What can Spectroscopy with ISO on Galactic Sources Teach us about Requirements for SPICABLISS

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What can Spectroscopy with ISO on Galactic
Sources Teach us about Requirements for
SPICA/BLISS ?
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What is the best Spectral Resolution for which we
should aim?
With SPICA/BLISS we will undoubtedly wish to look
at stars in different stages of evolution as well
as outflows, protostars and star forming
regions, and Solar System objects
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ISO Grating Spectra of Comet Hale-Bopp at 2.9 AU
from the Sun, on 10/6/1996
Right ISO/LWS H2O spectrum of the comet at a
resolving power R150. Left An ISO/SWS H2O
spectrum at R 2000 gave an ortho-para ratio
2.45, corresponding to Tspin 25K. Spectral line
ratios gaveTrotation 28K. In principle long
wavelength spectra can also provide such
temperatures.
Hale-Bopp observations
model spectrum
The CII line probably is due to background
contamination
J. Crovisier et al., Science, 275, 1904 (1997)
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ISO Spectra of Protostellar Objects
All three spectra were obtained with the ISO
Long Wavelength Spectrometer, LWS, at spectral
resolving powers R 150 200. A significant
number of spectral lines are clearly identified
in uncrowded regions and indicate a potential use
for characterizing different classes of
protostars .
From papers by Spinoglio et al. 1999 Saraceno et
al. 1999 Nisini et al. 1999
Courtesy of Harold Yorke
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VY CMa Properties
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VY CMa image
The Highly Evolved Star VY CMa
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Spectrophotometry of VY CMa
Harwit et al., ApJ 557, 844 (2002)
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VY CMa Mid-Infrared Grating Spectrum
ISO Short-Wavelength Spectrometer, SWS, Grating
Spectrum of VY CMa at Resolving Power 2000
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VY CMa P Cygni Profiles
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VY CMa 557 GHz
VY CMa o-H2O SWAS Spectrum
Spherical Outflow
Efstathiou / Rowan-Robinson Model
The 557 GHz (538 micron) ortho transition at R
3 x 105
Harwit Bergin, ApJ 565, L105, 2002
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At Spectral Resolution R 3 x 105
the cold primary mirror on SPICA no longer
provides advantages over Herschel. So,
SPICA/BLISS should probably restrict itself to
lower spectral resolving powers
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NML Cygnus Properties
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NML Cyg H2O SWS line collage
NML Cygnus H2O at ISO/SWS Resolving Power 20,000
V. Zubko, D. Li, T. Lim M. Harwit, ApJ 610,
427, 2004
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ISO/LWS Observations of the NML Cyg H2O 100.983
µm line at spectral resolving power R 9,700
V. Zubko, D. Li, T. Lim M. Harwit, ApJ 610,
427, 2004
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Orion Nebula Seen with the Infrared Spectrometer
and Array Camera, ISAAC, at the VLT
M. R. Lerate et al., MNRAS, 370, 597 (2006)
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Spectral Lines Observed Centered on Orion
IRc2-BN/KL at Grating and F-P resolution
The region observed is shown against a false
color continuum emission map obtained by D. Lis
at 350 µm with the Submillimeter High Resolution
Camera (SHARC). ISO Long Wavelength Spectrometer
(LWS) observations were approximately centered on
a region offset from the source IRC2 by 5.4
arcsec or, alternatively, offset from the BN
object by 10.5 arcsec. As can be seen, the 80
arcsec beam provided significant overlap of these
two regions. A list of more than 150 different
spectral lines was compiled from features
identified in absorption, emission, or both.
M. R. Lerate et al., MNRAS, 370, 597 (2006)
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Orion KL Region at Different Spectral Resolving
Powers
ISO Grating ??/?? 50 - 200
ISO Fabry-Perot ?/??9600
Comparison of the two resolving powers in a part
of these spectra
M. R. Lerate et al., MNRAS, 370, 597 (2006)
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Orion KL Region Fine Structure Lines
These lines, observed in the Fabry-Perot mode
are sufficiently bright to be observed at lower
spectral resolution. But the F-P mode teaches us
that, except for the 145.5 µm line, the LSR
velocities of line peaks lie at 10 km s-1, in
agreement with the 9 km s-1 velocity of the
quiescent gas .
M. R. Lerate et al., MNRAS, 370, 597 (2006)
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Orion KL Carbon Monoxide Lines
Shown here are 9 of the 27 carbon monoxide lines
detected by ISO at wavelengths from 50 to 190
µm. The spectral resolving power ranges from
9600 at 118 µm to 7000 at 186 µm . This
clearly separates the lines from the continuum
but does not provide the velocity resolution
needed for Galactic work.
M. R. Lerate et al., MNRAS, 370, 597 (2006)
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Orion KL H216O Water Vapor Lines
Seventy water vapor lines were detected, in
Fabry-Perot mode, in absorption or emission over
the wavelength range from 44 to 190 µm . Of
these the ten lines at longest wavelengths are
shown here. The temperatures indicated on the
individual panels are rotation temperatures
modeled, along with other parameters, on the
basis of the large aggregate of observed lines.
M. R. Lerate et al., MNRAS, 370, 597 (2006)
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Orion KL Water Isotope Lines H218O Detected
with ISO
A selection of six water vapor lines with
isotopes 18O observed at resolving powers of 9700
6800 ranging from 67 to 197 µm . Both
absorption and emission can be detected in these
relatively weak lines.
M. R. Lerate et al., MNRAS, 370, 597 (2006)
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Orion KL Three H3O Lines Detected with the
Fabry-Perot LWS Spectrometer on ISO
H3O plays a key role in interstellar chemistry,
leading to the formation of OH and H2O by
dissociative recombination with poorly known
branching ratios. It can be formed through
reactions with H3 , one reaction being H3
H2O ? H3O H2 , but other pathways also
exist. Destruction occurs through electron
recombination to form OH or water. Modeling the
lines observed in the Orion KL region suggests
that they have optical depths ? gt 10.
M. R. Lerate et al., MNRAS, 370, 597 (2006)
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Orion KL Ammonia Lines NH3 Detected with the
Fabry-Perot LWS Spectrometer on ISO
These lines should have moderate optical depths ?
1 for an inferred column density N 1014 cm-2,
T 80 K and n(H2) 105 cm-3. If the column
density is gt 1015 cm-2, however, the optical
depths could be much higher.
M. R. Lerate et al., MNRAS, 370, 597 (2006)
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Orion KL 16OH and 18OH Isotope Lines Detected
with ISO
The complete Orion KL survey yielded 21 spectral
lines of 16OH and two of the molecular isotope
18OH. All exhibit P Cygni profiles indicating
outflow.
16OH
18OH
M. R. Lerate et al., MNRAS, 370, 597 (2006)
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Orion KL Tentative Detection of Five
Transitions of HDO
From these observations a total column density N
3 x 1014 cm-2 is derived. This is significantly
lower than obtained from millimeter wave
observations, but the two findings could be
explained by a clumped HDO distribution.
M. R. Lerate et al., MNRAS, 370, 597 (2006)
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What Does this Tell us about the Most Desirable
Spectral Resolution for SPICA/BLISS?
HIFI will have carried out observations at
resolving powers yielding velocities lt 1 km s-1.
At this resolution a cold primary mirror is no
advantage. But a velocity resolution of a few km
s-1 to separate closely spaced lines, or
determine outflow or infall velocities, or
co-moving regions could be a great advantage.
If SPICA/BLISS were able to provide at least
one observing mode with R 30,000 this could
have great advantages for many types of Galactic
observations .
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Hinge Spectrometer
M. Harwit et al. Applied Optics, 26, 669 (1987
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Spectra of Star Forming Regions
Emission from a star forming region ( 70-100 K)
with spectral lines imposed on the dust continuum
Courtesy of Harold Yorke, JPL
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Spectral Sensitivity of SPICA
Courtesy of Matt Bradford, JPL