodgrass, K. Horne, & Y. Tsapras 2004, MNRAS, 351, 967

Cumulated planet detection efficiency

q = 10-3

q = 10-4

m = mjup

2002 OGLE-III data - 321 events

~ 1.5 %

~ 3 %

Survey detection efficiency for planets

OGLE 2003-BLG-235MOA 2003-BLG-53

I. A. Bond et al. (MOA and OGLE collaborations), 2004, ApJ 606, L155

tE = 61.5 d, d = 1.12, q = 3.9 × 10-3, t✶ = 0.059 dθ✶ = (0.50 +/- 0.05) μas

M ~ 1.5 M♃

The first microlensing planet

A. Udalski et al. (OGLE, MicroFUN, MOA, and PLANET/RoboNet collaborations), 2005, ApJ 628, L109

OGLE 2005-BLG-071

close binarytE = 73.9 dd = 0.758

q = 6.7 × 10-3

wide binarytE = 70.9 dd = 1.294

q = 7.1 × 10-3

M ~ 3 M♃

.... and the second one

April 2004:“Earth-like

planet search to start”

Dominik: “If 20% of these stars are surrounded by planets, we expect to find 10-15 giant planets and one or two Earth-sized worlds within three years.”

From Jupiters to Earths

Stellar mass probed by microlensing

Ida S., Lin D. N. C., 2005, ApJ 626, 1045

Host stars and expected planet abundance

True-colour image composed from BVI taken with Danish 1.54m at ESO LaSilla(PLANET collaboration)

OGLE 2005-BLG-390

Zur Anzeige wird der QuickTime™ Dekompressor „YUV420 codec“

benötigt.

Image taken with Danish 1.54m at ESO LaSilla,

convolved with model light curve(animation by Daniel Kubas)

OGLE 2005-BLG-390

J.-P. Beaulieu et al. (PLANET/RoboNet, OGLE, and MOA collaborations),

2006, Nature, in press (26-Jan)

10-Aug

OGLE 2005-BLG-39031-Jul

J.-P. Beaulieu, D.P. Bennett, P. Fouqué, A. Williams, M. Dominik, and 68 others

(PLANET/RoboNet, OGLE, and MOA collaborations),2006, Nature 439, 437

source trajectory

Einstein ring

OGLE-2005-BLG-390 magnification map

map by Aarno Korpela, animation by Martin Dominik

Zur Anzeige wird der QuickTime™ Dekompressor „“

benötigt.

Mp = 5.5 M♁ (2.1), M✶= 0.22 M☉ (2.1),a = 2.9 AU (1.6), P = 10.4 yr (2.0),

DL = (0.85 ± 0.15) RGCμ= ✶/t✶= 7 mas/yr, θE = tE = 210θ asμμ

RP ~ 2.4 R♁, gP ~ 0.9 g♁ (for ρ= ♇)ρ

J.-P. Beaulieu, D.P. Bennett, P. Fouqué, A. Williams, M. Dominik, and 68 others,(PLANET/RoboNet, OGLE, and MOA collaborations), 2006, Nature 439, 437

M. Dominik, 2006, MNRAS 367, 669

Artist’s impression of OGLE-2005-BLG-390Lb © ESO

figure courtesy of K. Horne

Exoplanet discovery space

mic

role

nsi

ng

transits

radial

velocity

http://www.ibiblio.org/astrobiology(follows J. F. Kasting, D. P. Whitmire, R. T. Reynolds, 1993, Icarus 101, 108)

Approaching the habitable zone

informal consortium, involving amateur astronomersonly observe highly-promising close-alignment

events

OGLE 2005-BLG-169

M ~ 13 M♁

A. Gould et al., 2006, ApJ 644, L37

figure courtesy of K. Horne

Exoplanet discovery space (II)

Ida S., Lin D. N. C., 2005, ApJ 626, 1045

Distribution of planets (simulation) Microlensing detections

A. Cassan, D. Kubas, M. Dominik et al. (PLANET collaboration), in preparation

Average detection efficiency14 prime events - PLANET 2004

Detections and planetary abundance

RoboNet RoboNet 1.01.0

http://www.astro.livjm.ac.uk

2.0m robotic telescopes, funded by

Common PLANET/RoboNet microlensing campaign since 2005

5.5 M♁

1 M♁

simulated data

tE = 11.0 dd = 1.61

u0 = 0.359

LCO #1LCO #1LCO #1LCO #1 LCO #2?LCO #2?

simulated data

simulated data

tE = 11.0 dd = 1.61

u0 = 0.359

simulated data

tE = 11.0 dd = 1.61

u0 = 0.359

simulated data

tE = 11.0 dd = 1.61

u0 = 0.359

tE = 11.0 dd = 1.2

u0 = 0.359

Planet with 0.1 Earth masses

Microlensing live

continue

light curve plotter

SIGNALMEN

Optical Gravitational Lensing Experiment

RoboNet 1.0RoboNet 1.0

Future projects (I)Automated Robotic Terrestrial Exoplanet MIcrolensing

Search

M. Dominik, K. Horne, A. Allan, N.J. Rattenbury, Y. Tsapras, C. Snodgrass et al.

A possible expert-system based cooperative effort to hunt for planets of Earth mass and below

Future projects (II)

GAlactic BAR Infrared Time-domain Survey (GABARIT)A UKIRT Large Project Proposal

E. Kerins et al.

Planets detected by microlensing ( ) 2007 2008 2009 2010 2006

NOT The End