A Search for Hydroxlyamine (NH2OH) Towards IRC+10216, Orion-S, Orion(KL), SgrB2(N), SgrB2(OH), W512M, W3(IRS5)

R. L. PulliamNRAO / North American ALMA Science Center

A.J. Remijan, NRAO/ NAASCJ. Corby, University of Virginia, NRAO

2

Background• Nitrogen chemistry in the ISM– 5th most abundant element with >50 nitrogen

species identified in gas phase in space

Nitrogen chemistry is still poorly understood

Hydroxylamine – NH2OH Formation first studied by Nishi et al. (1984)

[NH2 + H*] + H2O → NH2OH + H2

NH2,3OH+ + CH3COOH → N2,3CH2COOH+ + H2O

NH2,3OH+ + CH3CH2COOH → NH2,3CH2CH2COOH+ + H2O

Suggested in its role towards formation of interstellar amino acids (Blagojevic et al. 2003)

Astrobiology implications and the origin of life

NH + OH addition on grain followed by hydrogenationNH2 + OH → NH2OH (dominates - as OH becomes more

mobile)

3

Models

NH2OH should be within detectable limits in star forming regions

Charnley et al. (2001) A&A, 378, 1024 -- NO possibly converted to NH2OH through hydrogenation

Garrod et al. (2008) ApJ, 682, 283 --- Radical recombination reactions and uses gradual warm up technique within star forming regions

[NH2OH]/[H2] ~10-6

B.E. Turner Survey

arXiv: 0802.2273v1Data taken between 1993-1995 at the 12m TelescopeData are available and distributed through the Spectral Line Search Engine (SLiSE) www.cv.nrao.edu/~aremijan/SLiSE

SLiSE

5

NH2OH

6

Asymmetric Top

a, c-type transitions with the a-dipole ~ 10 x c-dipole

3(1,3) – 2(1,2): 151020.7

3(2,2) – 2(2,1): 151101.9

3(2,1) – 2(2,0): 151102.3

3(0,3) – 2(0,2): 151117.7

3(1,2) – 2(1,1): 151207.0

The Data

7

Frequency (MHz)

151000 151100 151200

TR

* (K

)

0.00

0.05

0.10

0.15

31,3

- 21,2

32,1- 22,0

30,3- 20,2

31,2- 21,1

32,2- 22,1

Sgr B2(N)

Frequency (MHz)

151000 151100 151200

TR

* (K

)

0.00

0.05

0.10

0.15

31,3

- 21,2

32,1- 22,0

30,3- 20,2

31,2- 21,132,2- 22,1

Orion-KL

8Frequency (MHz)

151000 151100 151200

TR

* (K

)

0.00

0.02

0.04

31,3

- 21,2

32,1- 22,0

30,3- 20,2

31,2- 21,1

32,2- 22,1

Orion S

Frequency (MHz)

151000 151100 151200

TR

* (K

)

0.00

0.02

0.04

31,3

- 21,2

32,1- 22,0

30,3- 20,2

31,2- 21,132,2- 22,1

W3IRS5

Frequency (MHz)

151000 151100 151200

TR

* (K)

0.00

0.05

0.10

0.15

31,3

- 21,2

32,1- 22,0

30,3- 20,2

31,2- 21,1

32,2- 22,1

W51M

Frequency (MHz)

151000 151100 151200

TR

* (K)

0.00

0.05

0.10

31,3

- 21,2

32,1- 22,0

30,3- 20,2

31,2- 21,1

32,2- 22,1

Sgr B2(OH)

Frequency (MHz)

151000 151100 151200

TR

* (K

)

0.00

0.02

0.04

31,3

- 21,2

32,1- 22,030,3- 20,2 31,2- 21,1

32,2- 22,1

IRC+10216

NH2OH Column Densities

9

Source Column Density (cm-2)Orion (KL) <4 x 1012

Orion S <2 x 1012

IRC+10216 <2 x 1012

SgrB2 (OH) <4 x 1012

SgrB2 (N) <6 x 1012

W51M <2 x 1012

W3IRS5 <3 x 1012

•Simple Radiative Transfer Analysis•T ~ 130 K (Garrod et al.), optically thin•upper limits calculated

Formation Mechanism?

10

Is NH2OH formed through radical- radical recombination on the surface of grains?

Grain surface? Experimental study of a solid argon matrix – NH2 disappears when the ice sample was warmed up to 20K.

NH2 recombines very efficiently with HMore complex ices?

Ices in the ISM are more complex – free hydrogen can collide with other molecules or recombine with other H atoms to yield H2

NH2 free to combine with other species (such as OH)

Gas phase production? (Blagojevic et al. 2003)

HNO+ + H2→ NH2OH+

Temperature Problem?

11

Formation of NH2OH in Ammonia-Water ices (Zheng and Kaiser, J. Chem. Phys. A (2010) 114, 5251)

NH2OH was observed in the gas phase around 174 K

Is NH2OH in the gas phase of these regions?Are higher resolution observations needed?•Cycle 0 ALMA proposals deadline June 30th, 2011

NH2 + OH → NH2OH

12

Protonated NH2OH?

Is NH2OH quickly protonated after formation?

* High proton affinity (Blajojevic et al. 2003) → H3

+, HCO+, CH5+, H3O+

*Snow et al. 2007→ Reaction of CH5+ or

H3+ with NH2OH is barrier-less and

exothermically favorable under ISM conditions

If NH2OH is formed through grain chemistry or other methods, the sequence of protonation could result in a very low abundance

NH3OH+ or NH2OH2+ in the ISM?

Lab Data is Needed

13

Summary

• NH2OH not detected within any of the sources with upper limits on the order of ~ 1012 cm-2

• Current NH2OH abundance predications too high

– Is NH2OH formed through the suggested mechanisms?

– Is there a temperature problem? • Higher resolution observations needed

– Is NH2OH quickly protonated following release into the gas phase?• NH3OH+/NH2OH2

+ in the ISM?

• Laboratory data is needed

14

The Atacama Large Millimeter/sub-millimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA. 14

Acknowledgments

B.E. TurnerA.J. Remijan

NRAO, ALMANAASC