Adaptive Optics Observations of Vega: Eight Detected Sources and Upper Limits to Planetary‐Mass Companions

Abstract

From adaptive optics observations with the Palomar 5 m telescope we place upper limits on the masses of any planetary companions located between ~30 and 230 AU away from Vega, where our data are sensitive to depths ranging from H = 12.5-19.0 mag fainter than Vega itself. Our observations cover a plus-shaped area with two 25″ × 57″ elements, excluding 7″ × 7″ centered on the star. We have identified two double and four single point sources. These projected companions are 14.9-18.9 mag fainter than Vega and, if physically associated, would have masses ranging from 4 to 35 M_J and orbital radii of 170-260 AU. Recent simulations of dusty rings around Vega predict the presence of a perturbing body with a mass of less than 2-3 M_J and an orbital radius of ~40-100 AU, and more massive (≾10 M_J) planets cannot be excluded. None of the detected objects are this predicted planet. Based on a color-magnitude, spectroscopic, and proper motion analysis, all objects are consistent with being background sources. Given the glare of Vega, a 2 M_J object near the expected orbital radii would not have been visible at the 5 σ level in our data, though any brown dwarf with mass greater than 10 M_J could have been seen at a separation greater than 80 AU.