Transcript X-Ray Emission from Planetary Nebulae and Their Central

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…
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 31475
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)
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
NGC 5315 spectrum shows enhanced Ne,
detected!
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
*”Hot bubble” discovered spectroscopically; requires spatial confirmation via on-axis Chandra imaging
“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
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
Blue: optical
Red: X-rays
– R Aqr, CH Cyg, Hen 2104, Mz 3, & Mira itself
• OH 231.8+4.2 only
nondetection: X-rays
highly absorbed?
Menzel 3
(Chandra & HST)
– Wide range of (highly
variable) source Lx
• ~ 1028 erg/s to ~ 1032 erg/s
R Aqr
(Chandra & NOT)
(Thanks, Romano…)
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?