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 h igh 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 (209. ° 13 ± 2. ° 12) and the projected separation to its host star (0.″.354 ± 0. ″.012, 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 theo retical 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.