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

A Status ReportJoel Kastner

Rochester Institute of Technologyw/ 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…

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)

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

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

NGC 2346 is an X-ray NONdetection (Gruendl et al. 2006)

X-ray images (blue): XMM & ChandraX-ray/visual image overlays: M. Guerrero

Montage: B. Balick

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)

Diffuse X-ray sources: properties“Hot Bubbles”

Object

Vw

(km/s)

dM/dt

(Msun/yr)

Tx

(K)

Lx

(erg/s)

WR type?

H2

?

NGC 5315* 2400 1.5x10-6 2.6x106 2.2x1032 Y …

BD +303639 700 1.6x10-6 2.7x106 1.6x1032 Y Y

NGC 7026 3500 4.6x10-7 1.1x106 1.5x1032 Y N

NGC 6543 1900 4.0x10-8 1.7x106 1.0x1032 Y* N

NGC 7009 2700 3.0x10-10 1.8x106 3.0x1031 N N

NGC 2392 420 1.8x10-8 2.0x106 2.6x1031 N N

NGC 40 1000 1.8x10-6 8.0x105 1.5x1030 Y N

NGC 3242 … … (Unpubl.) (Unpubl.) N N

“Jets”Object

Vw

(km/s)

Tx

(K)

Lx

(erg/s)

WR

type?

H2

?

NGC 7027 … 3.0x106 1.2x1032 … Y

Hen 3-1475 2300 5.0x106 4.0x1031 N …

Menzel 3 400: 6.0x106 2.4x1031 N Y

*”Hot bubble” discovered spectroscopically; requires spatial confirmation via on-axis Chandra imaging

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?

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

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”?

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

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

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.

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/sR Aqr

(Chandra & NOT)(Thanks, Romano…)

Menzel 3(Chandra & HST)

Blue: opticalRed: X-rays

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?