Abstract

This paper discusses the further work in experimental and theoretical spectroscopy still urgently needed for the understanding of many astronomical phenomena. Most lines or bands in astronomical spectra have been identified, thanks to the laboratory and analysis work performed during the last twenty five years; nevertheless, there remain many unidentified astrophysical lines or bands. Their assignment proceeds at a rather slow pace, owing probably to the fact that pure laboratory spectroscopy has lost some of the glamor it used to have. Also, the interests of astrophysicists are not always identical with those of laboratory spectroscopists. The first part of this paper discusses the spectral sequence, pointing out characteristic cases of unidentified emission or absorption lines. In the second part are indicated some of the essential needs of the astrophysicists. Except in a few rare cases reference is made to only astrophysical investigations of the last twelve years. A complete compilation of all the literature on unidentified lines or bands is not included in the present paper; but rather, typical examples have been indicated. Single identification may occasionally lead to important developments: for example, the assignment of the single interstellar line 4300.3 A to CH [ P. Swings and L. Rosenfeld, Ap. J. 86, 483 ( 1937)], or of the Wolf-Rayet emission of WN-stars 5806 A to C IV (see reference 19), had interesting consequences.

© 1951 Optical Society of America

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  114. R. B. King, Ap. J. 108, 429 (1948).
    [Crossref]

1950 (10)

A. Colacevich, Ap. J. 111, 197 (1950).
[Crossref]

P. Swings and P. D. Jose, Ap. J. 111, 513 (1950).
[Crossref]

P. Swings, Ann. Astrophys. 13, 134 (1950); P. Swings and O. Struve, Ap. J. 91, 546 (1940); Ap. J. 93, 455 (1941); Ap. J. 97, 194 (1943); P. Swings, Pub. Astron. Soc. Pacific 55, 276 (1943).
[Crossref]

P. W. Merrill, Ap. J. 111, 484 (1950).
[Crossref]

W. B. Bidelman, Ap. J. 111, 333 (1950).
[Crossref]

M. V. Migeotte and L. Neven, Physica 16, 423 (1950) and Communication to the 3rd National Scientific Meeting, Brussels, 1950.
[Crossref]

P. C. Keenan, A. J. 55, 74 (1950); Sky and Telescope 9, 134 (1950).
[Crossref]

R. F. Sanford, Ap. J. 111, 262 (1950).
[Crossref]

J. L. Greenstein and L. H. Aller, Ap. J. 111, 328 (1950), and references indicated.
[Crossref]

P. Swings and Thornton Page, Ap. J. 111, 530 (1950); P. Swings, Bull. Acad. Roy. Belgique 36, 113 (1950).
[Crossref]

1949 (9)

G. P. Kuiper, Ap. J. 109, 540 (1949); Reports on Progress in Physics13, 247 (1950).
[Crossref]

J. Hunaerts, Ann. Obs. R. Belgique 5, fasc. 1 (1949).

G. H. Herbig, Ap. J. 109, 109 (1949).
[Crossref]

B. Rosen and A. Monfils, Nature 164, 713 (1949).

Goldberg, Mohler, and McMath, Ap. J. 109, 28 (1949) (region 1.52 to 1.75μ of the solar spectrum); Goldberg, Mohler, Pierce, and McMath, Ap. J. 111, 565 (1950) (region 1.97 to 2.49μ of the solar spectrum).
[Crossref]

G. H. Herbig, Ap. J. 110, 143 (1949).
[Crossref]

Nassau, van Albada, and Keenan, Ap. J. 109, 333 (1949).
[Crossref]

Tcheng-Mao-Lin, Compt. rend. 229, 348 (1949).

P. Swings and P. D. Jose, Pub. Astron. Soc. Pacific 61, 181 (1949).
[Crossref]

1948 (16)

R. Herman, Compt. rend. 226, 1800 (1948).

M. Bloch, Compt. rend. 227, 333 (1948).

G. Herzberg, Ap. J. 107, 94 (1948).
[Crossref]

P. Swings, Ann. Astrophys. 11, 228 (1948).

Babcock, Moore, and Coffeen, Ap. J. 107, 287 (1948).
[Crossref]

I. S. Bowen, Revs. Modern Phys. 20, 109 (1948) (identification of [O I]).
[Crossref]

J. Cabannes and J. Dufay, Compt. rend. 226, 1569 (1948) ([O I]) and Compt. rend. 226, 2032 (1948) (suggested identification of [Fe II]).

M. V. Migeotte, Phys. Rev. 73, 519 (1948); Phys. Rev. 74, 112 (1948) and Phys. Rev. 75, 1108 (1949); Ap. J. 107, 400 (1948) and Ap. J. 112, 136 (1950); Astron. J. 54, 45 (1948); M. V. Migeotte and R. M. Chapman, J. Opt. Soc. Am. 38, 1094 (1948) and Phys. Rev. 75, 1611 (1949); R. M. Chapman and J. H. Shaw, Phys. Rev. 78, 71 (1950).
[Crossref]

A. McKellar, Ap. J. 108, 453 (1948).
[Crossref]

P. Swings and A. McKellar, Ap. J. 108, 458 (1948).
[Crossref]

P. C. Keenan, Ap. J. 107, 420 (1948).
[Crossref]

P. Swings, Annales d’Astrophysique 11, 124 (1948).

J. Dufay and M. Bloch, Annales d’Astrophysique 11, 58 and 107 (1948).

A. B. Meinel, Pub. Astron. Soc. Pacific 60, 357 (1948); Trans. Amer. Geophys. Union 31, 21 (1950); Ap. J. 111, 207, 433, and 555 (1950).
[Crossref]

J. Cabannes and J. Dufay, Compt. rend. 226, 2032 (1948).

R. B. King, Ap. J. 108, 429 (1948).
[Crossref]

1947 (6)

I. S. Bowen, Pub. Astron. Soc. Pacific 59, 196 (1947).
[Crossref]

A. McKellar, J. Roy. Astron. Soc., Can. 41, 147 (1947); Contrib. Pub. Dominion Astrophys. Obs., No. 7, 1947.

G. Shajn and O. Struve, Ap. J. 106, 86 (1947).
[Crossref]

D. N. Davis, Ap. J. 106, 28 (1947).
[Crossref]

J. L. Greenstein and W. S. Adams, Ap. J. 106, 339 (1947).
[Crossref]

P. W. Merrill, Ap. J. 105, 120 (1947); Ap. J. 107, 317 (1948).
[Crossref]

1946 (5)

L. H. Aller and R. Minkowski, Pub. Astron. Soc. Pacific 58, 258 (1946).
[Crossref]

J. W. Swensson, Ap. J. 103, 207 (1946).
[Crossref]

D. M. Popper, Harvard Announcement Card 752 (1946); A. J. 52, 129 (1946). P. C. Keenan, Ap. J. 106, 295 (1947). A. D. Thackeray, Nature 160, 370 (1947); Monthly Notices Roy. Astron. Soc. 108, 276 (1948). J. L. Greenstein, Ap. J. 108, 78 (1948).
[Crossref]

J. L. Greenstein and P. W. Merrill, Ap. J. 104, 177 (1946).
[Crossref]

P. W. Merrill, Ap. J. 103, 275 (1946) (atomic lines in R Leonis, Class Me); Ap. J. 105, 360 (1947) (atomic lines in R Andromedae, class Se); Ap. J. 106, 274 (1947) (post maximum spectrum of χ-Cygni, class Me+Se); Ap. J. 107, 303 (1948) (absorption lines in long period variables). For a description of the absorption spectrum of χ-Cygni a few days before maximum, see Tcheng-Mao-Lin, Compt. rend. 229, 1301 (1949).
[Crossref]

1945 (4)

H. D. Babcock, Ap. J. 102, 166 (1945).

W. A. Hiltner, Ap. J. 102, 438 (1945).
[Crossref]

R. F. Sanford, Ap. J. 102, 357 (1945).
[Crossref]

For the 1933 spectrum (from September 2 to November 10), see A. H. Joy and P. Swings, Ap. J. 102, 353 (1945). For the 1942 spectrum, see P. Swings and O. Struve, Ap. J. 97, 194 (1943).
[Crossref]

1944 (8)

P. Swings, Pub. Astron. Soc. Pacific 56, 242 (1944).
[Crossref]

O. Struve, Ap. J. 99, 70 (1944); P. Swings and O. Struve, Ap. J. 101, 224 (1945).
[Crossref]

P. W. Merrill, Pub. A.S.P. 56, 42 (1944).

P. Swings, Pub. A.S.P. 56, 242 (1944).

P. W. Merrill, Pub. A.S.P. 55, 42 (1944).

J. W. Swensson, Ap. J. 99, 258 (1944).
[Crossref]

P. Swings, Pub. Astron. Soc. Pacific 56, 80 (1944).
[Crossref]

A. McKellar, Ap. J. 99, 162 (1944).
[Crossref]

1943 (5)

P. Swings, A. McKellar, and R. Minkowski, Ap. J. 98, 142 (1943); P. Swings and Thornton Page, Ap. J. 108, 526 (1948), and Ap. J. 111, 530 (1950); P. D. Jose and P. Swings, Ap. J. 111, 41 (1950).
[Crossref]

O. Struve and P. Swings, Ap. J. 98, 361 (1943); P. Swings, Ap. J. 100, 132 (1944).
[Crossref]

O. Struve and P. Swings, Ap. J. 97, 426 (1943).
[Crossref]

O. Struve, Ap. J. 98, 98 (1943).
[Crossref]

P. Swings and O. Struve, Ap. J. 97, 194 (1943).
[Crossref]

1942 (7)

P. Swings and O. Struve, Ap. J. 96, 472 (1942).

P. Swings, Ap. J. 95, 112 (1942).
[Crossref]

Region λλ3000–3300: J. H. Rush, Ap. J. 95, 213 (1942). Region λλ3300–3940: O. Struve, Ap. J. 90, 699 (1939). Region λλ3862–6587 (α-Cygni): O. Struve and P. Swings, Ap. J.  94, 344 (1941). Region λλ3300–6500 (1 Puppis, cA2ep): P. Swings, Annales d’Astrophysique 13, 114 (1950).
[Crossref]

D. M. Popper, Pub. A.S.P. 54, 160 (1942); Pub. A.S.P. 58, 370 (1946); Pub. A.S.P. 59, 320 (1947).

J. L. Greenstein, Ap. J. 95, 161 (1942).
[Crossref]

F. E. Roach, Ap. J. 96, 272 (1942).
[Crossref]

P. Swings, Ap. J. 95, 270 (1942).
[Crossref]

1941 (9)

P. Swings and O. Struve, Ap. J. 93, 455 (1941).
[Crossref]

P. Swings and O. Struve, Ap. J. 94, 307 (1941).

B. Edlén, Arkiv Mat., Astron. Fys. 28B, No. 1 (1941); Z. Astrophys. 22, 30 (1942).

R. Minkowski, Pub. Astron. Soc. Pacific 53, 224 (1941).
[Crossref]

C. P. Gaposchkin and F. E. Whipple, Proc. Am. Phil. Soc. 84, 1 (1941).

P. Swings and O. Struve, Ap. J. 93, 356 (1941).
[Crossref]

R. B. Baldwin, Ap. J. 93, 421 (1941).

R. B. Baldwin, Ap. J. 93, 333 (1941).
[Crossref]

Swings and O. Struve, Ap. J. 93, 349 (1941).
[Crossref]

1940 (9)

Region 3000 to 3300A: P. Swings and O. Struve, Pub. Astron. Soc. Pacific 52, 392 (1940); region 3300 to 4025A: O. Struve and F. E. Roach, Ap. J. 90, 727 (1939); region 3900A–Hβ: O. Struve, Ap. J. 81, 66 (1935), and C. S. Beals, Monthly Notices Roy. Astron. Soc. 95, 581 (1935); region Hβ–6700A: P. Swings and O. Struve, Ap. J. 91, 571 (1940) (preliminary examination by C. S. Beals, see above, and by Kharadze, Z. Astrophys. 11, 304 (1935); region Hα–8900A: P. W. Merrill, Ap. J. 79, 183 (1934), and P. Swings, Pub. Astron. Soc. Pacific 56, 238 (1944).
[Crossref]

P. Swings and O. Struve, Ap. J. 91, 546 (1940). (This star may also be considered as a symbiotic object.)
[Crossref]

P. Swings and O. Struve, Ap. J. 91, 546 (1940).
[Crossref]

P. Swings and O. Struve, Proc. Nat. Acad. Sci. 26, 548 (1940); P. Swings, Ap. J. 95, 112 (1942); L. H. Aller, Ap. J. 97, 135 (1943).
[Crossref]

P. Swings and O. Struve, Ap. J. 91, 600 (1940); Ap. J. 93, 457 (1941); Ap. J. 98, 94 (1943); P. Swings, Pub. Astron. Soc. Pacific 55, 276 (1943).
[Crossref]

A. B. Wyse, Lick Obser. Pub. 14, 93 and 217 (1940).

P. Swings and O. Struve, Ap. J. 92, 295 (1940).
[Crossref]

J. L. Greenstein, Ap. J. 91, 438 (1940).
[Crossref]

S. Pasternack, Ap. J. 92, 129 (1940).
[Crossref]

1939 (2)

P. Swings and Y. Öhman, Observatory 62, 150 (1939); P. Swings and M. Désirant, Ciel et Terre 55, 161 (1939); P. Swings, J. Roy. Astron. Soc., Can. 35, 71 (1941); A. McKellar, Pub. Dominion Astrophys. Obs. 7, 251 (1941); van de Hulst, Recherches astronomiques de l’Observatoire d’Utrecht, Vol.  XI, pt. 2 (1949). (The Solid Particles in Interstellar Space.)

I. S. Bowen and A. B. Wyse, Lick Obs. Bull. 19, 1 (1939); A. B. Wyse, Ap. J. 95, 356, (1942).
[Crossref]

1938 (3)

Ultraviolet region: W. S. Adams and Th. Dunham, Ap. J. 87, 102 (1938); O. Struve, Ap. J. 90, 699 (1939). Photographic region: O. Struve, Ap. J. 74, 225 (1931); O. Struve and Th. Dunham (τ-Scorpii), Ap. J. 77, 321 (1933); R. K. Marshall, Pub. Observ. Univ. Mich. 5, 137 (1934); H. Kühlborn (γ-Peg, ξ-Per, γ-Ori and ξ-Cas) Veröff. Babelsberg 12, Heft 1 (1938); Anne B. Underhill (γ-Pegasi), Ap. J. 107, 337 (1948) (region 3965 to 4921A) and Ap. J. 108, 476 (1948) (region Hβ–5323).
[Crossref]

P. Swings and B. Edlén, Ap. J. 88, 618 (1938); P. Swings, B. Edlén, and J. Grandjean, Ap. J. 90, 378 (1939); B. Edlén and P. Swings, Ap. J.,  95, 532 (1942).
[Crossref]

D. N. Davis, Ap. J. 87, 335 (1938) and Ap. J. 89, 41 (1939).
[Crossref]

1936 (1)

P. W. Merrill and A. D. Thackeray, Pub. Astron. Soc. Pacific 48, 33 (1936), and Pub. Astron. Soc. Pacific 49, 120 (1937); A. D. Thackeray, Ap. J. 86, 499 (1937).
[Crossref]

1934 (2)

I. S. Bowen, Pub. Astron. Soc. Pacific. 46, 146 (1934).
[Crossref]

P. W. Merrill, Pub. Astron. Soc. Pacific 46, 206 (1934); P. W. Merrill and O. C. Wilson, Ap. J. 87, 375 (1938).
[Crossref]

1932 (1)

C. E. Moore, Ap. J. 75, 222 (1932).
[Crossref]

1931 (1)

O. Struve, Ap. J. 74, 225 (1931); Ap. J. 90, 699 (1939).
[Crossref]

1929 (1)

Th. Dunham, Contr. Princeton Obser., n°9 (1929).

1928 (1)

C. D. Shane, Lick Obs. Bull. 13, 127 (1928).

1926 (2)

P. W. Merrill, Pub. Astron. Soc. Pacific 38, 175 (1926).
[Crossref]

R. F. Sanford, Pub. Astron. Soc. Pacific 38, 177 (1926).
[Crossref]

1923 (1)

Rimmer, Proc. Roy. Soc. (London),  A103, 696 (1923).
[Crossref]

Adams, W. S.

J. L. Greenstein and W. S. Adams, Ap. J. 106, 339 (1947).
[Crossref]

Ultraviolet region: W. S. Adams and Th. Dunham, Ap. J. 87, 102 (1938); O. Struve, Ap. J. 90, 699 (1939). Photographic region: O. Struve, Ap. J. 74, 225 (1931); O. Struve and Th. Dunham (τ-Scorpii), Ap. J. 77, 321 (1933); R. K. Marshall, Pub. Observ. Univ. Mich. 5, 137 (1934); H. Kühlborn (γ-Peg, ξ-Per, γ-Ori and ξ-Cas) Veröff. Babelsberg 12, Heft 1 (1938); Anne B. Underhill (γ-Pegasi), Ap. J. 107, 337 (1948) (region 3965 to 4921A) and Ap. J. 108, 476 (1948) (region Hβ–5323).
[Crossref]

Aller, L. H.

J. L. Greenstein and L. H. Aller, Ap. J. 111, 328 (1950), and references indicated.
[Crossref]

L. H. Aller and R. Minkowski, Pub. Astron. Soc. Pacific 58, 258 (1946).
[Crossref]

Babcock,

Babcock, Moore, and Coffeen, Ap. J. 107, 287 (1948).
[Crossref]

Babcock, H. D.

H. D. Babcock, Ap. J. 102, 166 (1945).

H. D. Babcock and C. E. Moore, The Solar Spectrum, 6600A to 13,495A, Carnegie Institution of Washington, Publication 579 (1947).

Baldwin, R. B.

R. B. Baldwin, Ap. J. 93, 421 (1941).

R. B. Baldwin, Ap. J. 93, 333 (1941).
[Crossref]

R. B. Baldwin, Pub. Observ. Univ. Mich. VIII, No. 5, p. 61.

Bidelman, W. B.

W. B. Bidelman, Ap. J. 111, 333 (1950).
[Crossref]

Bloch, M.

M. Bloch, Compt. rend. 227, 333 (1948).

J. Dufay and M. Bloch, Annales d’Astrophysique 11, 58 and 107 (1948).

Bowen, I. S.

I. S. Bowen, Revs. Modern Phys. 20, 109 (1948) (identification of [O I]).
[Crossref]

I. S. Bowen, Pub. Astron. Soc. Pacific 59, 196 (1947).
[Crossref]

I. S. Bowen and A. B. Wyse, Lick Obs. Bull. 19, 1 (1939); A. B. Wyse, Ap. J. 95, 356, (1942).
[Crossref]

I. S. Bowen, Pub. Astron. Soc. Pacific. 46, 146 (1934).
[Crossref]

Cabannes, J.

J. Cabannes and J. Dufay, Compt. rend. 226, 1569 (1948) ([O I]) and Compt. rend. 226, 2032 (1948) (suggested identification of [Fe II]).

J. Cabannes and J. Dufay, Compt. rend. 226, 2032 (1948).

Coffeen,

Babcock, Moore, and Coffeen, Ap. J. 107, 287 (1948).
[Crossref]

Colacevich, A.

A. Colacevich, Ap. J. 111, 197 (1950).
[Crossref]

Davis, D. N.

D. N. Davis, Ap. J. 106, 28 (1947).
[Crossref]

D. N. Davis, Ap. J. 87, 335 (1938) and Ap. J. 89, 41 (1939).
[Crossref]

Dufay, J.

J. Cabannes and J. Dufay, Compt. rend. 226, 1569 (1948) ([O I]) and Compt. rend. 226, 2032 (1948) (suggested identification of [Fe II]).

J. Cabannes and J. Dufay, Compt. rend. 226, 2032 (1948).

J. Dufay and M. Bloch, Annales d’Astrophysique 11, 58 and 107 (1948).

Dunham, Th.

Ultraviolet region: W. S. Adams and Th. Dunham, Ap. J. 87, 102 (1938); O. Struve, Ap. J. 90, 699 (1939). Photographic region: O. Struve, Ap. J. 74, 225 (1931); O. Struve and Th. Dunham (τ-Scorpii), Ap. J. 77, 321 (1933); R. K. Marshall, Pub. Observ. Univ. Mich. 5, 137 (1934); H. Kühlborn (γ-Peg, ξ-Per, γ-Ori and ξ-Cas) Veröff. Babelsberg 12, Heft 1 (1938); Anne B. Underhill (γ-Pegasi), Ap. J. 107, 337 (1948) (region 3965 to 4921A) and Ap. J. 108, 476 (1948) (region Hβ–5323).
[Crossref]

Th. Dunham, Contr. Princeton Obser., n°9 (1929).

Edlén, B.

B. Edlén, Arkiv Mat., Astron. Fys. 28B, No. 1 (1941); Z. Astrophys. 22, 30 (1942).

P. Swings and B. Edlén, Ap. J. 88, 618 (1938); P. Swings, B. Edlén, and J. Grandjean, Ap. J. 90, 378 (1939); B. Edlén and P. Swings, Ap. J.,  95, 532 (1942).
[Crossref]

B. Edlén, Report to the Paris Symposium on Novae and White Dwarfs, 1939 (Actualités scientifiques et industrielles, n° 895, 1941).

Etienne, R.

R. Etienne, private communication.

Gaposchkin, C. P.

C. P. Gaposchkin and F. E. Whipple, Proc. Am. Phil. Soc. 84, 1 (1941).

Goldberg,

Goldberg, Mohler, and McMath, Ap. J. 109, 28 (1949) (region 1.52 to 1.75μ of the solar spectrum); Goldberg, Mohler, Pierce, and McMath, Ap. J. 111, 565 (1950) (region 1.97 to 2.49μ of the solar spectrum).
[Crossref]

Greenstein, J. L.

J. L. Greenstein and L. H. Aller, Ap. J. 111, 328 (1950), and references indicated.
[Crossref]

J. L. Greenstein and W. S. Adams, Ap. J. 106, 339 (1947).
[Crossref]

J. L. Greenstein and P. W. Merrill, Ap. J. 104, 177 (1946).
[Crossref]

J. L. Greenstein, Ap. J. 95, 161 (1942).
[Crossref]

J. L. Greenstein, Ap. J. 91, 438 (1940).
[Crossref]

J. L. Greenstein, private communication (1950).

Herbig, G. H.

G. H. Herbig, Ap. J. 110, 143 (1949).
[Crossref]

G. H. Herbig, Ap. J. 109, 109 (1949).
[Crossref]

Herman, R.

R. Herman, Compt. rend. 226, 1800 (1948).

Herzberg, G.

G. Herzberg, Ap. J. 107, 94 (1948).
[Crossref]

G. Herzberg, private communication.

G. Herzberg, private communication.

G. Herzberg, private communication.

Hiltner, W. A.

W. A. Hiltner, Ap. J. 102, 438 (1945).
[Crossref]

Hunaerts, J.

J. Hunaerts, Ann. Obs. R. Belgique 5, fasc. 1 (1949).

Jose, P. D.

P. Swings and P. D. Jose, Ap. J. 111, 513 (1950).
[Crossref]

P. Swings and P. D. Jose, Pub. Astron. Soc. Pacific 61, 181 (1949).
[Crossref]

Joy, A. H.

For the 1933 spectrum (from September 2 to November 10), see A. H. Joy and P. Swings, Ap. J. 102, 353 (1945). For the 1942 spectrum, see P. Swings and O. Struve, Ap. J. 97, 194 (1943).
[Crossref]

Keenan,

Nassau, van Albada, and Keenan, Ap. J. 109, 333 (1949).
[Crossref]

Keenan, P. C.

P. C. Keenan, A. J. 55, 74 (1950); Sky and Telescope 9, 134 (1950).
[Crossref]

P. C. Keenan, Ap. J. 107, 420 (1948).
[Crossref]

King, R. B.

R. B. King, Ap. J. 108, 429 (1948).
[Crossref]

Kuiper, G. P.

G. P. Kuiper, Ap. J. 109, 540 (1949); Reports on Progress in Physics13, 247 (1950).
[Crossref]

McKellar, A.

A. McKellar, Ap. J. 108, 453 (1948).
[Crossref]

P. Swings and A. McKellar, Ap. J. 108, 458 (1948).
[Crossref]

A. McKellar, J. Roy. Astron. Soc., Can. 41, 147 (1947); Contrib. Pub. Dominion Astrophys. Obs., No. 7, 1947.

A. McKellar, Ap. J. 99, 162 (1944).
[Crossref]

P. Swings, A. McKellar, and R. Minkowski, Ap. J. 98, 142 (1943); P. Swings and Thornton Page, Ap. J. 108, 526 (1948), and Ap. J. 111, 530 (1950); P. D. Jose and P. Swings, Ap. J. 111, 41 (1950).
[Crossref]

McLaughlin, D. B.

D. B. McLaughlin, Pub. Observ. Univ. Mich. IX, No. 3, p. 13.

D. B. McLaughlin, Pub. Observ. Univ. Mich. VI, No. 12, p. 107.

McMath,

Goldberg, Mohler, and McMath, Ap. J. 109, 28 (1949) (region 1.52 to 1.75μ of the solar spectrum); Goldberg, Mohler, Pierce, and McMath, Ap. J. 111, 565 (1950) (region 1.97 to 2.49μ of the solar spectrum).
[Crossref]

Meinel, A. B.

A. B. Meinel, Pub. Astron. Soc. Pacific 60, 357 (1948); Trans. Amer. Geophys. Union 31, 21 (1950); Ap. J. 111, 207, 433, and 555 (1950).
[Crossref]

Merrill, P. W.

P. W. Merrill, Ap. J. 111, 484 (1950).
[Crossref]

P. W. Merrill, Ap. J. 105, 120 (1947); Ap. J. 107, 317 (1948).
[Crossref]

J. L. Greenstein and P. W. Merrill, Ap. J. 104, 177 (1946).
[Crossref]

P. W. Merrill, Ap. J. 103, 275 (1946) (atomic lines in R Leonis, Class Me); Ap. J. 105, 360 (1947) (atomic lines in R Andromedae, class Se); Ap. J. 106, 274 (1947) (post maximum spectrum of χ-Cygni, class Me+Se); Ap. J. 107, 303 (1948) (absorption lines in long period variables). For a description of the absorption spectrum of χ-Cygni a few days before maximum, see Tcheng-Mao-Lin, Compt. rend. 229, 1301 (1949).
[Crossref]

P. W. Merrill, Pub. A.S.P. 56, 42 (1944).

P. W. Merrill, Pub. A.S.P. 55, 42 (1944).

P. W. Merrill and A. D. Thackeray, Pub. Astron. Soc. Pacific 48, 33 (1936), and Pub. Astron. Soc. Pacific 49, 120 (1937); A. D. Thackeray, Ap. J. 86, 499 (1937).
[Crossref]

P. W. Merrill, Pub. Astron. Soc. Pacific 46, 206 (1934); P. W. Merrill and O. C. Wilson, Ap. J. 87, 375 (1938).
[Crossref]

P. W. Merrill, Pub. Astron. Soc. Pacific 38, 175 (1926).
[Crossref]

Migeotte, M. V.

M. V. Migeotte and L. Neven, Physica 16, 423 (1950) and Communication to the 3rd National Scientific Meeting, Brussels, 1950.
[Crossref]

M. V. Migeotte, Phys. Rev. 73, 519 (1948); Phys. Rev. 74, 112 (1948) and Phys. Rev. 75, 1108 (1949); Ap. J. 107, 400 (1948) and Ap. J. 112, 136 (1950); Astron. J. 54, 45 (1948); M. V. Migeotte and R. M. Chapman, J. Opt. Soc. Am. 38, 1094 (1948) and Phys. Rev. 75, 1611 (1949); R. M. Chapman and J. H. Shaw, Phys. Rev. 78, 71 (1950).
[Crossref]

Minkowski, R.

L. H. Aller and R. Minkowski, Pub. Astron. Soc. Pacific 58, 258 (1946).
[Crossref]

P. Swings, A. McKellar, and R. Minkowski, Ap. J. 98, 142 (1943); P. Swings and Thornton Page, Ap. J. 108, 526 (1948), and Ap. J. 111, 530 (1950); P. D. Jose and P. Swings, Ap. J. 111, 41 (1950).
[Crossref]

R. Minkowski, Pub. Astron. Soc. Pacific 53, 224 (1941).
[Crossref]

Mohler,

Goldberg, Mohler, and McMath, Ap. J. 109, 28 (1949) (region 1.52 to 1.75μ of the solar spectrum); Goldberg, Mohler, Pierce, and McMath, Ap. J. 111, 565 (1950) (region 1.97 to 2.49μ of the solar spectrum).
[Crossref]

Monfils, A.

B. Rosen and A. Monfils, Nature 164, 713 (1949).

Moore,

Babcock, Moore, and Coffeen, Ap. J. 107, 287 (1948).
[Crossref]

Moore, C. E.

C. E. Moore, Ap. J. 75, 222 (1932).
[Crossref]

H. D. Babcock and C. E. Moore, The Solar Spectrum, 6600A to 13,495A, Carnegie Institution of Washington, Publication 579 (1947).

Nassau,

Nassau, van Albada, and Keenan, Ap. J. 109, 333 (1949).
[Crossref]

Neven, L.

M. V. Migeotte and L. Neven, Physica 16, 423 (1950) and Communication to the 3rd National Scientific Meeting, Brussels, 1950.
[Crossref]

Öhman, Y.

P. Swings and Y. Öhman, Observatory 62, 150 (1939); P. Swings and M. Désirant, Ciel et Terre 55, 161 (1939); P. Swings, J. Roy. Astron. Soc., Can. 35, 71 (1941); A. McKellar, Pub. Dominion Astrophys. Obs. 7, 251 (1941); van de Hulst, Recherches astronomiques de l’Observatoire d’Utrecht, Vol.  XI, pt. 2 (1949). (The Solid Particles in Interstellar Space.)

Page, Thornton

P. Swings and Thornton Page, Ap. J. 111, 530 (1950); P. Swings, Bull. Acad. Roy. Belgique 36, 113 (1950).
[Crossref]

Pasternack, S.

S. Pasternack, Ap. J. 92, 129 (1940).
[Crossref]

Popper, D. M.

D. M. Popper, Harvard Announcement Card 752 (1946); A. J. 52, 129 (1946). P. C. Keenan, Ap. J. 106, 295 (1947). A. D. Thackeray, Nature 160, 370 (1947); Monthly Notices Roy. Astron. Soc. 108, 276 (1948). J. L. Greenstein, Ap. J. 108, 78 (1948).
[Crossref]

D. M. Popper, Pub. A.S.P. 54, 160 (1942); Pub. A.S.P. 58, 370 (1946); Pub. A.S.P. 59, 320 (1947).

Rao, K. N.

P. Swings and K. N. Rao (in preparation).

Rimmer,

Rimmer, Proc. Roy. Soc. (London),  A103, 696 (1923).
[Crossref]

Roach, F. E.

F. E. Roach, Ap. J. 96, 272 (1942).
[Crossref]

Rosen, B.

B. Rosen and A. Monfils, Nature 164, 713 (1949).

Rush, J. H.

Region λλ3000–3300: J. H. Rush, Ap. J. 95, 213 (1942). Region λλ3300–3940: O. Struve, Ap. J. 90, 699 (1939). Region λλ3862–6587 (α-Cygni): O. Struve and P. Swings, Ap. J.  94, 344 (1941). Region λλ3300–6500 (1 Puppis, cA2ep): P. Swings, Annales d’Astrophysique 13, 114 (1950).
[Crossref]

Sanford, R. F.

R. F. Sanford, Ap. J. 111, 262 (1950).
[Crossref]

R. F. Sanford, Ap. J. 102, 357 (1945).
[Crossref]

R. F. Sanford, Pub. Astron. Soc. Pacific 38, 177 (1926).
[Crossref]

Shajn, G.

G. Shajn and O. Struve, Ap. J. 106, 86 (1947).
[Crossref]

Shane, C. D.

C. D. Shane, Lick Obs. Bull. 13, 127 (1928).

Struve, O.

G. Shajn and O. Struve, Ap. J. 106, 86 (1947).
[Crossref]

O. Struve, Ap. J. 99, 70 (1944); P. Swings and O. Struve, Ap. J. 101, 224 (1945).
[Crossref]

P. Swings and O. Struve, Ap. J. 97, 194 (1943).
[Crossref]

O. Struve and P. Swings, Ap. J. 97, 426 (1943).
[Crossref]

O. Struve, Ap. J. 98, 98 (1943).
[Crossref]

O. Struve and P. Swings, Ap. J. 98, 361 (1943); P. Swings, Ap. J. 100, 132 (1944).
[Crossref]

P. Swings and O. Struve, Ap. J. 96, 472 (1942).

P. Swings and O. Struve, Ap. J. 93, 356 (1941).
[Crossref]

Swings and O. Struve, Ap. J. 93, 349 (1941).
[Crossref]

P. Swings and O. Struve, Ap. J. 94, 307 (1941).

P. Swings and O. Struve, Ap. J. 93, 455 (1941).
[Crossref]

P. Swings and O. Struve, Ap. J. 91, 546 (1940). (This star may also be considered as a symbiotic object.)
[Crossref]

Region 3000 to 3300A: P. Swings and O. Struve, Pub. Astron. Soc. Pacific 52, 392 (1940); region 3300 to 4025A: O. Struve and F. E. Roach, Ap. J. 90, 727 (1939); region 3900A–Hβ: O. Struve, Ap. J. 81, 66 (1935), and C. S. Beals, Monthly Notices Roy. Astron. Soc. 95, 581 (1935); region Hβ–6700A: P. Swings and O. Struve, Ap. J. 91, 571 (1940) (preliminary examination by C. S. Beals, see above, and by Kharadze, Z. Astrophys. 11, 304 (1935); region Hα–8900A: P. W. Merrill, Ap. J. 79, 183 (1934), and P. Swings, Pub. Astron. Soc. Pacific 56, 238 (1944).
[Crossref]

P. Swings and O. Struve, Ap. J. 92, 295 (1940).
[Crossref]

P. Swings and O. Struve, Ap. J. 91, 600 (1940); Ap. J. 93, 457 (1941); Ap. J. 98, 94 (1943); P. Swings, Pub. Astron. Soc. Pacific 55, 276 (1943).
[Crossref]

P. Swings and O. Struve, Ap. J. 91, 546 (1940).
[Crossref]

P. Swings and O. Struve, Proc. Nat. Acad. Sci. 26, 548 (1940); P. Swings, Ap. J. 95, 112 (1942); L. H. Aller, Ap. J. 97, 135 (1943).
[Crossref]

O. Struve, Ap. J. 74, 225 (1931); Ap. J. 90, 699 (1939).
[Crossref]

Swensson, J. W.

J. W. Swensson, Ap. J. 103, 207 (1946).
[Crossref]

J. W. Swensson, Ap. J. 99, 258 (1944).
[Crossref]

Swings,

Swings and O. Struve, Ap. J. 93, 349 (1941).
[Crossref]

Swings, P.

P. Swings, Ann. Astrophys. 13, 134 (1950); P. Swings and O. Struve, Ap. J. 91, 546 (1940); Ap. J. 93, 455 (1941); Ap. J. 97, 194 (1943); P. Swings, Pub. Astron. Soc. Pacific 55, 276 (1943).
[Crossref]

P. Swings and P. D. Jose, Ap. J. 111, 513 (1950).
[Crossref]

P. Swings and Thornton Page, Ap. J. 111, 530 (1950); P. Swings, Bull. Acad. Roy. Belgique 36, 113 (1950).
[Crossref]

P. Swings and P. D. Jose, Pub. Astron. Soc. Pacific 61, 181 (1949).
[Crossref]

P. Swings, Ann. Astrophys. 11, 228 (1948).

P. Swings and A. McKellar, Ap. J. 108, 458 (1948).
[Crossref]

P. Swings, Annales d’Astrophysique 11, 124 (1948).

For the 1933 spectrum (from September 2 to November 10), see A. H. Joy and P. Swings, Ap. J. 102, 353 (1945). For the 1942 spectrum, see P. Swings and O. Struve, Ap. J. 97, 194 (1943).
[Crossref]

P. Swings, Pub. Astron. Soc. Pacific 56, 242 (1944).
[Crossref]

P. Swings, Pub. Astron. Soc. Pacific 56, 80 (1944).
[Crossref]

P. Swings, Pub. A.S.P. 56, 242 (1944).

P. Swings, A. McKellar, and R. Minkowski, Ap. J. 98, 142 (1943); P. Swings and Thornton Page, Ap. J. 108, 526 (1948), and Ap. J. 111, 530 (1950); P. D. Jose and P. Swings, Ap. J. 111, 41 (1950).
[Crossref]

P. Swings and O. Struve, Ap. J. 97, 194 (1943).
[Crossref]

O. Struve and P. Swings, Ap. J. 98, 361 (1943); P. Swings, Ap. J. 100, 132 (1944).
[Crossref]

O. Struve and P. Swings, Ap. J. 97, 426 (1943).
[Crossref]

P. Swings and O. Struve, Ap. J. 96, 472 (1942).

P. Swings, Ap. J. 95, 112 (1942).
[Crossref]

P. Swings, Ap. J. 95, 270 (1942).
[Crossref]

P. Swings and O. Struve, Ap. J. 93, 455 (1941).
[Crossref]

P. Swings and O. Struve, Ap. J. 93, 356 (1941).
[Crossref]

P. Swings and O. Struve, Ap. J. 94, 307 (1941).

P. Swings and O. Struve, Ap. J. 91, 546 (1940). (This star may also be considered as a symbiotic object.)
[Crossref]

P. Swings and O. Struve, Proc. Nat. Acad. Sci. 26, 548 (1940); P. Swings, Ap. J. 95, 112 (1942); L. H. Aller, Ap. J. 97, 135 (1943).
[Crossref]

Region 3000 to 3300A: P. Swings and O. Struve, Pub. Astron. Soc. Pacific 52, 392 (1940); region 3300 to 4025A: O. Struve and F. E. Roach, Ap. J. 90, 727 (1939); region 3900A–Hβ: O. Struve, Ap. J. 81, 66 (1935), and C. S. Beals, Monthly Notices Roy. Astron. Soc. 95, 581 (1935); region Hβ–6700A: P. Swings and O. Struve, Ap. J. 91, 571 (1940) (preliminary examination by C. S. Beals, see above, and by Kharadze, Z. Astrophys. 11, 304 (1935); region Hα–8900A: P. W. Merrill, Ap. J. 79, 183 (1934), and P. Swings, Pub. Astron. Soc. Pacific 56, 238 (1944).
[Crossref]

P. Swings and O. Struve, Ap. J. 91, 546 (1940).
[Crossref]

P. Swings and O. Struve, Ap. J. 91, 600 (1940); Ap. J. 93, 457 (1941); Ap. J. 98, 94 (1943); P. Swings, Pub. Astron. Soc. Pacific 55, 276 (1943).
[Crossref]

P. Swings and O. Struve, Ap. J. 92, 295 (1940).
[Crossref]

P. Swings and Y. Öhman, Observatory 62, 150 (1939); P. Swings and M. Désirant, Ciel et Terre 55, 161 (1939); P. Swings, J. Roy. Astron. Soc., Can. 35, 71 (1941); A. McKellar, Pub. Dominion Astrophys. Obs. 7, 251 (1941); van de Hulst, Recherches astronomiques de l’Observatoire d’Utrecht, Vol.  XI, pt. 2 (1949). (The Solid Particles in Interstellar Space.)

P. Swings and B. Edlén, Ap. J. 88, 618 (1938); P. Swings, B. Edlén, and J. Grandjean, Ap. J. 90, 378 (1939); B. Edlén and P. Swings, Ap. J.,  95, 532 (1942).
[Crossref]

P. Swings and K. N. Rao (in preparation).

Tcheng-Mao-Lin,

Tcheng-Mao-Lin, Compt. rend. 229, 348 (1949).

Thackeray, A. D.

P. W. Merrill and A. D. Thackeray, Pub. Astron. Soc. Pacific 48, 33 (1936), and Pub. Astron. Soc. Pacific 49, 120 (1937); A. D. Thackeray, Ap. J. 86, 499 (1937).
[Crossref]

van Albada,

Nassau, van Albada, and Keenan, Ap. J. 109, 333 (1949).
[Crossref]

Whipple, F. E.

C. P. Gaposchkin and F. E. Whipple, Proc. Am. Phil. Soc. 84, 1 (1941).

Wyse, A. B.

A. B. Wyse, Lick Obser. Pub. 14, 93 and 217 (1940).

I. S. Bowen and A. B. Wyse, Lick Obs. Bull. 19, 1 (1939); A. B. Wyse, Ap. J. 95, 356, (1942).
[Crossref]

A. J. (1)

P. C. Keenan, A. J. 55, 74 (1950); Sky and Telescope 9, 134 (1950).
[Crossref]

Ann. Astrophys. (2)

P. Swings, Ann. Astrophys. 13, 134 (1950); P. Swings and O. Struve, Ap. J. 91, 546 (1940); Ap. J. 93, 455 (1941); Ap. J. 97, 194 (1943); P. Swings, Pub. Astron. Soc. Pacific 55, 276 (1943).
[Crossref]

P. Swings, Ann. Astrophys. 11, 228 (1948).

Ann. Obs. R. Belgique (1)

J. Hunaerts, Ann. Obs. R. Belgique 5, fasc. 1 (1949).

Annales d’Astrophysique (2)

P. Swings, Annales d’Astrophysique 11, 124 (1948).

J. Dufay and M. Bloch, Annales d’Astrophysique 11, 58 and 107 (1948).

Ap. J. (60)

P. Swings and Thornton Page, Ap. J. 111, 530 (1950); P. Swings, Bull. Acad. Roy. Belgique 36, 113 (1950).
[Crossref]

A. McKellar, Ap. J. 99, 162 (1944).
[Crossref]

P. Swings, Ap. J. 95, 270 (1942).
[Crossref]

S. Pasternack, Ap. J. 92, 129 (1940).
[Crossref]

P. Swings and O. Struve, Ap. J. 93, 455 (1941).
[Crossref]

R. B. King, Ap. J. 108, 429 (1948).
[Crossref]

R. F. Sanford, Ap. J. 111, 262 (1950).
[Crossref]

G. Shajn and O. Struve, Ap. J. 106, 86 (1947).
[Crossref]

A. McKellar, Ap. J. 108, 453 (1948).
[Crossref]

P. Swings and A. McKellar, Ap. J. 108, 458 (1948).
[Crossref]

P. C. Keenan, Ap. J. 107, 420 (1948).
[Crossref]

J. L. Greenstein and L. H. Aller, Ap. J. 111, 328 (1950), and references indicated.
[Crossref]

G. P. Kuiper, Ap. J. 109, 540 (1949); Reports on Progress in Physics13, 247 (1950).
[Crossref]

P. Swings, A. McKellar, and R. Minkowski, Ap. J. 98, 142 (1943); P. Swings and Thornton Page, Ap. J. 108, 526 (1948), and Ap. J. 111, 530 (1950); P. D. Jose and P. Swings, Ap. J. 111, 41 (1950).
[Crossref]

P. Swings and P. D. Jose, Ap. J. 111, 513 (1950).
[Crossref]

O. Struve, Ap. J. 74, 225 (1931); Ap. J. 90, 699 (1939).
[Crossref]

P. Swings and O. Struve, Ap. J. 91, 546 (1940).
[Crossref]

P. Swings and O. Struve, Ap. J. 91, 546 (1940). (This star may also be considered as a symbiotic object.)
[Crossref]

R. B. Baldwin, Ap. J. 93, 421 (1941).

R. B. Baldwin, Ap. J. 93, 333 (1941).
[Crossref]

Swings and O. Struve, Ap. J. 93, 349 (1941).
[Crossref]

P. Swings and O. Struve, Ap. J. 96, 472 (1942).

G. Herzberg, Ap. J. 107, 94 (1948).
[Crossref]

Ultraviolet region: W. S. Adams and Th. Dunham, Ap. J. 87, 102 (1938); O. Struve, Ap. J. 90, 699 (1939). Photographic region: O. Struve, Ap. J. 74, 225 (1931); O. Struve and Th. Dunham (τ-Scorpii), Ap. J. 77, 321 (1933); R. K. Marshall, Pub. Observ. Univ. Mich. 5, 137 (1934); H. Kühlborn (γ-Peg, ξ-Per, γ-Ori and ξ-Cas) Veröff. Babelsberg 12, Heft 1 (1938); Anne B. Underhill (γ-Pegasi), Ap. J. 107, 337 (1948) (region 3965 to 4921A) and Ap. J. 108, 476 (1948) (region Hβ–5323).
[Crossref]

P. Swings and B. Edlén, Ap. J. 88, 618 (1938); P. Swings, B. Edlén, and J. Grandjean, Ap. J. 90, 378 (1939); B. Edlén and P. Swings, Ap. J.,  95, 532 (1942).
[Crossref]

Region λλ3000–3300: J. H. Rush, Ap. J. 95, 213 (1942). Region λλ3300–3940: O. Struve, Ap. J. 90, 699 (1939). Region λλ3862–6587 (α-Cygni): O. Struve and P. Swings, Ap. J.  94, 344 (1941). Region λλ3300–6500 (1 Puppis, cA2ep): P. Swings, Annales d’Astrophysique 13, 114 (1950).
[Crossref]

O. Struve and P. Swings, Ap. J. 97, 426 (1943).
[Crossref]

O. Struve, Ap. J. 98, 98 (1943).
[Crossref]

J. W. Swensson, Ap. J. 99, 258 (1944).
[Crossref]

O. Struve and P. Swings, Ap. J. 98, 361 (1943); P. Swings, Ap. J. 100, 132 (1944).
[Crossref]

J. L. Greenstein, Ap. J. 91, 438 (1940).
[Crossref]

P. Swings and O. Struve, Ap. J. 92, 295 (1940).
[Crossref]

R. F. Sanford, Ap. J. 102, 357 (1945).
[Crossref]

For the 1933 spectrum (from September 2 to November 10), see A. H. Joy and P. Swings, Ap. J. 102, 353 (1945). For the 1942 spectrum, see P. Swings and O. Struve, Ap. J. 97, 194 (1943).
[Crossref]

A. Colacevich, Ap. J. 111, 197 (1950).
[Crossref]

P. Swings and O. Struve, Ap. J. 91, 600 (1940); Ap. J. 93, 457 (1941); Ap. J. 98, 94 (1943); P. Swings, Pub. Astron. Soc. Pacific 55, 276 (1943).
[Crossref]

P. Swings, Ap. J. 95, 112 (1942).
[Crossref]

O. Struve, Ap. J. 99, 70 (1944); P. Swings and O. Struve, Ap. J. 101, 224 (1945).
[Crossref]

P. W. Merrill, Ap. J. 111, 484 (1950).
[Crossref]

P. Swings and O. Struve, Ap. J. 97, 194 (1943).
[Crossref]

P. Swings and O. Struve, Ap. J. 93, 356 (1941).
[Crossref]

P. W. Merrill, Ap. J. 105, 120 (1947); Ap. J. 107, 317 (1948).
[Crossref]

J. L. Greenstein and P. W. Merrill, Ap. J. 104, 177 (1946).
[Crossref]

J. L. Greenstein and W. S. Adams, Ap. J. 106, 339 (1947).
[Crossref]

W. B. Bidelman, Ap. J. 111, 333 (1950).
[Crossref]

J. W. Swensson, Ap. J. 103, 207 (1946).
[Crossref]

J. L. Greenstein, Ap. J. 95, 161 (1942).
[Crossref]

F. E. Roach, Ap. J. 96, 272 (1942).
[Crossref]

W. A. Hiltner, Ap. J. 102, 438 (1945).
[Crossref]

P. Swings and O. Struve, Ap. J. 94, 307 (1941).

G. H. Herbig, Ap. J. 110, 143 (1949).
[Crossref]

Babcock, Moore, and Coffeen, Ap. J. 107, 287 (1948).
[Crossref]

P. W. Merrill, Ap. J. 103, 275 (1946) (atomic lines in R Leonis, Class Me); Ap. J. 105, 360 (1947) (atomic lines in R Andromedae, class Se); Ap. J. 106, 274 (1947) (post maximum spectrum of χ-Cygni, class Me+Se); Ap. J. 107, 303 (1948) (absorption lines in long period variables). For a description of the absorption spectrum of χ-Cygni a few days before maximum, see Tcheng-Mao-Lin, Compt. rend. 229, 1301 (1949).
[Crossref]

G. H. Herbig, Ap. J. 109, 109 (1949).
[Crossref]

D. N. Davis, Ap. J. 106, 28 (1947).
[Crossref]

D. N. Davis, Ap. J. 87, 335 (1938) and Ap. J. 89, 41 (1939).
[Crossref]

Nassau, van Albada, and Keenan, Ap. J. 109, 333 (1949).
[Crossref]

Goldberg, Mohler, and McMath, Ap. J. 109, 28 (1949) (region 1.52 to 1.75μ of the solar spectrum); Goldberg, Mohler, Pierce, and McMath, Ap. J. 111, 565 (1950) (region 1.97 to 2.49μ of the solar spectrum).
[Crossref]

C. E. Moore, Ap. J. 75, 222 (1932).
[Crossref]

H. D. Babcock, Ap. J. 102, 166 (1945).

Arkiv Mat., Astron. Fys. (1)

B. Edlén, Arkiv Mat., Astron. Fys. 28B, No. 1 (1941); Z. Astrophys. 22, 30 (1942).

Compt. rend. (5)

J. Cabannes and J. Dufay, Compt. rend. 226, 1569 (1948) ([O I]) and Compt. rend. 226, 2032 (1948) (suggested identification of [Fe II]).

Tcheng-Mao-Lin, Compt. rend. 229, 348 (1949).

R. Herman, Compt. rend. 226, 1800 (1948).

M. Bloch, Compt. rend. 227, 333 (1948).

J. Cabannes and J. Dufay, Compt. rend. 226, 2032 (1948).

Contr. Princeton Obser. (1)

Th. Dunham, Contr. Princeton Obser., n°9 (1929).

Harvard Announcement Card 752 (1)

D. M. Popper, Harvard Announcement Card 752 (1946); A. J. 52, 129 (1946). P. C. Keenan, Ap. J. 106, 295 (1947). A. D. Thackeray, Nature 160, 370 (1947); Monthly Notices Roy. Astron. Soc. 108, 276 (1948). J. L. Greenstein, Ap. J. 108, 78 (1948).
[Crossref]

J. Roy. Astron. Soc., Can. (1)

A. McKellar, J. Roy. Astron. Soc., Can. 41, 147 (1947); Contrib. Pub. Dominion Astrophys. Obs., No. 7, 1947.

Lick Obs. Bull. (2)

C. D. Shane, Lick Obs. Bull. 13, 127 (1928).

I. S. Bowen and A. B. Wyse, Lick Obs. Bull. 19, 1 (1939); A. B. Wyse, Ap. J. 95, 356, (1942).
[Crossref]

Lick Obser. Pub. (1)

A. B. Wyse, Lick Obser. Pub. 14, 93 and 217 (1940).

Nature (1)

B. Rosen and A. Monfils, Nature 164, 713 (1949).

Observatory (1)

P. Swings and Y. Öhman, Observatory 62, 150 (1939); P. Swings and M. Désirant, Ciel et Terre 55, 161 (1939); P. Swings, J. Roy. Astron. Soc., Can. 35, 71 (1941); A. McKellar, Pub. Dominion Astrophys. Obs. 7, 251 (1941); van de Hulst, Recherches astronomiques de l’Observatoire d’Utrecht, Vol.  XI, pt. 2 (1949). (The Solid Particles in Interstellar Space.)

Phys. Rev. (1)

M. V. Migeotte, Phys. Rev. 73, 519 (1948); Phys. Rev. 74, 112 (1948) and Phys. Rev. 75, 1108 (1949); Ap. J. 107, 400 (1948) and Ap. J. 112, 136 (1950); Astron. J. 54, 45 (1948); M. V. Migeotte and R. M. Chapman, J. Opt. Soc. Am. 38, 1094 (1948) and Phys. Rev. 75, 1611 (1949); R. M. Chapman and J. H. Shaw, Phys. Rev. 78, 71 (1950).
[Crossref]

Physica (1)

M. V. Migeotte and L. Neven, Physica 16, 423 (1950) and Communication to the 3rd National Scientific Meeting, Brussels, 1950.
[Crossref]

Proc. Am. Phil. Soc. (1)

C. P. Gaposchkin and F. E. Whipple, Proc. Am. Phil. Soc. 84, 1 (1941).

Proc. Nat. Acad. Sci. (1)

P. Swings and O. Struve, Proc. Nat. Acad. Sci. 26, 548 (1940); P. Swings, Ap. J. 95, 112 (1942); L. H. Aller, Ap. J. 97, 135 (1943).
[Crossref]

Proc. Roy. Soc. (London) (1)

Rimmer, Proc. Roy. Soc. (London),  A103, 696 (1923).
[Crossref]

Pub. A.S.P. (4)

P. W. Merrill, Pub. A.S.P. 55, 42 (1944).

P. W. Merrill, Pub. A.S.P. 56, 42 (1944).

P. Swings, Pub. A.S.P. 56, 242 (1944).

D. M. Popper, Pub. A.S.P. 54, 160 (1942); Pub. A.S.P. 58, 370 (1946); Pub. A.S.P. 59, 320 (1947).

Pub. Astron. Soc. Pacific (12)

P. Swings, Pub. Astron. Soc. Pacific 56, 80 (1944).
[Crossref]

Region 3000 to 3300A: P. Swings and O. Struve, Pub. Astron. Soc. Pacific 52, 392 (1940); region 3300 to 4025A: O. Struve and F. E. Roach, Ap. J. 90, 727 (1939); region 3900A–Hβ: O. Struve, Ap. J. 81, 66 (1935), and C. S. Beals, Monthly Notices Roy. Astron. Soc. 95, 581 (1935); region Hβ–6700A: P. Swings and O. Struve, Ap. J. 91, 571 (1940) (preliminary examination by C. S. Beals, see above, and by Kharadze, Z. Astrophys. 11, 304 (1935); region Hα–8900A: P. W. Merrill, Ap. J. 79, 183 (1934), and P. Swings, Pub. Astron. Soc. Pacific 56, 238 (1944).
[Crossref]

R. Minkowski, Pub. Astron. Soc. Pacific 53, 224 (1941).
[Crossref]

P. Swings, Pub. Astron. Soc. Pacific 56, 242 (1944).
[Crossref]

L. H. Aller and R. Minkowski, Pub. Astron. Soc. Pacific 58, 258 (1946).
[Crossref]

P. Swings and P. D. Jose, Pub. Astron. Soc. Pacific 61, 181 (1949).
[Crossref]

P. W. Merrill, Pub. Astron. Soc. Pacific 46, 206 (1934); P. W. Merrill and O. C. Wilson, Ap. J. 87, 375 (1938).
[Crossref]

P. W. Merrill, Pub. Astron. Soc. Pacific 38, 175 (1926).
[Crossref]

R. F. Sanford, Pub. Astron. Soc. Pacific 38, 177 (1926).
[Crossref]

P. W. Merrill and A. D. Thackeray, Pub. Astron. Soc. Pacific 48, 33 (1936), and Pub. Astron. Soc. Pacific 49, 120 (1937); A. D. Thackeray, Ap. J. 86, 499 (1937).
[Crossref]

I. S. Bowen, Pub. Astron. Soc. Pacific 59, 196 (1947).
[Crossref]

A. B. Meinel, Pub. Astron. Soc. Pacific 60, 357 (1948); Trans. Amer. Geophys. Union 31, 21 (1950); Ap. J. 111, 207, 433, and 555 (1950).
[Crossref]

Pub. Astron. Soc. Pacific. (1)

I. S. Bowen, Pub. Astron. Soc. Pacific. 46, 146 (1934).
[Crossref]

Pub. Observ. Univ. Mich. (3)

D. B. McLaughlin, Pub. Observ. Univ. Mich. VI, No. 12, p. 107.

D. B. McLaughlin, Pub. Observ. Univ. Mich. IX, No. 3, p. 13.

R. B. Baldwin, Pub. Observ. Univ. Mich. VIII, No. 5, p. 61.

Revs. Modern Phys. (1)

I. S. Bowen, Revs. Modern Phys. 20, 109 (1948) (identification of [O I]).
[Crossref]

Other (8)

H. D. Babcock and C. E. Moore, The Solar Spectrum, 6600A to 13,495A, Carnegie Institution of Washington, Publication 579 (1947).

J. L. Greenstein, private communication (1950).

B. Edlén, Report to the Paris Symposium on Novae and White Dwarfs, 1939 (Actualités scientifiques et industrielles, n° 895, 1941).

G. Herzberg, private communication.

R. Etienne, private communication.

G. Herzberg, private communication.

P. Swings and K. N. Rao (in preparation).

G. Herzberg, private communication.

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Equations (5)

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3454.1 , 3800.8 , 4311 , 4412 , 4567 , and 4586 A .
7344.4 ( 3 ) , 7376.6 ( 4 ) , 7404.7 ( 3 ) , and 7433.4 A ( 3 ) .
7865.1 ( 3 ) , 7939.3 ( 4 ) , and 7974.3 A ( 4 ) .
3525 ( 1 - 0 ) , 3741 ( 1 ) , 4096 ( 0 - 1 ) , and 4171 A ( 1 )
3263 ( 5 ) ,     3571 ( 7 ) ,     3622 ( 5 ) ,     3700 ( 6 ) ,     3916 ( 8 ) ,     and     3960 A ( 4 ) .