High-contrast imaging with AO

Claire Max

with help of Bruce Macintosh

GSMT Science Working Group

December 2002

Slide 2

Types of high-contrast AO imaging

• Point sources near bright stars: images and spectra– Brown dwarfs– Young Jupiters (still shining in IR)– Older Jupiters shining by reflected light– Ultimately, Earth-like planets (?)

• Disks– Debris disks best observed in thermal IR: good motivation for

separate cooled AO system aimed at mid-IR– Protostellar and protoplanetary disks

– Have proven to be a challenge for current AO systems– But AO polarimetry is VERY promising

Slide 3

Context

• All detailed AO simulation results are for 8-10m telescopes

• Simulations for 30m telescopes still need to be done

Slide 4

Extreme AO Phase Space

(Impressionistic chart originally done for 10m telescope)

Slide 5

Young vs. old Jupiters

Slide 6

Point-source sensitivities of Keck AO, NICMOS

Slide 7

Current examples of high contrast images

• High Dynamic Range at modest separations (~1 arc sec)– Existence supported by disk structures– Confirmation by proper motion essential– Current 8-10m contrast ratios: ~106

NICMOS image of HD141569Showing gap at 250 AU possibly created by wide planet(s)

Keck AO image showing a candidate for young extra-solar planet (224 AU, 3-7 MJ, if confirmed)

Slide 8

“Extreme” AO

Slide 10

Keck AO simulations

Slide 11

Detection of Jupiters in reflected light

30m telescopes

• Imaging AO polarimetry is central to detecting structure in circumstellar disks

• Dan Potter, UH

Slide 14

Disk Structures with AO Polarimetry

• Lick AO Near-infrared polarimetry studies– Measure two orthogonal polarization states simultaneously,

subtract to get only polarized light (dust only!)– Dan Potter (UH), Marshall Perrin (UC Berkeley - Lick)

LkH 234

I Q U P

R Mon results

Slide 15

Points to importance of differential detection methods

• Polarimetry

• Comparison of different spectral bands– Example: methane vs. non-methane– Integral field AO spectrographs will be inherently very

capable for this task

Slide 16

Summary

• Current state of the art for AO on 8-10m telescopes:– Contrast ratio of ~ 106 at separation of ~1 arc sec

– Polarimetry, coronagraphy, two-color detection will be very important

– “Extreme AO” under active investigation

• “Extreme AO” on 8-10m telescopes will increase this by factor of 10 - 50

– Can clearly do Jupiters (young and old); Uranus-Neptune

• Critical issues: – Can Extreme AO on GSMT detect Earthlike planets??

– Specifically how does AO performance affect the various GSMT Science Cases?

– How will GSMT performance compare with JWST?