High Contrast Spectral Imaging:High Contrast Spectral Imaging:the Case of GQ Lupthe Case of GQ Lup

Michael McElwain (UCLA)Michael McElwain (UCLA) James Larkin (UCLA)James Larkin (UCLA) Stanimir Metchev (UCLA)Stanimir Metchev (UCLA) OSIRIS commissioning teamOSIRIS commissioning team

0.73”0.73”

GQ LupGQ Lup BB

Keck AO + OSIRIS

GQ Lup B – An Exoplanet GQ Lup B – An Exoplanet or a Brown Dwarf?or a Brown Dwarf?

1–2 1–2 MMJupJup planet? planet? VLT AO slit VLT AO slit

spectroscopy spectroscopy Neuhaüser et al. Neuhaüser et al.

(2005)(2005)

10–40 10–40 MMJupJup brown brown

dwarf?dwarf? Keck AO + OSIRIS Keck AO + OSIRIS

spectroscopyspectroscopy McElwain, Metchev, McElwain, Metchev,

Larkin et al., Larkin et al., ApJApJ, , acceptedaccepted

Discovery images of GQ Discovery images of GQ Lup A/BLup A/B

(Neuhaüser et al. 2005)

∆K = 6 mag

cTTS in Lupus 1; age 0.1–2 Myr(Hughes et al. 1994)

M8 VL2

2000 K, log g = 2.0

GQ Lup B

2.2

2.4

2.3

2.0

2.1

Wavelength [µm]

Spectral type: M9–L4

2.5

H2O

Na I

12CO

OSIRIS (OH-Suppressing OSIRIS (OH-Suppressing InfraRed Imaging InfraRed Imaging Spectograph)Spectograph)

Spatial resolution at the Keck Diffraction Limit (<0.050”)Spatial resolution at the Keck Diffraction Limit (<0.050”) Spectral resolution (Spectral resolution () ~ 3800) ~ 3800 Full z, J, H, or K spectra with single exposure (16x64 lenslets)Full z, J, H, or K spectra with single exposure (16x64 lenslets) Integrated Data Reduction PipelineIntegrated Data Reduction Pipeline

Integral Field SpectrographIntegral Field Spectrograph Spectra over a contiguous rectangular field.Spectra over a contiguous rectangular field.

x

y

OSIRIS - A Lenslet Based OSIRIS - A Lenslet Based Integral Field Spectrograph Integral Field Spectrograph (IFS)(IFS)

xy

1. 1. Image on LensletsImage on Lenslets 2. 2. Pupil imagesPupil images 3. 3. Pupil images dispersedPupil images dispersed 4. 4. Extracted Data CubeExtracted Data CubeFocus Image ontoFocus Image ontoa Lenslet Arraya Lenslet Array

Pre-observing planning Pre-observing planning checklistchecklist

Natural Guide Star – GQ Natural Guide Star – GQ Lup ALup A R magnitude of 11.0R magnitude of 11.0

Choose scaleChoose scale 0.020”0.020”

Choose integration time Choose integration time for desired sensitivityfor desired sensitivity From instrument zero From instrument zero

pointspoints Determine dither patternDetermine dither pattern Make an execution fileMake an execution file

Keck/OSIRIS Spectra of Keck/OSIRIS Spectra of GQ Lup BGQ Lup B

(McElwain, Metchev et al., ApJ, in press)

J

M6

M9

L2

L5

H

L0, 2 Gyr

L0, 10 Myr

integral field spectrographintegral field spectrograph behind Keck II AO systembehind Keck II AO system(PI: J. Larkin, UCLA)(PI: J. Larkin, UCLA)

OSIRIS commissioning data OSIRIS commissioning data (June 2005)(June 2005)

0.73”0.73”

GQ LupGQ Lup BB

J-band

GQ Lup B

GQ Lup B

K I H2O H2O FeH H2O

AO Integral Field Spectroscopy AO Integral Field Spectroscopy Is More Reliable Than AO Slit Is More Reliable Than AO Slit SpectroscopySpectroscopy

AO slit spectroscopy:AO slit spectroscopy: slit width (40–100 mas), PSF (40–80 mas) comparable to pointing precision slit width (40–100 mas), PSF (40–80 mas) comparable to pointing precision

(~20–40 mas)(~20–40 mas) differential refraction (atmosphere, AO transmission optics)differential refraction (atmosphere, AO transmission optics)

especially important in high-contrast regimeespecially important in high-contrast regime IFS AO spectroscopy :IFS AO spectroscopy :

no slit losses due to centering on slitno slit losses due to centering on slit no slit losses due to differential refraction no slit losses due to differential refraction

trace PSF centroid as a function of trace PSF centroid as a function of variable extraction aperture as PSF changes?variable extraction aperture as PSF changes?

elevation,differential refraction

H-band53 mas-wide slitGQ Lup A/B aligned on slit

IFS is Good for Target Extraction IFS is Good for Target Extraction and Primary Background and Primary Background SubtractionSubtraction

Correct cube for differential dispersion.Correct cube for differential dispersion. Extract the companion spectrum.Extract the companion spectrum. Fit host star PSF to estimate the background Fit host star PSF to estimate the background

contribution at the location of the secondary.contribution at the location of the secondary. Subtract host background from the Subtract host background from the

companion spectrum.companion spectrum.

J

M6

M9

L2

L5

Keck/OSIRIS Spectra of Keck/OSIRIS Spectra of GQ Lup BGQ Lup B

(McElwain, Metchev et al., ApJ, in press)

H

L0, 2 Gyr

L0, 10 Myr

commissioning OSIRIS commissioning OSIRIS data (Aug 2005)data (Aug 2005)

J-J- and and H-H-bandband

spectral type: spectral type: M8 ± 2M8 ± 2 Neuhaüser et alNeuhaüser et al.: .: M9–L4M9–L4

0.73”0.73”

GQ LupGQ Lup BB

J-band

GQ Lup B

GQ Lup B

K I H2O H2O FeH H2O

GQ Lup A/B Astrometry & GQ Lup A/B Astrometry & PhotometryPhotometry

AstrometryAstrometry Similar to imagingSimilar to imaging

PhotometryPhotometry Curve of growth for the Curve of growth for the

telluric and GQ Lup A – telluric and GQ Lup A – find flux ratio and find flux ratio and magnitude for GQ Lup Amagnitude for GQ Lup A

Compare the flux ratios of Compare the flux ratios of the same aperture for GQ the same aperture for GQ Lup A/BLup A/B

Determine GQ Lup B Determine GQ Lup B magnitude magnitude

J-band

High Contrast Imaging: High Contrast Imaging: Speckle SuppressionSpeckle SuppressionAt moderate Strehl ratios (< 0.95) and At moderate Strehl ratios (< 0.95) and

small separations (< 1”), speckle small separations (< 1”), speckle noise produced by atmospheric noise produced by atmospheric wavefront distortion and imperfect wavefront distortion and imperfect optics are the dominate noise source.optics are the dominate noise source.

Innovative techniques for enhancing Innovative techniques for enhancing contrastcontrast Simultaneous Differential ImagingSimultaneous Differential Imaging Spectral SuppressionSpectral Suppression

Typical speckle pattern forKeck II + OSIRIS Imager in the Kn3 filter

Keck II + OSIRIS Spec in the Kbb filterSpeckles are wavelength dependent and can be

modelled for each wavelength.

SummarySummary

AO integral field spectroscopy is more AO integral field spectroscopy is more reliable than AO slit spectroscopyreliable than AO slit spectroscopy

An IFS is efficient for halo subtraction.An IFS is efficient for halo subtraction. Astrometry and photometry procedures Astrometry and photometry procedures

are the similar to those for direct imaging.are the similar to those for direct imaging. An IFS can perform speckle suppression.An IFS can perform speckle suppression. GQ Lup B is probably a brown dwarf and GQ Lup B is probably a brown dwarf and

not an exoplanet.not an exoplanet.

Steps in Characterizing Steps in Characterizing Sub-Stellar CompanionsSub-Stellar Companions

Determine age and distanceDetermine age and distance from parent stellar association (best) or primary starfrom parent stellar association (best) or primary star

Determine Determine spectral typespectral type, effective , effective temperaturetemperature direct near-IR spectroscopy (with AO)direct near-IR spectroscopy (with AO)

Determine mass, surface gravityDetermine mass, surface gravity from evolutionary modelsfrom evolutionary models

McElwain, Metchev et al.:McElwain, Metchev et al.: spectral type:spectral type: M6–L0 (~2600 M6–L0 (~2600

K)K)

age: age: 1–10 Myr1–10 Myr

Neuhaüser et al. (2005):Neuhaüser et al. (2005): spectral type: spectral type: M9–L4 (~2000 M9–L4 (~2000

K)K) AO slit losses affecting AO slit losses affecting K-K-

band continuum?band continuum? weakening Hweakening H22 CIA absorption CIA absorption

at 1.5–2.5 µmat 1.5–2.5 µm

age: age: 0.1–2 Myr0.1–2 Myr

GQ Lup B is GQ Lup B is Hotter and OlderHotter and Older Than Inferred by Neuhaüser Than Inferred by Neuhaüser et al.et al.

GQ Lup B is GQ Lup B is Hotter and OlderHotter and Older Than Inferred by Neuhaüser Than Inferred by Neuhaüser et al.et al.

Testing Evolutionary Testing Evolutionary Models: Models: “Hot-Start” Models Better “Hot-Start” Models Better at ≤3 Myrat ≤3 Myr

2MASS 0535 A/B (0–3 Myr)

A (0.054 MSun)

B (0.034 MSun)

GQ Lup B (1–10 Myr)

(Neuhaüser et al. 2005,Wuchterl & Tscharnuter 2003 models)

(Stassun et al. 2006,Chabrier et al. 2000 models)

N05M06

3.0

GQ Lup B is Probably a Brown GQ Lup B is Probably a Brown DwarfDwarf

McElwain, Metchev et al.: McElwain, Metchev et al.: spectral type:spectral type: M6–L0 (~2600 K) M6–L0 (~2600 K)

age: age: 1–10 Myr1–10 Myr

““hot-start” models hot-start” models (Burrows et (Burrows et al. 1997; Chabrier et al. 2000)al. 1997; Chabrier et al. 2000)

mass: mass: 10–40 10–40 MMJupJup

Neuhaüser et al. (2005): Neuhaüser et al. (2005): spectral type: spectral type: M9–L4 (~2000 K)M9–L4 (~2000 K)

AO slit losses affecting AO slit losses affecting K-K-band band continuum?continuum?

weakening Hweakening H22 CIA absorption CIA absorption

at 1.5–2.5 µmat 1.5–2.5 µm

age age 0.1–2 Myr0.1–2 Myr

““cold-start” models cold-start” models (Wuchterl (Wuchterl & Tscharnuter 2003)& Tscharnuter 2003)

mass: mass: 1–2 1–2 MMJupJup

Marois et al. (accepted), 0.6–3.5 µm SED analysisMarois et al. (accepted), 0.6–3.5 µm SED analysis: 9–20 MJup

The Mass of GQ Lup BThe Mass of GQ Lup B

““hot-start” models predict hot-start” models predict 3–3–42 42 MMJupJup Burrows et al. (1997), Burrows et al. (1997),

Baraffe et al. (2002)Baraffe et al. (2002) uncertain at ≤3 Myr agesuncertain at ≤3 Myr ages

nucleated instability and nucleated instability and collapse models predictcollapse models predict 1–2 1–2 MMJupJup

Wuchterl et al. (2000), Wuchterl et al. (2000), Wuchterl & Tscharnuter Wuchterl & Tscharnuter (2003)(2003)

better at young ages?better at young ages?

(Neuhaüser et al. 2005)

Which theoretical models are Which theoretical models are more accurate?more accurate?

Is GQ Lup B an exoplanet?Is GQ Lup B an exoplanet?

Thanks to the OSIRIS teamThanks to the OSIRIS teamACADEMICACADEMIC Principal Investigator - James Larkin (UCLA)Principal Investigator - James Larkin (UCLA) Project Scientist - Andreas Quirrenbach (University of Heidelberg)Project Scientist - Andreas Quirrenbach (University of Heidelberg) Co-Investigator – Alfred Krabbe (Cologne)Co-Investigator – Alfred Krabbe (Cologne) Research Astronomer – Inseok Song, Christof Iserlohe (Cologne)Research Astronomer – Inseok Song, Christof Iserlohe (Cologne) Graduate Students - Matthew Barczys, David LaFreniere*, Michael McElwain, Tommer Graduate Students - Matthew Barczys, David LaFreniere*, Michael McElwain, Tommer

Wizansky, Shelley WrightWizansky, Shelley Wright Close collaboration – Ian McLean, Eric BecklinClose collaboration – Ian McLean, Eric BecklinENGINEERINGENGINEERING Project Engineer - George BrimsProject Engineer - George Brims Mechanical – Ted Aliado, Mechanical – Ted Aliado, John CanfieldJohn Canfield, Nick Magnone, Evan Kress, Nick Magnone, Evan Kress Software – Tom Gasaway (UCSD), Chris Johnson, John Milburn, Software – Tom Gasaway (UCSD), Chris Johnson, John Milburn, Jason WeissJason Weiss Electrical – Ken Magnone, Electrical – Ken Magnone, Michael SpencerMichael Spencer, Gunnar Skulason, , Gunnar Skulason, CARA - Paola Amico, Allan Honey, Junichi Meguro, Grant Tolleth, & othersCARA - Paola Amico, Allan Honey, Junichi Meguro, Grant Tolleth, & othersADMINISTRATIVEADMINISTRATIVE CARA Project Manager – Sean Adkins, David Sprayberry*CARA Project Manager – Sean Adkins, David Sprayberry* Management – Juleen Moon, Jim KolonkoManagement – Juleen Moon, Jim Kolonko Secretarial – Melinda LaranetaSecretarial – Melinda Laraneta

((lead engineer in each area for OSIRIS in lead engineer in each area for OSIRIS in boldbold, * denotes non-active team members), * denotes non-active team members)

Spectral Classification of Spectral Classification of Ultra-Cool Objects is Age-Ultra-Cool Objects is Age-DependentDependent

spectral typespectral type proxy for proxy for TTeffeff

determined by continuum determined by continuum shape in brown dwarfsshape in brown dwarfs

but: young (<100 Myr) but: young (<100 Myr) brown dwarfsbrown dwarfs larger radiuslarger radius lower surface gravity lower surface gravity

((g = GM/Rg = GM/R22)) weaker K I, Na I weaker K I, Na I

absorptionabsorption weaker Hweaker H22 CIA over 1.5– CIA over 1.5–

2.5 µm2.5 µm

spectral classification most spectral classification most reliable from Hreliable from H22O dip at 1.3 O dip at 1.3

µm µm (Slesnick et al. 2004)(Slesnick et al. 2004)

(Kirkpatrick et al. 2006)

J H K

Na I

K I

H2 CIA

H2O H2O

1-50 Myr