ogle-2003-blg-235/moa-2003-blg-53: a definitive planetary microlensing event david bennett...
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OGLE-2003-BLG-235/MOA-2003-BLG-53: A Definitive Planetary Microlensing
Event
David BennettUniversity of Notre Dame
Author List:I.A. Bond, A. Udalski, M. Jaroszynski, N.J. Rattenbury, B. Paczynski, I. Soszynski, L. Wyrzykowski, M.K. Szymanski, M. Kubiak, O. Szewczyk, K. Zebrun, G. Pietrzynski, F.Abe, D.P. Bennett, S. Eguchi, Y. Furuta, J.B. Hearnshaw, K. Kamiya, P.M. Kilmartin, Y. Kurata, K. Masuda, Y. Matsubara, Y. Muraki, S. Noda, K. Okajima, T. Sako, T. Sekiguchi, D.J. Sullivan, T. Sumi, P.J. Tristram, T. Yanagisawa, and P.C.M. Yock
(the MOA and OGLE collaborations)
Real-Time Lightcurve Monitoring is Critical!
• Ian Bond (IFA, Edinburgh) noticed a caustic crossing for this event on July 23, 2003.
• He contacted the telescope and requested additional images
• The requested images caught the caustic crossing endpoint.
• This caustic endpoint data is critical to the conclusion that a planet is required.
Lightcurve
OGLEalert
Definition of a Planet• Formed by core accretion? (with a rocky core)
– But we don’t know that this is how planets form!
– We aren’t even sure about Jupiter’s rocky core!
• Secondary Mass < 13 Mjupiter?– This is the Deuterium burning threshold for solar
metalicity, but why is that important?
– What if binary is a 0.08 M?• Mass ratio may only be 0.16!
– In the brown dwarf desert
• Planetary mass fraction < 0.03– In the brown dwarf desert
– Easily measured in a microlensing lightcurve!!
Lightcurve close-up & fit• Cyan curve is the
best fit single lens model 2 = 651
• Magenta curve is the best fit model w/ mass fraction 0.03 2 = 323
• 7 days inside caustic = 0.12 tE
– Long for a planet,– but mag = only
20-25%– as expected for a
planet near the Einstein Ring
Caustic Structure & Magnification PatternBlue and red dots indicate times of observations
Parameters:tE = 61.6 1.8 days
t0 = 2848.06 0.13 MJD
umin = 0.133 0.003
ap = 1.120 0.007 = 0.0039 0.007
q = /(1+ ) = 223.8 1.4t* = 0.059 0.007 days
or */E = 0.00096
0.00011
Alternative Models: ap < 1
2 = 110.4
tE = 75.3 days
t0 = 2850.64 MJD
umin = 0.098
ap = 0.926
= 0.0117
= -6.1t* = 0.036 days
Also planetary!
Alternative Models: ap < 1
2 = 110.4
tE = 75.3 days
t0 = 2850.64 MJD
umin = 0.098
ap = 0.926
= 0.0117
= -6.1t* = 0.036 days
Also planetary!
Alternative Models: ~ 180
2 = 40.15
tE = 76.0 days
t0 = 2847.09 MJD
umin = 0.100
ap = 1.064
= 0.0127
= 185.6t* = 0.034 days
Also planetary!
Alternative Models: ~ 180
2 = 40.15
tE = 76.0 days
t0 = 2847.09 MJD
umin = 0.100
ap = 1.064
= 0.0127
= 185.6t* = 0.034 days
Also planetary!
Alternative Models: Early 1st Caustic Crossing
2 = 7.37
tE = 58.5 days
t0 = 2847.90 MJD
umin = 0.140
ap = 1.121 = 0.0069 = 218.9t* = 0.061 days
Excluded by 2.7Adjust = 0.0039 0.007
to = 0.0039 0.011
Lens Star ConstraintsUsing Isource = 19.7
and V-I = 1.58,we conclude that the source is a bulge G dwarf of radius:
* = 520 80 as
Iblend= 20.7 0.4
Gives likelihood curve
Planetary Parameters in Physical Units
• Best fit lens distance = 5.2 kpc– 90% c.l. range is 2.3-5.4 kpc
• Best fit separation = 3.0 AU– 90% c.l. range is 1.3-3.1 AU
• Best fit stellar mass = 0.36 M
– 90% c.l. range is 0.08-0.39 M
• Best fit planet mass = 1.5 Mjup
– 90% c.l. range is 0.3-1.6 Mjup
• If lens star is a 0.6 M white dwarf– Dlens = 6.1 kpc– ap = 1.8 AU– Mp = 2.5 Mjup
Conclusions
1st definitive lensing planetary discovery
- complete coverage not required for characterization
Real-time data monitoring was critical!
S. Gaudi video