HST imaging of the planetary nebula K 648 in M 15.
Abstract
Two images of the Planetary Nebula K 648 in M 15 were taken in the PC mode of the WFPC1 camera on HST in the narrow [OIII] and Halpha_ filters, and an image in [OIII] light with the FOC. This object, never resolved before in ground-based data, is resolved in the HST images. It shows a bipolar structure: a spherical shell containing a brighter torus, of about 2.5 arcsec diameter. A surrounding fainter spherical emission extending to about 5 arcsec diameter is detected. The measured diameter allows to determine better than was previously possible the mass of the ionized gas, M_gas_=~0.07+/-0.02Msun_. The stellar and nebular parameters derived from the HST data and archive IUE data, confirm a distance of K 648 consistent with that of M 15. The morphological structure can be studied in the resolved HST images. The observed intensity distribution is modeled with a 3-D density distribution with cylindrical symmetry, the equatorial plane being close to the line of sight. On reanalysing IUE archive data, we derive the following parameters for the central star: T_eff_=35000K, consistent with most previous findings, M_*_=0.58+/-0.02Msun_, R_*_=1.9Rsun_, L=4680Lsun_, V_edge_=-1630km/s of the wind line, V_esc_=300km/s. The object is still evolving towards hotter temperatures in the constant-luminosity post-AGB phase.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- September 1995
- Bibcode:
- 1995A&A...301..537B
- Keywords:
-
- PLANETARY NEBULAE: INDIVIDUAL: K 648;
- STARS: POPULATION II;
- STARS: POST AGB;
- STARS: EVOLUTION;
- ULTRAVIOLET: ISM