Slide 1Nulling Interferometry for Studying Other Planetary Systems: Techniques and ObservationsChallenges of Finding PlanetsAdvantages of Direct DetectionBracewell InterferometryFizeau InterferometryResolving Faint CompanionsNulling MeasurementsSubtlety 1: Chromaticity of NullSubtlety 2: True Image FormationFirst Telescope Demonstration of NullingBeam-splitter designPhase Compensation of NullBeam-splitter PerformanceThe Bracewell Infrared Nulling CryostatMechanical DesignBLINC’s First YearLaboratory SetupLaboratory ResultsLaboratory Results IILaboratory NullTelescope NullingObserving at the MMTPupil Alignment of BLINCDust outflow around AntaresAntaresIRC+10216Slide 28Herbig Ae/Be starsSlide 30Main Sequence StarsNulling SensitivityDepth of Null:Star DiameterMMT Nulling Error BudgetExpected SensitivityMMT Dust Limits for stars at 10 pcMMT zodiacal dust detectionLBT dust limits for stars at 10 pcPlanet LimitsSlide 40Phase space of Direct DetectionPMH-131 Jan. 2000PMH-231 Jan. 2000Nulling Interferometry for Studying Other Planetary Systems: Techniques and ObservationsPhil HinzPhD Thesis DefenseWednesday Jan. 31, 2000PMH-331 Jan. 2000Challenges of Finding PlanetsMass of Jupiter is 10-3 MsunGiant Planet Brightness is: 10-9 Lsun in visible 10-6 Lsun in IRDust Disk is 10-4 Lsun in IRDirect Detection Requirements: large aperture telescopeswavefront correctionsuppression of starlightNeed instrumental development to make scientific progess.PMH-431 Jan. 2000Advantages of Direct Detection•We want to see planets not just infer their existence.•Direct emission from planets can tell us about their chemical make-up, temperature, etc. . . We can learn more about it.•Wide orbit planets such as Jupiter or Saturn require prohibitive time baselines for Doppler velocity detection.PMH-531 Jan. 2000Bracewell InterferometryCollector 1Collector 2Semi-transparent mirrorleft output right outputΔΦStellar wavefrontCompanion wavefrontPMH-631 Jan. 2000Fizeau InterferometryCollector 1 Collector 2PMH-731 Jan. 2000Resolving Faint CompanionsFizeau interferometry is well –suited forhigh spatial resulotion studiesPupil-plane interferometry is well-suited forsuppression of starlight.StarCompanion(1% of star brightness)Star+CompanionPMH-831 Jan. 2000Nulling Measurementsdust trdust trdust2 Source Orientation 1 Orientation 22PSF of single elementNulling interferometry measures the total flux transmitted by the interference pattern ofthe two elements, convolved with the PSF of a single element.PMH-931 Jan. 2000Subtlety 1: Chromaticity of NullFraction of light remaining in nulled out put is given bywhere Level of suppression is good over only a narrow bandwidth.Three fixes: Rotate one beam 180 degrees (Shao and Colavita)Send one beam through focus (Gay and Rabbia)Balance dispersion in air by dispersion in glass (Angel, Burge and Woolf)Dispersion Compensation allows out-of band light to be used to sense phase (Angel and Woolf 1997)414)(2))(cos(1)(0NPMH-1031 Jan. 2000Subtlety 2: True Image FormationIn Bracewell’s concept the beams form images which are mirror versions of one another.Rotation nulls create images which are rotated versions of one another.It is only possible to create a true image of the field using dispersion compensation for thesuppression and an interferometer which has an equal number of reflections in each beam.PMH-1131 Jan. 2000First Telescope Demonstration of NullingNulling at the MMTNature 1998; 395, 251.Ambient Temperature OpticsPMH-1231 Jan. 2000Beam-splitter designRequirements: Equal reflection and transmission at nulling wavelengthEqual reflection and transmission at phasing wavelengthSymmetric design (to avoid chromatic phase shifts)Substrate suitable for dispersion compensation.Design:ZnSe substrateλ0 /4 air gapdifference in substrate thickness of 39 μmPMH-1331 Jan. 2000Phase Compensation of Null9 9.5 10 10.5 11 11.5 12 12.5 130.460.480.50.520.549 9.5 10 10.5 11 11.5 12 12.5 1311061105110411030.01Phase (waves)IntensityWavelength (μm)PMH-1431 Jan. 2000Beam-splitter Performance2 4 6 8 10 1200.512 4 6 8 10 1200.51Reflection IntensityWavelength (μm)Phase difference (waves)phase sensingpassbandNullingpassbandPMH-1531 Jan. 2000The Bracewell Infrared Nulling CryostatPMH-1631 Jan. 2000telescope beamreimaging ellipsoidbeam-splitter2 μm detector10 micron detectorimaging “channel”nulling “channel”Mechanical DesignPMH-1731 Jan. 2000BLINC’s First YearPMH-1831 Jan. 2000Laboratory SetupHeNe laserDichroicCO2 laserBall mirror“Telescope” mirrorFold mirrorInterferometerInfrared CameraPMH-1931 Jan. 2000Laboratory ResultsCO2 laser source yielded a null with an integrated flux of 3x10-4Entire Airy pattern along with the scattered light disappears in nulled image.0.5 s exposure images at 10.6 μmPMH-2031 Jan. 200020 15 10 5 0 5 10 15 2000.250.50.751path-length (microns)IntensityLaboratory Results II50% bandwidth causes adjacent nulls to be significantly > 0.Relative depth of theadjacent nulls determinesachromaticity of centralnull.PMH-2131 Jan. 2000Constructive image Scanning pathlength0.5% of peak2% of peakWhite=5% of peakLaboratory NullPMH-2231 Jan. 2000Telescope NullingPMH-2331 Jan. 2000•Commissioning run of MIRAC-BLINC, June 10-17, 2000.•Aligned and phased the interferometer during the first night of observing•Observed AGB stars, several Herbig Ae stars, and several main-sequence stars.•Observed again in October, but weather was poor.Observing at the MMTPMH-2431 Jan. 2000Pupil Alignment of BLINCRight beamouter edge of primary Left beamouter edge of primary Left beamsecondary obscurationRight beamsecondary obscurationPupil stop sizefor nullingobservationsPMH-2531 Jan. 2000Dust outflow around Antaresα Booα Scoconstructive destructiveBest nulls of α Boohave a peak ratio of3%. The integrated light is 6% of the constructive image.The nulled images ofα Sco are 25% of theconstructive images. Suppression of the starlight allows us toform direct images of thedust outflow around thestarPMH-2631 Jan. 2000Antaresbaseline verticalNEbaseline horizontal5 arcsecPMH-2731 Jan. 2000IRC+10216Constructive -- Destructive = Point SourcePoint source in IRC+10216 is faint compared to its extended dust nebula.By modulating the point source we can determine its contribution as well as its registration to the nebula. This has been a source of confusion for IRC+10216PMH-2831 Jan.