5672

There is a well marked difference in the radial velocities of the different spectral subdivisions in the 0-type stars, the Oeg- stars showing positive velocities and the earlier subdivisions

Zeit Bem. 2424.. .

negative velocities. The results of an examination of 27 stars of this type in the Yerkes and Lick catalogues are given in table I.

. . 597.30 I, M' 598.35 I, M' 699.45 I, M' 601.51 11, M' 606.32 I1 607.38 I1 608.31 I11

610.35 I

617.37 I1 618.38 I 619.40 I1 620.35 11-111 621.33 I, M 624.33 I, M 631.33 11, M' 634.34 111, M' 2425 ... 157.6 I1 163.5 111, M 164.5 11, M' 166.5 I, M

181.4 I1

609.35 1

614.44 1

172.4 11

Vgl.-Steme Gr.

b-C d-C 6-d

6-C

b-C b-C b Y-b

Y-b

r-b *:b Y - b

r-b r-b Y-b r-b b

b-C b-C 6-C 6-C

d-C b-C

C

Die Beobachtunnen

9mo5 9.2 9.25 9.2 8.95 8.65 8-55 8.35 8.3 8.3 8.25 8.2 8.35 8.3 8.3 8.25 8.3 8.45

8.75 8.65 8.6 8.65 8.8 8.65

Zeit 2.425.. 182.4 183.4 185.4 188.5 198.4 209-4 211.4 212.4 217.4 218.4 220.3 240.3 243.7 244.2 245.2 246i2 247.3 248.2 249.2 255.3 256.2 258.3 259.3 262.3

von 192q SeDt. bis

Bern.

I I I I1 111, M' I1 I1 I1 I 11, M 11, M' I11 I I, M 11, M 11, M' 11, M' 11, M' 11, M' 111 I11 I11 I I11

VgLSteme

b-C b-C b b-C 6-c 6-6 b-C 6 - C b-C b-C

b-C b-C Y-b

Y -b b b 6-C b 6-6 b - C b-C b b - C

C

Gr.

8m65 8.55 8.45 8-55 8.55 8.75 8.75 8.7 8.95 9.1 9.T 8.2 8.15 8.2 8.3 8.45 8.45 8.55 8.45 8-55 8.6 8.55 8.45 8.65

Zeit

271.3 272.5 274.2 275.2 276.4 301.3 302.3 303.3 304.5 305.3 308.3 309.4 3'0.3 321.5 322.3 323.3 325.4 326.4 328.3

346.4 348.3 362.3

2425 ...

331.3 344.4

Bern.

I1 I 11, M 11, M' 111, M' I I, M I, M

11-111, M' 11, M

11, M' 11, M' 11, M' I1 I1 I I1 I I1 111, M I I1 I1 I1

Vgl.-Sterne

b-C b 6-C

b 6 6-C

6-c b-C b-C 6-6

C

C

C

b b b b b b-C b-C 6 - C 6 b b

Gr.

8% 8.45 8.55 8.45 8.45 8.7 8.8 8.9 9.0 9.05 9-2 9.2 9.2 8.4 8.5 8.45 8.35 8-35 8.25 8.25 8.2 8.35 8.45 8.45

1926 Febr. I Die Werte in der Spalte ,Rechnungcc sind der Tabelle Y . I 1

sind zu wenig zahlreich, um eine sichere Kurve ableiten zu konnen. Sie fugen sich aber den Beyerschen Beobachtungen gut an, wenn man den durch die anders angenommenen VergleichstemgroBen bedingten systematischen Helligkeits- unterschied berucksichtigt.

Aus den ubrigen Beobachtungen ergeben sich die folgenden Hauptphasen : E Phase Beob. Rechn. B-R Gr.

m 1926 Mar2 24.8 J.D.24599.8 J.D.24597.1 + 2d7 9m25 2 5 MI AprilII.1 617.1 614.2 +2.9 8.25

n 1g27Okt. 20.5 25174.5 25177.6 -3.1 8.8

m Dez. 6.8 221.8 222.2 -0.4 9.2

n 1928 Jan. 16.7 262.7 266.9 -4.2 8.65 40 Ma Febr. 6.0 283.0(:) 284.0 -1.0 8.3

m Marz 4.5 3'0.5 311.5 -1.0 9.2 41 MI MLrz27.4 333.4 328.6 +4.8 8.15

It April 19.1 356.1 356.2 -0.1 8.6 M = Maximum; m = Haupt-, ~t = Nebenminimum.

Wittgensdorf b. Chtz., Anfang Mai 1929.

9

_ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ . ~ . ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ . ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

38 M, Nov. 8.9 '93.9 194.7 -0.8 8.4

39 MI Dez. 27.2 242.2 239.3 4-2.9 8.2

M. Beyers in A.N. 5616 entnommen. Im ubrigen werden die Ergebnisse, die M. Beyer a. a. 0.

findet, durch die vorliegenden Beobachtungen durchaus bestiitigt. Genaue zahlenmal3ige ubereinstimmung ist natiirlich wegen der unvermeidlichen Beobachtungsfehler und wegen des verschiedenen Umfangs beider Reihen nicht zu erwarten. Aber die kleinen Verschiebungen der ver- schiedenen Epochen erfolgen hier im gleichen Sinne wie dort :

Maximumepochen Minimumepochen gerade (M,) ungerade (MI) gerade (n) ungerade (m)

- odg + 3d5 - 2515 + 0d4 Ebenso wird die fur die RVTauri-Steme typische

Form der Lichtkurve fur den vorliegenden Zeitraum be- statigt. Die gefundenen Helligkeiten liegen wegen der Ver- schiedenheit der angewandten Vergleichsternskalen und Instrumente hoher als bei M. Beyer:

Maxima Minima gerade (MI) ungerade (MI) gerade (n) ungerade (m)

8m35 8m2o 8m68 gm22 Eine Ableitung der Elemente des Lichtwechsels wurde

wegen des geringen Umfangs dieser Reihe nicht versucht.

-

B-R B-R B-R B-R

P. Ahnert.

5 6 7 2

The velocities were cleared of solar motion toward 270°, + 30' and velocity 2 0 km without the application of any K term. Considering the nature of these spectra, the results are remarkably consistent. In these 27 stars there are but four cases, two in each group which are of opposite sign. None of these is large and two have but il single observation. One has a value of only 4 km leaving but a single object which might be considered as contrary. That is y Argus with a velocity of + 18 km and spectral type Oap.

The reality of the phenomenon is further indicated by the individual stars. Of the 16 Oeg-stars, two have large (positive) velocities and 7 have medium sized ones. Of the eleven early 0-stars six have large (negative) velocities.

Most of these stars show wide ranges in the observed velocities and are rated as spectroscopic binaries. As a rule the lines are broadened but this cannot account (as uncer- tainties) for the variations observed nor for the departures from assumed orbital curves. Such broadening is, with other evidence, prima facie evidence of activity. Several of these velocities are small and some uncertainty must exist as to others, but the number of observations involved is such that

there can be little doubt of the correctness of the general conclusion of a relation to spectral condition.

This difference in the radial velocities is especially significant in view of the fact that the Oeg-stars contain only absorption lines. In other words the 0-stars with absorption only have a strong tendency toward positive velocities whereas the appearance of emission is accompanied by negative velocity.

We have thus as great a difference in the radial velocities of these two groups of 0-stars as we find in their spectra.

Both in the matter of radial velocity and spectral condition, the Oeg-stars are seen to belong with the B-stars rather than with the earlier 0-stars.

J . S. Plaskeff has given the velocities of 10 0-type stars showing no emission and seven showing emission l). W. C. Rufus gives the (variable) velocities of 5 Oeg-type starsz). Of these one, + 3 7 O 1 146, is not included in any of the other lists. These 18 stars are given in table 2.

These results for stars which average nearly two magni- tudes fainter, definitely confirm the dependence found in the

') bfN 84.84 (1923). ') ApJ 51.252 (1920).

* 33 5672 = 34

No.

+40° 501 + 5 2 726 +37 11461 + 5 1282 + 4 1302 + 6 1303 + 6 1351 -10 1892 +35 3930s +35 3949 +44 3639

stars of table I, although not so consistently. are fainter?

with its velocity of + 2 7 km.

Because they

Rufus classes +18'4276 as Oeg which agrees better

a IgOO.0

zhr6m7 .3 48.1

5 14.0 6 26.6 6 27.0 6 31.1 6 36.6 7 4.6

2 0 1.9 2 0 53.1

'9 59.8

Tab le 2.

-14 D +26 H + 2 5 * + 2 7 H + 1 5 D

7 5 4 6 8

+62 2363 +58 467 +56 693 + 6 1309 + 17 1623 + 1 8 4276 +35 39301

+63 7 +58 25 +56 28 + 6 13 + I 7 7 +IS 2 5

+35 45

o 0.8 2 '9.5 2 35.5 6 32.0 7 31.4

'9 47.9 '9 59.8

7.4 8.0 8.4 6.1 7.7 6.3 7.2

Addi t iona l 0-stars').

Oge 06e 08e 08e 07es) Oge

_._____

1 7.0

-51 b

-39 H + 8 Y

+13 D + 2 7 + I D

l) With one exceDtion from Victoria

- Spect.

0 9 0 9 0 % 0 8 0 5 0 8 0 6 0 7 0 9

__ -

0 6 0 6 Mean __

I 1

I 0

6 30

5 14 I 2

lbservations, 3. S. Plmkctt, MN 84.84 (1923).

from 5 plates in 1918.

'e) Rufus, ApJ51.252 (1920). ') Classed by Rufus (ApJ51.252) as Oeg, with u of + 12km

From 6 plates of Boss 5565 Rufus obtains a velocity of + 28 km, instead of - 10 given by the single plate of F~ost . From 6 plates of + 44O3639 he also finds + 22 km, instead of + 5 found by Haskeft.

Boss 5474 yields anomalous results. Frost found + 2 6 km in 1903, +42 km in 1904 and -28 km in 1919. Campbell and Moore found +40 km in 1915. Rufus gives +29 km in 1915 and -28, + 7 , and -54 km in 1918 as well as one plate on which the lines appeared to be doubled but not yielding consistent velocities. The simple mean of all 8 observations gives + '9 km as the residual velocity for this star which is Oeg. The behavior of this star is not uncommon.

The considerable negative velocities which some of these Oeg stars show, at times suggests the query whether about such times there is any emission,

In the groups of both tables I and 2 the stars showing emission are sensibly fainter than those with absorption only. Interpreted in the light of radial motions this indicates that expansion tends to reduce the amount of light notwithstanding the increase of size, a conclusion which appears to be the re- verse of the behavior of the d Cephei-stars but which requires confirmation.

PZaskeff in his work on the Ca Absorption assumes that the observed velocities of these stars are of translation which

'\ MN4.89 (1923).

leads him to the conclusion that D * - - the hypothesis of an individual surrounding cloud belonging to each star must trlso be abandoned6l).

The explanation of radial oscillations for these stars, proposed in this paper, harmonizes such difTerences between stars and calcium clouds and renders tenable the hypothesis that they may be closely connected. At the same time, the evidence of an underlying and close relationship of both cal- cium clouds and stars to the general stellar system is so strong as to leave little doubt of its reality.

This subject which involves all the early-type objects including the B and A stars, is under investigation.

Internal oscillations appear to furnish a satisfactory explanation of the excesses of positive velocity observed in the B-type stars and are being investigated also in connection with similar excesses in the K- and M-stars.

In te rpre ta t ion . Such relationships as these at once oppose the hypothesis that these radial velocities are wholly motions of translation. yor we cannot suppose that stars of this class having only absorption are moving away from us whereas those showing emission are all coming toward the observer with considerable velocities. Furthermore if they were due to translation there should be some correlation between radial velocity and proper motion. The proper motions in the last column of table I show no such correlation.

If these stars were confined to small areas of the sky an explanation of translation might have some weight, but such is not the case. Both groups are widely distributed in nearly all parts of the Milky Way. Two stars Boss 1901 and 1899, the former having an absorption spectrum and velocity of + 23 km, the latter showing emission and having a velocity of -38 km are within half a degree of each other.

These stars nearly all show wide variations of velocity and a number of them have had orbits determined upon the assumption that they are binary. From which it is evident that the measures of velocity are considered to be real and to result from motion. This fact .also shows general confidence in the underlying positions of lines used and methods.

Examination of the individual results from different plates and measures confirms the reality of the resulting veloci- ties. There can be no reasonable doubt that they represent real conditions in these stars, nor that they are due to some form of motion.

As has already been remarked these velocities, which may be said to correspond to velocities of the systems if they were binaries, can not be supposed to be due to motions of translation. They can be explained as motions of expansion and contraction within the bodies themselves. And that is the only plausible explanation that I can find.

Furthermore investigation of the radial velocities of the planetary nebulae showed phenomena which strongly indicate, if they do not establish, that their observed radial velocities are in reality not motions of translation, but expansions and contractions of the shells which compose such bodies. This is fairly strong collateral evidence that a similar condition may prevail in these 0-type stars and that it is there closely connected with spectral condition.

If this be true it would seem difficult to avoid the con- clusion that the variations of velocity so common in these stars are due largely to motions of expansion and contraction, rather than to orbital motion.

A very natural explanation of the reversal of motion between the absorption condition and one of emission is that increase of temperature resulting from contraction has caused. a general expansion accompanied by the breaking through of the vapors giving rise to the bright lines. Such expansion would manifest itself to an observer as a velocity of approach.

Observatorio Nacional Argentino, Cdrdoba, June 10,

1930 oh w.-Z. a Vera 8 Vera log I log A Jan. 25 I I ~ 3m40?65 + 9' 5'5173 0.4310 0.2701

27 2 52.35 '5 31.3 29 1 57-98 25 47.6 0.2620 3' 11 0 57.73 36 38.4

Febr. 2 10 59 51.78 48 1.6 0.2546 4 58 40.32 9 59 55.0 6 57 23.62 10 12 16.1 4.2480 8 56 1-97 25 2.1 10 54 35.68 38 9-9 0.4303 0.2423 12 53 5.09 10 51 36.2 14 51 30.55 I I 5 18.0 0.2377 16 49 52.44 19 12.2 18 48 11.18 33 15.3 0.2341 20 46 27.20 II 47 23.9 22 44 40.97 12 1 34.3 0.2316 24 42 52.97 15 42.6 26 I 0 41 3.74 +I2 29 45.0 0.4295 0.2303

The widening of such emission in many of these stars and especially in the novae is in harmony with such a condition.

The foregoing evidence is of sufficient weight to justify the assumption that the 0-types of spectra are intermediate between the early B-type and the planetary nebulae and form the link connecting these three (or four) spectral conditions into a single series.

The further conclusion is indicated that the observed radial velocities of all of these early type objects are to some extent at least due to motions of expansion and contraction. 1929. C. D. Perrine.

1930 oh w.-Z. a Vera 8 Vera logr l o g A Febr.28 1oh39m13!82 + 12~43'3717 Marz 2 37 23.76 12 57 17.2 0.2303

4 35 34.09 '3 1 0 39.9

8 31 58.19 36 20.9 10 30 13.02 13 48 32.8 0.2336 12 28 30.33 14 o 15.6

22 .4.8

20 22 13.21 41 32.9 22 20 49.28 50 20.2 0.2467 24 19 30.21 14 58 28.2 26 18 16.30 15 5 55.8 0.2529 28 17 7.81 12 42.1 30 10 16 4.97 + I S 18 46.7 0.4274 0.2599

6 33 45.38 23 42.3 0.2314

14 26 50.58 I 1 26.9 0.4285 0.2370 16 25 14.23 18 23 41.65 32 7.3 0.2414

Opp. in RA. Febr. 27, GroBe 9918.

Auf dem Runden Turm, dem altesten noch existierenden Staatssternwartenbau in Europa wurde eine neue Sternwarte errichtet. Unter einer Drehkuppel von 5 m Durchmesser be- findet sich ein 6-26ll. Refraktor (Objektivvon Merz, Aufstellung von Cornelius Knudsen in Kopenhagen). Die Sternwarte gehort der Stadt Kopenhagen und steht unter der Leitung des Unterzeichneten. Die neue Sternwarte ist in erster Linie eine Volkssternwarte, doch ist auch wissenschaftliche Tatigkeit in Vorbereitung. Die Sternwarte ist in den Nachmittags- stunden fur Sonnenbeobachtungen und in den Abendstunden fur Beobachtungen am Sternenhimmel geoffnet und erfreut

Inhalt zu Nr. 5672. P. Ahnnt. ' Beobachtungen von T Monocerotis. 121. - P. Alncrf. Beobachtungen von V Vulpeculae und SS Geminorurn. 123. - C. D. P m n s . 0-Type stars. Dependence of Radial .Velocities upon Spectral Condition. 129. - H. Osten. Oppositions-Ephemeride fur I I Parthenope. 135. C. Luplau Jamsen. Das Observatorium auf dem aRundetaame in Kopenhagen. 135. - Todesanzeige. 135. - Benchtigung. 135.

Ccschlorseo xpl9 Der. 2. Hcraugeber: H. Kobold. Expedition: Kid, Moltkestr. 80. Portwhcck-Konio Nr. 6238 Hamburg 11, Druck Ton C. Scbaidt, Inhnber Georg Ohcim, K i d .

sich eines lebhaften Besuches. In der nachsten Zeit wird ein Vortragssaal in Benutzung genommen und gleichzeitig eine Sammlung astronomischen Charakters zuganglich gemacht werden. Ich benutze die Gelegenheit, um die ffberlassung von Photographien von Stemwarten, Instrumenten, Kopien von Himmelsaufnahmen, Spektren usw. zu erbitten. Sie werden in der Sammlung aufgehangt werden und dadurch sehr weiten Kreisen in einem Lande, wo jedermann sich fur den Himmel interessiert, zugiinglich. Die Adresse der neuen Sternwarte ist : Observatoriet Rundetaarn, Kopenhagen.

G. Luphu /anssen. Kopenhagen, 1929 Sept. 9.