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 )

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

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

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

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

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

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

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

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

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

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)

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

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

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

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