Accurate diameter measurement of etelgeuse using the VLTIAMBE使用vltiambe参宿四直径准确的测量

1、accurate diameter measurement of betelgeuse using the vlti/amber instrumento. hernndez, a. chellilaboratoire dastrophysique de grenoblelaboratoire dastrophysique de grenobleindexastrophysical source & experimental conditionsbetelgeusestrong fluxes & low contrastdata reductionframe selectionp

2、2vm vs. fouriervisibility analysisuniform disk diameter (perrin et al. 2004)uniform disk + spot model or jitter ?conclusionsgoalsdemonstrate amber capability to precisely measure low contrast visibilitiesvalidate p2vm methodgive a very accurate measurement of betelgeuse diameterbetelgeuseapparent ma

3、gnitude (v) +0.3 to +1.2spectral type m2iab(3600k)variable type sr c (semi-regular)distance approx.130 pcsirius (calibrator)apparent magnitude (v)a = 1.47b = 8.44variable type eclipsing binaryspectral type a = a1v (9,900k)b = da2 (25,200k)distance approx. 2.64 0.01 pcobservationsbetelgeusebaseline 1

4、6m5 observation files1000 frames/filefebruary 2006, at1-at3, r=1500siriusbaseline 13m5 observation files500 frames/fileraw data & final visibilityframe selection - snrframe selection - fluxframe selection p2vm 2p2vm vs. fourierbetelgeuse calibrated visibilityvalidate method p2vm for low contrast

5、uniform disk diameterperrin et al. 2004 = 43.33 0.04 mas(blue)amber = 42.85 0.02 mas(red)uniform disk diameter slope?uniform disk + spot = 42.50 0.02 masijitter correction = 42.60 0.02 masvm=ve2222siriuss = 0.343 mbetelgeuse 25%conclusionsamber is capable to give very low contrast visibilities in high flux conditionsp2vm method is consistent with fourier methodp2vm validation can be used to properly measure the bias substraction in low contrast and low flux databetelgeuse