NGC 2022, a case study of a multiple-shell planetary nebula

We present a detailed study of the physical properties, history of mass loss, and chemical abundances of the planetary nebula NGC 2022. New imaging observations obtained with the OAJ/JAST80 and NOT/ALFOSC confirm the presence of a faint similar to 88 arcsec halo surrounding a double-layered elliptical structure that consists of a bright 21.4 x16.7 arcsec inner shell and a 32 arcsec diameter envelope. The long-slit high-dispersion echelle observations obtained with MES on the OAN-SPM 2.1-m telescope can be well described by a SHAPE model with expansion velocities of 43 +/- 3 and 34 +/- 3 km s(-1) along the major and minor axes of the elliptical inner shell, respectively. In addition, a deep long-slit high-dispersion echelle observation made with the KPNO 4-m telescope detected line-splitting in the faint halo, revealing an expansion velocity of 15.5 +/- 2 km s(-1). We have also used new intermediate-dispersion optical spectra with the NOT, complemented with IUE data, to study the chemical abundances of each shell. The abundances of the three shells are typical of a Type II in the Peimbert classification of PNe and do not exhibit any notable anomalies. Finally, we estimate the total mass of NGC 2022 to be approximate to 0.9 M-circle dot, which consists of 0.64 M-circle dot from the CSPN and 0.1, 0.11, and 0.1 x f(halo)(1/2) M-circle dot from the ionized inner shell, outer shell, and halo, respectively.

Automated summary

We conducted a detailed study on NGC 2022, a planetary nebula, including its physical properties, mass loss history, and chemical abundances. Our observations confirmed the existence of a faint halo surrounding a double-layered elliptical structure. The expansion velocities along the major and minor axes of the inner shell were determined to be 43 +/- 3 and 34 +/- 3 km s(-1) respectively. The chemical abundances of each shell were found to be typical of Type II in the Peimbert classification of PNe.