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MW Spectroscopy of -Alanine
and a Search in Orion-KL
Shiori Watanabe ( Kyoto Univ. JAPAN ),Shiori Watanabe ( Kyoto Univ. JAPAN ),Satoshi Kubota, Kentarou Kawaguchi ( Okayama Univ. JAPAN ),Satoshi Kubota, Kentarou Kawaguchi ( Okayama Univ. JAPAN ),
Yasuko Kasai ( NICT, JAPAN ),Yasuko Kasai ( NICT, JAPAN ),andand
Takamasa Momose ( UBC, CANADA )Takamasa Momose ( UBC, CANADA )
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Amino acid in ISMThe origin of biomolecules Interstellar Medium?
Astronomical studies
Detection (2003)Reassigned to acetone (2005)[ ]
-alanine: The simplest chiral amino acid
Laboratory measurements in 100 and 170 GHzA search in Orion KL by NRO 45m telescope in 100 GHz
Glycine:
Our objectiveOur objective
Previous searchPrevious search
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52 ~ 72 GHz; Godfrey et al. (1993)
6 ~ 18 GHz; Blanco et al. (2004)
Available spectroscopic data of Available spectroscopic data of -alanine-alanine
Laboratory Observation
Laboratory observations in 100 GHz were indispensable for the definite identification in interstellar medium.
Astronomical searchAstronomical search at Nobeyama
80 ~ 115 GHz
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Continuous Molecular Beam Source
High J transitions (J = 18 - 24) in 80 ~ 115 GHzRotational temperature needs to be 50 ~ 100 K
- alanine- alanineLow vapor pressure at room temperature
Sample has to be heated up moderately.Fresh sample has to be supplied continuously.
Molecular beam sourceMolecular beam sourceNozzle aperture = 0.4 mmNozzle Temp. = 250 cStagnation pressure (Ar) ~ 150 Torr
Rotational temp. ~ 50 K
Easily decomposed at high temperatures
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Laboratory Data
98.216 98.218 98.220 [GHz]
170.610 170.612 170.614 [GHz]
202,18 - 193,17
1816,3 - 1715,2
S/N= 3 ~ 10
J’ Ka’ Kc’
J” Ka” Kc”
17 lines 9 lines in 83 - 99 GHz (NRO 45 m)8 lines in 167 - 177 GHz (IRAM 30 m)
Obs.Fitting
frequency accuracy = 25kHz
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Laboratory Data (Frequencies) 1
Transition Predicted [MHz] Observed[MHz] Obs. - Pre. Fitting error
{J’Ka’Kc’-J”Ka”Kc”} (Blanco et al.) [MHz] O-C [MHz]18 1 18 - 17 0 17 83 010.668 83 011.028 (23) 0.360 0.03218 1 18 - 17 1 17 83 010.668 0.360 0.03318 0 18 - 17 0 17 83 010.668 0.360 0.03218 0 18 - 17 1 17 83 010.668 0.360 0.033 9 8 2 - 8 7 1 84 142.568 84 142.520 (7) -0.048 0.075 9 8 1 - 8 7 1 84 142.583 -0.063 0.060 9 8 2 - 8 7 2 84 142.687 -0.067 -0.044 9 8 1 - 8 7 2 84 142.702 -0.182 -0.05919 1 19 - 18 0 18 87 533.785 87 534.136 (18) 0.352 -0.03619 1 19 - 18 1 18 87 533.785 0.352 -0.03519 0 19 - 18 0 18 87 533.785 0.352 -0.03619 0 19 - 18 1 18 87 533.785 0.352 -0.035
9 9 1 - 8 8 0 88 839.545 88 839.350 (8) -0.195 0.011 9 9 0 - 8 8 1 88 839.545 -0.195 0.01019 1 18 - 18 2 17 90 609.211 90 609.553 (9) 0.342 0.00919 2 18 - 18 2 17 90 609.216 0.337 0.00419 1 18 - 18 1 17 90 609.224 0.329 -0.00419 2 18 - 18 1 17 90 609.228 0.325 -0.008
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Laboratory Data (Frequencies) 2
Transition Predicted [MHz] Observed [MHz] Obs. - Pre. Fitting error{J’Ka’Kc’-J”Ka”Kc”} (Blanco et al.) [MHz] O-C [MHz]
20 1 10 - 19 0 19 92 056.344 92 056.794 (6) 0.450 -0.00320 1 10 - 19 1 19 92 056.344 0.450 -0.00320 0 20 - 19 0 19 92 056.344 0.450 -0.00320 0 20 - 19 1 29 92 056.344 0.450 -0.00321 1 21 - 20 0 20 96 578.311 96 578.847 (13) 0.537 0.00921 1 21 - 20 1 20 96 578.311 0.537 0.00921 0 21 - 20 0 20 96 578.311 0.537 0.00921 0 21 - 20 1 20 96 578.311 0.537 0.00920 2 18 - 19 3 17 98 218.038 98 218.520 (6) 0.482 0.12720 3 18 - 19 3 17 98 218.108 0.412 0.05820 2 18 - 19 2 17 98 218.233 0.288 -0.06720 3 18 - 19 2 17 98 218.302 0.218 -0.13710 10 1 - 9 9 0 98 970.358 98 970.085 (7) -0.273 0.01810 10 0 - 9 9 1 98 970.358 -0.273 0.018
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Laboratory Data (Frequencies) 3
Transition Predicted [MHz] Observed [MHz] Obs. - Pre. Fitting error{J’Ka’Kc’-J”Ka”Kc”} (Blanco et al.) [MHz] O-C [MHz]
21 12 10 - 20 11 9 167 728.133 167 728.282(20) 0.149 0.06717 17 0 - 16 16 1 169 873.965 169 872.413(4) -1.552 0.02717 17 1 - 16 16 0 169 873.965 -1.552 0.02718 16 3 - 17 15 2 170 612.698 170 611.501(7) -1.198 -0.02718 16 2 - 17 15 3 170 612.698 -1.198 -0.02719 15 5 - 18 14 4 171 335.509 171 334.693(11) -0.817 -0.02619 15 4 - 18 14 5 171 335.509 -0.817 -0.02620 14 7 - 19 13 6 172 018.206 172 017.774(15) -0.432 0.00520 14 6 - 19 13 7 172 018.215 -0.440 -0.00418 17 1 - 17 16 2 175 307.893 175 306.408 (4) -1.486 0.02218 17 2 - 17 16 1 175 307.893 -1.486 0.02219 16 4 - 18 15 3 176 041.083 176 039.962 (7) -1.122 -0.03219 16 3 - 18 15 4 176 041.083 -1.122 -0.03220 15 6 - 19 14 5 176 750.314 176 749.596 (14) -0.718 -0.019
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Molecular Constants
Least square fitting error ~ = 42 kHz
Blanco et al.A / MHz 5066.14612(14) 5066.14560(42)B / MHz 3100.94994(10) 3100.95058(29)C / MHz 2264.013439(67) 2264.01342(24)J / kHz 2.4248(26) 2.452(13)JK / kHz 6.340(11) 6.391(31)K / kHz 5.4773(92) 5.410(79)J / kHz 0.5637(12) 0.5696(31)K / kHz 10.293(10) 10.3777(54)
This study
Laboratory data freq. – Calculated freq. < 0.14 MHz
Spectra were analyzed by the Watson A- reduced Hamiltonian
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Astronomical Search
Abundance of -alanine could be higher than that in other region.
ObjectObject OrionKL
Organic molecules (HCOOH, CH3OH, etc. )N-containing molecules (NH2, HCN, NH2CHO, etc. )
Hot molecular core (LTE at 100 K)
Chemically rich
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Signal Estimation
r.m.s. noise: Tb ~ 10 mK
OrionKLOrionKLColumn density (estimation):
[-alanine] = [Z] x 10-1~-2 = 2 x 1014 cm-2
Z = {HCOOH, HCN, alcohols etc.}
Tb ~ 30 mK
Search by the Nobeyama 45 m telescopeSearch by the Nobeyama 45 m telescope140 hours observation
Estimated signal intensity: LTE condition (Tex = 100 K)
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Searched Transitions
Transition(J’Ka’Kc’ - J”Ka”Kc”)
Lab. Freq. [MHz]
Pred. Freq. [MHz]
220,22 - 211,21
221,22 - 210,21101100.3
230,23 - 221,22
231,23 - 220,22105621.0
180,18 - 171,17
181,18 - 170,17107261.0
180,18 - 171,17
181,18 - 170,17109100.4
180,18 - 171,17
181,18 - 170,17110141.1
Transition (J’Ka’Kc’ - J”Ka”Kc”)
Lab. Freq. [MHz]
Pred. Freq. [MHz]
180,18 - 171,17
181,18 - 170,1783011.0
201,19 - 192,18
202,19 - 191,1895132.6
210,21 - 201,20
211,21 - 200,2096578.8
202,18 - 193,17
203,18 - 192,1798218.5
Searched for 9 lines in 83 - 110 GHz
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Astronomical Data96
GHz
95GHz
83GHz
105GHz
101GHz
107GHz
110GHz
109GHz
98GHz
2. Weak peaks may exist, but two velocity components at 6 and 7.5 km/s
3. Intensities are not consistent with LTE predictions
1. No clear peaks except at 110 GHz
100mK
Tb
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Upper Limit of Column Density
Upper limit of column density Upper limit of column density
ca. 1014 cm-2
LTE at 100 K Line width = 6 km/s
OrionKL
r.m.s. noise: Tb ~ 10 mK
Nobeyama 45 m telescope
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Conclusions
AcknowledgementNobeyama Radio ObservatoryNobeyama Radio Observatory
Laboratory measurementsMolecular constants were sufficiently determinedfor astronomically observations in the 100 GHz region.
Astronomical observationsNo clear peaks of -alanine were detected.
Upper limit of -alanine in OriKL were determined as ~1014 cm-2