Abstract:
We present the ultraviolet (UV) imaging observation of planetary nebulae (PNe) using archival data of Galaxy Evolution Explorer (GALEX). We found 358 PNe detected by GALEX in near-UV (NUV). We have compiled a catalogue of 108 extended PNe with sizes greater than 8′′ and provided the angular diameters for all the 108 extended PNe in NUV and 28 in FUV from the GALEX images considering 3σ surface brightness level above the background. Of the 108 PNe, 74 are elliptical, 24 are circular and 10 are bipolar in NUV with most being larger in the UV than in the radio, Hα or optical. We derived luminosities for 33 PNe in FUV (LFUV) and 89 PNe in NUV (LNUV) and found that most of the sources are very bright in UV. The FUV emission of the GALEX band includes contribution from prominent emission lines N IV] (1487 Å), C IV (1550 Å), and O III] (1661 Å) whereas the NUV emission includes C III] (1907 Å) and C II (2325 Å) for PNe of all excitation classes. The other emission lines seen in low excitation PNe are O IV] (1403 Å) and N III (1892 Å) in FUV, and O II (2470 Å) and Mg II (2830 Å) in NUV. Similarly the emission lines O V (1371 Å) and He II (1666 Å) strongly contribute in FUV for high and medium excitation PNe but not for low excitation PNe. A mixture of other emission lines seen in all excitation PNe. We have also provided images of 34 PNe in NUV and 9 PNe in FUV.
