. 

DEPARTXENT OF PHYSICS AflD ASTIIONOYY ft'. UNIVERSITY OF MASSACHUSETTS 

NASA GRANT NAGW-$36 

BOUNDARY CONDITIONS FOR THE PALEOENYIRONMENT: CHEHICAL AND 

PHYSICAL PROCESSES IN THE PRE-SOLAR NEBULA 

SEX-ANNUAL STATUS REPORT NO. 8 

AUGUST 16, 1986 - FEBRUARY 15, 1987 

Principal Investigator: William M. Irvine 

Co-Principal Investigator: F. Peter Schloerb 

Current Research 

Detailed study of the first interstellar hydrocarbon zing, cyclopropenylidene 

(C3H2), is continuing by Irvine, graduate student S. Madden, and H. Matthews and 

L. Avery (National Research Council of Canada). 

singly deuterated isotope of this molecule, CjHD, in several cold interstellar 

clouds. 

observed, together with the main isotopic variant. 

We have successfully observed the 

In the same plus additional sources the 13C-isotopic form has also been 

As a result, the optical depth 

of the observed 

tions about the 

found. Initial 

transitions can be accurately determined, given reasonable assump13C/12C ratio. A very high degree of deuterium fractionation is 

estimates indicate that C3HD/C3H2 - 0.05 in at least some cold 

clouds, which is among the highest degrees of fractionation ever observed in 

interstellar chemistry. This result places severe constraints on models of the 

formation of C3B2, apparently requiring gas phase formation via ion-molecule 

chemistry, with acetylene as a possible precursor. 

A paper containing the results of a large sur~ey for C3H2 in galactic sources 

of various types is nearing completion. It appears that cyclopropenylidene is 
indepth study or' four specific clouds of diffsring types is being pursued by S. 

Madden as part of her Ph.D. dissertation. Multiple transition maps of these 

sources are currently being taken at both FCRAO (University of Massachusetts) and 

NRAO (Graen Bank, WV) . 

In order to make the first determinations of the C02/C0 abundance ratio in 

interstellar sources, we have been pursuing observations of protonated CO 

CO itself has no permanent electric dipole moment, and hence no allowed rotational transitions). Following extensi*~e observations at 21 GHz at NRAO and 85 

GHz at FCRAO, we have been able to detect KO2 in only one molecular cloud. 

Interestingly enough, in that source it appears both relatively abundant and 

(since 2 

2 

+ 

extended over a considerable region in space. Column densities and abundances 

are currently being calculated by graduate student Y. Ninh. It appears that 

C02/CO<(1 in all sources surveyed. 

A proposal by Irvine and colleagues in Canada and Sweden to systematically 

measure the spectrum from 18.5 to 22 GHz for several interstellar clouds has been 

accepted by the NRAO, and the project has begun. Particular attention is being 

given to the cold, dark clouds TMC-1 and L134N, which may be formation sites for 

solar mass stars. These two clouds, which are very similar in physical characteristics (temperature and density), exhibit interesting differences in their 

chemistry, particularly in regard to the polyacetylenes and their derivatives. 

number of unidentified emission lines have been discovered. Identification will 

be pursued by looking for patterns of emission and for additional transitions that 

are predicted by hypotheses concerning the carrier of the observed lines. 

A 

Graduate student Y, Minh, in collaboration with astronomers from the Daeduk 

Radio Astronomical Observatory in Korea, has been studying a new phenomenon of 

maser emission from molecules of methanol in certain interstellar clouds. New 

sources of this emission have been detected, and a careful search has been carried 

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L 

. 

out for polarization. Detection of polarization might provide clues as to the 

excitation mechanism. 

Irvine, Ziurys, and L. Avery (National Researcfi Council of Canada) have been 

pursuing the identification of several pressntly unidentified but strong emission 

lines in the millimeter-wavalength spectrum of the cold cloud TXC-1. Additional 

emission features have been discovered, the distribution of emission in TMC-1 has 

been deterininad, and comparisons made with the spectrum of the giant molecular 

cloud Sgr B2. 

Schloerb and colleagues at both the University of Massachusetts and the 

University of Wyoaing ‘nave been carrying out high angular resolution observations 

of the material outflowing from the infrared source in the dark cloud L1551. The 

bi-polar nature of this outflow suggests the presence of a circunstellar disk 

around this (presumably) young or protostellar object. It appears that the 

outflow has evacuated a cavity in the ambient interstellar material. 

Since molecular hydrogen is not directly observable in cold interstellar 

clouds (because of its symmetry, it exhibits only electric quadrupole transitions, 

the lowest of which is still quite high in energy above the ground state), two 

tracers of molecular material have traditionally been used by radio astronomers: 

carbon monoxide rotational transitions and thermal emission from dust. Schloerb 

and colleagues at the University of Massachusetts have completed a comparison of 

the 1 millimeter continuum emission from dust with the column density of carbon 

monoxide as determined from the rare C 0 isotope for 4 molecular clouds in our 18 

Galaxy. 

clouds. 

of CO from the gas phase onto the particulate grains in regions of high density in 

these clouds. In addition, the results show that observations at this wavelength 

do provide a useful tracer of the total amount of mass in an interstellar cloud. 

The results are consistent with a constant gas-to-dust ratio among these 

This result is important, since it argues against significant depletion 

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Note that the longest wavelength IRAS band is still ,at too short a wavelength to 

detect dust in cold, dark interstellar clouds. 

In collaboration with astronomers at the University of Illinois, Ziurys has 

completed'a study of the abundance of the HCO radical in cold, dark interstellar 

clouds. 

maximum abundance in regions of intermediate density. 

The results are consistent with theoretical models, which predict a 

Ziurys has been continuing her study of "high temperature" interstellar 

chemistry in order to investigate possible differences with respect to that in 

cold, quiescent clouds, where ion-molecule reactions are' assumed to dominate. A 

particularly interesting source for these investigations is the supernova remnant 

IC443, where it is apparent that the supernova blast wave has created dense, 

shocked regions in the ambient gas. The chemistry in such clumps is being studied 

at FCRAO. Another region crhere high temperatures clearly occur is in the vicinity 

of the infrared source IRc2 in the Orion molecular cloud. This region is being 

investigated through study of vibrationally excited HCN, whose excitation requires 

unusually hot and dense gas andlor strong infrared radiation, and through studies 

of the silicon-containing molecules Si0 and SiS, whose abundance is anomalously 

high. The latter effect may be due to destruction of silicate grains, with 

resultant liberation of Si into the gas phase. 

Madden presented a paper describing observations of C H isotopes at the 169th 32 

m'eeting of the American Astronomical Society in January, 1987. 

Papers supported by this grant and published during the period of report: 

1. "CO Mapping of the Orion Molecular Cloud: the Influence of Star Formation 

on Cloud Structure", Schloerb, F.P., Snell, R.L., Goldsmith, P.F., and 

Horgan, J.A., in Summer School on Interstellar Processes, ed. D. Hollenbach 

and H. Thronson (NASA Tech. Mem. 883421, 27 (1986). 

2. "High Resolution Qbsersaticns sf the L1551 Biclpolar Outflow'', Snell, R.L. , Moriarty-Schieven, G. , Strom, S., Schloerb, P., Strom, K. , and Grasdalen, 

G.., in Mer Schonl on Interstellar Processes, ed. D. Hollenbach and €I. 

Thronson (NASA Tech. Mem. 88342) , 5 (1986). 

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3. "Yariatiozs in the HCZ!/H?IC Abundacce Ratlc in the Orion :loiacular cloud", 

_- Goidsi;.irk, ?.?. , ir:;ins, '4.2". , Hjalcarsos, Aa., and Eilder, 2. Fttrsphy's. 0. 

- 310, 383 (1986). 

4. "Studies or' orgasic Molecules Containing ::zthyi Grcups in Dark Clmds", 

Fr:2Erg, P. , imins, W.X. , Had&n, S.C. , Hjaiaarson, 4. , in Xsrrochaistry 

(IXU Syxg. 1201, ed. it-S. Yardya and S.P. Tarafdzr (D. %idsi), pp. 201-202 

(1986). 

.. 

5. Thz Chemistry of Cold Dark Interstellar Clouds", Irvine, W.X., in 

Astrcchemistry (IAU Symp. 1201, ed. X.S. Vardya and S.P. Tarafdar (D. 

Reidel) , pp. 245-252 (1986). 

5. yes^ Inttrstellar Detxtions: Iapiications for Shock Chemistry", Ziurys, 

L.X., and Turner. B.E., in Astrochernistrv (IXJ Svmp. 120), ed. M.S. Vardya 

and S.P. Tarafdar (D. Reidel), pp. 289-292 (1986). 

"Decsctions of i3C-Substituted C H 

Ir-iin?, W.Y., and Matthsws, H.E.: astrophys. J. (Lett.) , 311 L29 (1986). 

"The C H, 2,0-2 

H.E., hlde6, S.C., Avery, L.V. and Ir-;ine, W.X., Astrophys. J. (Lett.), 

r, 30" L69 (1986). 

"A Search for Interstellar H,O+", Wootten, A., Boulanger, F., Bogey, M., 

7. in Xstrcnornical Sourczs", Haadm, S.C., 

Transition: Absorption in Cold Dark Clouds", Ilatthews, 1' 8. 

9. 

Combes, F. , Encrenaz, P. , Zihys, L.M. , and Gerin, M. , Astron. Astrophus. , - 166, L15 (1986). 

10. "Studies of Interstellar Vibrationally Excited Molecules", Ziurys, L.M., 

Snell, R.L., Erickson, N.R., in Summer School on Intgrstellar Processes, 

ed. D. Hollenbach and H. Thronson (NASA Tech. Mem. 883421, 153 (1986). 

11. "Exobiology in Earth Orbit", Tarter, J., DeFrees, D., Brownless, D., 

Usher, D. , Klein, H.P., and Irvine, W.M. , Fifth ISSOL Meeting, Berkeley, 

CA., July, (1986). 

12. "Multitransition Studies of C3H2", lladden, S.C., Irvine, W.M., Matthews, 

H.E. and Avery, L.M., in Summer School on Interstellar Processes, ed. D. 

Hollenbach and H. Thronson (NASA Tech. Mem. 88342), 155 (1986). 

13. Madden, S.C., Irvine, W.M. and Matthews, H.E., "Multi-level Study of C,H,, 

J the First Interstellar Hydrocarbon Ring Molecule", Bull. Amer. Astron. Sdc. 

- 18, 4 (1986). 

Research supported by this grant currently in press: 

1. "Observations of Si0 Toward OMC-1: a New Outflow Source 1.5' South of 

Orion-KL?", Ziurys, L.M. and Friberg, P., Astrophys. J. (Lett.), in press. 

6. -) "Int~rstellar Ilolecules and. Sstrochaistry", Turner, B.E., and Ziurys, 

L.X., in Galactic and Extragalactic iiaciio Astronomy, ad. K. Kellerxan 

ana c;. Yerschurr (Springer-Yerlag: Beriin, Heidelbsrg, and X2w ?fork) , 

submitted for publication. 

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3. 

4. 

5. 

6. 

7. 

8. 

9. 

"Obszr-:ations cf OCS and a Search for OC S in the Incerstgllar >Iedium, 

Elatch@ws, H.Z., MacLzcd, J.X. , Brsten, M.W. , F'riberg, P. and ?<addai, S.C., 

Ascropnys. J., in press (1387). 

3 

"Obser-?ational Astrochenistry", Ir-Jine, V.X. and Hjaharscn, a. , Ads. 

Sp;zce Scl., in press. 

"Chemical Abundances in Molecular Clouds", Irvine, W.Y., Goldsmith, P.F., 

and Hjalmarson, 8. in Interstellar Processes, ed. D. Hollenbach and E. 

Thronson (Dordrecht: Reidel) , in press. 

"1300 -m Continuurn and C 0 Line Mapping of the Giant Molecular Cloud Cores 

in Orion, W49 acd #5i", Schloerb, F.?., Snell, R.L., and Schwartz, P.R., 

Astrophys. J., in press (1987). 

18 

"HiGh Resolution Inagss of the L1551 Bipolar Outflow: 

Expanding Accel2rated Shell", Moriarty-Schieven, G., Snell, R.L., Strom, 

S.E., Schlcerb, F.P., Stron, K.E., and Grasdalgn, G.L., Astrophys. J., in 

press (i987). 

Evidence for an 

"SiS in Orion-KL: Evidence for "Outflow" Chemistry", Ziurys, L.M. , 

Astrophys. J., in press. 

"HCO Enission from HII/Molecuiar Cloud Interfaces", Scheneverk, M. S. , 

Snyder, L.E. , Hollis, J.M. , Jewell, P.R. , and Ziurys, L.M. , Astrophys. J. , submitted. 

Future Plans 

Research will continue on the abundance and distribution of cyclopropenylidene 

in interstellar sources. The goal is to obtain accurate abundances for this 

species under a variety of interstellar conditions, to investigate formation 

mechanisms, and to determine the extent to which C3B2 emission and absorption can 

be used as a probe of physical conditions in molecular clouds. 

The systematic investigation of the spectrum of cold, dark interstellar clouds 

will continue in an effort to identify new chemical constituents of these regions, 

determine accurate abundances (particularly for heavier species) , and to investigate differences in chemical composition among molecular clouds. Additional 

observing time has been scheduled at MRAO for the coming spring. 

Ue anticipate obsarsaticns at th2 Onsala Space Observatory in Sweden in order 

to pursue our investigation of unidentified lines in TYC-1 in the 7 nm region. In 

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addition, important transitions of C3H2 can be studied in this wavelength band 

with the particularly sensitive equipment available at that Observatory. 

lladden and Irvine will continue their study of methanol in cold, dark interstellar clouds. 

facilities of the Onsala Space Observatory in Sweden, in collaboration with P. 

Friberg and 8. Hjalmarson of the Chalmers University of Technology. Combining 

this data with the 3 millimeter observations obtained at FCRAO will enable the 

excitation and the abundance of CH OH to be accurately determined. 

The lowest rotational transitions will be observed using the 

3 

Ziurys vi11 continue to pursue radio astronomical studies of high temperature 

chertistry through the detection and study of new interstellar species, and through 

observations of molecules vhose presencn and excitation provoide indicators of 

elevated temperatures. In pa.rticular, rotational transitions of metal-containing 

species such as MgH, CaH, CaOH, and MgOH will be sought. 

The study of vibrationally-excited species is also being continued. Ziurys is 

+ + conducting searches for vibrationally-excited HCO 

meter antenna at 270 GHz. Preliminary results indicate that vibrationally-excited 

HCO may be present in the hot, shocked gas of Orion-KL, but not nearly with the 

abundance found for vibrationally-excited HCN by Ziurys and Turner. Such data 

suggests that, in very hot, dense gas, nolecular ions tend to be destroyed. 

and M2H , using the NRAO 12 

+ 

Ziurys and M. Claussen are pursuing studies of vibrationally-excitcd HCN and 

CS in both carbon and oxygen rich circumstellar envelopes, using the FCRAO 

telescope. Past theoretical studies have suggested that vibrationally-excited 

molecules with large dipole moments are collisionally-excited under non-LTE 

conditions. Ziurys and Claussen have evidence that this may be the case for HCN, 

and may also find this th2 situation for CS. 

Ziurys and Kulkarni (U.C. Berkeley) plan a survey of the J=1-0 transition of 

CO towards clouds in the galactic plane vhere atomic hydrogen absorption lines 

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ha-;s bein detzctsd. Th? purgose of the 3sasureaents is to fine a corrslation 

between CO an6 atomic hydrogen, and thereby nelp establish the atomic vs. 

::olecular cont2nt of danse clouds. 

Schloerb is ccntinuing th2 study of the struciure and kineaacics of nearby 

nolecular clouds in order to study the process of star (and presumably) planetary 

formation, and the resulting disruptive effects of these processes on the initial 

molecular clouds. 

Principal Investigator 

F. Peter Schloerb 

Co-Principal Investigator 

April 3, 1987 

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