FIRST SPECTROSCOPIC INVESTIGATION OF A MICROLENSING EVENT: NO EVIDENCE FOR THE BINARYI. BOISSE (LAM), A. SANTERNE (IA), J.-P. BEAULIEU (IAP), B. ROYA-AYALA (IA),C. RANC, N.C. SANTOS, V. BATISTA, D. BENNETT, E. SCHLAWIN, J.B. MARQUETTE, S. SOUSA, R. DIAZ, J.-M. ALMENARA, D. JAMES, T. HERTER

Introduction

V

J

E

U

S

N

30 cm/s

3 m/s

1 m/s

RV

Imaging

Transit

!-lensing

from exoplanet.eu and exoplanet.orgJune 2014

OGLE-2011-BLG-0417

Shin et al. 2012Binary system

OGLE-2011-BLG-0417Characteristics

Lens Source

K3 red giant8 kpc

binary M dwarfs0.95 kpcI = 16.3

I = 16.74V = 18.23 V = 19.42

OGLE-2011-BLG-0417Characteristics

Lens Source

K3 red giant8 kpc

binary M dwarfs0.95 kpcI = 16.3

I = 16.74V = 18.23 V = 19.42

OGLE-2011-BLG-0417Gould et al. 2013Predicted RV curve

OGLE-2011-BLG-0417Gould et al. 2013Predicted RV curve

Several km/s

OGLE-2011-BLG-0417Gould et al. 2013Predicted RV curve

Several km/s

P = 1.42 yr

OGLE-2011-BLG-0417Gould et al. 2013Predicted RV curve

Several km/s

P = 1.42 yr

Phase is lost

ObservationsUVES @ VLT, ESO

ObservationsUVES @ VLT, ESO

Crowded field

ObservationsUVES @ VLT, ESO

Crowded field

10 spectra of ~1h

SNR ~ 20 (550nm)

ObservationsUVES @ VLT, ESO

Crowded field

10 spectra of ~1h

SNR ~ 20 (550nm)

1” slit: R~40 000

ObservationsUVES @ VLT, ESO

Crowded field

10 spectra of ~1h

SNR ~ 20 (550nm)

1” slit: R~40 000

Th-Ar calib before and after exposures

Data reductionReduced with Reflex (ESO)

Data reductionCCF with K5 maskReduced with Reflex (ESO)

�80 �60 �40 �20 0 20 40 60 80Radial velocity [km.s�1]

0.75

0.80

0.85

0.90

0.95

1.00

1.05

CC

Fco

ntra

st

source lens

3300 – 4500 A

4800 – 5800 A

5800 – 6800 A

Data reductionCCF with K5 maskReduced with Reflex (ESO)

�80 �60 �40 �20 0 20 40 60 80Radial velocity [km.s�1]

0.75

0.80

0.85

0.90

0.95

1.00

1.05

CC

Fco

ntra

st

source lens

3300 – 4500 A

4800 – 5800 A

5800 – 6800 A

Data reductionCCF with K5 mask

(V-I) = 1.93 ; (V-I) = 2.68sourcelens

Reduced with Reflex (ESO)

�80 �60 �40 �20 0 20 40 60 80Radial velocity [km.s�1]

0.75

0.80

0.85

0.90

0.95

1.00

1.05

CC

Fco

ntra

st

source lens

3300 – 4500 A

4800 – 5800 A

5800 – 6800 A

Data reductionCCF with K5 mask

(V-I) = 1.93 ; (V-I) = 2.68sourcelens

Reduced with Reflex (ESO)

Bluer lens

�80 �60 �40 �20 0 20 40 60 80Radial velocity [km.s�1]

0.75

0.80

0.85

0.90

0.95

1.00

1.05

CC

Fco

ntra

st

source lens

3300 – 4500 A

4800 – 5800 A

5800 – 6800 A

Data reductionCCF with K5 mask

(V-I) = 1.93 ; (V-I) = 2.68sourcelens

Reduced with Reflex (ESO)

Bluer lens

lens source

Data reductionCorrected from BERV

Data reductionCorrected from BERV

Corrected from spectrograph drift (15 to 400 m/s in 1 h)

Data reductionCorrected from BERV

Corrected from spectrograph drift (15 to 400 m/s in 1 h)

But Variation of the illumination of the slit

Data reductionCorrected from BERV

Corrected from spectrograph drift (15 to 400 m/s in 1 h)

But Variation of the illumination of the slit

Corrected from RV telluric reference (O2 lines)

Data reduction

6550 6600 6650 6700 6750 6800 6850 6900 6950Time [BJD - 2 450 000]

�0.6

�0.4

�0.2

0.0

0.2

0.4

0.6

0.8

Rel

ativ

eR

V[k

m.s

�1]

lenssource

Data reduction

6550 6600 6650 6700 6750 6800 6850 6900 6950Time [BJD - 2 450 000]

�0.6

�0.4

�0.2

0.0

0.2

0.4

0.6

0.8

Rel

ativ

eR

V[k

m.s

�1]

lenssource

Stars RV share same systematics !

Data reduction

6550 6600 6650 6700 6750 6800 6850 6900 6950Time [BJD - 2 450 000]

�0.6

�0.4

�0.2

0.0

0.2

0.4

0.6

0.8

Rel

ativ

eR

V[k

m.s

�1]

lenssource

Stars RV share same systematics !

Used RV source as a reference for RV lens

Results

RMS = 94 m/s

6500 6600 6700 6800 6900 7000Time [BJD - 2 450 000]

40

42

44

46

48

50

52

54

Diff

eren

tialR

V(R

Vle

ns

-RV

sourc

e)[k

m.s

�1]

OGLE-2011-BLG-0417

predictedbest modelobserved

6500 6600 6700 6800 6900 7000

42.2

42.4

42.6

42.8

43.0

Results

RMS = 94 m/s

6500 6600 6700 6800 6900 7000Time [BJD - 2 450 000]

40

42

44

46

48

50

52

54

Diff

eren

tialR

V(R

Vle

ns

-RV

sourc

e)[k

m.s

�1]

OGLE-2011-BLG-0417

predictedbest modelobserved

6500 6600 6700 6800 6900 7000

42.2

42.4

42.6

42.8

43.0

Results

RMS = 94 m/s PASTIS validation tool

Diaz et al. 2014

6500 6600 6700 6800 6900 7000Time [BJD - 2 450 000]

40

42

44

46

48

50

52

54

Diff

eren

tialR

V(R

Vle

ns

-RV

sourc

e)[k

m.s

�1]

OGLE-2011-BLG-0417

predictedbest modelobserved

6500 6600 6700 6800 6900 7000

42.2

42.4

42.6

42.8

43.0

Results

RMS = 94 m/s PASTIS validation tool

Diaz et al. 2014Probability < 2 10 -7

Conclusion

Spectroscopic follow-up observations of microlensing event is possible

We don’t confirm the Gould et al. prediction

Boisse et al. 2015

Conclusion

Spectroscopic follow-up observations of microlensing event is possible

We don’t confirm the Gould et al. prediction

Boisse et al. 2015

Yee et al. 2015Recently same method on a different target

Conclusion

Bright component is most probably not the light from the lens

Spectroscopic follow-up observations of microlensing event is possible

We don’t confirm the Gould et al. prediction

Boisse et al. 2015

Yee et al. 2015Recently same method on a different target

Conclusion

Bright component is most probably not the light from the lens

Spectroscopic follow-up observations of microlensing event is possible

The lens is not detectable

We don’t confirm the Gould et al. prediction

Boisse et al. 2015

Yee et al. 2015Recently same method on a different target

Conclusion

Bright component is most probably not the light from the lens

Spectroscopic follow-up observations of microlensing event is possible

The lens is not detectable

We don’t confirm the Gould et al. prediction

High angular resolution observations planned

Boisse et al. 2015

Yee et al. 2015Recently same method on a different target

Keck AO imaging

No blend within 130mas

Probability to have another star within 130mas ~ 50ppm

Santerne et al. (submitted)

Spectral Energy Distribution

0.3 0.4 0.5 0.6 0.7 0.8 1.0 1.3 1.5 1.8 2.0 2.5Wavelength [µm]

10�18

10�17

10�16

10�15

Cal

ibra

ted

flux

[erg

.s�

1.c

m�

2.A

�1]

J H K

Santerne et al. (submitted)

Spectral Energy Distribution

0.3 0.4 0.5 0.6 0.7 0.8 1.0 1.3 1.5 1.8 2.0 2.5Wavelength [µm]

10�18

10�17

10�16

10�15

Cal

ibra

ted

flux

[erg

.s�

1.c

m�

2.A

�1]

Keck AO

J H K

Santerne et al. (submitted)

Spectral Energy Distribution

0.3 0.4 0.5 0.6 0.7 0.8 1.0 1.3 1.5 1.8 2.0 2.5Wavelength [µm]

10�18

10�17

10�16

10�15

Cal

ibra

ted

flux

[erg

.s�

1.c

m�

2.A

�1]

ARCoIRIS @ CTIO

Keck AO

J H K

Santerne et al. (submitted)

Spectral Energy Distribution

0.3 0.4 0.5 0.6 0.7 0.8 1.0 1.3 1.5 1.8 2.0 2.5Wavelength [µm]

10�18

10�17

10�16

10�15

Cal

ibra

ted

flux

[erg

.s�

1.c

m�

2.A

�1]

UVES @ VLT

ARCoIRIS @ CTIO

Keck AO

J H K

Santerne et al. (submitted)

SED analysisA simple model

Foreground star Source

Díaz et al. (2014) Santerne et al. (2015)

Interstellar extinction from Arôme & Lépine (2005)

Assumed K giant in the Bulge

Fitted extinction

Stellar tracks: Dartmouth (Dotter et al. 2008)

Stellar Atmosphere Models: BT-SETTL (Allard et al. 2012) Sa

nter

ne e

t al.

(subm

itted

)

Results

10�18

10�17

10�16

10�15

Cal

ibra

ted

flux

[erg

.s�

1.c

m�

2.A

�1]

Best model Foreground star Source

0.3 0.4 0.5 0.6 0.7 0.8 1.0 1.3 1.5 1.8 2.0 2.5Wavelength [µm]

�0.30.00.3

O-C

[mag

]

Santerne et al. (submitted)

Source giant

Foreground star 0.95 Msun 1.1kpc

The foreground star

0.4 0.5 0.6 0.7 0.8 1.0 2.0 3.0Lens distance [kpc]

0.4

0.6

0.8

1.0

1.2

1.4

Lens

mas

s[M

�]

Value of Gould et al. (2013)SED constraints

Lens total mass assuming ΘE = 2.44mas (Shin et al., 2012)

and Ds = 8.2 kpc

Santerne et al. (submitted)

Sanity checks (I)

10�18

10�17

10�16

10�15

Cal

ibra

ted

flux

[erg

.s�

1.c

m�

2.A

�1]

Best model Foreground star Source

0.3 0.4 0.5 0.6 0.7 0.8 1.0 1.3 1.5 1.8 2.0 2.5Wavelength [µm]

�0.30.00.3

O-C

[mag

]

I-band magnitude observed by OGLE

Santerne et al. (submitted)

Sanity checks (II)

6550 6555 6560 6565 6570 6575

Wavelength [A]

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Nor

mal

ised

flux

OGLE-417GJ825 (M0V)HD147513 (G5V)

5150 5160 5170 5180 5190 5200

Wavelength [A]

0.0

0.5

1.0

1.5N

orm

alis

edflu

x

H alpha

Mg triplet

HR spectrum of OGLE-417 is closer

from a G dwarf than a M dwarf

Lot of contamination from the source star

Source star

Santerne et al. (submitted)

ConclusionsRV observations rule out massive companion to the lens (Boisse, Santerne, Beaulieu et al., 2015)

SED analysis shows the lens primary is a G dwarf and not a M dwarf (Santerne, Beaulieu, Rojas Ayala et al., subm.)

ConclusionsRV observations rule out massive companion to the lens (Boisse, Santerne, Beaulieu et al., 2015)

SED analysis shows the lens primary is a G dwarf and not a M dwarf (Santerne, Beaulieu, Rojas Ayala et al., subm.)

SED characterisation of microlensing event is possible

ConclusionsRV observations rule out massive companion to the lens (Boisse, Santerne, Beaulieu et al., 2015)

SED analysis shows the lens primary is a G dwarf and not a M dwarf (Santerne, Beaulieu, Rojas Ayala et al., subm.)

The Astrophysical Journal, 755:91 (10pp), 2012 August 20 Shin et al.

Figure 2. Light curve of OGLE-2011-BLG-0417. Notations are same as in Figure 1.(A color version of this figure is available in the online journal.)

for thorough investigation of possible degeneracy of solutions.We choose of s⊥, q, and α as the grid parameters because they arerelated to the light curve features in a complex way such that asmall change in the values of the parameters can lead to dramaticchanges in the resulting light curve. On the other hand, the otherparameters are more directly related to the light curve featuresand thus they are searched for by using a downhill approach.For the χ2 minimization in the downhill approach, we use theMarkov Chain Monte Carlo (MCMC) method. Once a solutionof the parameters is found, we estimate the uncertainties of theindividual parameters based on the chain of solutions obtainedfrom MCMC runs.

To compute lensing magnifications affected by the finite-source effect, we use the ray-shooting method (Schneider &Weiss 1986; Kayser et al. 1986; Wambsganss 1997). In thismethod, rays are uniformly shot from the image plane, bentaccording to the lens equation, and land on the source plane.Then, a finite magnification is computed by comparing thenumber densities of rays on the image and source planes.Precise computation of finite magnifications by using thisnumerical technique requires a large number of rays and thusdemands heavy computation. To minimize computation, welimit finite-magnification computation by using the ray-shootingmethod only when the lens is very close to caustics. In theadjacent region, we use an analytic hexadecapole approximation(Pejcha & Heyrovsky 2009; Gould 2008). In the region withlarge enough distances from caustics, we use point-sourcemagnifications.

Table 2Limb-darkening Coefficients

Quantity MOA-2011-BLG-090 OGLE-2011-BLG-0417

ΓV 0.52 0.71ΓR 0.45 0.61ΓI 0.37 0.51Source type FV KIIITeff (K) 6650 4660vturb (km s−1) 2 2log g (cm s−2) 4.5 2.5

In the finite magnification computation, we consider thevariation of the magnification caused by the limb darkeningof the source star’s surface. We model the surface brightnessprofile of a source star as

Sλ = Fλ

πθ⋆2

!1 − Γλ

"1 − 3

2cos ψ

#$, (7)

where Γλ is the linear limb-darkening coefficients, Fλ is thesource star flux, and ψ is the angle between the normal to thesource star’s surface and the line of sight toward the star.The limb-darkening coefficients are set based on the source typethat is determined on the basis of the color and magnitude of thesource. In Table 2, we present the limb-darkening coefficientsused, the corresponding source types, and the measured de-reddened color along with the assumed values of the effective

6

Shin

et al

. (20

12)

An exceptionally long event (> 6months)

Strong degeneracies between Earth orbit, Lens & Source motions (+orbital motion)

Is there a planet after all ?

SED characterisation of microlensing event is possible