The progress of galactochemistry over the past two decades has been rapid and controversial. Using the concepts and methodologies of several disciplines, galactochemistry is concerned with the genesis and probable reactions of molecules in space, in galaxies at different stages of development and, by extension, with the prebiotic stage of a just-cooled planet. The present article reviews the current state-of-the-art and indicates probable future developments.
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References
1.
HartmannJ., Sitzb. Kgl. Akad, Wiss. 527 (1904) translated in Astrophys. J. 19, 268 (1904).
van de HulstH. C., Rech. Astr. Obs. Utrecht11Part 1 (1946).
17.
HoyleF. and WickramasingheN. C., Mon. Not. R. astr. Soc. 124, 417 (1962).
18.
PlattJ. R., Astrophys. J. 123, 486 (1956).
19.
SaslawW. C. and GaustadJ. E., Nature221, 160 (1969).
20.
MieG., Ann. Physik. 25, 377–445 (1908).
21.
van de HulstH. C., Light Scattering by Small Panicles. Wiley, New York (1957).
22.
NandyK. and WickramasingheN. C., Mon. Not. R. astr. Soc. 154, 255 (1971).
23.
SalpeterE. E., Rev. Mod. Phys, 46, 433 (1974).
24.
FieldG. B., Astrophys. J. 187, 453 (1974).
25.
WickramasingheN. C., Nature252, 462 (1974).
26.
GillenF. C. and ForrestW. J., Astrophys. J. 179, 483 (1973).
27.
GreenbergJ. M., Astrophys, J. 189, L81 (1974).
28.
GreenbergJ. M., Astron. and Astrophys. 12, 240 (1971).
29.
LeungChun Ming, Astrophys. J. 199, 340 (1975).
30.
DonnS., WickramasingheN. C., HudsonJ. P. and StecherT. P., Astrophys, J. 153, 451 (1968).
31.
FixJ. D., Mon. Not. R. astr. Soc. 146, 37 (1969).
32.
FixJ. D., Mon. Not, R. astr, Soc. 146, 51 (1969).
33.
GilmanR. C., Astrophys. J. 155, L185 (1969).
34.
FixJ. D., Astrophys. J. 161, 359 (1970).
35.
HoyleF. and WickramasingheN. C., Nature226, 62 (1970).
36.
WoolfN. J., SympI.A.U.. No. 52Interstellar Dust and Related Topics, p. 485Reidel, Dordrecht, Holland (1973).
37.
WeinrebS., BarrettA. H., MeeksM. L. and HenryJ. C., Nature200, 829 (1963).
38.
CheungA. C., RankD. M., TownesC. H., ThorntonD. D. and WelchW. J., Phys. Rev, Let21, 1701 (1968).
39.
BrownR. D., GodfreyP. D. and StoreyJ. C., J. Molec. Spectr. 58, 445–450 (1975).
40.
DousmanisG. C., SandersT. M. and TownesC. H., Phys. Rev. 100, 1735 (1955).
41.
KewleyR., SastryK. V. L. N., WinnewisserM. and GordyW., J. Chem. Phys. 39, 2856 (1963).
42.
PowellF. X. and LideD. R., J. Chem. Phys, 41, 1413 (1964).
43.
JohnsonD. R. and PowellF. X., Science169, 679 (1970).
44.
JohnsonD. R. and LovasF. J., Chem, Phys, Letters15, 65.(1972).
45.
GodfreyP. D., BrownR. D., RobinsonB. J. and SinclairM. W., Astrophys. Letters13, 119 (1973).
46.
WoodsR. C., DixonT. A., SaykallyR. J. and SzantoP. G., Phys. Rev. Lett. 35, 1269 (1975).
47.
BlackmanG. L, BrownR. D., GodfreyP. D. and GunnH. I., Nature261, 395 (1976).
48.
SaykallyR. J., SzantoP. G., AndersonT. G. and WoodsR. C., Astrophys. J. 204, L143 (1976).
49.
CreswellR. A., PearsonE. F., WinnewisserM. and WinnewisserG., Z. Naturforsch. 31a, 221 (1976).
50.
For the linear molecules the rotational energy is EJ = BJ(J + 1) where B is the rotational constant of the molecule (B = ℏ/2/) I being the molecular moment of inertia, ℏ Planck's constant divided by 2π, and J the rotational quantum number, and so the transition from EJ+1 → EJ corresponds to an energy of 2B(J + 1). Carbon monoxide is an example of a small linear molecule and for it, B = 57.636 GHz, so that the 1 → 0 transition lies at 115.2712 GHz (λ = 2.60 mm).
51.
For non-linear molecules the expressions for rotational energies become more complicated. Several good textbooks on microwave spectroscopy (see refs. 52–58) give full details and a particularly clear short account appears in a recent book on spectra of radicals (ref. 59).
52.
GordyW., SmithW. V. and TrambaruloR. F., Microwave Spectroscopy, Wiley, Chichester, Sussex (1953).
53.
StrandberyM. W. P., Microwave Spectroscopy. Methuen, London (1954).
54.
TownesC. H. and SchawlowA. L.Microwave Spectroscopy, McGraw Hill, New York (1955).
55.
SugdenT. M. and KenneyC. N., Microwave Spectroscopy of Gases. Van Nostrand, New York (1965).
56.
WollrabJ. E., Rotational Spectra and Molecular Structure. Academic Press, London (1967).
57.
GordyW. and CookR. L., Microwave Molecular SpectraWiley-lnterscience, New York (1970).
58.
KrotoH. W.Molecular Rotation Spectra, Wileylnterscience, New York (1975).
59.
CarringtonA., Microwave Spectroscopy of Free Radicals, Academic Press, London (1974).
60.
It is customary in radioastronomy to express signal strengths in terms of temperatures. The brightness temperature of an observed source at a particular frequency v is defined as the temperature of a black body that subtends the same solid angle as the source and emits the same specific intensity of radiation at the frequency v. When the molecular line strength is quoted for example as 0.1 K it implies that the radiation temperatu re at the tine frequency is 0.1 K greater than that of the continuum radiation at nearby frequencies.
61.
This aspect of the performance of receivers is described by quoting its system noise temperature. A good cooled parametric amplifier for the centimetre range might have a single sideband noise figure of 100 K or less. Maser amplifiers can have considerably lower noise figures but usually have a very restricted tuning range. The receiver noise adds to the source noise and this combined noise has to be overcome by using sufficiently long integration times.
62.
The frequencies of molecular lines in a particular source such as Sgr B2 all show a slight shift in frequency relative to the frequency measured in the laboratory. The shifts all correspond to the Doppler effect to be expected if the source is moving relative to the Sun, or the local standard of rest (LSR) i.e. the average position of stars in the Sun's neighbourhood. With respect to the LSR, the Sun is moving at about 20 km s−1 towards the constellation of Hercules. For Sgr B2 the molecular cloud is moving at about 62 kms−1 away from the LSR.
63.
ScovilleN. Z., Astrophys. J. 175, L127 (1972).
64.
ZuckermanB., Astrophys. J. 183, 863 (1973).
65.
McGeeR. X., NewtonL. M. and ButlerP. W., Astrophys. J. 202, 76 (1975).
66.
ZuckermanB. and PalmerP., Ann. Rev. Astron, and Astrophys. 12, 279 (1974).
67.
LitvakM. M., Ann. Rev. Astron. and Astrophys. 12, 97 (1974).
68.
ter HaarD. and PellingM. A., Rep. Prog. Phys. 37, 481 (1974).
69.
GarrisonB. J., LesterW. A., MillerW. H. and GreenS., Astrophys. J. 200, L175 (1975).
70.
PellingM. A. and ter HaarD., Mon. Not. R. astr. Soc. 171, 103 (1975).
71.
PellingM. A., Mon. Not. R. astr. Soc. 172, 41 (1975).
72.
PellingM. A., Mon. Not. R. astr. Soc. 172, 421 (1975).
73.
The radiation is limited to wavelengths greater than 91.2 nm. The substantial amount of radiation of shorter wavelengths emitted by the hottest stars (0 and B type) ionizes the surrounding H atoms, producing ‘Stromgren spheres’ of H II. This process effectively shields the remainder of the interstellar medium from the very short wavelength radiation.
74.
StiefL. J., DonnB., GlickerS., GentieuE. P. and MentallJ. E., Astrophys. J. 171, 21 (1972).
75.
StiefL J.inMolecules in the Galactic Environment, p. 313, GordonM. A. and SnyderL. E.(Eds). Wiley, New York (1973).
76.
SandellG. and HilaK. Ma, Astron. and Astrophys. 42, 357 (1975).
77.
ShimizuM., IAU Symposium No. 52Interstellar Dust and Related Topics, p. 405. Reidel, Dordrecht, Holland (1973).
78.
BatesD. R. and SpitzerL.Jr., Astrophys. J. 113, 441 (1951).
79.
McCreaW. H. and McNallyD., Mon. Nat. R. astr. Soc. 121, 238 (1960).
80.
WatsonW. D. and SalpeterE. E., Astrophys. J. 174, 321 (1972).
81.
StecherT. P. and WilliamsD. A., Mon. Nat. R. astr. Soc. 168, 23P (1974).
82.
HollenbachD. and SalpeterE. E., Astrophys. J. 163, 155 (1971).
83.
HollenbachD. J., WernerM. W. and SalpeterE. E., Astrophys. J. 163, 165 (1971).
84.
SolomonP. M. and KlempererW., Astrophys. J. 178, 389 (1972).
85.
JulienneP. S. and KrausM., inMolecules in the Galactic Environment, p. 353, GordonM. A. and SnyderL. E.(Eds). Wiley, New York (1973).
86.
SmithW. H., LisztH. S. and LutzB. L., Astrophys, J. 183, 69 (1973).
87.
YoshimineM., GreenS. and ThaddeusP., Astrophys. J. 183, 899 (1973).
88.
BlackJ. H. and DalgarnoA., Astrophys. Lett. 15, 79 (1973).
89.
SlackJ. H., DalgarnoA. and OppenheimerM., Astrophys. J. 199, 633 (1975).
90.
This was one of the distant, hot stars in front of which interstellar molecules were first detected in the visible/u.v. spectral region. The molecules are now considered to be in dust clouds of the standard type (see Table 1) and have been a popular subject for theoretical treatment of galactochemistry.
91.
JulienneP., KrausM. and DonnB., Astrophys. J. 170, 65 (1971).
92.
AannestadP. A., Astrophys. J. Suppl. 25, 205 (1973).
93.
DaviesR. D. and MatthewsH. E., Mon. Not. R. astr. Soc. 156, 253 (1972).
94.
TurnerC. E., HeilesC. E. and ScharlemannE., Astrophys. Lett. 5, 197 (1970).
95.
GottliebC. A., BallJ. A., GottliebE. W., LadaC. J. and PenfieldH., Astrophys. J. 200, L147 (1975).
96.
KuiperT. B. H., ZuckermanB., KakarR. K. and KuiperE. N. R., Astrophys. J. 200, L151 (1975).
97.
WatsonW. D. and SalpeterE. E., Astrophys. J. 174, 321 (1972).
98.
HerbstE. and KlempererW., Astrophys. J. 185, 505 (1973).
99.
WatsonW. D., Astrophys. J. 183, L17 (1973).
100.
BarrettA. H., SchwartzP. R. and WatersJ. W., Astrophys. J. 168, L101 (1971).
101.
FourikisN., SinclairM. W., BrownR. D., CroftsJ. G. and GodfreyP. D., Astrophys. J. 194, 41 (1974).
102.
BrownR. D., GodfreyP. D. and RibesJ. C., unpublished data.
103.
FlygareW. H., BensonR. C., TigelaarH. L., RubinR. H. and SwensonG. W.Jr., inMolecules in the Galactic Environment, p. 173, GordonM. A. and SnyderL. E.(Eds). Wiley, New York (1973).
104.
De ZafraR. L, ThaddeusP., KutnerM., ScovilleN., SolomonP. M., WeaverH. and WilliamsD. R. W., Astrophys. Lett. 10, 1 (1971).
105.
GodfreyP. D., BrownR. D., et al.unpublished observations.
106.
GiguereP. T., ClarkF. O., SnyderL. E., BuhlD., JohnsonD. R. and LovusF. J., Astrophys, J. 182, 477 (1973).
107.
SimonM. N. and SimonM., Astrophys. J. 184, 757 (1973).
108.
FertelJ. H. and TurnerB. E., Astrophys. Lett. 16, 61 (1975).
109.
BrownR. D., Chemistry in Britain9, 450 (1973).
110.
AndersonJ. R. and BakerB. G.inChemisorption and Reactions on Metallic FilmsVol. 2Chapter 8, AndersonJ. R.(Ed.). Academic Press, New York (1971).
111.
NietoM. M., The Titius-Bode Law of Planetary Distances; its History and Theory. Pergamon, Oxford (1972).
112.
PrenticeA. J. R.inIn the Beginning... WildJ. P.(Ed.). Australian Academy of Science (1974).
113.
CameronA. G. W., Sci. Amer. 233, 33(September1975).
114.
AustC. and WoolfsonM. M., Mon. Nat. R. astr. Soc. 161, 7 (1973).
115.
BrownW. K., Icarus15, 120 (1971).
116.
WoodJ. A.Meteorites and the Origin of Planets. McGraw-Hill, New York (1968).
117.
AndersE., HyatsuR. and StudierM. H., Science182, 781 (1973).
118.
KvenvoldenK., LawlersJ. G. and PonnamperumaC., Proc. Nat. Acad. Sci. 68, 486 (1971).
119.
PonnamperumaC., inMolecules in the Galactic Environment. GordonM. A. and SnyderL E., (Eds.). Wiley Interscience, New York (1973).
120.
ClarkS. P., TurekianK. and GrossmanL., inThe Nature of the Solid Earth, p. 3, RobertsonE. C.(Ed,), McGraw-Hill, New York (1972).
121.
GastP. W., ibid., p. 19.
122.
CameronA. G. W., Icarus18, 407 (1973).
123.
RingwoodA. E., Geochim. Cosmochim. Acta20, 241 (1960).
124.
AndersonD. L. and HankoT. C., Nature237, 387 (1972).
125.
RingwoodA. E., Composition and Petrology of the Earth's Mantle, Chapter 16, McGraw-Hill, New York (1975).
126.
RingwoodA. E., Geochim. Cosmochim. Acta30, 41 (1966).
127.
CameronA. G. W., Icarus18, 407 (1973).
128.
RubeyW. W., Bull. Geo. Soc. Am, 62, 1111 (1951).
129.
MilterS. L. and OrgelL. E.The Origins of Life on the Earth. Prentice-Hall, London (1974).
130.
HollandH. D., inPetrologic Studies, EngelA. E. F., JamesH. L. and LeonardB. F.(Eds.). Princeton Univ. Press, Princeton, N.J. (1962).
131.
Grecjo-GrafK., Freiburger Forschungshefte C210. VEB Deutscher Verlag (1966).
132.
OparinA. I., Proiskhozhdenic Zhizni (Origin of Life). Moscow (1924).
133.
OparinA. I., Genesis and Evolutionary Development of Life. Academic Press, New York (1968).
134.
UreyH. C., The Planets. Yale Univ. Press, New Haven, Connecticut (1952).
135.
BernalJ. D., The Physical Basis of Life. Routledgeand Kegan Paul, London (1957).
136.
RubeyW. W., Geol. Soc. Amer. Spec. Pap. 62, 631 (1955).
137.
RubeyW. W.inThe Origin and Evolution of Atmospheres and Oceans, BrancajioP. J. and CameronA. G. W.(Eds.). Wiley, New York (1964).
138.
RevelleR. J., J. Marine Res. 14, 446 (1965).
139.
AbelsonP. H., Proc. Nat. Acad. Sci. 55, 1365 (1966).
140.
MasonB., Meteorites. Wiley, New York (1962).
141.
AndersE., Accounts of Chem. Res. 1, 289 (1968).
142.
StudierM. H., HayatsuR. and AndersE., Geochim. Cosmochim. Acta32, 151 (1968).
KenyonD. H. and SteinmanG., Biochemical Predestination. McGraw-Hill, New York (1969).
146.
FoxS. W. and DoseK., Molecular Evolution and the Origin of Life. W. H. Freeman (1972).
147.
DoleS. H., Habitable Planets for Man. Elsevier, New York (1970).
148.
MillerS. L., Science117, 528 (1953).
149.
For example when shock heating is used, simulating the effects of atmospheric passage of meteors, or thunderclaps, the production of amino acids occurs with particularly high efficiency (up to 36% of ammonia is converted to amino acids) (see ref. 150).
150.
Bar-NunA., Bar-NunN., BauerS. H. and SaganC., Science168, 470 (1970).
151.
AbelsonP. H., Ann. N.Y. Acad. Sci. 69, 274 (1970).
152.
AbelsonP. H., Proc. Nat. Acad. Sci. 55, 1365 (1966).
153.
BerzeliusJ. J., Ann. Phys. Chem. 33, 113 (1834).
154.
KvenvoldenK., LawlessJ.PeringK., PetersonE, FloresJ., PonnamperumaC, KaplawI. A. and MoorC., Nature228, 923 (1970).
155.
SillenL. G., Arkiv Kemi24, 431 (1965).
156.
VinogradovA. P. and VdovikinG. P., Ooklady Akad. Nauk SSR206, 563 (1972).