  Optical spectropolarimetry of the normal thermonuclear supernova SN2019np
from -14.5 to +14.5 days relative to B-band maximum detected an intrinsic
continuum polarization, p(cont), of 0.21+-0.09% at the first epoch. Between
days -11.5 to +05, p(cont) remained about 0 and by day +14.5 was again
significant at 0.19+-0.10%. Not considering the first epoch, the dominant axis
of SiII(6355A) was roughly constant, staying close to the continuum until both
rotated in opposite directions on day +14.5. Detailed radiation-hydrodynamical
simulations produce a very steep density slope in the outermost ejecta so that
the low first-epoch p(const) of about 0.2% nevertheless suggests a separate
structure with an axis ratio of about 2 in the outer carbon-rich 3...5E-3 Mo.
Large-amplitude fluctuations in the polarization profiles and a flocculent
appearance of the polar diagram for the CaII near-infrared triplet (NIR3) may
be related by a common origin. The temporal evolution of the polarization
spectra agrees with an off-center delayed detonation. The late-time increase in
polarization and the possible change in position angle are also consistent with
an aspherical 56Ni core. The p(cont) and the absorptions due to Si II(6355A)
and the CaII NIR3 form in the same region of the extended photosphere, with an
interplay between line occultation and thermalization producing p. Small-scale
polarization features may be due to small-scale structures, but many could be
related to atomic patterns of the quasi-continuum; the hardly have an
equivalent in the total-flux spectrum. We compare SN2019np to other SNe and
develop future objectives and strategies for SNIa spectropolarimetry.
