X-Ray Emission from Planetary Nebulae and Their Central Stars: A Status Report

1. X-Ray Emission from Planetary Nebulae and Their Central Stars: A Status Report Joel Kastner Rochester Institute of Technology w/ help from lots of other folks, including: Rudy Montez, Young Sam Yu (RIT grad students) Noam Soker, Ehud Behar, Bruce Balick, Adam Frank, Eric Blackman, Orsola DeMarco, Pat Huggins…

2. Chandra & XMM-Newton: The story so far • Since 2000, X-ray imaging of PNe by the Chandra and XMM-Newton X-ray observatories has provided new & compelling observational evidence for hot bubbles, highly energetic jets, and/or “active” PN cores • Eight planetaries observed by Chandra and XMM have been detected as diffuse X-ray sources thus far • Kastner et al. (2000, 2001, 2003); Chu et al. (2001); Montez et al. (2005); Guerrero et al. (2002, 2005); Gruendl et al. 2006) • An additional handful have been detected as X-ray point sources • e.g. NGC 6534, 7293; Guerrero et al. (2001)

3. X-rays and the structure of PNs • Two key areas where Chandra & XMM-Newton X-ray imaging spectroscopy observations yield important/unique insight into PN shaping: 1. Diffuse X-ray sources: origin and evolution of wind interaction regions • X-ray hot bubbles: quasi-spherical central star wind interacting w/ former AGB wind • a la Kwok et al. 1978 • Collimated, X-ray-luminous outflows & jets: evidence for disks and/or binarity • Subject of next talk by M. Guerrero; also see poster by R. Montez 2. Central X-ray point sources: magnetic fields, disks, and binarity in PN cores

4. 1. Diffuse X-ray sources in PNs • Two “classes” emerging: • Hot bubbles • BD+303639; NGC 40, 2392, 3242, 6543, 7009, 7026 • Collimated jets & outflows • NGC 7027, Menzel 3, Hen 3-1475 X-ray images (blue): XMM & Chandra X-ray/visual image overlays: M. Guerrero Montage: B. Balick NGC 2346 is an X-ray NONdetection (Gruendl et al. 2006)

5. You Won’t Believe This… Chandra target: the WR-type PN Hen 2-99 …not detected… But a second WR-type PN, NGC 5315, is in the field: and it’s detected! NGC 5315 spectrum shows enhanced Ne, depleted Fe…just like BD +303639 (see poster by Young Sam Yu)

6. Diffuse X-ray sources: properties *”Hot bubble” discovered spectroscopically; requires spatial confirmation via on-axis Chandra imaging

7. Characteristics of planetaries that are diffuse X-ray sources • Hot bubble sources: • High frequency of WR-type central stars • Large Lw (i.e. large product dM/dt x Vw2) • “Closed” morphologies • No classical bipolars among hot bubble X-ray sources • Only one hot bubble X-ray source is also an H2 source • Dense, dusty molecular tori are rare • Collimated outflow & Jet sources: • High frequency of H2 detections • Dense, dusty molecular tori are common • Higher Tx than hot bubble sources?

8. Hot bubble X-ray sources: trends • X-ray temperature and present central star Vw are uncorrelated • Other effects (evolution of Vw, heat conduction, adiabatic cooling, …) are important • Weak correlation between Lx and Lw • However, NGC 40 is a conspicuous outlier

9. Hot bubble X-ray sources: trends (cont.) • Both Tx and Lx are anticorrelated w/ central bubble radius • Are we seeing the temporal evolution of PN hot bubbles? • And has NGC 40’s bubble recently “popped”?

10. 2. X-ray Point Sources at PN cores • We have been systematically revisiting all Chandra observations of PNe to place constraints on pt. source X-ray luminosities • ~0.5” spatial resolution of Chandra essential to distinguish between diffuse & pt.-like emission • Technique: determine X-ray flux (or background noise level, i.e. upper limits) within Chandra PSF at position of PN central star

11. Results:X-ray Point Sources at PN cores • Point sources detected in ~30% of PNe observed by Chandra (not including symbiotic Mira systems) • Detections (4): NGC 246, 4361, 6543, 7293 • Typical Lx ~ 1030-31 erg/s • NGC 246, 4361 far softer than typical coronal sources • Nondetections (10): NGC 40, 3132, 7027; BD+30; Hen 2-99, 3-1475; M 1-16, 2-9; MyCn 18; Water Lily • Typical Lx limits: < 1029-30 erg/s

12. PN X-ray pt sources vs. T Tauri stars(Orion cluster T Tauri X-ray luminosities: Feigelson et al. 2005) Orion TTS: <0.3 Mo 0.3-1.0 Mo 1.0-3.0 Mo PN nondetections (~70%) Comparison suggests that cores of many (most?) PNs – including some in classical bipolars - are neither highly magnetic nor display significant star-disk magnetic interactions.

13. X-ray point sources are common (ubiquitous?) among symbiotic Miras • X-ray pt. sources detected in 5 of 6 systems • R Aqr, CH Cyg, Hen 2-104, Mz 3, & Mira itself • OH 231.8+4.2 only nondetection: X-rays highly absorbed? • Wide range of (highly variable) source Lx • ~ 1028 erg/s to ~ 1032 erg/s Blue: optical Red: X-rays Menzel 3 (Chandra & HST) R Aqr (Chandra & NOT) (Thanks, Romano…)

14. X-rays from PNe: Summary • Diffuse X-ray sources • PNe w/ “hot bubble” X-ray emission tend to have closed morphologies and very energetic present-day central star winds • Wind “inflates” and heats bubble, which eventually pops…? • But Tx and Lx better correlated with bubble size (therefore age) than present central star wind velocity or wind kinetic energy • Supports models in which X-ray bubble is initiated very early in PN evolution and/or mechanisms like heat conduction can moderate Tx • X-ray point sources • Majority of “classical” PNs lack them • suggests central star systems are usually magnetically inactive • Symbiotic Miras almost always have them • Indicative of star-disk interactions and/or accretion onto central WD companions?