Integral field spectroscopy of HII regions in M33

JESÚS LÓPEZ-HERNÁNDEZ; ELENA TERLEVICH; ROBERTO TERLEVICH; DANIEL ROSA-GONZÁLEZ; ÁNGELES DÍAZ; RUBÉN GARCÍA-BENITO; JOSÉ VÍLCHEZ; GUILLERMO HÄGELE

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2013 vol. 430 p. 472 - 508

0035-8711

Integral field spectroscopy is presented for star-forming regions in M33. A central area of300 × 500 pc2 and the external HII region IC 132, at a galactocentric distance ∼19 arcmin(4.69 kpc), were observed with the Potsdam Multi-Aperture Spectrophotometer instrumentat the 3.5-m telescope of the Centro Astron´omico Hispano–Alem´an (CAHA, aka Calar AltoObservatory). The spectral coverage goes from 3600 Å to 1 μm to include from [O II] λ3727Å to the near-infrared lines required for deriving sulphur electron temperature and abundancediagnostics.Local conditions within individual HII regions are presented in the form of emission-linefluxes and physical conditions for each spatial resolution element (spaxel) and for segmentswith similar Hα surface brightness.A clear dichotomy is observed when comparing the central to outer disc HII regions. Whilethe external HII region has higher electron temperature plus larger Hβ equivalent width, sizeand excitation, the central region has higher extinction and metal content.The dichotomy extends to the Baldwin–Phillips–Terlevich (BPT) diagnostic diagrams thatshow two orthogonal broad distributions of points. By comparing with pseudo-3D photoionizationmodels, we conclude that the bulk of observed differences are probably related to adifferent ionization parameter and metallicity.Wolf–Rayet (WR) features are detected in IC 132, and resolved into two concentrationswhose integrated spectra were used to estimate the characteristic number of WR stars. No WRfeatures were detected in the central HII regions despite their higher metallicity.