SPITZER 24 {mu}m IMAGES OF PLANETARY NEBULAE

• Published in: The Astronomical journal 2009-08, Vol.138 (2)
• Main Authors: Chu, Y.-H., Gruendl, Robert A., Bilikova, Jana, Caulet, Adeline, Guerrero, Martin A., Su, Kate Y. L., Cohen, Martin, Parker, Quentin A., Volk, Kevin, Chen, W.-P., Hora, Joseph L., Rauch, Thomas
• Format: Article
• Language: English
• Subjects: ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BRIGHTNESS; DUSTS; EMISSION; GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; PLANETARY NEBULAE; WHITE DWARF STARS
• ISSN: 1538-3881; 1538-3881
• DOI: 10.1088/0004-6256/138/2/691;COUNTRYOFINPUT:INTERNATIONALATOMICENERGYAGENCY(IAEA)

Spitzer MIPS 24 {mu}m images were obtained for 36 Galactic planetary nebulae (PNe) whose central stars are hot white dwarfs (WDs) or pre-WDs with effective temperatures of {approx}100,000 K or higher. Diffuse 24 {mu}m emission is detected in 28 of these PNe. The eight nondetections are angularly large PNe with very low H{alpha} surface brightnesses. We find three types of correspondence between the 24 {mu}m emission and H{alpha} line emission of these PNe: six show 24 {mu}m emission more extended than H{alpha} emission, nine have a similar extent at 24 {mu}m and H{alpha}, and 13 show diffuse 24 {mu}m emission near the center of the H{alpha} shell. The sizes and surface brightnesses of these three groups of PNe and the nondetections suggest an evolutionary sequence, with the youngest ones being brightest and the most evolved ones undetected. The 24 {mu}m band emission from these PNe is attributed to [O IV] 25.9 {mu}m and [Ne V] 24.3 {mu}m line emission and dust continuum emission, but the relative contributions of these three components depend on the temperature of the central star and the distribution of gas and dust in the nebula.