KATE FOLLETTE Stanford University 2016 Sagan Fellow

Finding and Characterizing Forming Protoplanets with Next- Generation

Adaptive Optics Systems

ImageCredit:KarenTeramura,UHIfA

MY SAGAN PROJECT Surveytwentytransi.onaldisksinsearchofaccre.ngproto-planets(planetss.llintheprocessofgrowing)withtheMagellanAdap.veOp.cs(MagAO)system,andcharacterizetheirenvironmentswiththeGeminiPlanetImager.

Transi.onaldisksareasub-classoftheubiquitouscircumstellardisksthatsurroundyoungstars.Generically,circumstellardisksaretheremnants(gasanddust)ofthestarforma.onprocess.Transi.ondiskshavegiant(solar-systemsized)clearedcentralcavi.esthatwebelievearecarvedbythegravita.onalinfluenceofplanetsand/orprotoplanets

Stellarphotospheresemitlightofallwavelengths(asmallpropor.onofwhichareabsorbedinitsouterlayers,notpicturedhere).Purehydrogengas,ontheotherhand,hasauniquespectralfingerprintconsis.ngofconcentratedemissionatjustafewspecificwavelengths,includinghydrogen-alpha.

wavelength

Inte

nsity

stellarcon.nuum

Stellarcon.nuum

Hydrogengas

H-alpha

H-gammaH-beta

Hydrogengas

1-DSpectrumofStellarCon.nuumEmissionvs.Hydrogengas

2-DSpectrumofStellarCon.nuumEmissionvs.Hydrogengas

stellarcon.nuum

Hydrogengas

2-DSpectrum-Zoomed

H-alphafilterCon.nuumfilter

wavelength

Inte

nsity

MagAO’sSimultaneousDifferen.alImaging(SDI)modeimagesintwofilterssimultaneously.Stellarcon.nuumemissionisnearlyequalinbothfilters,whileemissionfromhydrogengasappearspreferen.allyinonefilter(H-alpha)andnottheother(con.nuum).Thedifferenceofimagesinthetwofilters(withthecon.nuumscaledtocorrectfortheslightdifferenceinbrightness),allowsustoisolatethecontribu.onofglowinghydrogengas.

H-alpha

LkCa15 b – An Accreting Protoplanet Continuum Difference Image Hydrogen-alpha

Location of the star LkCa15 (light removed)

LkCa15 b protoplanet

PlanetsandstarsgrowbyaUrac.nghydrogengas,whichheatsupasitfallsontotheminaprocesscalledaccre.on.Wemightexpectthattheobjectscarvinggapsintransi.ondiskswillhavearangeofmasses,soit’simportanttobeabletodis.nguishbetweenstellarbinariesandtrueplanetarymasscompanions.Accre.ngprotoplanets,likeLkCa15b,aretoolowinmasstohaveadetectablelevelofcon.nuumemission,sotheyappearonlyintheH-alphaimage,andnotinthecon.nuum,whereasstellarcompanionslikeHD142527Bappearinboth.

HD142527B– An Accreting Stellar Companion

Location of the star HD142527 (light removed)

Continuum (642nm)

Difference Image Hydrogen-alpha (656nm)

HD142527B stellar companion