Young stars and Educational outreach -- Oral Presentation
Large magnetic structures in YSO in Orion
Fabio Favata, European Space Agency
The COUP (Chandra Orion Ultradeep Project) observation of the
ONC has for the first time allowed to observe in detail long (up to a
few days) flaring events in YSOs. One of the key results of the study of
the COUP flares is the existence of a number of flaring events whose
spectral evolution implies very long confining magnetic structures, up
to 5 stellar radii. Many X-ray flares in more evolved stars have been
studied in the past, and in all cases the flaring corona is compact,
confined to a fraction of the stellar radius from the photosphere. Very
large magnetic structures are thus unique to young stellar objects,
which are typically surrounded by accretion disks. From stability
considerations (linked to the large rotational velocity of these YSOs)
the large flaring structures are likely linking the star with the inner
rim of the circumstellar disk. Such magnetic structures are predicted by
the magnetospheric accretion scenario, and flaring X-ray emission from
them was predicted in the Shu et al. `X-wind' model. The COUP flares are
the first opportunity to determine the size of these magnetic structures
and the intensity of the magnetic field. We will present an overview of
the results from the COUP flare analysis and a detailed analysis of the
evolution of the most notable of the COUP flaring events.