An ultraviolet, optical and infrared study of Herbig Ae/Be stars ?

Abstract

Wehaveselectedalistof45HerbigAe/Be-typecan- didatesonthebaseoftheirIRAScolorsandtheirspectraltypes. Weproposethepresenceofabroadinfraredexcessasadening criterionforthesestars,ratherthanthedetectionofcircumstellar nebulosity.Inthisway,ourselectionalsoincludesmoreevolved young stars, that are no longer embedded in their star-forming region. A few objects in our sample are well-known Herbig Ae/Be stars, others are new. New optical and near-infrared pho- tometric observations, as well as ultraviolet ones, are presented. The position of the objects in several color-color diagrams, as well as their de-reddened energy distributions, permit a reliable classication. Three objects probably are binaries with a cool secondary, 9 appear to be related to the Vega-type stars and 33 objects can be classied as genuine Herbig Ae/Be stars. The majority of the Herbig Ae/Be stars have a dusty environment consisting of a distinct hot and cool component. These isolated HerbigAe/BestarssuggestanevolutionfromembeddedHerbig Ae/Be stars to Pictoris-like main-sequence stars, an evolution in which planet formation may play an important role.