Abstract We present spectrophotometric results of the Seyfert~2 galaxy NGC~2273. The presence of high-order Balmer absorption lines (H8, H9, H10) and weak equivalent widths of CaII K λ3933, CN λ4200, G-band λ4300 and MgIb λ5173 clearly indicate recent star-forming activity in the nuclear region. Using a simple stellar population synthesis model, we find that for the best fit, the contributions of a power-law featureless continuum, an intermediate-age (∼ 108 yr) and an old (>109 yr) stellar population to the total light at the reference normalization wavelength are 10.0%, 33.4% and 56.6%, respectively. The existence of recent starburst activity is also consistent with its high far-infrared luminosity ( 9.9), its infrared color indexes [α(25, 60) = –1.81 and α(60, 100)= –0.79, typical values for Seyfert galaxies with circumnuclear starburst], and its q-value (2.23, ratio of infrared to radio flux, very similar to that of normal spirals and starburst galaxies). Byrd et al. have suggested that NGC 2273 might have interacted with NGC 2273B in less than 109 yr ago, so the starburst activity in this galaxy could have been triggered by tidal interaction, as indicated in recent numerical simulations.

Keywords galaxies: Seyfert --- galaxies: starburst --- galaxies: stellar content

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