The overall goal of this tutorial is to become familiar with VOSpec. For that, we are going to build the Spectral Energy Distribution (SED) of a Herbig Ae/Be star.
A Herbig Ae/Be star is a 2-8 solar mass, pre-main-sequence star (that is, young objects with typical ages of <10Myr) of spectral types A or B. These stars are still embedded in gas-dust envelopes and are sometimes accompanied by circumstellar disks. They are in the gravitational contraction stage and approaching the main sequence (i.e. they are not burning hydrogen in their centre).
Herbig Ae/Be stars show Balmer emission lines in their stellar spectrum and infrared excess due to circumstellar dust. Sometimes Herbig Ae/Be stars show significant brightness variability associated to clumps (protoplanets and planetesimals) in the circumstellar disk.
The SEDs of Herbig Ae/Be stars fall roughly into two groups: Group I sources have a relatively strong far-IR flux, which is energetically comparable with the flux in the near-IR showing an almost flat spectral energy distribution. Group II sources show a similar near-IR excess as group I sources but their flux falls off strongly towards the far-IR. These were first classified by Meeus et al (2001, A&A, 365, 476), see below figure.
Dullemond and Dominik (2004, A&A, 417, 159) provided a physical explanation for this difference: Group II sources have an outer disk which is protected against direct stellar radiation by a puffed-up inner disc. If the outer disc emerges from the inner disc's shadow, i.e. has a large flaring angle, then its SED resembles that of a Group I source.
NOTE:A more description of this tutorial as well as other VOSpec functionalities can be found here
The tutorial can be found here