Special Session SS9  4 July 2016

Episodic accretion in star formation

Aims and scope

The topic of episodic accretion has gained significant interest in the star formation community. It is now viewed as a common, though still poorly understood, phenomenon in low-mass star formation. The FU Orionis objects (FUor) are long-studied examples of this phenomenon. FUors are believed to undergo accretion outbursts during which the accretion rate rapidly increases from typically 1E-7 Msun/yr to 1E-4 Msun/yr, and remains elevated over timescales of several decades or more. EXors, a loosely defined class of pre-main sequence stars, exhibit similar but shorter and repetitive outbursts, associated with lower accretion rates. The relationship between the two classes, and their relationship to the standard pre-main sequence evolutionary sequence, is an open question: do they form two distinct classes, are they triggered by the same physical mechanism, and do they occur in the same evolutionary phases? Over the past couple of decades, many theoretical and numerical models have been developed to explain the origin of FUor and EXor outbursts, and suggest that this phenomenon may be universal in star formation. In parallel, such accretion bursts have been detected at increasing rate, and each individual outburst is more carefully scrutinized and monitored across the electromagnetic spectrum.

Within EWASS 2016, a special session is dedicated to present and discuss our contemporary understanding of episodic accretion from the theoretical, numerical, and observational points of view, and to determine the most promising directions for this field of star formation in the near- and long-term.


  • The Burst Mode of Accretion in Primordial Star Formation
    • Shantana Basu University of Western Ontario
  • Episodic accretion in the context of star and planet formation
    • Neal J. Evans University of Texas, Austin
  • Outburst mechanisms in FUors and EXors
    • Eduard Vorobyov University of Vienna
  • Disk-star interactions during episodic accretion
    • Caroline d'Angelo Leiden Observatory
  • Observational properties of outbursting sources
    • Agnes Kospal Konkoly Observatory
  • Promising directions in episodic accretion
    • Marc Audard University of Geneva
Contributed talks and Posters will be accepted.

Invited speakers

Scientific organisers
M. Audard (University of Geneva), P. Abraham (Konkoly Observatory), M. Dunham (Harvard-Smithsonian Center for Astrophysics), J. Green (Space Telescope Science Institute), N. Grosso (Observatoire de Strasbourg), K. Hamaguchi (NASA/GSFC and University of Maryland Baltimore County), J. Kastner (Rochester Institute of Technology), A. Kospal (Konkoly Observatory), G. Lodato (University of Milano), M. Romanova (Cornell University), S. Skinner (University of Colorado, Boulder), E. Vorobyov (University of Vienna), Z. Zhu (Princeton University).

Marc.Audard @ unige.ch

Updated on Mon Mar 07 17:51:18 CET 2016