Upload
oscar-benson
View
218
Download
0
Embed Size (px)
Citation preview
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
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
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
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
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
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.