Abstract

Contributed Talk - Splinter StarFormation

Time-dependent radiative transfer modeling of accretion outbursts of massive young stellar objects

Verena Wolf, Bringfried Stecklum
Thuringian State Observatory Tautenburg

Although massive stars with more than 8 solar masses account for only ~1% of the stellar population, they shape the evolution and formation of entire galaxies because of their strong feedback. This talk focuses on the formation of massive stars on small scales of up to ~0.1pc. Similar to low-mass young stellar objects (YSOs), massive YSOs (MYSOs) gather a significant fraction of their final mass within short periods of strongly enhanced mass accretion, the so called accretion bursts. For MYSOs only a handful of such outbursts have been observed so far. As MYSOs are deeply embedded throughout their entire formation, these events are best visible in the infrared (IR). The bulk of their luminosity stems from reprocessed protostellar emission, radiated away as thermal dust continuum emission. Time-dependent radiative transfer (TDRT) modeling allows us to simulate the propagation of the heatwave caused by the burst within the dusty environment of the MYSO. Its imprint on the emergent SED depends on the dust properties, the geometry of the system, and the burst history. We compare TDRT models with IR observations for two specific objects with different viewing angles. Hereby we are able to obtain more reliable estimates of the burst energy. This will help to distinguish between different burst triggering mechanisms. Furthermore, accretion bursts are often followed by ejection bursts, which can impact the galaxies on larger scales. The accreted energy provides a limit for the energy that can be released in the ejection burst. In addition, TDRT allows one to study other processes in the circumstellar environment, e.g. the excitation of masers.