Fabry-Pérot Radial Velocities of S274: a Planetary Nebula

Extract

The bright nebula S274 (YM29), 8′ across has been classified as a planetary by Abell (1966) although it has been considered a SNR by other authors. We have determined radial velocities at 173 points on this nebula from four Fabry-Pérot interferograms. The velocity field exhibits a great deal of structure. The average expansion velocity is + 31.5 ± 8 km s⁻¹. The mean radial velocity of S274 is not well determined due to the nature of the velocity field, while the overall velocity (173 points) is + 33 ± 21 km s⁻¹. Points at the outer boundary yield an average of 22 ± 14 km s⁻¹ while the average of the double points is 25 km s⁻¹. The age of expansion of the nebula is estimated at 6.8 × 10³yr. The physical parameters of this object are consistent with those of a planetary nebula.