Download NGC 7027

William B. Latter
SIRTF Science Center and
California Institute of Technology
APN III 29 July 2003
Outline
Overview of NGC 7027
 NGC 7027 as a carbon-rich
photodissociation region (PDR)
 Summary of some recent ground- and
space-based observations

NGC 7027 is among the most observed objects in
the sky – both as a standard calibrator object and
as a prototypical young planetary nebula. The
wealth of data of this object is both remarkable
and extraordinary.
Latter: APN3-2
29 July 2003
NGC 7027 Central Star Properties
Coordinates (J2000)
21h 7m 1.83s/+42O 14’ 9.93”
Zanstra Temperature
198100 +/- 10500 K
Luminosity (D=880pc)
7710 +/- 860 L⊙
Radius
5.21 x 109 cm
Core mass
0.7 M⊙
Initial Mass
4 M⊙
Evolutionary timescale
700 yr
from Latter et al. 2000, ApJ, 539, 783
Latter: APN3-3
29 July 2003
Photodissociation Region
Schematic (O-rich vs. C-rich)
C2H2
CN
CO+
HCO+
Latter: APN3-4
HCN
C/C2
29 July 2003
NGC 7027 HST/NICMOS
-- The PDR Revealed
Latter: APN3-5
29 July 2003
Two components of a three component
model of the emission regions
Latter et al. 2000, ApJ, 539, 783
Latter: APN3-6
29 July 2003
See also Latter et al. 2000, ApJ, 539, 783
Latter: APN3-7
29 July 2003
C-rich PDR Models and ISO Observed
Infrared Emission Lines
Rotational CO emission
detected using ISO-LWS
NGC7027
Justtanont et al. 2000, A&A, 360,
1117
See also: Fong et al. 2001,
A&A, 367, p. 652 and p. 674
Latter: APN3-8
29 July 2003
High resolution near-IR spectro-imaging
Cox et al. 2002, A&A, 384, 603
Molecular hydrogen emission @
2.121 microns
CFHT and Bear
** See poster: D. Mekarnia **
Latter: APN3-9
29 July 2003
Chandra NGC 7027 Data
Kastner et al. 2002, ApJ, 581, 1225
See also Maness et al. 2003, ApJ, 589, 439 and refs therein
Latter: APN3-10
29 July 2003
NGC 7027 at Radio Wavelengths
Bains et al. 2003, MNRAS, 340, 381
18 cm continuum (L-band) = contours
6 cm continuum (C-band) = greyscale
Latter: APN3-11
29 July 2003
PDR and Wind
Evolution in NGC 7027
There is now direct observational confirmation that the molecular
hydrogen emission from NGC 7027 is PDR emission, as well as other
definite PDR tracers detected, including CO+.
 Steady state, plane parallel and more complex models of C-rich PDR
reproduce the NGC 7027 chemical properties reasonably well.
 The PDR in NGC 7027 is at least 600 years old, with the star having
begun evolution off the AGB about 1000 years ago.
 The NGC 7027 CSE is not spherically symmetric and is highly nonuniform. Very dense from heavy mass loss from massive progenitor
(about 4 M⊙).
 There is clear evidence in multiple tracers form the effects of two or
more jets or jet-like flows that have disrupted the surrounding nebula.
The jets themselves have not been seen, and might have shut down.
Latter: APN3-12
29 July 2003
HST/STIS Observations
Bieging et al. in preparation
Latter: APN3-13
29 July 2003
HST/STIS Data (example)
Bieging et al. in preparation
52” x 0.1” slits x 5
G430L and G750L gratings
Latter: APN3-14
29 July 2003