Slide 1
1Current: Matt Richter (UCD), Mark McKelvey (Ames), Curtis
DeWitt (UCD), Mike Case (UCD), Jeff Huang (Ames), Kristin Kulas
(Ames), Robert McMurray (Ames), Damon Flansburg (Ames), Jeff Blair
(Ames), Emmett Quigley (Ames), Reed Porter (Ames)
Past: Pete Zell (Ames), Andreas Seifahrt (UCD), John Reimer
(Ames), Bala Balakrishnan (Ames), Dana Lynch (Ames), John Lacy (UT
Austin), Doug Mar (UT Austin), Bill Moller (UT Austin)
Honorary (SOFIA): Melanie Clarke, Bill Vacca, Adwin BoogertFirst
flights of EXES on SOFIA
Adapted from Scott Sandfords 2009 teletalk2OutlineMid-IR
spectroscopy featuresatmospheric effectsImportance of high
resolution About EXESSome highlightsFurther informationAdapted from
Scott Sandfords 2009 teletalkAdapted from Scott Sandfords 2009
teletalk
3IR spectroscopy, particularly in the 2-40 m range, can detect
and identify many molecular species since different molecules have
different IR spectral fingerprintsMolecules seen with TEXESwithout
dipole moments: H2, C2H2, CH4, CH3other molecules: H2O, HDO, HCN,
NH3, SO2, CO, HNCO, OH, SiO, CS, C2H4, C2H6, C3H4, C4H2, C6H2, PH3,
CH3DAdapted from Scott Sandfords 2009 teletalkmolecules in stars,
planets, mass-loss regions (Fonfria et al), star forming regions
(Knez, et al. 2009; Barentine & Lacy 2012)(T)EXES lowAdapted
from Scott Sandfords 2009 teletalkArmed with the appropriate
spectral resolutions, one can also distinguish between solids and
gases
45.0Spitzer IRS HighISO SWS (about)JWST MIRI (about)NOTE:
(T)EXES do not observe this full spectral region. IRS did not cover
any of this region.Adapted from Scott Sandfords 2009 teletalkPoint
out the resolving powers of Spitzer, ISO SWS (2000), MIRI (3000),
(T)EXES low - high = 80,000, med ~15,000
SOFIA vs Mauna Kea5TEXES cutoff (optics)Atmospheric
comparisonEXES cutoff (Si:As)Adapted from Scott Sandfords 2009
teletalkMention wavelength cut-off for TEXES6Advantage of
EXES/SOFIAhigh spectral resolution at wavelengths inaccessible from
ground
Comparison of transmission from SOFIA and Mauna Kea for some
important moleculesH2OC2H2CH3CH4HCNSO2Effect of atmosphere in
background limit (Mason et al 2008)
S/N T / ( (1-T) + e )0.5
where:T is atmospheric transmissione is system emissivity
Adapted from Scott Sandfords 2009 teletalk7High Spectral
ResolutionLine profile informationLimit confusionother source
lineslines from atmosphereMaximize sensitivity for narrow lines
SOFIAMauna Kea100 km/s
PropaneRoe et al. 2003
40 km/sJaffe et al (2003) R~80,000Adapted from Scott Sandfords
2009 teletalkUpper Right is from [NeII] map of Mon R2 - histogram
for data as observed. Dashed line is convolved with thermal
broadening for ionized H.Lower Right shows propane detection from
Titan - Strongest lines are not propane so would cause confusion.
Lower Left shows model atmosphere near J=3-1 H2 line from Mauna Kea
and from SOFIA. From ground, careful about Doppler shift. 8
Tau OrinoiseEXES/TEXES niche
Designed and built to emphasize high resolutionEvolution from J.
Lacy work with Irshell, R=10,000 grating spectrographHigher
resolving power than other mid-IR grating and FP instrumentsHigher
sensitivity than FTS or HeterodyneJennings et al. 1986TEXES on
IRTF: 4 minutes, R=80,000 1.20.6Adapted from Scott Sandfords 2009
teletalkFTS on 4m - R=50,000 and 4 hrs on alpha Ori, 6.4 hrs on
alpha TauTEXES on IRTF in 2000 with R=80,000 and 3x spectral
coverage. Note vertical scale. almost no noise.EXES/TEXES
niche9
TEXES survey of IRC +10216 (Fonfria et al. 2008) 1 of 6
pages
zoom of upper leftProvide data unobtainable elsewhereComplement
ALMA, GREAT on SOFIA, Herschelvibrational transitionsmolecules with
no dipole momentAdapted from Scott Sandfords 2009 teletalkTEXES
observations10Other Mid-IR Spectrographs
Adapted from Scott Sandfords 2009 teletalkNOTE that VISIR
detector upgrade keeping it out of commission for next year.11Other
Mid-IR Spectrographs
EXESozoneAdapted from Scott Sandfords 2009 teletalkTEXES is
smaller due to atmosphere and detector.12Echelon grating40
long0.300 groove spacing0.131 grooves/mm84.2 degree incidence
angle0.03 groove heightDiamond machined Al 6061Hyperfine Inc
0.30.3
Adapted from Scott Sandfords 2009 teletalk13DetectorsEXES10242
pixels25 mm per pixelOversampled0.38 km/s per pixel0.21 per pixel60
e- single sample readmatches size of high resolution orders ~19
mTEXES2562 pixelfocal reduced to 63 mm pixels0.97 km/s per
pixel0.13 per pixel on Gemini30 e- single sample read (IRAC
array)matches size of high resolution orders ~11 mBoth:Si:As
Optimized for low background (space)shallow wells ~1.e5 e- for 40%
transmission from ground)Same general guidelines as EXESAdapted
from Scott Sandfords 2009 teletalk26Further informationFor EXES on
SOFIAMatt Richter (PI): [email protected] McKelvey (Co-I):
[email protected] DeWitt (postdoc):
[email protected]://irastro.physics.ucdavis.edu/exeswebsite
still work in progressEXES exposure time calculator:
http://irastro.physics.ucdavis.edu/exes/etcFor TEXES on
Gemini/IRTFJohn Lacy (PI): [email protected] Greathouse
(solar system): [email protected] Richter (Galactic):
[email protected] from Scott Sandfords 2009 teletalk