Post on 27-Apr-2022
Darek Lis (Caltech)!On behalf of the HEXOS Team: !
PI E. Bergin + ~60 (hexos.org/team.php)!!
Emory, October 29, 2012 !
HEXOS: Broad Perspective!
•! Stars are born in molecular clouds that exhibit a high degree of chemical complexity—dominated by organics, water, carbon monoxide, and carbon dioxide!
•! How this complexity develops is uncertain—gas phase? catalytic chemistry on grain surfaces?!
•! We have been hindered by our inability to view the entire spectrum of star forming gas—cannot trace water and key coolants (e.g., C II, O I, high-J CO ladder)!
•! How do organics and water form in space? How are they delivered to the planet-forming disks and then to young planets?!
Orion and Sagittarius B2: "Extra-Ordinary Objects!
•! Contain the classic examples of phenomena found throughout the ISM:!•! Hot cores: Orion KL, Sgr B2 (M) and (N)!•! Photodissociation region (PDR): Orion Bar!•! Shocks: Orion KL!•! Diffuse gas in Milky Way: Sgr B2 (M) as a background beacon!
•! Main parts of program: !•! Full HIFI spectral scans of Orion KL, Orion S, Orion Bar, Sgr
B2 (M), Sgr B2(N)!•! PACS range scans of same sources!•! Water maps of the Orion KL shock/deep integrations/search
for large molecules!
ESO! 1 !
Orion KL!Comito et al. 2005 !
E. Bergin!
Orion KL!
Tracing Physics!
Wang!
•! Very difficult data product!!•! One million independent data channels!•! Blended lines!
Spectral Data Mining!•! How to deal with this unique data set and what new
information can it reveal?!•! HIFI offers excellent calibration providing greater reliability
for multi-transition studies!•! Beam coupling to source is changing—model entire spectrum
at once—assume LTE but can have multiple physical components (different temperature, abundance, source size)!
•! Effort is well underway for Orion KL (Nathan Crockett) and Sgr B2(N) (Justin Neil)!
•! Model what we know is there—look for new things....!•! Synthesize/compare to models!•! Knowledge of precise line frequencies critical for the analysis!
Orion KL Full Band Analysis!
•! Over 60 species, including isotopologues, modeled by a team of ~20 people!
•! From residual fit: ~2500 U-lines out of 20,000 (~10%)!•! Identification of species that probe the hottest gas—harder
to evaporate off the grains?!
Crockett!
Hot Molecular Gas!
•! Fraction of emission as a function of upper level energy!•! Ethyl cyanide and methyl cyanide show significant emission
from energy levels > 800 K!•! Ethanol and methyl formate probe cooler regions!
0 - 200 K200 - 800 K800 - 2000 K
Hot Core
Compact Ridge
Orion Bar"PACS!
Color: CO J = 6-5 (Lis & Schilke 2003)!Contours: H2 v=1-0 S(1) (Walmsley et al. 2000)!
•! Integral Field Spectrometer!
•! Simultaneous spectroscopy at 57-105 and 105-210 μm !
•! FOV 47″ x 47″ (5x5 pixels) !
•! R ~ 1000-2000!
Cooling & PDR Chemistry!Strong [OI], [CII] + high-J CO + excited OH, CH+, H2O… !
Goicoechea/Joblin/Contursi !
Goicoechea!
•! Five rotational !–doublets up to 510 K!
•! Emission extended, correlates with high-J CO and CH+, but not H2O!
•! Warm (160–220 K), dense (106-7 cm-3) gas; unresolved clumps exposed to FUV radiation (O + vib H2)!
Detection of OH in Orion Bar!
van der Tak /Nagy!
•! A rare case of HF being seen in emission!•! Large line width suggests origin in the
interclump gas!•! Electron impact excitation reproduces
observations (also works for CH+)!•! Similar conditions may apply to AGNs!
HF, CH+, CF+ in !Orion Bar!
! !
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HF!
CH+!
CF+!
Water Maps""
1113 GHz!
Melnick/Tolls!557 !GHz!
-100 0 1001.0
0.5
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0.5 68.9 101.6
240
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0.5 60.6 103.1
209
-100 0 100
0.5
0.0
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1.0 50.5 102.6
208
-100 0 100
0.5
0.0
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1.0 41.6 103.3
177
-100 0 1001.0
0.5
0.0
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1.0 31.4 101.3
176
-100 0 100
0.5
0.0
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1.0 22.5 102.8
145
-100 0 100
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0.0
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1.0 12.4 101.4
144
-100 0 100
0.5
0.0
0.5 3.8 103.9
113
-100 0 100
0.5
0.0
0.5 -6.6
102.0112
-100 0 100
0.5
0.0
0.5
1.0
-15.0 103.9
81
-100 0 1000.5
0.0
0.5
1.0 -25.4 102.1
80
-100 0 100
0.5
0.0
0.5 -33.8 103.2
49
-100 0 100
0.5
0.0
0.5 -43.9 101.8
48
-100 0 100
0.5
0.0
0.5
1.0 -52.8 103.3
17
-100 0 100
0.5
0.0
0.5 -63.0 102.0
16
-100 0 1001.0
0.5
0.0
0.5
1.0 69.1 92.4
239
-100 0 100
0.5
0.0
0.5 60.4 93.8
210
-100 0 100
0.5
0.0
0.5
1.0 50.3 92.6
207
-100 0 100
0.5
0.0
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1.0 41.4 93.6
178
-100 0 100
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0.0
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1.0 31.2 92.2
175
-100 0 100
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1.0 22.6 93.5
146
-100 0 100
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0.0
0.5 12.3 91.9
143
-100 0 100
0.5
0.0
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1.0 3.8 94.6
114
-100 0 100
0.5
0.0
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111
-100 0 100
0.5
0.0
0.5 -15.0 94.4
82
-100 0 100
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0.0
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1.0 -25.4 92.8
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-100 0 100
0.5
0.0
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50
-100 0 100
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0.0
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-100 0 100
0.5
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1.0 -52.9 93.9
18
-100 0 100
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0.0
0.5
1.0 -63.1 92.0
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-100 0 100
1.0
0.5
0.0
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1.0 69.2 82.8
238
-100 0 100
0.5
0.0
0.5
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211
-100 0 100
0.5
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206
-100 0 100
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179
-100 0 100
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-100 0 100
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-100 0 1000.5
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-100 0 100
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212
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180
-100 0 100
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173
-100 0 100
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148
-100 0 100
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-100 0 100
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1
2 -6.7 74.0
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-100 0 100
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-100 0 1001.0
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-100 0 100
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-100 0 100
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-100 0 100
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-100 0 100
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213
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1
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1
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1
2
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-100 0 100
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1
2
3
4
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1
2
3
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1
2
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1
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1
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1
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1
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1
2
3
4
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6
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216
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1
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1
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3
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2
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6
8
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1
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1
2
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1
2
3
4
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4
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8 21.5 29.6
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-100 0 10002468
101214
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10
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10
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8
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2
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15
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20
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20
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20
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1
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3
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2
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6 21.5 -16.6
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2
4
6
8 13.0 -18.3
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10
15 2.7
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10
15 -5.8 -17.3
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10
15 -15.9 -15.9
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2
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6
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226
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223
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1
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1
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191
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1
2
3 32.1 -27.5
162
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2
4 21.5 -25.7
159
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2
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130
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2
4
6
8 2.8
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2
4
6
8 -5.4 -26.4
98
-100 0 100
0
2
4
6 -15.8 -24.9
95
-100 0 100
0
1
2
3
4 -24.4 -26.6
66
-100 0 100
0
1
2 -34.4 -25.9
63
-100 0 100
0
1
2 -43.2 -27.1
34
-100 0 100
0.5
0.0
0.5
1.0
1.5 -53.5 -25.6
31
-100 0 100
1.0
0.5
0.0
0.5
1.0
1.5 -62.2 -27.3
2
-100 0 100
0.5
0.0
0.5 69.9 -36.3
225
-100 0 100
0.5
0.0
0.5
1.0 59.8 -34.8
224
-100 0 100
0.5
0.0
0.5
1.0
1.5
2.0 51.2 -35.6
193
-100 0 100
0
1
2 40.8 -34.8
192
-100 0 100
0
1
2
3 32.1 -36.3
161
-100 0 100
0
1
2
3
4 21.5 -34.9
160
-100 0 100
0
1
2
3
4 13.1 -36.3
129
-100 0 100
0
2
4 3.0
-34.2128
-100 0 100
0
2
4 -5.4 -35.8
97
-100 0 100
0
1
2
3 -15.7 -33.9
96
-100 0 100
0
1
2 -24.5 -35.8
65
-100 0 100
0.5
0.0
0.5
1.0
1.5
2.0 -34.4 -35.1
64
-100 0 100
0
1
2 -43.2 -36.3
33
-100 0 100
0.5
0.0
0.5
1.0
1.5
2.0 -53.5 -34.8
32
-100 0 100
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0.0
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1.0 -62.2 -36.5
1
Small Water Maps!
•! Water associated with low-velocity outflow, not C-shocks traced by H2 or the hot core!
•! Water molecules photodissociated by UV?!
Melnick/Tolls!
Absorption Spectroscopy:"Sampling Galactic Spiral Arms!
NASA/SSC R. Monje!
Hydrides!•! OH+!
•! H2O+!•! H3O+!•! H2O!•! HDO!•! HF!•! CH+!•! CH!•! H2S!•! SH+!•! NH!•! ND!•! NH2!
•! NH3!•! HCl!•! HCl+!•! H2Cl+!•! …!•! NH+!
SgrB2N!
SgrB2M!
SLWA2!
SPIRE-FTS Sgr B2! !
~20 minutes Etxaluze/Goicoechea/Cernicharo!
!"#$ !!#$
HEXOS Sagittarius B2(N)!
•! Complete HIFI scans of Sgr B2(N) and (M); excellent continuum stability!
Sgr B2(N)!
Sagittarius B2(N) HEB!
•! HEB bands dominated by absorption lines—water isotopologues, low energy ammonia lines, C3, C+…!
o-H2O!
C+!
C3!
NH3!NH3!
H3O+!
metastable J=K!inversion transitions!
H3O+ in Sgr B2(N)!
Lis!
Formation Pumping!
•! Cosmic/X-ray + H2 → H3+!
•! H3+ + O → OH+ + H2!
•! OH+ + H2 → H2O+ + H!
•! H2O+ + H2 → H3O+ + H + 21,710 K!
•! If we assume # of the enthalpy change goes into rotation then we can match observations (J. Black) !
•! Need high ionization rate > 10-16 s-1 to maintain population !
•! Related to Sgr A* activity 100-200 years ago?!
•! Molecule present in all spiral arm clouds between us and the galactic center, but not the Sgr B2 envelope (difficult to get precise ν)!
First FIR DIB Analog?!
http://www.submm.caltech.edu/labspec/!
Pasadena Workshop!
Workshop Report!•! Defined characteristics of “weeds”!•! Identified most prominent weeds:!•! Class 1: CH3OH (methanol), HCOOCH3
(methyl formate), CH3OCH3
(dimethyl ether),CH3CH2CN (ethyl cyanide), and their isotopologues!•! Class 2: Five somewhat less prominent (Class 2) weeds are C2H3CN (vinyl
cyanide), SO2 (sulfur dioxide), CH3CN (methyl cyanide), HC3N
(cyanoacetylene), and CH3CHO (acetaldehyde)!•! Together species possess approximately half of the identified interstellar lines
emanating from cold and hot portions of interstellar clouds through 700 GHz!•! Recommendations:!•! Establish a program to measure the frequencies of the weed transitions!•! Estimated cost $250k$$800k to equip spectroscopy laboratories and $600k$
$900k per year for a minimum of 3 years to take and analyze the data and provide them to molecular line databases!
•! Community must work with US funding agencies and international partners to ensure a solution!
Workshop Outcome!
Herschel Space Observatory, NASA Participation, Cycle-0 Proposals—Theory/Laboratory Astrophysics!
•! Request: 28 proposals, 22 institutions, $4.8M!•! Funded: 15 proposals, ~$2M—many PIs are here this week and will
present their results!•! There was only one such call with a modest funding level!•! No further funding from Herschel; have to rely on the NASA
Laboratory Astrophysics and APRA programs!
Example: HF J = 1–0!
Weeds!
Phillips!
HF!H2O!
•! Improved frequencies essential for the analysis of the HEXOS spectral scans (e.g., methanol, including excited tortional states, methyl cyanide, dimethyl ether, ethyl cyanide…)!
Current Goals!
•! Re-evaluate where we stand six years after the Pasadena workshop, with the Herschel data in hand!
•! Understand better what the needs are for ALMA, and also SOFIA, JWST, SPICA!
•! With Herschel/HIFI we were extending the high-resolution spectroscopy to a new frequency range!
•! With ALMA we will go much deeper—increasing importance of isotopologues and less abundant molecular species !
•! Precise frequencies needed to identify new species, in particular more complex organics!
Panel Discussion!
Lessons from Herschel!•! Important to understand early on what the needs are and to set
specific goals that are reachable within the limited resources!•! In 2006, we had very few direct lab measurements of line frequencies
above a few 100 GHz!•! The lab community came through and provided the necessary data!•! As a result, only ~10% of (mostly weak) lines remain unidentified in the
Orion KL spectral scan—that’s a big success!!•! It was a multinational collaboration, with funding from many agencies,
including NASA (Herschel Cycle 0)!•! Lab spectroscopists were invited to join the Herschel GT teams!•! Good model to follow for JWST!!
Goal 1: Astrochemistry!•! Line identification of abundant species to allow searches for new
molecules (COMs)!•! Lesson from HEXOS: LTE approximation works well enough in hot
cores for the purpose of line identification!
•! What are the flowers?!•! We have heard a lot during this meeting about the importance of
isotopologues (D, 15N, 18O…)—connection between ISM and solar system materials—particularly important for ALMA!•! Also symmetry states—ortho and para species, isomers!
•! To be useful to the astronomical community, lab spectra have to be easily accessible in a format that astronomers can understand!
Goal 2:"Astrophysics!
•! Broader appeal!•! Use molecular spectra to
determine the physical conditions: temperature, density, ionization rate in starforming regions!•! Which are the most important
species in different environments?!•! Collisional rates needed to
determine the physical conditions (have to prioritize) !•! Need 3d radiative transfer models
for both dust and gas!•! Importance of IR pumping (H2S)
and formation pumping (H3O+)!•! All this has to be incorporated into
user-friendly software packages that people can actually use!