First Results from Very Large Telescope NACO Apodizing Phase Plate: 4 μm Images of The Exoplanet β Pictoris b

Direct imaging of exoplanets requires both high contrast and high spatial resolution. Here, we present the first scientific results obtained with the newly commissioned apodizing phase plate coronagraph (APP) on VLT/NACO. We detected the exoplanet β Pictoris b in the narrowband filter centered at 4.05 μm (NB4.05). The position angle (20913 ± 212) and the projected separation to its host star (0354 ± 0012, i.e., 6.8 ± 0.2 AU at a distance of 19.3 pc) are in good agreement with the recently presented data from Lagrange et al. Comparing the observed NB4.05 magnitude of 11.20 ± 0.23 mag to theoretical atmospheric models, we find a best fit with a 7-10 M Jupiter object for an age of 12 Myr, again in agreement with previous estimates. Combining our results with published L' photometry, we can compare the planet's [L' – NB4.05] color to that of cool field dwarfs of higher surface gravity suggesting an effective temperature of ~1700 K. The best-fit theoretical model predicts an effective temperature of ~1470 K, but this difference is not significant given our photometric uncertainties. Our results demonstrate the potential of NACO/APP for future planet searches and provide independent confirmation as well as complementary data for β Pic b.