variations in the spectrum of the orion nebula

207 3541 208

1898 1 M. 2. Kiel da 1 Ad /Vgl.

Nov. 6 gh 6m28s -0O"19?62 -11'23!'4 7 6 8 6 2 8 -0 35.80 ~ - 4 36.9 1 7

P o s i t i o n s m o y e n n e s d e s e t o i l e s d e c o n i p a r a i s o n .

a app. 1 logf.dl dapp . I1ogf.d Red. ad 1. app. 1 * 1 7 ~ 3 7 ~ 4 3 f o z 1 9.553 I +16O44' oP4 0.825 +zSor + 419 I

I 7 37 43.68 9.553 + I 6 43 58.2 0 . 8 2 5 + Z . O I + 4.9 2

-

8 I R.4. 1898.0 I DP. 1898.0 Autorite

17~38"' of63 2 1 7 38 17.47 II

7 8 9

10

I 1

1 2

'3

+16O 55' 181'9 AG. Berlin A. 6404 t 1 6 48 30.2 AG. Berlin A. 6405

96O 19' 54!'2 96 2 2 50.5 96 1 0 11.6 96 18 7 . 7 96 2 5 25-6 96 18 56.6 96 1 5 30.0 96 23 52.0 96 2 1 1 2 . 0

90 5 2 12.6 91 2 0 27.3 92 4 29.4 80 56 18.6

Some doubt having been expressed as to the reality of variations which have been observed in the spectrum of the Orion Nebula, I made some visual observations with reference to this question on the night of Dee. 12 , with a spectroscope attached to the 36 inch refractor.

The slit was first Placed on the nebulosity Surrounding the Star Bond 734. 'l?he night being hazy, only a single line was visible. It was occulted by the coarse micrometer wire, and, on throwing in the light from a hydrogen tube, was identified as f@.

The slit was then placed on the Huyghenian region, near the trapezium. The usual spectrum was well seen. f@ and the second nebular line (2, = 4959) were about equally

Schj. 8561 Schj. 8 5 4 5 MI 2 7 2 1 5

Ml 26345 M, 1099.2 M, 10916 M, 10889 M, 10832 WI 2Ot997 M, 13106 ' / a (MI 32777 -C Y. 10491) '/, (M, 32765 + Y. 10482) \V, 6h227

bright ; the chief line (2 = 5007) was several times brighter than either.

The intensity of the spectrum was then diminished by contracting the vertical aperture of the spectroscope, the resolving power remaining therefore unchanged. When the brightness was sufficiently reduced, f@ and the second line disappeared, the chief nebular line being then alone visible.

In other words, with a sufficiently feeble spectrum the FlB line was alone visible in one part of the nebula, and the chief line was alone visible in another part. This result is inexplicable on physioIogica1 grounds. It can only be due to real differences in the spectrum of the nebula.

H: RA. 1898.0 1 DP. 1898.0 1 Autorite

I 4 ' 5 16 1 7 I 8 '9 2 0

2 1

2 2

23 24 2 5

6h 9"'38?32 6 1 2 5 8 x 1

' 7 43 18.51 ' 7 45 58.59 ' 7 50 21.49 '7 5' 9.98 '7 54 32.48 ' 7 56 30.46

I 8 4 18.02

I 8 7 58.09

1 8 I 4747

18 6 1.40

8 1 ~ 3 1 ' 2 2 1 0

81 44 3 3 . 7 75 1 2 36.8 76 48 48.3 78 36 32.3 80 13 44.6 81 46 7 . 1 86 2 59.1 87 2 2 19.8 89 37 26.1 90 40 43.6 9' 44 42.1

Par. 7470 Anonyme; rapp. A Q 14 Schj. 6398 Schj. 6415 Schj. 6453 Par. 23034

Schj. 6498 Schj. 6543

Schj. 6582 Schj. 6600

M, 6984

Ml '5509

Q 1 5 - B 1 4 : d A R . = +3"19579; d D P . = i-13' I I ! ' ~ ; 6.6 comparaisons. Le Directeur de l'observatoire :

L. J. Gruey. Besanson, le 26 Novembre 1898.

Beobachtungen des Cometen 1898. . . (Brooks Qct. 20) a m R e f r a c t o r d e r S t e r n w a r t e in Kie l .

Geschlossen 1899 Jan. ZT. Herausgeber: H. K r e u t z . Druck YOU 0. Sci ih i dt . Expedition: Kiel, Niemannsweg 102.