SOFIA FORCAST Images of the Bipolar Planetary Nebula M2-9...• SOFIA images of M2-9 show not only a...
Transcript of SOFIA FORCAST Images of the Bipolar Planetary Nebula M2-9...• SOFIA images of M2-9 show not only a...
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SOFIA FORCAST Images of the Bipolar Planetary Nebula M2-9
M.W.Werner1, J. Davis2, R. Sahai1, M. Morris3, L. Keller4, T. Herter5
1JPL, 2Caltech, 3UCLA, 4Ithaca College, 5Cornell University.
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Compact Planetary Nebula are ideal initial targets for FORCAST:
• Bright in the infrared – often too bright for Spitzer
• Infrared emission known to peak in the 30um region
• Well matched in size to FORCAST 3.2 arcmin field of view
• Werner, Morris and Sahai were awarded 4 hours of SOFIA time to observe four such targets:
• NGC7027, M2-9, NGC6543, Frosty Leo 2
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Minkowski 2-9 Classic bipolar nebula
• Previous work estimates L=2500 Lsun
Stellar temperature 15000K
• Distance = 1.2 Kpc
• Observed with FORCAST in six bands:
6.6, 11.1, 19.7, 24.2, 33.6, 37.1um 6-to-10 min per filter
• Photometry done on SOFIA Science Center Level 3 data products
16””
3
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SOFIA Images of M2-9 6.6 11.1 17.9
24.2 33.6 37.1
40”
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Properties of Central Point Source
• FWHM = 3.5 to 4.7 arcsec, increasing with wavelength – not resolved • Luminosity = 760 Lsolar. IRAS measured 1100Lsolar
• Breadth of Spectral Energy Distribution indicates that we are seeing a disk rather than a thick spherical dust shell (Lykou et al, A+A , 2011)
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1.5
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2.5
0 0.5 1 1.5 2 2.5
Log
Flux
(Jy)
Log Wavelength (Microns}
SOFIA Central 5” Radius
IRAS
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SOFIA Photometry ( )of Central Source Compared to Lykou et al Disk
Model
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Turning to the Lobes
Halpha+[NII] 24.2um [OIII] (2010) (2010)
• Infrared emission comes from region comparable in size to that seen in the optical
• Lobes show structure and limb brightening in visible
• Distribution smoother in the infrared, although some structure is seen
• Difference in spatial resolution partly, not totally responsible for this
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Turning to the Lobes
Halpha+[NII] 24.2um [OIII] (2010) (2010)
• Infrared emission comes from region comparable in size to that seen in the optical
• Lobes show structure and limb brightening in visible
• Distribution smoother in the infrared, although some structure is seen
• Difference in spatial resolution partly, not totally responsible for this
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Turning to the Lobes (2)
19.7
24.2
33.6
37.1
44” 2.000
2.500
3.000
3.500
4.000
1.000 1.250 1.500 1.750 Log
Flux
[mJy
]
Log Wavelength (Microns)
SED of 3.75”x3.75” areas centered 7.5, 11.25, 15” S of central source.
• Color Temperature about 100K • Assuming emission due to dust….
• Particle size <0.1 um • Total dust mass in lobes 0.004 solar masses
Horizontal scans through lobes, 10” N. of central source
• Profiles suggest lobes not uniformly filled with dust but modestly “limb brightened”
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Modeling Lobe Structure Cross Section #4, 24.2um, convolved with
beam
0
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0 0.2 0.4 0.6 0.8 1 1.2 1.4
p/R
n = .15
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0.65
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LOBE MODELLED AS THIN CYLINDRICAL SHELL
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LOBE MODELLED AS THIN, LARGELY EMPTY
CYLINDER
LOBE MODELLED AS UNIFORM ANNULAR CYLINDER WITH ONLY
DATA
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Conclusions • SOFIA images of M2-9 show not only a bright, compact central source but also emission from the lobes at 19.7um and beyond.
• The central source is not resolved by SOFIA at any wavelength, with angular size less than about 5 arcsec • The central source has a 5-40um luminosity of 760 solar luminosities, more than half the luminosity measured by IRAS • The broad infrared SED of this source is more suggestive of emission from a disk than of emission from a spherical shell
• The emission from the lobes extends +/- 20 arcsec from the center • The infrared emission is confined EW to a region comparable in width to the optical lobes • The emission can be attributed to a cylindrical distribution of dust within the lobes with a small central empty region but without extreme limb brightening as suggested by the optical images