  The interaction between emerging active regions and the pre-existing coronal
magnetic field is important to understand better the mechanisms of storage and
release of magnetic energy from the convection zone to the high corona. We are
aiming at describing the first steps of the emergence of an active region
within a pre-existing quiet-Sun corona in terms of the thermal and magnetic
structure. We use unprecedented spatial, temporal and spectral coverage from
the Atmospheric Imager Assembly (AIA) and from the Helioseismic and Magnetic
Imager (HMI) on board the Solar Dynamics Observatory (SDO). Starting on 30 May
2010 at 17:00 UT and for 8 hours, we follow the emergence of the active region
AR11076 within a quiet-Sun region. Using several SDO/AIA filters covering
temperatures from 50000K to 10 MK, we show that the emerging process is
characterised by a thermal shield at the interface between the emerging flux
and pre-existing quiet-Sun corona. The active region 11076 can be considered as
a peculiar example of emerging active region as (i) the polarities emerge in a
photospheric quiet-Sun region near a supergranular-like distribution, (ii) the
polarities forming the bipolar emerging structure do not rotate with respect to
each other indicating a small amount of twist in the emerging flux bundle.
There is a thermal shield formed at the interface between the emerging active
region and the pre-existing quiet-Sun region. The thermal shielding structure
deduced from all SDO/AIA channels exhibits a strong asymmetry between the two
polarities of the active region suggesting that the heating mechanism for one
polarity is more likely to be magnetic reconnection, whilst it is due to
increasing magnetic pressure for the opposite polarity.
