x-ray emission from planetary nebulae and their central stars: a status report joel kastner...
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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?